E-50 motor - replacing sintered bearings with standard bronze
I am curious as to whether anyone who has worked on the E-50 motor has decided to change out the sintered bronze bearings for standard bronze. Seems this is being done by some people who have been restoring professionally for some time, but I've only recently learned of it. If you've gone this route, I'd like to hear how it's worked for you.
I am curious as to whether anyone who has worked on the E-50 motor has decided to change out the sintered bronze bearings for standard bronze. Seems this is being done by some people who have been restoring professionally for some time, but I've only recently learned of it. If you've gone this route, I'd like to hear how it's worked for you.
E50
My experience the motor works a little bit hotter .You have to lube the standard bronze much ofter as sintered
My experience the motor works a little bit hotter .You have to lube the standard bronze much ofter as sintered
Thanks Oregon. I wonder if this is why one rebuilder is using an oil formulation that includes ceramic micro particles (boron nitride).
Thorens rated the stocked sintered bronze bearings for 5000 hr service intervals, it is pretty hard to imagine bettering that without some pretty exotic engineering. I will concede that a single weight synthetic might be a suitable replacement for the petroleum based 20wt most of us use. I do wonder about how you compensate for the change in drag (main, motor and intermediate pulley bearings) due to the lubricants used without having a good understanding of fluid dynamics - I say this because the first table I rebuilt ran way too fast once completed, the problem turned out to be mostly the lubricants I used initially. Once I switched to the 20wt oil I still recommend (I cannot take credit for the recommendation as it came from someone else) I was able to get everything dialed in, and it has remained very stable over the past few years. (The eddy current brake magnet was fine, I have since run into one that was almost completely dead and have heard of others.)
When everything is working correctly the bearings are essentially running on a film of oil, and the characteristics of that oil determine the bearing drag, all of this undoubtedly taken into consideration in original sizing and (sloppy) calibration of the eddy current brake. The amount of torque the motor is required to deliver is one of the variables that determines the table's speed. Remember these are induction not synchronous motors.
When everything is working correctly the bearings are essentially running on a film of oil, and the characteristics of that oil determine the bearing drag, all of this undoubtedly taken into consideration in original sizing and (sloppy) calibration of the eddy current brake. The amount of torque the motor is required to deliver is one of the variables that determines the table's speed. Remember these are induction not synchronous motors.
oils bushings and the E50
fwiw dept.
My early motor rebuilds did result in motors that tended to run hot. By hot I mean hot to the touch if you put a finger to the bottom case while it was running. Not hot enough to damage skin. Not even a first degree burn. But hot enough to make you want to remove that finger.
Since then I discovered a few things about E50 rehab.
1) correct oil makes a difference. Service manual mentions a 20 wt. turbine oil produced by Texaco. That oil is NLA. But it has been replaced by a more modern formula. Texaco, currently has a turbine oil called "Regal R&O 46. This is approximately 20 wt. I've been using it for the past several years in the motor and platter bearings of all my Thorens players. They seem happy.
2) When disassembling and reassembling it might seem impossible to restore the factory bushing to rotor shaft alignment. I've spent some serious quality time in the quest to optimize bushing to shaft alignment inside that E50. Ultimately I found my best results after taking a close look at surface roughness on the pieces that mate together in this assembly.
Firstly I noticed the surface roughness on both of the upper and lower sheet metal "CAPS" that hold each bushing. Then I observed the surface roughness on the stator cores that mate with the sheet metal caps. Mine had some irregularities with regard to flatness. Nicks and dents.
The sheet metal caps are simple to restore into good flatness at the mounting surfaces while using tools designed to gently persuade sheet metal. It also helps to have a nice flat surface to place each cap over and observe how perfectly flat the cap sits. Keep adjusting until it does.
The core metal is far more solid. Mine had some nicks and dents. I used a large lap stone to restore flatness to each mating surface at the core. A few strokes to remove the high points. The same lap stone was used on each cap. This was done until I could place each cap against its mating core surface and easily slide the two surfaces over each other without there being any snags or sticking points.
3) Bushing mounting. Into each upper and lower cap the bushing are held captive in an assembly that allows the bushing to swivel against its spherical surface. This assembly should hold the bushing secure enough to prevent its rattling with motor vibes, but not so secure that it can't swivel into position during the bushing to shaft alignment process. If yours seems a bit too stiff, maybe check for a few things; 1: too thick of lube retaining felt....or ....2: nicks dents in the matching spherical surfaces of both bushing and cap.....or....put some lube in there. Additionally, the flat end of the cap can be slightly imperfect in form. It helps to make certain that this portion of the cap is perfectly flat. And that the retaining pieces that secure the bushing also are perfectly flat and mate perfectly to the surface to which it is bolted.
4) thrust bushing assembly. The little piece of sheet metal that retains the thrust pad can get bent out of shape. Restore flatness to this piece so that you don't see any gaps of daylight as it fits to the lower cap surface.
Lube is installed during all of this process. You know, that 20wt turbine oil. Liberally, the lube is soaked into the felts that surround each bushing assembly. Liberally, lube is allowed to pool into each bushing. Lube is drizzled onto the rotor shaft during the assembly process. Excess lube may run over. So wipe up the mess. Do this assembly a few times to get a sense of how much lube is enough and how much is too much. Big oily mess = too much lube. common sense can be applied. We don't want to get the stator coils wet with lube. But we want lube where it needs to be, in the bushings, so that the shaft may rotate and so that the bushings may swivel in their spherical socket. Common sense. Not rocket science. No secret formula.
