ws6duramax

I installed a USED Moser 9'' in my M6 T/A several years ago and it had a vibration starting around 70mph and progressively gets much worse as the speed goes up . It does it any gear . I've tried to track it down and never had any luck . As a result the car has not been driven in about 3 yrs , I would really like to try to get it back on the road this year .

I haven't work on the car for awhile now , so I will try to post what I have done to the best of what I remember .

Rear is a M9 with 411 and a Detroit locker and 31 spline axles . Driveshaft came with the rear and has been balanced and new u-joints . Bmr torque arm and cross member . I have now idea where the pinion angle is currently at , but I have tried it about everywhere with no change .

Any suggestions or ideas would be greatly appreciated . The one thing to remember is the rear and driveshaft were used parts , so anything is possible .

Thanks in advance

ramairetransam

iTrader: (18)

i would get a magnetic angle finder and make sure you have the pinion angle set correctly .

Second i would get your wheels and tires road force balanced if setting the pinion angle correctly doesn't help .

MidwestChassis2

iTrader: (1)

Try clocking the driveshaft 180, sounds odd but some times it works. Make sure the driveshaft is the correct length. Look for warn bushings on the torque arm, PHB, and LCA. Ramairetransam is also correct on checking your pinion angle, 1.5 is a good starting point.

ws6duramax

I have an angle finder , I'll have to check to see exactly where it's at right now . I have changed it several times and never seen any change at all .

Driveshaft has been out several times , I'm sure it's been clocked 180 a time a two , but I will make it a point to do it . The driveshaft is definitely not to short . It seats to about 1/2'' from the output shaft seal .

As for the rest of the suspension , it is all new bmr . Panhard , lca and torque arm .

Rims and tires are good to . They are the same as what I had used with my 10 bolt . It is not tire balance type of vibration .

guppymech

iTrader: (7)

Check out this tech tip from Hurst Driveline,
http://www.hurst-drivelines.com/wp-c...roc_111606.pdf
also,
http://www.hurst-drivelines.com/wp-c...ration-FAQ.pdf

From what I've read aftermarket trans TA relo crossmembers don't position the trans at the same height as stock. My UMI crossmember positioned my trans .375 too low. That would cause a vib if not corrected for.

01ssreda4

iTrader: (96)

Zero your pinion angle and see if your vibe is gone. Meaning the u joint cap at the front and rear (when facing down) are the exact same angle. Bet your vibe goes away immediately.

ws6duramax

I will give that a try this weekend and see what happens .

ws6duramax

I clocked DS 180 , no change .

Set pinion angle same as transmission angle , no change . Rotated DS again no change .

Tried several other pinion angles combinations with no change .

I got tired of chasing this around , so I put the 10 bolt back in and no vibration !

Maybe when I get some more time I'll put the 9'' back in and try to figure it again . Thanks for the advice , it was worth a try .