Hey guys and gals,
I recently put in a Strange 12-bolt. The install went great and during the breakin period I thought everything was fine. Well, now that it is broke in and I am starting to drive it more normal I have noticed 2 things. First off I have a cluncking noise coming form the backend whenever I go over a decent bump. I never had this before --- my guess is that the new 12-bolt is making contact with something whenever I go over a bump. I tried to recreate it in my garage by pushing in all direction on the car so that it would compress the shocks in hopes to hear or see something .... but no luck. Any guesses??? The second issue is that I have started to drive it harder and the first time I got it above 75mph I noticed a very bad vibration in the rear. My guess here is that maybe the 12-bolt isn't balanced properly??? Any ideas on this would be appreciated as well. I think I'm going to have to take it to my mechanic and have him check it out if I don't figure something out soon since I do not feel comfortable driving it -- afraid of breaking something. Please help me out -- thanks.

 

Check where the torque arm bolts up. When I had mine rebuilt, I had a weird clunking. I found loose bolts. That could also cause a vibration.

 

I would say the vibration would/is from the driveshaft, have you had it balanced when you swapped the U-Joint out for the Strange?

The clunk could be from a bunch of things, I'd suggest checking all your bolts and re-torquing all of them; this is typically what causes clunks.

I fought a HORRID vibration issue for almost 2 summers... I finally bit the bullet and replaced the stock axle (Strange 12-bolt), stock driveshaft; Tried both Steel, and AL ones with no luck, (Denny's Nitrous Ready), and suspension (Billet Aluminum LCA's, and PHR, with a BMR TA), I have NO vibration well past the 140 mark, but I have some clunks due to it being a Rod-Ended/Heim Jointed rear suspension now.

 

I've heard that a stock length driveshaft is about 1/2" too long for a 12-bolt - the slip yoke may be bottoming out on the transmission which is not good. The stock panhard bar also can hit the al. structural covers on 12-bolts so check to see if you have any rub marks on it. Your sig doesn't specify any aftermarket rear suspension parts.

 

Nope...no aftermarket suspension for my car as of yet. I plan on this weekend going through it and making sure that everything is tight. I'll also check for rub marks although I've done this once and didn't really see anything, but I'll check again. I asked alot about the driveshaft length and was told that there would be no issues with the length of it. Although in the last couple of days I have started to wonder if the driveshaft was my problem. When the 10-bolt rear broke I originally thought that it was the ring and pinion that broke, but ended up finding that the (correct me if I'm wrong) yoke that comes out the back of the rear and the u-joint bolts into was what broke. So maybe the driveshaft is bent and caused stress at this point and snapped it. Might explain why I'm still having issues. Keep the ideas coming as I'll try them all this weekend when I take a look at it. Also is there any way other than taking the driveshaft in to check for balancing to see if it is bent?

 

Do you still have that rear? I just put a brand new pinion yoke on mine (to stop seal from leaking) but I've broken the ring gear and have a bad axle. I'm going into serious withdrawal already, lol.

 

Ya, I do still have the original 10-bolt. I don't have a need for it if you want to work something out. Let me know.

 

browneye97ss -- sent you a PM.