5) bushing to rotor shaft alignment. Having done all of the above, the shaft to bushing alignment process goes a lot easier. I carry this out in multiple steps. Firstly on the initial assembly on the bench. I can now slide each cap around against its mating core surface and notice that the bushing does adjust its position relative to the shaft that fits through it with each movement. That is what I want. Having established this much, I move both upper and lower caps into a position that allows the motor to spin "most freely" prior to assembling the motor into the TD124 chassis. That's step 1 of this process.
Once in the chassis, and with its wire loom assembled, .....and with power on....... Oh, but wait a minute. I have the TD124 up on a test bench where I can operate the thing while having access to the underneath parts. The drive belt is mounted. The flywheel is mounted. Did I mention that the motor had its lube? Yeah, see above somewhere. Anyway, now is the time to bench test the player for operation. For bench work I have mine up on a stand like this:
In this position we can carry out another bushing-rotor shaft-alignment session. This process is done by leaving the 4 securing machine screws just slightly loose. Loose enough so that both upper and lower bearing cap can be -slid- in one direction or another while the central core remains stationary. This process forces the bushing to swivel into a new position each time position of the cap is adjusted. Refer back to the above photo and notice that a long skinny probe is in contact against the lower bushing cap. What you don't see in that photo is me wearing the mechanics stethoscope and listening to motor vibes and the motor runs. I do this after each cap position adjustment. Quietest vibes are the goal. Carry this out at both upper and lower bushing caps. Eventually, you will tighten the 4 cap screws securing the motor caps to the core. But only after the last adjustment is made. And then you listen with the stethoscope to be certain that adjustment is still optimum after bolt tightening.
And then, using that mechanics stethoscope to listen to the chassis while the turntable is in operation. Listen to the chassis with the scope probe placed at the armboard area. Then to the chassis above where the motor is mounted. Use the stethoscope as a means to understand how the mechanical vibes flow through-out the chassis during its operation. Quieter = better. Now, maybe you think you've got it as good as it is going to be. Great. It is now time to put the TT into its plinth, mount the tonearm, align the cartridge and play records for a week.
If all seems well. And motor start-up times seem reasonable, play records for a week or maybe two. But then, just to be complete, take the TD124 down out of the plinth and put it up on the test bench again. Maybe you want to remove the tonearm simply by removing the armboard from its chassis. It will re-assembly more easily that way when you're done.
The final motor rehab step is next. Your TD124 has had a week or two to run in. But now it is time to disassemble the E50 one last time. When apart, observe the bushing to shaft areas for evidence of having or not having lube. Examine the thrust bushing. ensure that the tiny 2mm bearing ball is still there. Look at the thrust pad to see if there is evidence of wear. Typically, you won't see much of an indentation after only a couple of weeks use at the thrust pad. If you do, replace the thrust pad with a unused side. Should have replaced it during the initial process!
Observe that the bushings still swivel as they should in their captive spherical joints. But are not loose. Wipe the rotor shaft clean. Put new lube in both bushings and felts. A tiny spot of grease on the thrust ball. Reassemble. Carry out the bushing to shaft alignment process one more time. Same as before. But this time it should be apparent that the motor bumps into alignment easier than before. You should be able to achieve your quietest running adjustment during this final process. The stethoscope is your measure of success. And by now, after running the motor for an hour, you should notice that the bottom motor cap is not as hot to the touch as it was during the first assembly process. !!!
Now it is finally time to put the TD124 back into its plinth and up on the audio rack. Start-up times should be the best you've seen yet. Playback quality should be absolutely stunning.
-Steve
Ps: important note. It is the final dissassemble/reassemble/adjust session that truly restores best possible motor operation. Skip this and and you suffer.
fwiw dept.
My early motor rebuilds did result in motors that tended to run hot. By hot I mean hot to the touch if you put a finger to the bottom case while it was running. Not hot enough to damage skin. Not even a first degree burn. But hot enough to make you want to remove that finger.
Since then I discovered a few things about E50 rehab.
1) correct oil makes a difference. Service manual mentions a 20 wt. turbine oil produced by Texaco. That oil is NLA. But it has been replaced by a more modern formula. Texaco, currently has a turbine oil called "Regal R&O 46. This is approximately 20 wt. I've been using it for the past several years in the motor and platter bearings of all my Thorens players. They seem happy.
2) When disassembling and reassembling it might seem impossible to restore the factory bushing to rotor shaft alignment. I've spent some serious quality time in the quest to optimize bushing to shaft alignment inside that E50. Ultimately I found my best results after taking a close look at surface roughness on the pieces that mate together in this assembly.
Firstly I noticed the surface roughness on both of the upper and lower sheet metal "CAPS" that hold each bushing. Then I observed the surface roughness on the stator cores that mate with the sheet metal caps. Mine had some irregularities with regard to flatness. Nicks and dents.
The sheet metal caps are simple to restore into good flatness at the mounting surfaces while using tools designed to gently persuade sheet metal. It also helps to have a nice flat surface to place each cap over and observe how perfectly flat the cap sits. Keep adjusting until it does.
