Grace 707 Tonearm Lift - need fixing...

[coolmaster]

Originally posted by JesseG

Since I have had mine apart so many times, I am going to try it with gear grease. If this gives the right sort of response, then hunt down some of the proper stuff from Rega or wohever.
Thanks again
Jess

Jess: I think its futile to use any automotive grease for lifter damping. I believe this silicone grease product is much thicker and suited for damping than the grease you intend to use, even that automotive additive STP viscosity thickener would not work to your satisfaction. You'd have to de-grease and ensure a surgically clean mechanism entirely. You'd only need less than a gram, drop (sorry if I'm unsure of describing the measure) of it to re-lube.

This is the data sheet of the Dow Corning product that points to suitablility.
http://www.polysi.com/dow%20corning%...0300000cst.pdf

They have an even thicker one of 600,000cST.

Have you consulted them?

http://www.turntablebasics.com/silicone.html

[JesseG]

Thanks, coolmaster:

when I said gear grease I was thinking of some silicone-base stuff I have for my modeler's lathe. However, you have a good point, and since suitable grease is readily available form your link or TheNeedleDoctor or a number of others, I will exercise patience and order some

Jess

[simonl8353]

Some time ago I found myself in the same position with a cueing lift - I lost the screw. I tried many sources (eyeglasses, watches, etc.) but could not find anything that would work

Thanks JesseG but I still have the screw, so all ok there.
I am interested in the outcome with the silicon grease though. I'll follow up on coolmasters suggestion also.

[coolmaster]

I did my own research and have come to this.

Rocol Kilopoise viscosity = 220,000cp (stated in datasheet)
This is the one Rega uses for all its arm lifter mechanism. IMHO, that product serves the purpose but I do not agree of its performance which still drops a little too fast for my liking. I would have liked it much slower and gentler like in some vintage Thorens or Japanese decks.

The 300,000cSt product, turntablebasics.com sells is very likely and most suitable to Grace or Rega (as a better lube alternative) arm lifter.
If anyone has tried this product, do feedback your results.

[simonl8353]

Confirmed fix.

Thanks Coolmaster, your suggestion with the 300cst silicon works 100%. I ordered a tube US$10 (I think) from Turntable Basics and completed the fix last night. see http://www.turntablebasics.com/silicone.html for the product.

Here is the repair in detail;
1. Cover the Cartridge Needle to protect. (I used the original stylus cover)
2. Remove Arm Rest top screw and remove Arm Rest. (curved piece)
3. Loosen Piston Clamp screw
4. Loosen Arm Lock Screw (on side of main Tone Arm shaft) to allow whole Tone Arm Assembly to rise up sufficiently to drop the complete Piston Assembly out the bottom of the Piston Clamp.
5. With the Piston Assembly removed, using a sharp blade prise off the black plastic Base Disc (take care, slight damage to the edge of the plastic is likely).
6. Look inside the Piston Cylinder and remove the small bronze Grub Screw located on the Lever Arm shaft (only takes approx 1 turn).
7. Remove the Lever Arm screw located on the opposite side to the Lever Arm.
8. Carefully, holding the Piston Shaft in the "raised" position, remove the Lever Arm.
9. Allow the Piston to "spring" back down and slide it out the bottom along with the Return Spring.
10. All components to now be throughtly cleaned, I did not have any rubbing alcohol so used mineral turpentine.
11. Thoroughly dry all components.
12. Assemble Return Spring back on to Piston Shaft.
13. Coat only the bronze Piston sides with the 300cst silicon, ensure the bronze Piston grooves are full. I used a small piece of cardboard as an applicator to build a very thin layer over the Piston sides. (do not cover the top or bottom of the piston)
14. Carefully slide the Piston (with the Return Spring) back into the Cylinder.
15. Hold Piston in the "raised" position (with a cotton bud) and re-fit the Lever Arm and Lever Arm screw.
16. Rotate the Piston to align the Piston "dog" with the Lever Arm cam.
17. Test assembly for smooth action.
18. Re-fit small bronze Grub Screw (this controls over rotation of the Lever Arm when in the "raised" position).
19. Re-fit black plastic Base Disc.
20. Re-fit Piston Assembly into Piston Clamp on Tone Arm body (do not tighten clamp yet).
21. Re-fit the curved Arm Rest (note this must align with square sides on Piston Shaft) and tighten Arm Rest top screw to secure.
22. Adjust Tone Arm height and tighten Arm Lock screw.
23. Adjust and secure Piston Assembly in desired position using the Piston Clamp screw.
24. Done.

