[kwilford]

I had read an earlier post regarding stiffening up the central joint donut. It recommended inserting lengths of fan vee belt material into the space around the rubber donut.

I have done this, but I am concerned that the result is (maybe)too stiff. I know I can get a heavy duty donut from OGTS, but a friend recommended an alternative. He is a drag racer, and says it is common practice to stiffen up engine mounts and other hollow rubber mounts and bushings by injecting silicon into the cavity. Just plain, houshold variety silicon caulking. It would be more "pliable" than the belts, and would never fall out. But it might be difficult to remove later.

What do you think? Anyone tried the fanbelt trick, and if so, how stiff did it make the suspension? How many belts, or rather, how full did you make the cavity? Anyone try the silicon idea? Thanks!

 

[RallyBob]

First of all, let me state that your subject line borders on pornographic.....

Anyway, back to the matter at hand. The v-belt trick works well. In fact, it is shown in some factory service manuals as a 'normal' Opel-approved procedure. In fact, I usually install three lengths of v-belt, but it's a bit of a pain in the ass to do admittedly.

Silicone is an option, but will require cleaning the inside of the donut well, and applying the silicone in many layers....otherwise it will take weeks for the stuff to cure fully, and it will probably come apart if used prior to a full cure.

Bob

 

[kwilford]

Stiff Donut

Bob,

Yea, I had to read that title AFTER again I posted it. Too many words with different connotations. I just wish I had MEANT to be funny....

As for the belts, I inserted a bunch of 4 to 6 inch lengths around the donut, in the space between it and the steel carrier, after first wiring the donut to the bearing to ensure that it stayed in place. And you are right, it is a heck of a job. I did it about 5 months ago, and my hands still ache. But I haven't tried it out for ride quality as of yet, as I am MONTHS from being ready to drive it. But since I am just about ready to reinstall the drivetrain, I wanted to be sure that I really should have filled up the donut, or that I shouldn't have used a more "compliant" filler, such as the silicon, or even some type of foam rubber. This is a street car, not a race car, and even though I prefer a firm ride to sloppy handling (which improved SUBSTANTIALLY with front and rear sway bars), I also don't want a kidney-killer.

I appreciate your comment about curing time for silicon. As I recall, silicon RTV (Room Temperature Vulcanization) requires moisture (in the air) to cure, so a 1 inch layer of silicon probably will take a good two weeks to fully cure. Or even longer in desert-dry Calgary. But this has been a 15 year restoration, so what's another 30 days?

 

[jpiper]

Silicone?

Keith;
I don't proclaim to be a silicone expert but just a thought on some RTV silicones and that is, some of the brands (DOW Corning 732/Loctite 66B for example) release acetic acid when curing, and therefore are corrosive. As a military Electrical technician on aircraft for the past 18 years, we had been directed a number of years back to cease using this type of silicon for sealing electrical plugs, etc. and for other uses on the aircraft (as most may be aware, we have to make our aircraft last a heck of along time). The above companies do produce the "non-acetic" silicones and you can usually distinguish between the two by sniffing the silicone in the tube (be carefull, you may get some strange looks in the store if you sniff too many tubes, if you know what I mean) and if the silicone smells like vinegar, then it is acetic. I would have to do some digging to find the numbers that we use ( now an "office weenie" vice "hands-on wire checker") but when I find them I will let you know, if you're interested.
Not using this type of silicone may be just a minor point, but hey if you can stop corrosion before it even starts, then you are saving yourself work some point down the road. Its not like rust is attracted to our vehicles up here,...... right?

John

 

[RallyBob]

Hopefully this won't be an issue in this case. The silicone would be injected in the cavity around the central bearing, but would actually only be in contact with the rubber bushing itself, not metal.

Bob

 

[Bosco2]

just read this thread from way back when........and I'll add that on the GT I owned 25 yrs ago I put heater hose or fuel line (whichever it was that fit) in around the donut and it worked well also......

 

[soybean (R.I.P.)]

I was reading the forums while I was redoing the rear end on my Gt, and this thread caught my attention as my torque tube donut seems a little loose, not much, but a little. Bosco, is the fix you did still working? and Keith, did you do the fanbelt fix and if so, does it work? Thanks, Jarrell

 

[kwilford]

Keith, did you do the fanbelt fix and if so, does it work? Thanks, Jarrell

I did the fan belt thing, but I (sadly) still haven't tried it out yet. Look at my avatar. I seem to have gone BACKWARDS from there. But with four more sleeps, I am officially retired for the summer (career hiatus) and July will be an Opel month

 

[Bosco2]

The fix is still working........
I used good fuel injection rubber hose (more substantial than ordinary fuel line) on my current car about 6 mos ago and it's stayed the same since the day I fixed it.

 

[jordan]

I put 4 pieces of 3/8" rubber hose in there and it is much better but there is still a little clunk.

 

[tekenaar]

SIX pieces of V-belt!

The rubber piece inside the metal housing is kind of accordion shaped with a central "rib". There are three rectangular holes in the metal bracket spaced roughly 120 deg apart. I cut 6 pieces of an old 3/8" fan belt 3"-4" long and push them in, wide part of the "V" out, one on each side of the "rib" at each of the 3 rectangular holes. A spray of WD-40 helps "fish" them into place.

I replaced the "donut" on my '73 GT with a new one in '79 and did this little trick. It's been in there since with NO worries of ever having to replace the donut again! Even if it cracks, the V-belts will keep the torque tube from "clunking". It stiffens up that central section considerably (good) without impairing ride quality to any great extent (also good). I routinely do that in all of mine since, after Pertronix and OttoStart!

THAT'S been my experience.