The core metal is far more solid. Mine had some nicks and dents. I used a large lap stone to restore flatness to each mating surface at the core. A few strokes to remove the high points. The same lap stone was used on each cap. This was done until I could place each cap against its mating core surface and easily slide the two surfaces over each other without there being any snags or sticking points.
3) Bushing mounting. Into each upper and lower cap the bushing are held captive in an assembly that allows the bushing to swivel against its spherical surface. This assembly should hold the bushing secure enough to prevent its rattling with motor vibes, but not so secure that it can't swivel into position during the bushing to shaft alignment process. If yours seems a bit too stiff, maybe check for a few things; 1: too thick of lube retaining felt....or ....2: nicks dents in the matching spherical surfaces of both bushing and cap.....or....put some lube in there. Additionally, the flat end of the cap can be slightly imperfect in form. It helps to make certain that this portion of the cap is perfectly flat. And that the retaining pieces that secure the bushing also are perfectly flat and mate perfectly to the surface to which it is bolted.
4) thrust bushing assembly. The little piece of sheet metal that retains the thrust pad can get bent out of shape. Restore flatness to this piece so that you don't see any gaps of daylight as it fits to the lower cap surface.
Lube is installed during all of this process. You know, that 20wt turbine oil. Liberally, the lube is soaked into the felts that surround each bushing assembly. Liberally, lube is allowed to pool into each bushing. Lube is drizzled onto the rotor shaft during the assembly process. Excess lube may run over. So wipe up the mess. Do this assembly a few times to get a sense of how much lube is enough and how much is too much. Big oily mess = too much lube. common sense can be applied. We don't want to get the stator coils wet with lube. But we want lube where it needs to be, in the bushings, so that the shaft may rotate and so that the bushings may swivel in their spherical socket. Common sense. Not rocket science. No secret formula.
5) bushing to rotor shaft alignment. Having done all of the above, the shaft to bushing alignment process goes a lot easier. I carry this out in multiple steps. Firstly on the initial assembly on the bench. I can now slide each cap around against its mating core surface and notice that the bushing does adjust its position relative to the shaft that fits through it with each movement. That is what I want. Having established this much, I move both upper and lower caps into a position that allows the motor to spin "most freely" prior to assembling the motor into the TD124 chassis. That's step 1 of this process.
Once in the chassis, and with its wire loom assembled, .....and with power on....... Oh, but wait a minute. I have the TD124 up on a test bench where I can operate the thing while having access to the underneath parts. The drive belt is mounted. The flywheel is mounted. Did I mention that the motor had its lube? Yeah, see above somewhere. Anyway, now is the time to bench test the player for operation. For bench work I have mine up on a stand like this:
In this position we can carry out another bushing-rotor shaft-alignment session. This process is done by leaving the 4 securing machine screws just slightly loose. Loose enough so that both upper and lower bearing cap can be -slid- in one direction or another while the central core remains stationary. This process forces the bushing to swivel into a new position each time position of the cap is adjusted. Refer back to the above photo and notice that a long skinny probe is in contact against the lower bushing cap. What you don't see in that photo is me wearing the mechanics stethoscope and listening to motor vibes and the motor runs. I do this after each cap position adjustment. Quietest vibes are the goal. Carry this out at both upper and lower bushing caps. Eventually, you will tighten the 4 cap screws securing the motor caps to the core. But only after the last adjustment is made. And then you listen with the stethoscope to be certain that adjustment is still optimum after bolt tightening.
And then, using that mechanics stethoscope to listen to the chassis while the turntable is in operation. Listen to the chassis with the scope probe placed at the armboard area. Then to the chassis above where the motor is mounted. Use the stethoscope as a means to understand how the mechanical vibes flow through-out the chassis during its operation. Quieter = better. Now, maybe you think you've got it as good as it is going to be. Great. It is now time to put the TT into its plinth, mount the tonearm, align the cartridge and play records for a week.
If all seems well. And motor start-up times seem reasonable, play records for a week or maybe two. But then, just to be complete, take the TD124 down out of the plinth and put it up on the test bench again. Maybe you want to remove the tonearm simply by removing the armboard from its chassis. It will re-assembly more easily that way when you're done.
The final motor rehab step is next. Your TD124 has had a week or two to run in. But now it is time to disassemble the E50 one last time. When apart, observe the bushing to shaft areas for evidence of having or not having lube. Examine the thrust bushing. ensure that the tiny 2mm bearing ball is still there. Look at the thrust pad to see if there is evidence of wear. Typically, you won't see much of an indentation after only a couple of weeks use at the thrust pad. If you do, replace the thrust pad with a unused side. Should have replaced it during the initial process!
Observe that the bushings still swivel as they should in their captive spherical joints. But are not loose. Wipe the rotor shaft clean. Put new lube in both bushings and felts. A tiny spot of grease on the thrust ball. Reassemble. Carry out the bushing to shaft alignment process one more time. Same as before. But this time it should be apparent that the motor bumps into alignment easier than before. You should be able to achieve your quietest running adjustment during this final process. The stethoscope is your measure of success. And by now, after running the motor for an hour, you should notice that the bottom motor cap is not as hot to the touch as it was during the first assembly process. !!!
