Well, I have been fighting vibration since I had my latest round of mods done. The problem is that I had a lot of stuff done at one time. (please learn from my mistake and do not do too many mods at one time) There were zero vibration issues before the mods. So something that was done is causing the vibs. I think it may be mulitple things which will make things even more difficult.

I just put a new set of shoes on the car, so that is ruled out. There seems to be less vibs since the new shoes. Before the shoes, there seemed to be a vib from the driveshaft, but it seemed to go away after the tires. I have a Denny shaft, but it is not on because of major vibs at 85 mph. I have not triedthe Denny shaftsince the new shoes. My tires also have a slight slant in from bottom to top.


Here are the mods doneand symptoms. Please give me any ideas on what to look at.


Mods done

3.73 FRRP gears
Adj. LCA's combo style
Adj. panhard bar
Relocation brackets
Pulleys
Eibach Prokit

Symptoms

steering wheel vibrates "sometimes"
passenger seat vibrates at higher speeds

 

-steering wheel vibrates "sometimes"
Any pattern to it? When tires are cold, when hot? Things to check - wheel balance, front end alignment, loose fasteners causing intermittent misalignment - also, any irregular wear pattern on the tires? If so,strongly suggestsalignment issues.

- passenger seat vibrates at higher speeds
At a certain road speed, or engine RPMs? If it only does it in motion strongly suggests driveline - check driveshaft alignment and balance.. may be transmitting thru the floorpan. Or since you've done gears - any gear whine? Did whomever did the gears possibly mess something up with the driveshaft?

 

Why are you ruling out the wheels? If they are recently installed that would be my first suspect. Is the vibration/vibrations related to rpms in anyway?

 

If you lowered your car you need to adjust the driveshaft angle to avoid high speed vibration.
The gears and pulleys can be a sorce of vibration becase they are rotating, if it is the pulleys you should notice the vibration by just revving up the engine in neutral, if youfeel it then it is the pulleys, To test for driveshaft or gears related vibration lift yor car, put a couple stands under the axle, turn the TC off and take it to 100+ mph to see if you feel the vibration, if you do, remove the rear wheels and repeat the procedure to discard wheel related vibration, at this point you've narrowed the problem to drive shaft or gears.

 

First can you narrow down where the vibration is coming from? meaning front or back? combo LCA's do produce some vibe since one end is a rod end. LCA brackets can as well- get them welded in. panhard should not as long as everything is tightened to spec. gears tend to wine more than vibe. did you get an alignment after lowering it?

 

I would mark the rear of the driveshaft to the pinion flange with a sharpie. Remove the rear of the driveshaft and turn it 180 degrees from the mark. Reinstall, torque bolts to 41 ft lbs in a star pattern, use loctite. Is the problem better or worse now?

 

I would have to agree with moosestang...the driveshaft is balanced. I had the same issue in my earlier days with another car. Marked, removed and turned the drveshaft 180 degrees, reinstalled and vibration went away.

 

+ 1.......Least likely to be a cause of the vibration is the UDP's

 

Thanks for the replies

A_J

The tires wore on the inside which was expected from the tires leaning in.

Moosestang

The vibes were worse with the old tires, which were visually in bad shape (30000 miles). Also, the steering wheel always vibed with the old tires. Now it only vibes "sometimes". This leads me to believe there may be somthing loose on the front end. Any ideas on what I can check for? I am suppose to have camber bolts, but I am not sure if the alignment was even done. Where are the camber bolts at?

jrm1900

I'm pretty sure the pinion angle is at stock. This is somewhere I may need to check. I am currently running the stock shaft. The shop tried to install the Denny shaft, but were not able to stop the vibes after several different rotations. Also, I put a dial indicator on the pinion flange when I had the shaft off, and it was out .003 Is this an issue?

likemike99

Because of the shaky steering wheel and shaky seat, I think there may be problems in front and back.


So what order should I tackle the various problems in? Should I do the alignment first? Should I do the pinion angle first?


Thanks for the help

Later

 

How long have the after market rims been on?