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Discussion Starter · #1 ·
I'm working my way through a full bushing and spring replacement at the rear of my '71 GT and my current focus is the failed central joint donut.

I removed the torque tube and drive pinion extension shaft. When I looked at the shaft I noticed bits of rubber or plastic in the socket at the rear - the bit that joins to the diff. I can't find any reference to this in the FSM or forums but do recall reading once that you shouldn't powder coat this piece as heat could damage something... I assume this bit.

430965


The dark ring forming the 'iris' in the middle of the socket appears very brittle. I noticed it as some bits are in the splines, which I scraped out.

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At first I was worried it was crap from the diff. The pinion seal seems in one piece (I'm replacing it anyway) and I don't see how anything would get in here. It seems likely this stuff is from whatever this rubber or plastic bit is in the socket itself.

My question is, can I replace this bit in the depths of the socket or should I even worry about it? I don't want to start cleaning the remains out if it's critical and not replaceable.
 

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1970 Opel Gt - Purchased July 1972 - Chartreuse - restored - 3000 miles as of 02-16, 2021 -
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This is very interesting as I just recently replaced both the torque doughnut and the bushings as well as the seal and the bearing, I also replaced the screws with bolt, less likely to be damaged when installed or reinstalled. I did not come across the same thing that you did, regarding anything at the end of the shaft or mixed in with the splines, clean as a whistle. I do not recall a part being offered by OGTS to fill a need as described by your response from Commodaren. Just curious, is this something that was used in all years or specific to just some. Also, it appears not to have been in place for my car, a 1970 GT, how important is it, that is, should I worry about it. Thanks, Carl
 

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Discussion Starter · #4 ·
Yeah i didn't find reference to it at OGTS (I only checked their site, I didn't call anyone about it). On two bits of documentation they had sent with some of the other parts I'd ordered the diagrams certainly seem to match what Commodåren linked to, but in both cases it's not labelled (unless i'm misreading the labelling of 15 and 17 on the first diagram below). Not sure what year those diagrams come from.

As it was apparently there on mine i'm going to replace it. Carl, hopefully you'll never miss what you never had (y)

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431025
 

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It’s original for all years. Often disintegrated however...
 

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I'm working my way through a full bushing and spring replacement at the rear of my '71 GT and my current focus is the failed central joint donut.

I removed the torque tube and drive pinion extension shaft. When I looked at the shaft I noticed bits of rubber or plastic in the socket at the rear - the bit that joins to the diff. I can't find any reference to this in the FSM or forums but do recall reading once that you shouldn't powder coat this piece as heat could damage something... I assume this bit.

View attachment 430965

The dark ring forming the 'iris' in the middle of the socket appears very brittle. I noticed it as some bits are in the splines, which I scraped out.

View attachment 430966

At first I was worried it was crap from the diff. The pinion seal seems in one piece (I'm replacing it anyway) and I don't see how anything would get in here. It seems likely this stuff is from whatever this rubber or plastic bit is in the socket itself.

My question is, can I replace this bit in the depths of the socket or should I even worry about it? I don't want to start cleaning the remains out if it's critical and not replaceable.
Here’s what I did
 

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Opeler
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As I understand it, the role of those pieces is to dampen metal to metal knocking sound if the drive shaft jerks backward. Personally I never heard such knock even though the damping washer did not exist in my GT.

I am not sure what kind of material Opel used but it was likely rubber that hardened and disintegrated. As Edelschmiede’s made the dampening kit available, I installed it. Their washer is not made of rubber but rather of some kind silicone. There is also a single steel washer to be installed on one side of the silicone washer.

After driving the car for a few months, it happened that I had to remove the driveshaft again as I obtained new, reinforced one from Germany. To my surprise, silicone washer was all beat-up; it got kind of concave shape and was close to start breaking. Hmm…that driveshaft is moving indeed. I ordered new damper kit from Edelschmiede but at that time I installed steel washers on both sides of the silicone piece to prevent its deformation. Never had a chance to inspect it after, hope it is doing fine.

One more thing: Those washers are not wedged inside the driveshaft socket, so in order to secure that they will stay in the position during installation, I used few drops of Goop between washers themselves and the bottom of the driveshaft socket.

431033
 

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Opel Rallier since 1977
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I never put one in any of my rally cars and who know how disintigrated those got. So I'll guess that it is for some low level noise more than anything else. (That's a pure guess however...)
 
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