re-rx7

iTrader: (1)

My buddy just got in his aristo swap. Before we swap it in we are trying to figure out this weird rear suspension problem. It has a vibration that shakes the cabin. Seats vibrate, floor ect. He had the wheels sent off for repair and the tires balanced multiple times but same vibration above 65 before its really pronounced. So today we put the car on jackstands and the car vibrates with the rear wheels off the ground. So we took the wheels off, and it still vibrates the same just less violently. Looking at the axles they appear to wobble some on both sides. They make no noise. Im pretty convinced this is the problem. Would yall agree? Also we accelerated the car up to 40 on the stands.

Cliff: Car vibrates when wheels are on or off. LEss with wheels off. Axles look wobbly.

xlr8steve

iTrader: (1)

It sounds more like there is a misalignment in the main driveshaft, more than the cv axles. Did it vibrate before the aristo swap? I also have a 2nd gen aristo swapped gs, but I did mine alittle different than everyone else, so I still have both halves of my original driveshaft and no vibration, just like before the swap.

re-rx7

iTrader: (1)

Interesting. The drive shaft looks fine from what I can see. No wobbles.

FrankT

How is your drive shaft carrier bearing?
This is interesting.

xlr8steve

iTrader: (1)

The reason I say main driveshaft is that I have seen probably 10 reinstalled incorrectly even without an engine swap! There are 5 things that go wrong if the tech is not paying attention, halves separated and no Mark to realign them( they are balanced together), frozen center joint,the carrier bearing bracket upside down, the small carrier bearing bracket spacers that go between the bracket and BODY ON the wrong side or just missing, rubber couplers cracked with chunks out of them, a little dry cracking while not desireable is normal and doesnt seem to cause problems until pcs are missing causing unbalance. The reason I'm not fingering the cv axles, is they do have slight radial movement when in the air , but they vibrate way more under power at any speed especially boosted and downshifting, and you didnt mention that issue. Did you reuse your crossmember or the aristo? What about trans mount? That shaft wants to be perfectly straight, you can raise the car, remove the exhaust shield and run it, put your hand on the carrier bearing crossmember,rear end, trans crossmember, and that may help you pinpoint the area, also did you have the shaft modified for the different coupler...need more info!

marshun

he said the problem was before the swap.

my bet, rear wheel bearings

Mcon

iTrader: (1)

also, one of the low or upper control arm bushing" or the rear Control arm bushing uh:

xlr8steve

iTrader: (1)

Sorry I missed the BEFORE WE SWAP IT IN... my fault. Take the cv axles loose from the rear diff at the 6 Allen bolts on each side, zip tie them from touching the diff flanges and run the vehicle to speed that it vibrates. If no vibration then cv axle, if still there rubber couplers, imbalanced center shaft, sunken trans mount.

xlr8steve

iTrader: (1)

Correction, cv axle and or wheel bearing, a wheel bearing that would be bad enough to feel without weight on it should be easy to feel by hand. Keep us posted!