Speedometer Problems

[cool80]

Hi everyone, I have two questions that someone will know the answer to. My speedometer doesen't start moving until the car is going about 10mph. If I remember, the gear in the auto transmission (TM350) was light brown, the rear gears are 3.07, and the speedometer has been changed to 140/160. Any ideas??? In addition, when the rear is jacked up and the trailing arms are supported at normal drive level and the car is started and placed in reverse, do both wheels turn? I am looking for a thumping noise comming from the rear/trailing arms. Do not hear any noise when the tires are off the ground, motor running and in forward or reverse. Any help is appreciated.

cool80

 

[black_81_vette]

Yes both wheels are supposed to turn in the same dirrection when in gear.If not the posi unit could be worn out thus making a clunk under load.Also there is a rubber bushing held by a single bolt right under the pinion yoke wich is secured to the frame.the bushing could be all spongy or even missing causing the same clunk when starting out in gear. also look at the u-joints for slop.

 

[cool80]

Thanks for the reply black 81. Both wheels do turn in forward, but not in reverse. I have replaced the bushing you are talking about along with all 6 of the U joints. The noise was there when I first got the vette so I proceeded to clean up the whole underside including new U joints, new strut rod bushings, new spring bolts/bushings, new diff seals, new trailing arm bushings, cleanup and repair/adjust parking brake assembly and completly rebuild transmission. I did notice a little slop in the yoke spline where it is connected to the trailing arm. This could be the problem. It could also be clutches in the diff. Thanks again

cool80