wgreenlee4

Well so I've been working on my new 92 lx and one of the biggest problems has been this vibration. If you accelerate up to about 70mph in 4th or 5th and you let off the throttle the whole car vibrates in a frightening manner (mostly seen in the shifter but you can feel it everywhere). It is a very fast vibration and it sounds dangerous. I cannot really drive on the highway because of it. It will vibrate both in gear, and in neutral.

I read that a driveshaft rotated wrong can cause such a problem, so I rotated it 180 degrees but the problem persists. I see that there are still weights on the driveshaft (one at each end). I inspected the Ujoint and it rotates fine and has no play.

Anyone know what the problem could be?

Thanks guys!

mattdel

Is there any play in the output shaft on the trans? Woulda been on the list of things to check while checking the driveshaft.

Tony71502

It doesn't vibrate when you are on the throttle?

rydinturbo

i have the same problem nd i have a aluminum driveshaft. does yours start to make a kinda of roaring noise from the back when it vibrates? can the weight thing bolted to the rear pumpkin cause this?

Tony71502

No, plenty of people remove the weight from the differential housing. Roaring noise from the back makes me think your gears are installed improperly or a bearing is bad.

Dj_Seph

I've had this in two foxes and here's how I fixed it.
First fox, it was the little weight thing at the bottom of the pumpkin. It wasn't bolted up correctly and snug so it caused god awful vibration. Bolted it up with new hardware and it stopped the vibrations. Also did new u-joints for good measure.

Second fox, it was the output shaft little retainer or whatever. It's a little ring in the rear of the transmission and is what supports the yoke of the driveshaft. That was worn to ****. I'd check to see if you have any wear in your yoke and if so, replace it immediately. I didn't and as high RPM, the whole rear of the tranny blew, causing me to have to get a new tranny and driveshaft.

After that though, the car is smooth no matter the speed. Aluminum driveshaft FTW!

wgreenlee4

Well yes it does make a roaring noise but I would think it's mostly just because of the crazy vibration, the car feels like it's gonna explode.

It will do it when I am on the throttle, but the worst is when I just let off the throttle at high speed.

When bolted in, the driveshaft has some play (but I think it did that in neutral, I didn't test in gear, which means the rear end was having the play). I was told this was not that abnormal.

So far things to check: tranny output shaft support/ring, rear end pumpkin anti-vibration thing hardware.

Thanks!

2011scgt

weight at the rear end housing is the "dog bone"things to check
1. universe joints
2. drive shaft play
3. transmission mount
4. engine mounts

5.

rydinturbo

thats what it seems like or tires are unbalanced but i know they are. but it did this before with my old rear end nd i jus installed a new rear diff nd gears and all new bearings nd it still does it. the weight on my rear pumpkin is loose it was hanging a lil lower on one side nd i jus pushed it up by hand lol. could this cause it? what are the side effects if i remove it. sory dont mean to hijack your thread
also how do you check the output shaft

Tony71502

The weight needs to be secured. Get new bolts or the stamped piece of steel that the bolts thread into.