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terrible vibration

2K views 13 replies 4 participants last post by  jfertita 
#1 ·
hi i have a 1986 325, and recently i have noticed a terrible vibration coming from what it sounds like the rear of my car. it only happens when i reach a certain rpm in 2nd gear..around 2500rpm, can anybody give any suggestions as to what it may be?

Joe
 
#5 ·
My guess would be the rear U-joint. Back when I first got my car it had the most god awful vibration that would go through the whole car at certain speeds and in later stages it also had a terrible clunk bang in the back. I finally yanked the e-brake up and crawled under there to check out what was wrong. I grabbed the drive shaft and twisted it back and forth right before the diff where the rear joint is and I could see the slack between when the shaft turned and when the yoke on the diff turned. I proceeded to go to Auto Parts at AutohausAZ - OEM Auto Parts - Discount Replacement Parts and purchase a new u-joint for $13 whole dollars (good SKF German one)! Then I was told that the shaft was unserviceable! BS! Just because it doesn't have retaining rings doesn't mean it's unserviceable, just means it's a bit of a pain in the ass and you have to have some good mechanical know how. I did an entire write up of the process I used and the steps and parts required on another site. I will try and locate that and post it here for you guys.
 
#9 ·
OK guys... here ya go. I wrote this probably 5 or 6 months ago so if you wan't further details, please feel free to ask as the instructions may be a little cloudy at pionts. Hope this helps you guys!

Ok guys, I got the clunk and slack fixed! Not without toil mind you but none the less! The culprit was a FUBAR'ed rear u-joint. It was causing a severe vibration, clunking, clanking, and lots of slack in the drive train! You should have seen this thing! It had one cap that was totaly busted and had no bearings left, much less grease! The other were still intact but none of them had any grease left! The T was actually tapered from wear! Anyhow I bought a new u-joint from Autohauzaz.com despite all the things I found on this and other forums about how they are unserviceable! I'm proud to anounce that this is NOT TRUE! Albeit they are considerably more difficult to service than your traditional types! All I had to do was this:
1. Remove drive shaft. Make corresponding marks to note the relationship between the pieces of the shaft.
2. Obtain a good carbide burr and die grinder!
- This is to remove the small "stamped" indentions that are retaining the caps. Go ahead and do all of them while your at it, no shortcuts. (I tried)
3. Grind off stampings with the burr. Carefully! And try to remove as little as absolutely necessary.
4. Get a good drift or punch and a ball peen hammer.
5. Get a large nut or socket bigger than the cap but smaller than the yoke of the joint so as to allow the cap to be driven down through the nut or socket from the opposite end of the joint.
6. Use the drift and hammer to drive one of the caps attached to the shaft part of the joint not the end that goes to the diff so as to allow that end to move when driving the cap out.
7. The cap will protrude from the outside of the shaft about a 1/4".
8. Get a chisle.
9. Use chisle corner to drive a dent into the protruding cap. Then proceed to drive against that dent with the drift or the chisle on opposite sides of the cap untill it comes out!
10. Flip the shaft 180degrees and drive on the exposed end that you just removed the cap from in order to remove the opposite cap.
11. Once the opposite cap has been driven out that 1/4" then you can remove the differential end of the shaft from the joint! Now your half way there!
12. Do the same thing on the remaining two caps!
13. Now assuming that you have already obtained a new joint, being very careful not to POP them off, walk the caps off of your new joint without dislodging the needle bearings inside of them!
14. Now this is where the marks you made earlier will come in. Being sure to align the yoke and the shaft correctly as marked, place the naked joint in line with the holes in the yoke.
15. Align one of the caps with the hole in the yoke and carefully drive it in while keeping the joint centered in it to keep the needles in.
16. Flip it over and do the same on the opposite side.
17. Drive the caps down on both sides to just beyond where the previous caps had set. You'll be able to tell by the marks left where you ground on it. This should be damn near centered!
18. Do the same thing on the other half! Again be careful to align the marks you made earlier as this is important to keep the shaft balanced!
19. Now obtain some wicking grade Loctite! This is green in color and you can get this from your local Fastenal Industrial and Contractor Supply store. Not cheap but still much cheaper than the $600.00 shaft!
20. Apply a very small amount to each cap and let it sink down into the edges and leave it to set up for a few hours.
21. Now this step you can do one of several ways, I used some JB weld around the ends of the caps to further aid in retaining the caps, but you could also obtain a good sharp drill bit and some matching spring pins and drill across the top of the caps (not through them but above) and drive a long enough pin through the holes to hold the caps in! A good bit more work and I doubt if it's neccesary as it takes a lot of force to drive the caps in I can't imagine them coming out anyhow!
22. WOW! That's it! DONE! That wasn't so hard. So much for all those $600 new shaft weve been getting shafted with! By the way it works like a dream! SMOOTH as SILK!
If you have any questions feel free to e-mail me directly @ fastenalebay@yahoo.com

Good luck!
Brandon
 
#10 ·
Ok, so I went under my car today and I tried to figure out what was causing the vibration. I looked at the front end of the driveshaft and I noticed that my rubber flex joint was all ripped apart and cracked. So I hope that is most of the problem and I am going to fix it tomorrow. Wish me luck! :lol:
 
#13 ·
Guibo

Yeh,
the front vibration damper can be a real problem. I to had a terrible vibration last month, only as you came off the line at a light. kept getting worse. found that the damper (often called a guibo) was completely loose!
One bolt missing. Put in a new bolt and tightened it down and voila! no more vibration. I understand these things are a wear item and need replaced when they crack. Check your bentley book.
Good luck!
 
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