bad driveline vibration?

ba#97 · Aug 9, 2012

ok so this is weirding me out cuz I want to be hitting a track day soon but idk if my car would handle it with how this is. earlier today i was just driving around and decided to get on it a bit, at about 80mph i lifted to shift 4th to 5th, car started vibrating pretty bad, only does it when i lift, it also happens when I'm driving on the highway at 75+ and lift off the gas. in gear or not. it's odd. my car has the old driveshaft on it right now, gonna be putting the aluminum one back on this weekend and give it another go. when i autocross or just normal daily drive it feels fine. car has original trans, ram aluminum flywheel and spec stage 2 clutch (both brand new), new throwout and pilot bearings. anybody have any ideas? could it be my trans? i'm afraid if i take a track day it might break or cause me to wreck. not sure what to do here.

JJhirsch · Aug 10, 2012

Do you have any Poly motor and trans mounts? some times those will give a little vibration at some speed and even more when you are going 70+ in gear. I even get come steering wheel vibration at some speeds from it until i take it out of gear.

Last year my 94 gt mustang with 120k miles on it would do this exact thing where when you let go of the gas after a pull or normal acceleration it would shutter or vibrate and at 75+ it would shutter bad no matter what you did. I would push in the clutch and let the motor rev down and it would still vibrate like a bad tire or off balance tire 75+.

I ended up taking it to a shop to take a look at it and they found a vibration in the rear end. So i had a Good shop replace all my bearings in the rear end and haven't had a problem since.

So i suggest you bring it to a shop that will look at it for free or low cost and go from there. Also do not get it fixed at the first shop you stop at always shop around for the best price.

ba#97 · Aug 10, 2012

wow...thanks...that is exactly in every way what this car is doing. Sadly just had a new rear diff put in too. so yeah gonna have to get it checked out. and no nothing poly in the car.

ttocs · Aug 10, 2012

tires check yer tires, front if you feel it when lifting/braking.

ba#97 · Aug 10, 2012

ttocs said:
tires check yer tires, front if you feel it when lifting/braking.

my tires or my wheel weights? i don't think anything is wrong with my tires but I'll check. it only happens at 75+ like what we talked about ^^.

Venom351R · Aug 12, 2012

can also be your U Joints. Mine when on my previous GT before and at a specific RPM/Speed it would vibtrate up through the drivetrain into the shifter. Got an aluminum Drive Shaft and fixed that issue pretty quick.

RichV · Aug 12, 2012

+1 for the balance 1st, then swap driveshafts, since you have another one. If it's still there, it will probably be something driveline related. Rear end, possibly alignment, could also be something in the trans. I don't think you could wreck a T5 tailshaft with relatively stock HP, but my buddy had a bent tailshaft in his Fox that was causing a vibration like this as well.

ba#97 · Aug 16, 2012

I have to take the aluminum driveshaft and get it balanced then I'm gonna check the tire balance. I noticed the other day the left front was missing 2 wheel weights so hopefully it was that. I'm gonna be doing routine maintenance after this last autox next weekend anyways, brake lines, turn rotors, fluids, alignment etc etc. so hopefully I can figure it out!