Whole car shake OK. If it were a stock vehicle never worked on I would first go U joints. Trans mount can cause issues, as can rear diff mount. Although rear diff mount was usually the complaint that the rear was trying to come out from under the car on take off.

If the clutch has been replaced, loose flywheel, loose clutch cover, broken clutch cover especially if it was a rebuilt unit.

60mph is the usual range for tire or wheel related vibrations. And you can usually know if it is front or rear by steering wheel or seat feel.

U joints should be obvious. You could remove the driveshaft and see if the shake goes away. If it does, driveshaft or rear. If it does not, motor, clutch, trans.

I have had a vehicles come in that had clutches done at a quick clutch place or just a general shop that had flywheel clutch issues. One the flywheel was loose, one had missing bolts on the clutch cover.

I had issues with whole car shake in the GT car, a bit unnerving when going through turn 12 and 13 at PIR in Phoenix. Needed to have the split driveshaft installed, once I did that I could run flat out through them. Then it was just - hope the Goodyears stick, and never cross that white line at the apex.

Check the motor mounts.
also the transmission mounts.
is this a Swap or was another engine PUT in?..Could it be that someone didn't tighten a mount up??.

If it is the u-joints make sure and cut the driveshaft away and save the yoke and the flange to use as a plug for the tranny. You'll never have to drain the fluid again...... unless you need to change it

Vibration is defiantly coming from the rear of the car. And it's not based on RPM or Speed, but load. Go figure. (Vibration will happen at any RPM and any Speed, but will not occur when engine braking) I'll try to find some time this weekend to get the rear in the air and check everything out. I'm thinking some mounts went out.

Mounts or bearings in the diff

Yeah, I'm thinking it's one of the mounts in the diff. I'm getting a "clink" everytime I shift between 1/2/3'rd. Just behind the driver seat. Makes me think it's the front mount, but doesn't rule out the rear diff mounts either. I don't want to rebuild the diff until I'm back in blacksburg and moved into my new place.

Diff mount has come loose and the nuts are no where to be seen. Anyone know of the correct thread pitch for the nuts? Would be very helpful.

I found the source of the vibrations. The front U-Joint has seized on me. I'm going to be putting it back together and since I don't have a U-Joint or anything that I can replace it with on hand I'm going to drive it like that until I order/receive a new drive shaft for replacement.

Last year before DGRR I had my driveshaft rebuilt locally. New u-joints (greseable) and balanced for around $200.

Wouldn't hurt to hit up some local driveline shops, may save some coin and be further ahead :)

Trouble is it's saturday. I'll look up some shops and see if they are able/willing to do it local to culpeper/gainesville. As it stands now, the drive shaft is out of the car and I can't get the F'ing sub frame back in. I can either mount the subframe or mount the rear diff mounts. But I can't do both. It's starting to tick me off a little bit.

Well, I got the new drive shaft installed. Total cost came in just under 300 shipped to my door. I would have had a drive line shop fab me up one for install but... well... they wanted close to 500 for it. On top of that they didn't install one of the bolts for my exhaust I came to find out when I took it in the first time. Looks like I'm off to get another stainless steel metric nut and bolt+washers. sigh....

Anyways like I was saying: I installed the new drive shaft. OMFG! It's like a completely different car. None of the weird noises that I just assumed were my cars natural noises, no more harsh vibrations that I attributed to road deformations and my hard suspension. It's a completely amazing feeling. It makes me want to fix the rest of the car up and get it looking and feeling just as amazing as this.

I still plan on cutting off the old drive shaft spline portion so I never have to drain tranny fluid when I pull it. But my brother-in-law doesn't have an oxy/acet torch I could use to make short work of it. Which leaves me little recourse right now (unless WE3RX7, do you has any tools I could use to chop it up?)

I still have a vibration in the rear of the car, but it's very minute and I think it's from the rear being out of alignment. I'll take it in to fire stone on sunday (if they're open) and see if they can't do an alignment for me (I do have a life time alignment thing with them).

And since I swapped drive shafts, it's amazing hitting boost. So smooth with none of the noise I used to associate with it and none of the vibrations either. :D

Good job :)

Also even a hack saw would be fine to chop off the yoke. Just might take a couple minutes.

Yup, I was going to say hack saw. I would havce a hard time choosing between my oxy/ace torch and the plasma though :D I'm a tool whore :rofl:

I felt the same way when we hunted down my vibration to the rear itself. Swapped it out and the car was silky smooth..... quite awesome actually. I know that elation well