Now it is finally time to put the TD124 back into its plinth and up on the audio rack. Start-up times should be the best you've seen yet. Playback quality should be absolutely stunning.
-Steve
Ps: important note. It is the final dissassemble/reassemble/adjust session that truly restores best possible motor operation. Skip this and and you suffer.
Last edited:
To Kevinkr & User510
Guys, thanks. First I'm a little late getting back to this subject, due to an OS meltdown that's had me limping along here for a week. I just got up & running again this afternoon and read what you'd posted.
I know at times I sound like I'm intent on reinventing the wheel. Hardly true, but I know I come off that way. My problem is I need detail, rationale, need to understand the logic behind a recommendation. "Hey use this, it works," has always been hard for me to swallow.
Kevin, Steve, I know with all the posts you've done over the years, with all you've done to help others, it has to be tough sometimes to take the time to write detailed responses that guys like me need. You've got lives, after all. But with these latest posts, you both have filled in so many blanks.
Man, Steve, you certainly delivered with your detailed account of how you came to understand how the various e-50 mating surfaces can over time get dinged up enough to make alignment a hassle. The reason this helps is not just because you've told me what I need to do, but because it answers one of my nagging questions: Why are people reporting that alignment, for lack of a better word, is such a b--ch to accomplish? Yes, it takes time and patience, but some of the accounts made it sound like something just wasn't right and I didn't want to fall into the same trap.
Same with the issues of getting speed right, of motors running hot, of getting the right lube etc. A lot of things just didn't make sense to me, but in one post you've resolved so, so much. I equated some of the reports of what I considered excessive heat to improper lube (and poor alignment), which is why I needed to be convinced that a specific lube had, indeed, been shown to make a difference. I equated speed variations to the same things, which made it critical I was confident in my choice of lube. Having a set of new sintered bronze bushings impregnated with Mobil 1 really set me back. I knew it was a lube of choice for many, but felt I'd moved past thinking that was going to get me where I wanted to go.
I also want to be clear that I do at times ask about procedures, alternate replacement parts (such as non-sintered bushings & "ceramic" oils) because I want to get some input. I do this even if something at the outset doesn't quite make sense to me. I know enough to know I don't know enough, thus it's always possible something that doesn't sound right might actually be a good idea. I won't know unless I put it out there.
To date, I've had little to contribute in return for all the help you two and others have given me. Hopefully as I get into the motor rebuild I can rectify that. Now I may have to finish that big closet in the old attic space before I can dive back into the Thorens, but at least you two have given me the information and confidence I need to stop asking and start doing.
Thanks again,
Jim Neal
Raymore, MO
Guys, thanks. First I'm a little late getting back to this subject, due to an OS meltdown that's had me limping along here for a week. I just got up & running again this afternoon and read what you'd posted.
I know at times I sound like I'm intent on reinventing the wheel. Hardly true, but I know I come off that way. My problem is I need detail, rationale, need to understand the logic behind a recommendation. "Hey use this, it works," has always been hard for me to swallow.
Kevin, Steve, I know with all the posts you've done over the years, with all you've done to help others, it has to be tough sometimes to take the time to write detailed responses that guys like me need. You've got lives, after all. But with these latest posts, you both have filled in so many blanks.
Man, Steve, you certainly delivered with your detailed account of how you came to understand how the various e-50 mating surfaces can over time get dinged up enough to make alignment a hassle. The reason this helps is not just because you've told me what I need to do, but because it answers one of my nagging questions: Why are people reporting that alignment, for lack of a better word, is such a b--ch to accomplish? Yes, it takes time and patience, but some of the accounts made it sound like something just wasn't right and I didn't want to fall into the same trap.
Same with the issues of getting speed right, of motors running hot, of getting the right lube etc. A lot of things just didn't make sense to me, but in one post you've resolved so, so much. I equated some of the reports of what I considered excessive heat to improper lube (and poor alignment), which is why I needed to be convinced that a specific lube had, indeed, been shown to make a difference. I equated speed variations to the same things, which made it critical I was confident in my choice of lube. Having a set of new sintered bronze bushings impregnated with Mobil 1 really set me back. I knew it was a lube of choice for many, but felt I'd moved past thinking that was going to get me where I wanted to go.
I also want to be clear that I do at times ask about procedures, alternate replacement parts (such as non-sintered bushings & "ceramic" oils) because I want to get some input. I do this even if something at the outset doesn't quite make sense to me. I know enough to know I don't know enough, thus it's always possible something that doesn't sound right might actually be a good idea. I won't know unless I put it out there.
To date, I've had little to contribute in return for all the help you two and others have given me. Hopefully as I get into the motor rebuild I can rectify that. Now I may have to finish that big closet in the old attic space before I can dive back into the Thorens, but at least you two have given me the information and confidence I need to stop asking and start doing.
Thanks again,
Jim Neal
Raymore, MO
Here is a slightly different question: I have received a td124 that had its top platter bent in the post. I know that Steve described a procedure for straightening a top platter on his website which included making a tool out of wood to straiten the sides of the platter. has anybody else done this? Are there (easy) alternatives that are good for newbies ?
