I have been working on rebuilding my rear suspension for some time now. The drivers side came apart and went back together without issue. The passenger side on the other hand...
As you can see it was missing one of the washers on the pivot bolt.
When I got the diagonal arm off I noticed that the part the pivot bolt threads into has been worn down on the back side.
This is what the steel insert in the pivot bolt bushing looked like. (The left one is a good one from the drivers side. The one on the right is from the passenger side.)
So I have removed, inspected, and adjusted the torsion bars. Replaced the spring plate bushings with urethane. and replaced the diagonal arm pivot bushing with urethane, and replace the missing pivot washer... Now the diagonal arm's flange is not even close to parallel with the spring plate it is supposed to mount to.
I am stumped. Anyone see anything like this before?
I noticed on mine that as I moved the diagonal arm around from the aft end, it would do that. The spring plate did sit off a few mm from it with all parts at rest, in a neutral state.
The spring plate and diagonal arm move in different arcs, since the pivot points of them are not in the same planes. That is why the Spring plate is made from spring steel, to allow for the required flexure.
Were you seeing any abnormal rear tire wear before?
Hello RSB, I see in your third picture, you show two bushings and refer to them as left and right sides of the car.
If so..., Wow and I'm sure by now you know their was supposed to have been two of those short steel tubes on a stock arm. Look at the bright side, it didn't come apart. and with the after market urethane end pieces it has one long tube per side now.
Anyway, as stated by Ol'fogasaurus (Lee), follow that link again and recheck your assembly.
When I replaced all the bushings in the back of Vivian, I had the same thing. Although the pivots were complete with all there parts, when I put it back together, the pass side spring plate sat almost exactly like yours. I have also seen this in other cars and haven't seen any issues from it yet from my friends car, and he has put over 5,000 miles on it since.
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Thank you all for the input. I haven't ever noticed any uneven tire wear. So I guess I will just bolt it back together and see if I can get my toe-in correct. Couldn't be any worse than what was there before. I can't wait to see how my car is going to handle after this!
Can you get in there with a small grinding wheel and dress the end off flat? It'd be a good idea - then slice a ring off of the good end of the old sleeve to make up the length. Even if you can't get the end perfectly perpendicular, the spacer could be ground to match the angle.
Otherwise, I'd be worried that the new sleeve will just get chewed up like the old one.
I noticed the exact issue of the spring plate not being parallel to the blade on the semi-trailing arm on my VW as well. When you bolt them together it results in a significant bend in the spring plate as the plate is forced against the blade. Flex may be a better word to use though.
I wondered if the blade on the trailing arm was bent or something. So I started searching the various forums to see if anyone else had the same issue.
After much searching and research on several forums I found your post showing the same thing. I found the same bend over and over in pictures I saw during my search. The owners seemingly unconcerned or just not noticing. I bet it is common.
The spring plate being at a different angle than the mounting tab on the trailing arm is perfectly normal when the spring plate is at full droop.
If the spring plate was sitting perfectly horizontal, the angle between it and the trailing arm tab would vary depending on what you had your toe set to, because changing toe requires you to move the trailing arm fore and aft. So you can see that the mounting tab points essentially straight ahead at 0 toe, with toe out the tab points outward (arm pulled back), and with toe in the tab points inward (arm pushed forward). Now one of the properties of the VW semi-trailing arm is that it toes in when the suspension moves either up or down from the horizontal plane. Because your spring plate points downward when on jackstands, the trailing arm, if it were connected, would be toed in. Since we know that toe in requires the arm's tab to point inward, and being disconnected, the spring plate isn't bending to meet the tab (which it must do as the suspension moves because its axis of rotation and the trailing arm's axis of rotation do not line up) so it's just pointing straight back, hence the difference in angles between the two.
After taking the passenger side diagonal arm off the car again to check how everything fits I noticed that the angle between the spring plate and diagonal arm flange is close to parallel when the pivot bolt is just hand tight. I decided to try moving one of the washers from the outside to the inside and everything seems to line up better. I am pretty happy with it now, so we will see what the alignment shop has to say when the time comes.
I did run across another issue with the torsion bar cover bolts. There is a typo in the Bentley manual. during the procedure it says to tighten the cover bolts to 80 ft.lb. but if you check the list of fastener specs and torques at the back of the chapter it says 25 ft.lb. I originally tried torquing them to 80 ft.lb. and sheared one. (the factory bolts have a 15mm head which is needed due to the tight space against the lip of the cover, modern replacements have a 17mm head which doesn't fit, but I was able to find a bolt with an Allan head) I have them torqued down as tight as I can with a 3/8" ratchet, and plan to check them periodically for tightness.
rsb wrote:After taking the passenger side diagonal arm off the car again to check how everything fits I noticed that the angle between the spring plate and diagonal arm flange is close to parallel when the pivot bolt is just hand tight. I decided to try moving one of the washers from the outside to the inside and everything seems to line up better. I am pretty happy with it now, so we will see what the alignment shop has to say when the time comes.
I did run across another issue with the torsion bar cover bolts. There is a typo in the Bentley manual. during the procedure it says to tighten the cover bolts to 80 ft.lb. but if you check the list of fastener specs and torques at the back of the chapter it says 25 ft.lb. I originally tried torquing them to 80 ft.lb. and sheared one. (the factory bolts have a 15mm head which is needed due to the tight space against the lip of the cover, modern replacements have a 17mm head which doesn't fit, but I was able to find a bolt with an Allan head) I have them torqued down as tight as I can with a 3/8" ratchet, and plan to check them periodically for tightness.
Moving one washer from the outside to the inside will increase toe-out. At least one washer must remain on the outside to hold the bushing in. If you run out of toe-in adjustment during the alignment, you may have to move the washer back to the outside.
Yeah, there's no way a 10mm bolt will take 80 ft-lbs, 25 is correct for the 4 cover bolts. 80 might be for the 3 spring plate to diagonal arm bolts.
and I'm sure by now you know their was supposed to have been two of those short steel tubes on a stock arm. Look at the bright side, it didn't come apart. 
and with the after market urethane end pieces it has one long tube per side now.
