Re: Rubber idler wheel rubber restoration

Jeff Liebermann <jeffl@xxxxxxxxxx> wrote in message
"Mr. Land" <graftonfot@xxxxxxxxx> hath wroth:

On Jan 12, 12:28 am, Jeff Liebermann <je...@xxxxxxxxxxxxxxxxxxxxxx>
Duz anyone have a better potion, elixer, process, or incantation for
softening rubber idler wheels?

Are they "slippery" hard or "brittle" hard?

Slippery hard. I spun both idlers while burnishing with fine emery
cloth to roughen the surface. That's helped, but without the
compression provided by the normally springy rubber, the turntable and
tape recorder both still slipped. Also, no flat spots.

The idler in the Gerrard turntable looks like the top row, 2nd from

Can you see any cracks on the drive surfaces?

No cracks. It's not like they're ready to crumble or fall apart. The
rubber is intact, but hard as a rock. I didn't photograph the idlers
but can do so when I return to the scene of the crime, er... customer,
because there's no obvious damage. Just a hardening of the rubber.

Others have suggested machining it down and adding a layer of new
rubber from a belt or rubber sheet. I've done that in the past and it
works. It might work with the Sony idler, which is quite wide.
However, the Gerrard turntable idler is only about 2mm wide at the
point of contact, and will therefore be difficult to resurface.

If they are brittle hard w/ major cracking
(i.e. cracks that run into the rubber below the drive surfaces) I
be surprised if you could find any chemical that will help.

Well, I may be lucky here as there is no obvious cracking. However, I
suspect if I bend the rubber sufficiently, it will crack instead of

If they're not that bad, I've had good luck with GC Electronics
Rubber Rejuvenator.

I've tried the stuff in the past. Like the other rubber cleaners,
rejuvenators, restorers, and recovery compounds, it softens only
surface of the rubber. My guess(tm) is about 0.3mm deep at most. The
rubber is not porous so the solvent only affects the surface. What
I'm looking for is something that has a sufficiently small molecular
diameter to penetrate deeper than just the surface.

For really, really hardened rubber I've had success with
Teac Rubber Cleaner (Part No. RC-2). This a potent,
oily liquid that smells like liquid moth balls. I found a
discussion thread that indicates it is no longer made,
but it looks like Rawn makes a close replacement:

Sounds interesting. I'll see if I can find some. Moth ball stench
would be a naphthalene. That can probably be found at the hardware

I've used the old TEAC rubber conditioner since about 1979 and I still
have about 1/2 oz left of an old 2 oz glass bottle. That's how far it
goes when used in moderation. That was my favorite for pinch rollers.
The bad news is TEAC doesn't sell it anymore. The good news is it was
made for TEAC by Rawn and they still sell the latest incarnation as
"Re-Grip" They changed the formula a couple times because someone in
California found some chemical in it to be carcinogenic. But none of
my tape decks have gotten cancer, so I guess the joke's on


I still have a mostly-full 7 oz can of the Teac cleaner from 20 yrs.
ago. Guess I'll keep the cap on it...

I'll probably order some tomorrow.


I just found a box of ancient idlers and belts to practice on. I've
got about a week to tinker before attacking the antiques.

Jeff Liebermann jeffl@xxxxxxxxxx
150 Felker St #D
Santa Cruz CA 95060
Skype: JeffLiebermann AE6KS 831-336-2558

When you've failed with the gooey stuff.
This is what I've done for a Beogram idler.
I assume from the pics you directed to , that it is based on a thin metal
I cut a strip of moped inner tube, left the original ribber moulding in
place just in case my fudge did not work, seriously stretched the moped
rubber over the pulley rim and glued in place.
There was axial room to allow for the greater thickness and adjusted for the
change in "gear ratio" at the adjuster cone mechanism

Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on