Inliners International Forums General Discussion Drive Train driveline vibrations

I am looking for suggestions on how to fix driveline vibrations. I have a 40 Chevy/GMC 302/T5/9inch combination that has major vibrations above 50 mph.

I have had the trans,driveshaft and rearend checked for runout. The engine,flywheel and clutch combo runs vib free when w/o the trans. The driveshaft angles are equal at both ends.

I have two front mounts on each side of the engine which are rubber mounted vertical posts off the crossmember. The rear mounts are standard chevy pads under each side of the bellhousing and mounted on a truck crossmember bolted across the chassis rails. The T5 trans is not mounted to the chassis. The engine/trans combo seems to be very solid in the car when gunned in neutral but it vibrates at high speed.

Any suggestions would be greatly appreciated Thanks, Frank H.

Dear Frank;

The only thing you didn't mention was the driveshaft ballance.

I'm sure you had this done when it was made. A 'double check' would eliminate one thing.

Are you running 'radial' tires?? My 57 never "felt right" till I got rid of mine.

Good luck, John M.....

You said your T-5 is not mounted to the chassis?
Do you mean you do not have a transmission cross member? If not, you should put on in with the rubber isolators. You might consider moving the rear pads on your bellhousing back or eliminating them and use a trans mount. This may be be the problem. Pinion angle too. The rear pinion should be parallel to the trans pinion yoke. The rear pinion should be approx.5-7 degrees (facing down)as the rear end will torque up during accerleration thus being faily level when driving.

RapRap
1940 ChoppedChevyCoupe