Replacing perished grommets on tuning gangs

[Mike Phelan]

The usual construction is that the grommet is fixed into a hole on the chassis, or other bracketry, and has a metal sleeve so the screw can be tightened up without squashing the grommet too hard.

These become perished and eventually rock-hard, so their function of avoiding microphony no longer works.

Most available grommets do not have thin enough walls to allow them to go into the annular gap between the spacer tube and chassis hole.

I have have tried using sleeving with rubber washers, O-rings and all sorts of similar things, but with limited success, until I settled on this:

If you select a grommet that is a tight fit in the metal sleeve, and cut it in two, the inner edges will squeeze into the hole far enough to hold the sleeve in position, as in the last picture.
A simple idea, but it does work.

[Hermit6345]

That is an excellent tip Mike, it so happens I am doing one at the present and was puzzling about how I was going to do it. Now I know!

Thanks,

Ian.

[newlite4]

Good tip this Mike. I have had no end of trouble with this fixing method. Modern grommets just dont seem to match the dimensions of the originals.
Neil

[howard]

Thanks Mike,

Good idea, I'll try that next time I acquire a TR82 with its tuning capacitor flopping around inside (won't be long !) cos modern ones do tend to be smaller and I usually have to add an extra washer to make up the difference in size.

Howard

[Robert Darwent]

...a TR82 with its tuning capacitor flopping around inside... - Howard

Yes I've got a couple of TR82's like that as well Howard

That's a really good idea Mike, thanks for posting it. Will definitely give it a try!

[Phil G4SPZ]

Yes, Mike, a good tip, thanks. I've got a Marconi set that needs the treatment so I'll bear your idea in mind. I also have a Garrard gram deck on which the motor mounting rubber grommets have gone hard, and that might be a candidate for similar treatment.

Phil

[Tim]

I bought a pack of small grommets a couple of years ago from RS or Rapid(can't remember which. ) They are an EXACT match for Roberts R200, Bush TR82 etc.

[Courtney Louise]

this idea would prolly work for turntable motor mounting grommets too

Andi

[Brian R Pateman]

Nice one Mike - definitely one for the archive!

Regards,

[Mike Phelan]

I was actually thinking of that, Brian!

[Aerodyne]

So far I've had no problems replacing grommets but I guess my stock is old. Perhaps metrication can be blamed for the differences between old stock and new! Neat idea, though, Mike. I'll store it away in the cavernous space between my ears.
-Tony

[Darren-UK]

I've also used the same method as Mike, with good results. Modern grommets appear to be somewhat harder than the originals and I used to wonder if this would have any effect on microphonics.....but it doesn't. Saying that, I don't know just how hard of soft the rubber of the 50 or so years old original grommets were when new.

As Andi suggested, this method does indeed work ok on turntable motor mountings.

[Sideband]

That's worth trying Mike! In the past I have used grommets with suitably cut washing machine hose washers and also tap washers to make up the difference.


Rich.

[Nickthedentist]

Not OT, I hope...

Are (synthetic) rubber grommets easily available these days? Most I've seen recently are PVC, which although fine for protecting wires where they pass through chassis etc., are too stiff for this kind of thing.

N

[Courtney Louise]

Good question Nick and one I would like to know the answer too as I have an old battery record player here that the motor needs re grommeting....

Andi

[telstar]

Hi. I might try that idea myself. I have a Philips 290U radio that has perished grommets under the tuning capacitor - it is not easy to work in that compact radio.
Regards
Mike