Alignment of the bushings
My dad, many years ago, (A manufacturing Mechanical engineer) told me how they aligned bearings like used in the E50. You have to understand that on the production line, it has to be simple and quick. He said all you do is while the motor is running, tap it gently with a rubber or plastic mallet. This allows the motor's bushing to align properly. I have done this very procedure many times, and it has always worked well.
My dad, many years ago, (A manufacturing Mechanical engineer) told me how they aligned bearings like used in the E50. You have to understand that on the production line, it has to be simple and quick. He said all you do is while the motor is running, tap it gently with a rubber or plastic mallet. This allows the motor's bushing to align properly. I have done this very procedure many times, and it has always worked well.
fwiw dept.
My early motor rebuilds did result in motors that tended to run hot. By hot I mean hot to the touch if you put a finger to the bottom case while it was running. Not hot enough to damage skin. Not even a first degree burn. But hot enough to make you want to remove that finger.
Since then I discovered a few things about E50 rehab.
1) correct oil makes a difference. Service manual mentions a 20 wt. turbine oil produced by Texaco. That oil is NLA. But it has been replaced by a more modern formula. Texaco, currently has a turbine oil called "Regal R&O 46. This is approximately 20 wt. I've been using it for the past several years in the motor and platter bearings of all my Thorens players. They seem happy.
2) When disassembling and reassembling it might seem impossible to restore the factory bushing to rotor shaft alignment. I've spent some serious quality time in the quest to optimize bushing to shaft alignment inside that E50. Ultimately I found my best results after taking a close look at surface roughness on the pieces that mate together in this assembly.
Firstly I noticed the surface roughness on both of the upper and lower sheet metal "CAPS" that hold each bushing. Then I observed the surface roughness on the stator cores that mate with the sheet metal caps. Mine had some irregularities with regard to flatness. Nicks and dents.
The sheet metal caps are simple to restore into good flatness at the mounting surfaces while using tools designed to gently persuade sheet metal. It also helps to have a nice flat surface to place each cap over and observe how perfectly flat the cap sits. Keep adjusting until it does.
The core metal is far more solid. Mine had some nicks and dents. I used a large lap stone to restore flatness to each mating surface at the core. A few strokes to remove the high points. The same lap stone was used on each cap. This was done until I could place each cap against its mating core surface and easily slide the two surfaces over each other without there being any snags or sticking points.
3) Bushing mounting. Into each upper and lower cap the bushing are held captive in an assembly that allows the bushing to swivel against its spherical surface. This assembly should hold the bushing secure enough to prevent its rattling with motor vibes, but not so secure that it can't swivel into position during the bushing to shaft alignment process. If yours seems a bit too stiff, maybe check for a few things; 1: too thick of lube retaining felt....or ....2: nicks dents in the matching spherical surfaces of both bushing and cap.....or....put some lube in there. Additionally, the flat end of the cap can be slightly imperfect in form. It helps to make certain that this portion of the cap is perfectly flat. And that the retaining pieces that secure the bushing also are perfectly flat and mate perfectly to the surface to which it is bolted.
4) thrust bushing assembly. The little piece of sheet metal that retains the thrust pad can get bent out of shape. Restore flatness to this piece so that you don't see any gaps of daylight as it fits to the lower cap surface.
Lube is installed during all of this process. You know, that 20wt turbine oil. Liberally, the lube is soaked into the felts that surround each bushing assembly. Liberally, lube is allowed to pool into each bushing. Lube is drizzled onto the rotor shaft during the assembly process. Excess lube may run over. So wipe up the mess. Do this assembly a few times to get a sense of how much lube is enough and how much is too much. Big oily mess = too much lube. common sense can be applied. We don't want to get the stator coils wet with lube. But we want lube where it needs to be, in the bushings, so that the shaft may rotate and so that the bushings may swivel in their spherical socket. Common sense. Not rocket science. No secret formula.
5) bushing to rotor shaft alignment. Having done all of the above, the shaft to bushing alignment process goes a lot easier. I carry this out in multiple steps. Firstly on the initial assembly on the bench. I can now slide each cap around against its mating core surface and notice that the bushing does adjust its position relative to the shaft that fits through it with each movement. That is what I want. Having established this much, I move both upper and lower caps into a position that allows the motor to spin "most freely" prior to assembling the motor into the TD124 chassis. That's step 1 of this process.
Once in the chassis, and with its wire loom assembled, .....and with power on....... Oh, but wait a minute. I have the TD124 up on a test bench where I can operate the thing while having access to the underneath parts. The drive belt is mounted. The flywheel is mounted. Did I mention that the motor had its lube? Yeah, see above somewhere. Anyway, now is the time to bench test the player for operation. For bench work I have mine up on a stand like this:
In this position we can carry out another bushing-rotor shaft-alignment session. This process is done by leaving the 4 securing machine screws just slightly loose. Loose enough so that both upper and lower bearing cap can be -slid- in one direction or another while the central core remains stationary. This process forces the bushing to swivel into a new position each time position of the cap is adjusted. Refer back to the above photo and notice that a long skinny probe is in contact against the lower bushing cap. What you don't see in that photo is me wearing the mechanics stethoscope and listening to motor vibes and the motor runs. I do this after each cap position adjustment. Quietest vibes are the goal. Carry this out at both upper and lower bushing caps. Eventually, you will tighten the 4 cap screws securing the motor caps to the core. But only after the last adjustment is made. And then you listen with the stethoscope to be certain that adjustment is still optimum after bolt tightening.
