I need some help trying to figure out what is causing this drivetrain vibration. I have a 388 SBC/T56, custom made driveshaft, and a Quick Performance ford 9". the vibration is only evident above 65 MPH. Any other time you can't notice it. And the faster I go the worse it gets. I tried adjusting the pinion angle with some adjustable upper control arms and have it set up at -3 degrees. Running out of ideas. Maybe improperly balanced driveshaft? Or maybe a bad U-joint? Any suggestions cause I am all ears! thanks!
Drivetrain vibration
- Thread starter T56elcamino
- Start date
Drive it again and try and feel where the vibration is felt first. Usually, wheel balance can be felt in the steering wheel first, if a front wheel is out of balance. If the vibration is felt in the seat it may be a rear wheel. Anything else more severe (dash, rear view mirror, etc.) than that may be a driveline issue. If the shocks are maginal, wheel tramp at high speed may start with a slightly out of balance wheel and tire but exaggerate with speed. At the 65 plus speeds your mentioning, it may be wheel trap. JMO
Steve
Steve
I do have an issue with my shocks, I have the QP ford 9" and the shock mounting is way out of wack for some reason, and I know I am not the first to complain about this. I can feel the vibration only in the seat. I may try also borrowing my buddies wheels and tires off S-10, should be the same bolt pattern right? Thanks guys!
Can you give us some info on your trans, where it came from, what style, how many miles, who rebuilt it etc? When does the vibe start and is it a pounding vibe or just a small one? I have a t56 in my regal that had a vibe in 5 and 6 at about 75 and up. Turns out one culprit is the press fit of the 5/6 gear on the main shaft and end plays on the shafts can cause it too. Should be getting mine back from texas drivetrain performance tomorrow for a rebuild needed to fix that exact problem. I am hoping that fixes it and i can finally enjoy my car. at least it is something to look into.
Mike
Mike
Is it a high speed vibration (like you're sitting inside an electric razor that will rattle your fillings)? That kind of vibration is caused by something forward of the pinion gear. Low speed vibrations are wheel/tire/axle issues.
Sometimes putting the rear up on jackstands and sliwly increasing speed can be a help diagnosing these situations. You can take the wheels off and see if there's any change. It also rules out any problems on the front end of the car.
I;m assuming it changes only with MPH, not with RPM. Anything that changes with RPM is a problem inside the bellhousing or the engine itself.
Sometimes putting the rear up on jackstands and sliwly increasing speed can be a help diagnosing these situations. You can take the wheels off and see if there's any change. It also rules out any problems on the front end of the car.
I;m assuming it changes only with MPH, not with RPM. Anything that changes with RPM is a problem inside the bellhousing or the engine itself.