My first attempt took approx 2 hrs. I had never dissassembled one of these before. I added too much of the silicon and coated everything inside the Cylinder as well. It worked but irratically, sometimes taking 2 minutes to drop, sometimes 5 seconds. I believe having too much silicon created an air-lock above and below the Piston which also caused some weeping of the silicon out through the Lever Arm screw.

My second attempt took 30 mins and the result was perfect function. Needless to say, the instructions above are from my second attempt. No weeping anywhere. Perfect repetition of dropping action. Cartridge takes approx 3 full seconds to drop.

See attached photo of disassembled parts.
Hope this helps.

Thanks again to Coolmaster for the tip on what type and where to get the silicon.

For info, I also spoke to Dow Corning who could only get me a 500ml tin of their product and never rang me back with availabliity or price.

[coolmaster]

simonl8353: Great to hear you've achieved something there.

I took the plunge and an hour's work to dismantle my Rega RB300 arm lift mechanism. Its so easy!.

1. Remove the arm completely off the plinth. (very important and neccessary)
2. Remove the allen lockbolt at the arm rest and remove the arm rest. Careful NOT to loose the allen bolt.
3. Remove the visible spring from the piston and plastic cap at bottom.
4. Using an appropriate fit needle nose pliers, unscrew very carefully the top cap till it comes off, ensuring the tool does not scratch the cap finish.
5. Withdraw the whole assembly from the bottom side.
6. Remove the piston from the cylinder bore and withdraw arm lift handle, TAKING NOTE of the hole side which the handle was withdrawn. There's NO plastic or rubber parts in the mechanism.
After degreasing, I used a camera lens hand blower to blow away any dust or debris.
7. Relube the piston carefully, packing the middle groove and the piston cam sufficiently.
8. A touch of lube on the handle cam where it contacts the cylinder bore, and refit the piston down the bore with the handle cam in correct position. Ensure smooth and correct operation before refitting back to the arm.
9. Re-install the arm lift assembly from the bottom and lock the top cap, tightening it just sufficiently with the needle nose pliers.

OK, the lube I used is 100,000cSt silicone fluid. It works but still not to expectation.The original Kilopoise was probably tackier but IMHO, not good enough but serves the purpose. Kilopoise is a pig to remove and not with spirit I had thought effective to do the job. I had to use some paint thinner to clean up the stuff.
I'll obtain the 300,000cSt later and re-lube it again.
I've never dismantled a Rega lift before. I did notice the lever is somewhat silky smoother now, perhaps due to a thinner viscosity. Meanwhile, I control the decent manually. I've certainly gained some experience here.

[simonl8353]

So there are now two tonearm damper fixes posted here, the RB300 and Grace 707. This thread should be a good reference source for others.
For US$10 its worth getting the 300cst goop from Turntable Basics. Postage is US$4 Domestic First Class or the same for Airmail to Australia, all up IMHO a small price to pay for the passion of having the equipment work perfectly.

ATB

[coolmaster]

I used to have two vintage SME Series III arms, 3009 & 3012 and have since sold them off. If only I had them now, I would have attempted this experiment for knowledge.

[mosin]

Gents,

I thought I would add that have repaired many lifts, and the above instructions are essentially the same as the steps I have taken. The only distinct difference is that I use 600,000cSt oil. The amount applied may affect the outcome, but the heavier also works nicely. In the case of the Audio-Technica at6006a end lifter, the heavier was necessary to get the mechanism going again. (I tried thinner oil, but it did not work.)

By the way, I keep a selection of thicknesses around because it is good for a variety of repairs, and sometimes blends are desirable. That being the case, I would suggest buying both the 300,000cSt and the 600,000cSt oils.

Regards,
mosin

[coolmaster]

Originally posted by mosin

By the way, I keep a selection of thicknesses around because it is good for a variety of repairs, and sometimes blends are desirable. That being the case, I would suggest buying both the 300,000cSt and the 600,000cSt oils.

I reckon arm manufacturers all have their own concoction, trouble is they don't disclose any specs, perhaps its deemed as something the user shouldn't dabble with till end of life.

I agree with you having different viscosities in hand and one can mix them up to form own concoction to one's satisfaction. I'm beginning to believe most arm lifts would require at least 200,000cST or thicker which is already a state of "thick gooey paste"?
Thanks to the internet, we're able to share info and experiences.
Good day gentlemen!.