And then, using that mechanics stethoscope to listen to the chassis while the turntable is in operation. Listen to the chassis with the scope probe placed at the armboard area. Then to the chassis above where the motor is mounted. Use the stethoscope as a means to understand how the mechanical vibes flow through-out the chassis during its operation. Quieter = better. Now, maybe you think you've got it as good as it is going to be. Great. It is now time to put the TT into its plinth, mount the tonearm, align the cartridge and play records for a week.
If all seems well. And motor start-up times seem reasonable, play records for a week or maybe two. But then, just to be complete, take the TD124 down out of the plinth and put it up on the test bench again. Maybe you want to remove the tonearm simply by removing the armboard from its chassis. It will re-assembly more easily that way when you're done.
The final motor rehab step is next. Your TD124 has had a week or two to run in. But now it is time to disassemble the E50 one last time. When apart, observe the bushing to shaft areas for evidence of having or not having lube. Examine the thrust bushing. ensure that the tiny 2mm bearing ball is still there. Look at the thrust pad to see if there is evidence of wear. Typically, you won't see much of an indentation after only a couple of weeks use at the thrust pad. If you do, replace the thrust pad with a unused side. Should have replaced it during the initial process!
Observe that the bushings still swivel as they should in their captive spherical joints. But are not loose. Wipe the rotor shaft clean. Put new lube in both bushings and felts. A tiny spot of grease on the thrust ball. Reassemble. Carry out the bushing to shaft alignment process one more time. Same as before. But this time it should be apparent that the motor bumps into alignment easier than before. You should be able to achieve your quietest running adjustment during this final process. The stethoscope is your measure of success. And by now, after running the motor for an hour, you should notice that the bottom motor cap is not as hot to the touch as it was during the first assembly process. !!!
Now it is finally time to put the TD124 back into its plinth and up on the audio rack. Start-up times should be the best you've seen yet. Playback quality should be absolutely stunning.
-Steve
Ps: important note. It is the final dissassemble/reassemble/adjust session that truly restores best possible motor operation. Skip this and and you suffer.
Found a Machinist, TD 124 restoration coming up!
First, looks like it's time for me to learn what the OEM clearances for all bushings & shafts should be, since I've got a machinist who asked!
I'm digging through the threads, through all that User510 posted on his site trying to find them, but if anyone knows them off the top of their head, well I'd sure love to gather all of that critical into into one place.
Ok, so here's where I'm at. I learned of a good machinist who has a nice shop set up out in the country about an hour from my house. He seems almost as intrigued by the project as I am, so we'll be working on it together, an evening here and there, likely starting this week.
In fact, the way we intend to proceed might net some interesting information for other TD 124 owners. I'll take a preamp, test record and laptop with me, so we can record before/after measurements each time we work on a part. While all I have for software is Audacity, that's enough so we can capture a waveform and spectrograph for every step.
Yesterday, I took the turntable out to him so he could get some idea of the drive train and decide what to focus on first. We confirmed that the idler wheel runs true when affixed to a lathe, but that the bushing I'd pressed in haphazardly was deformed, so first project will be cutting a drive pin and putting the second replacement bushing in - properly.
We'll take I.D. & O.D measurements of the bushing and the I.D. of the pulley so we've some idea of what clearance we should be obtaining once it's pressed into place. If the bushing's off, then no sense installing it and we'll look for some more suitable replacement. We plan on doing that as well for all replacement bushings.
The other piece we focused on yesterday was the stepped pulley, which I suspected had bad bushings as well, since we could see a slight shimmy in it.
Upon lifting it out, I noticed that what I'd earlier assumed was a small washer was actually a ring of grease that had turned to gum. Since last inspection this ring had broken up a bit, which is why I recognized it for what it was. I cleaned everything up, reinserted the pulley, placed a finger atop the shaft and checked for play. Sure enough, without that grease to lock things into place, it was very obvious the bushings were very worn.
I've not looked at the chassis close enough to know if the stepped pulley mounting assembly can be removed from the chassis, so studying that is on my agenda. Obviously if it can be removed, setting up to remove and replace the bushings would go a lot more smoothly.
I'll also be taking a tip from User510 (thanks Steve) and building a working jig so the chassis can be locked down safely and easily worked on underneath.
Been a long time coming, but looks like I'm finally getting into this project and have to say I'm pretty excited about it.
First, looks like it's time for me to learn what the OEM clearances for all bushings & shafts should be, since I've got a machinist who asked!
I'm digging through the threads, through all that User510 posted on his site trying to find them, but if anyone knows them off the top of their head, well I'd sure love to gather all of that critical into into one place.
Ok, so here's where I'm at. I learned of a good machinist who has a nice shop set up out in the country about an hour from my house. He seems almost as intrigued by the project as I am, so we'll be working on it together, an evening here and there, likely starting this week.
In fact, the way we intend to proceed might net some interesting information for other TD 124 owners. I'll take a preamp, test record and laptop with me, so we can record before/after measurements each time we work on a part. While all I have for software is Audacity, that's enough so we can capture a waveform and spectrograph for every step.
