I just got finished installing a 9 bolt with 3:27 LSD and PBR brakes in my 87 Formula (converted from a peg leg 10 bolt with drums and 2.73s). The internals in the rear are all stock 90 IROC and the only thing I did to it was take out the axles and put the backing plates on (they were missing when I rear). The brakes and POSI works great...no problems at all. The only thing is it is making a fairly loud high pitched whine (with the windows down and radio on you can still barely hear it) when at speed....I think its know as at float. Its perfectly quite at acceleration and decelleration...in fact if you increase or decrease speed through the throttle at even the slightest amount it will stop. It SEEMs to be coming from the drivers side but I am not sure...and the car also pulls to the left a little now (its not in the front end..everything is new and lined up...and it didnt do it before the swap). What do you guys think it could be....possilbly the outer axle bearing????

Any help or input would be most apprecaited...I hate to just live with it considering the money I have/am spending on this car. THANKS.

 

TTT...I am sure some of you 9-bolt experts can help me with this!

 

There is a cracked tooth in the gears, not enough lube in the differential, the gears were installed wrong, or they're just a bad set of gears. 9-bolt gears are usually noisier than 10-bolt gears, especially the 3.70's.