shaking badly at cruising speeds

[MaxHarvard]

the vibration starts around cruising speeds, 60-65mph, in 4th 5th and 6th gear, the entire car shakes.... bad. im taking the driveshaft back to the guy who shortened it so if he didnt balance it right... any other suggestions?? Pinion angle looks to be decent..

as a test i went up to cruising speed, felt the vibration, then put it in neutral and it still vibrated.

Thanks!

[XcYZ]

Driveshaft would be the first place I'd look since you just did the T56 swap. While your under there, check the pinion and driveline angle.

[camcojb]

driveline angle. Can't look at it and tell if it's okay, you need to measure it. I usually go with 2-3 degrees down on my street stuff.

Jody

[Payton King]

Not balanced or the u-joints are not lined up front to back.

Did you do your own cross member or did you get one from Tyler?

Get a protracor from Home Depot for about $12. Just like Jody said about 2 to 3 degrees "down" at the trans and the same amount "up" at the rear end.

[ProdigyCustoms]

FYI, almost all tire vibration starts at 60 MPH to 65 MPH and goes away at 70 MPH to 75MPH. If you can drive through it, its tires. If it gets progressivly worse, it is drivetrain as you never drive out of drivetrain. Based on your trouble zone of 65MPH which is the sweet spot for tire shake, I am betting tires. If it is in the seat of you pants, its rear tires, in the steering wheel, up front.

[Silver69Camaro]

Originally Posted by ProdigyCustoms

FYI, almost all tire vibration starts at 6 MPH to 65 MPH and goes away at 70 MPH to 75MPH. If you can drive through it, its tires. If it gets progressivly worse, it is drivetrain as you never drive out of drivetrain. Based on your trouble zone of 65MPH which is the sweet spot for tire shake, I am betting tires. If it is in the seat of you pants, its rear tires, in the steering wheel, up front.

Tires are my guess too. Doesn't sound like a driveshaft to me.

Be sure to update us, I'm curious!

[Payton King]

His car was running and driving before he did the swap. I am assuming he had driven the car before the swap and this started afterwards. Had a friend that had a vibration that was rpm and load sensitive...he was shearing off ring gear bolts one at a time...that was hard to find as it was the last place that was checked.

[camcojb]

yeah, since the only change was the trans install and he didn't have the issue until then I was leaning towards driveline angles (which need to be measured), especially as it gets worse the faster you go. If it was the wrong flywheel or other imbalance regarding the engine it seems like it would be rpm related in all gears.

Jody

[MaxHarvard]

hehe, thanks guys for the ideas... all those ideas went through my head.

Tires?... nope, didnt have that issue before.

Alignment?... it certainly needs one in a big way, but not this bad.

drive line angles... very possible, i did get the X-member from Tyler, still, could be possible something isnt right.

Driveshaft? .... lets see... its shortened... the guy F'd up the first time, wasnt too happy to see me bring it back and complain, he did it fairly quickly the second time... i bet he didnt balance it. So i sent it off to the guy (his name is Gary, i call him one-tooth-bucky because he has one tooth and i dont think his upper lip can ever contain it), once again he's not happy to hear from me since this is the third time its been at his shop. i call him a few hours later...

Me - did you get a chance to look at my driveshaft? Did it need balancing or a new U-joint?
bucky - Yea.... did you drop this thing?
Me - Uhh... no, did you?
Bucky - This thing was WAY off, we took off a 4 oz weight in the back near the rear end side and it was perfect after that.
Me - So that could have caused my shaking problem?
Buckey - Oh yea for sure.
Me - Ok, send it back to my shop.

So, one problem solved. That doesnt mean my shaking will go away, just one more piece to the puzzle

thanks again for the help fella's

[XcYZ]

Cool, thanks for the update, Eric. Glad to hear that you got it figured out.