anyone have a t56 crossmember?

[dyrt]

Howdy folks,

I have been fighting with a vibration problem in my 86 regal for some time after a t56 swap(low pitch vibe in 5th and 6th at around 73 and up). part of the problem is the fact that i was working on my back and, like a jackass, was rushing and didn't plan ahead enough to take better measurements when i pulled the 4l60e to swap in the t56. I welded a new perch to a 200r4 crossmember for the rear mount after getting the trans and rear at the same angle, but i have pretty much ruled out everything else and want to try to get the back of the trans as close to the stock regal angle as possible. can anyone with a stock suspension g-body and a t56 with no driveline problems give me a quick angle measurement at the tailshaft when the car is either sitting on the wheels or with the frame level on a lift? if not, does anyone have a t56 crossmember sitting around and can give me a quick measurement of the relationship between the frame mount surface(the surface that actually contacts the frame when mounted) and the top of the trans perch?



Thanks

By the way, i already had a new 3.5 inch aluminum driveshaft made to replace the stock one, replaced the drums with new ones, and looked for exhaust hitting the frame, etc. I have also been told that a possible reason this happens is because when my trans went back together the 5/6 gear just slipped into place but it is supposed to be a press fit, so the 5/6 gear may be causing a vibe due to the gear not being as tight on the shaft as it is supposed to be. I am pretty sure i swapped my wheels around also, but i will give that another try just for the hell of it too in case i didn't.

 

[454mali]

I had a similar problem and have measured both th350 crossmembers and the 2004r crossmember. both where the bottom of the rubber mount sits for the trans is the same level as where the crossmember bolts to the frame. the 200 mount is roughly 6" farther back than the th350 and the mount is at the same level. as long as you are close it should be ok

 

[dyrt]

Thanks for the info! the problem i recall with this swap is that the 6 speed tail housing is deeper, that is, from the center line of the output shaft to the rear mount surface is different from the t350. i remember reading a swap where someone said they took the original perch, turned it upside down, and welded it on as low as they could, but i never got a response from any emails. i think what i will have to do is remeasure the 700r4's shaft centerline to mount surface depth and try to get a measurement on a t-56 from someone since i really don't want to pull my driveline back apart. if the perch mount surface is level with the frame then i will just have to cut my perch off, remeasure, and reweld.


Mike