Yesterday, I took the turntable out to him so he could get some idea of the drive train and decide what to focus on first. We confirmed that the idler wheel runs true when affixed to a lathe, but that the bushing I'd pressed in haphazardly was deformed, so first project will be cutting a drive pin and putting the second replacement bushing in - properly.
We'll take I.D. & O.D measurements of the bushing and the I.D. of the pulley so we've some idea of what clearance we should be obtaining once it's pressed into place. If the bushing's off, then no sense installing it and we'll look for some more suitable replacement. We plan on doing that as well for all replacement bushings.
The other piece we focused on yesterday was the stepped pulley, which I suspected had bad bushings as well, since we could see a slight shimmy in it.
Upon lifting it out, I noticed that what I'd earlier assumed was a small washer was actually a ring of grease that had turned to gum. Since last inspection this ring had broken up a bit, which is why I recognized it for what it was. I cleaned everything up, reinserted the pulley, placed a finger atop the shaft and checked for play. Sure enough, without that grease to lock things into place, it was very obvious the bushings were very worn.
I've not looked at the chassis close enough to know if the stepped pulley mounting assembly can be removed from the chassis, so studying that is on my agenda. Obviously if it can be removed, setting up to remove and replace the bushings would go a lot more smoothly.
I'll also be taking a tip from User510 (thanks Steve) and building a working jig so the chassis can be locked down safely and easily worked on underneath.
Been a long time coming, but looks like I'm finally getting into this project and have to say I'm pretty excited about it.
Stepped pulley shaft
Thanks to User 510 I got the answer to one of my questions, re: can the stepped pulley shaft be easily removed from the chassis? Answer, as posted at VinylEngine seems to be no.
"later design. Shaft is fixed solid to the step pulley itself. Shaft fits down into a bearing well (that is machined into the cast chassis) with two bushings and a thrust pad. Beneath the thrust pad is a threaded plug which can be turned one way or the other to elevate the step pulley."
Thanks to User 510 I got the answer to one of my questions, re: can the stepped pulley shaft be easily removed from the chassis? Answer, as posted at VinylEngine seems to be no.
"later design. Shaft is fixed solid to the step pulley itself. Shaft fits down into a bearing well (that is machined into the cast chassis) with two bushings and a thrust pad. Beneath the thrust pad is a threaded plug which can be turned one way or the other to elevate the step pulley."
Idler wheel washer question
OK, so all the washers beneath my 124's idler wheel are missing! Hopefully tracking down replacements won't be an issue, although I note the fiber washers are reported to be of varying thickness to aid in proper alignment. My question though has to do with what material people are using for the thrust washer. Also am I correct in thinking that the idler wheel bushing is a little proud, so just the bushing takes the weight of the thrust washer? Certainly looked that way on mine.
OK, so all the washers beneath my 124's idler wheel are missing! Hopefully tracking down replacements won't be an issue, although I note the fiber washers are reported to be of varying thickness to aid in proper alignment. My question though has to do with what material people are using for the thrust washer. Also am I correct in thinking that the idler wheel bushing is a little proud, so just the bushing takes the weight of the thrust washer? Certainly looked that way on mine.
The idlerwheel runs on a white nylon washer from 0,5 mm thickness and 5mm ID -9mm OD.and for height correction one to three fibre washers !
Kevinkr - Any comments on using Delrin rod vs G10 for making the tool? I asked my friend if he could machine Delrin and said no problem, but didn't ask about G10. Delrin's softer, correct? Would that provide any additional protection against deformation when inserting new bushings?
Not sure, but I suspect softer may not be better. I think the key is to have well machined, burr free surfaces to protect the interior surfaces of the new bushing.
I'm thinking a beautifully machined piece of stainless steel could be better. I don't think the G10 is going to be durable enough if service many more tables.
Let me know how you do with the main bearing bushings, I may be interested in some. Most I've encountered (eBay) fit too loosely in the bearing bore and are easily and distressingly displaced by hydrostatic pressure when installing the spindle. This does NOT happen with the OEM bearings, but only my low hour TD-124/II has original bearings.
I'm thinking a beautifully machined piece of stainless steel could be better. I don't think the G10 is going to be durable enough if service many more tables.
Let me know how you do with the main bearing bushings, I may be interested in some. Most I've encountered (eBay) fit too loosely in the bearing bore and are easily and distressingly displaced by hydrostatic pressure when installing the spindle. This does NOT happen with the OEM bearings, but only my low hour TD-124/II has original bearings.
I'm still at a loss when it comes to the exact specs. for all this, in particular "pressed" I.D. for in each instance. It's this I.D. that that's critical as it assures clearance is right to allow for an oil film, a rock-steady rotation, and still keep drag to a minimum. For the life of me for all my reading, I've yet to find this info. Best I've come across was a mention by user 510 regarding his measurements of the clearance on an old spindle and old idler wheel bushing, the latter clearance I believe, he called "too sloppy". Barring finding anything more definitive, we'll use those and measurements of our own worn parts then do some seat-of-the pants subtraction to try and come up with optimal tolerances to shoot for, then compare that to what we are likely to achieve with the new bushings on hand. Man, I hate even saying that.
Kevinkr, I can see the advantages of stainless. I have in my head the design for a drive mechanism that came to me while thinking of the explosive impact hammer I use to drive nails through wood and into concrete.
Basically, it would employ a "gun barrel" to steady the bushing while being pressed and an inner stepped pin to push the bushing down the barrel and into the OEM part, all in perfect alignment. The clearance could be pretty tight on this outer barrel, tighter than than you could safely use if you were to try to steady the bushing by means of an inner pin, as that pin I.D. would have to take into account compression of the bushing from insertion into the OEM part.
Of course when I get to the spindle I'll let you know how it goes. I have two sets of main bearing bushings, both sourced from eBay, but different in that one set came as part of a kit supposedly purchased years ago. They do vary in length a few mm, but without OEM specs, I don't know which set is most accurate (hopefully one set is).
I had planned on trying to measure receiving shaft and bushings prior to insertion in part to try and avoid the slipping problem you've had, but also to try and gauge what the final clearance will be once the bushing is compressed. My thinking is if it's obvious from these measurements that once pressed in, the bushing will either slip or not provide proper clearance, there's no sense in proceeding. My hope then would be to see if my machinist friend feels he's up to speed on machining sintered bronze to give it a go.
Finally, on the continuing search for the perfect lubrication, I have on order a liter of Nye Oil 181b
http://productsearch.nyelubricants.com/pdf/TDS_English_SYNTHETIC OIL 181B.pdf
While the general applications mentioned along with the specs did catch my eye, what led me to it in the first place was that Nye does market the 181b and many of its other synthetics as having been designed for use in sintered bronze. Obviously a liter's a bit more than I need, but the little vial they were willing to sell me was both cost prohibitive and insufficient so I guess I'll be happy with yet another oil on the shelf.
Kevinkr, I can see the advantages of stainless. I have in my head the design for a drive mechanism that came to me while thinking of the explosive impact hammer I use to drive nails through wood and into concrete.
Basically, it would employ a "gun barrel" to steady the bushing while being pressed and an inner stepped pin to push the bushing down the barrel and into the OEM part, all in perfect alignment. The clearance could be pretty tight on this outer barrel, tighter than than you could safely use if you were to try to steady the bushing by means of an inner pin, as that pin I.D. would have to take into account compression of the bushing from insertion into the OEM part.
Of course when I get to the spindle I'll let you know how it goes. I have two sets of main bearing bushings, both sourced from eBay, but different in that one set came as part of a kit supposedly purchased years ago. They do vary in length a few mm, but without OEM specs, I don't know which set is most accurate (hopefully one set is).
I had planned on trying to measure receiving shaft and bushings prior to insertion in part to try and avoid the slipping problem you've had, but also to try and gauge what the final clearance will be once the bushing is compressed. My thinking is if it's obvious from these measurements that once pressed in, the bushing will either slip or not provide proper clearance, there's no sense in proceeding. My hope then would be to see if my machinist friend feels he's up to speed on machining sintered bronze to give it a go.
Finally, on the continuing search for the perfect lubrication, I have on order a liter of Nye Oil 181b
http://productsearch.nyelubricants.com/pdf/TDS_English_SYNTHETIC OIL 181B.pdf
While the general applications mentioned along with the specs did catch my eye, what led me to it in the first place was that Nye does market the 181b and many of its other synthetics as having been designed for use in sintered bronze. Obviously a liter's a bit more than I need, but the little vial they were willing to sell me was both cost prohibitive and insufficient so I guess I'll be happy with yet another oil on the shelf.
Hi Kevin, MCM,
Kevin you mentioned "Not sure, but I suspect softer may not be better. ".
My Dad is a (retired) mechnanical Engineer, and many years ago, I mentioned that I noticed that most plain or sleeve bearings always seemed to have a soft material, (such as brass), and a harder material, (such as hardened steel.)
I thought this was curious, and would cause premature wear.
He said that is not true, that the wear is minimized in this kind of situation. He pointed out some examples, such as clocks, (steel shaft, and brass plates, watches, (ruby or diamond outer bearing and hardened steel shaft), etc. Every plain bearing I've seen supports this, can you think of a plain bearing that that doesn't follow this rule?
What my be interesting is if we could make the outer bearings of Lignum vitae or a synthetic jewel.
Kevin you mentioned "Not sure, but I suspect softer may not be better. ".
My Dad is a (retired) mechnanical Engineer, and many years ago, I mentioned that I noticed that most plain or sleeve bearings always seemed to have a soft material, (such as brass), and a harder material, (such as hardened steel.)
I thought this was curious, and would cause premature wear.
He said that is not true, that the wear is minimized in this kind of situation. He pointed out some examples, such as clocks, (steel shaft, and brass plates, watches, (ruby or diamond outer bearing and hardened steel shaft), etc. Every plain bearing I've seen supports this, can you think of a plain bearing that that doesn't follow this rule?
What my be interesting is if we could make the outer bearings of Lignum vitae or a synthetic jewel.
I was of course talking specifically about the tool used to press in the new bushing. 
In this case a tool made of softer material does not seem like a big win to me if high quality machining is available for said tooling.
Obviously I agree with the other comments.. Maintained well these bearing assemblies are quite durable, unfortunately most weren't well maintained I suspect.
In this case a tool made of softer material does not seem like a big win to me if high quality machining is available for said tooling.Obviously I agree with the other comments.. Maintained well these bearing assemblies are quite durable, unfortunately most weren't well maintained I suspect.