[screamin340]

ok guys heres a question for ya.. Ive seen all kinds of articals about swapping from a 350/400 to a 200r4 . Now I want to swap from a 200r4 to a th400 In my 76 Vette. This 200 thats in here now is really making me mad..I hate the TV system the trans slips so bad (yes its full) its not even fun to drive anymore I cant keep the pan sealed I have to torque the pan so bad to get it by the exhaust I think its bent and my front main seal leaks (so its gotta come down anyway) Basically im planning for the future. Eventually i'm going to have a big block in there..but thats way down the line
I know im gonna hear alot of reasons not to do it. but the 200 is too expensive to repair for me. I got a freshly rebuilt TCI street fighter TH400 for 250.00 and was planning on getting the TCI breakaway converter.
I know these transmissions are close in size and I know I have to change the front driveshaft Yoke and get a flexplate. other than what else can I expect?
Thanks again for your help

[killerformula]

what rear gears do you have in your car? I would do everything I could to keep that 200 in it, that overdrive is really nice. Plus it uses less power, weighs less and has a lower first gear. If you trans is slipping you need to diagnose that first, clutches are probably the first thing you'd think about.

Why not just freshen up the 200? Get a nice, new, aluminum pan for it and a rebuild kit and do it up!

K

[Hippie]

I'd fix the 200 but you seem determined. Crossmember stays where it is but you'll need to shorten your driveshaft and change the yoke or get the correct Vette TH400 shaft. You'll also need to add the kickdown switch under the dash as TH400's used electric kickdown. That's all I can think of right now.

[71 c-10]

my buddy did the 400 to 200r4 swap in his 75 vette. he didnt need to change the length of his drive shaft, his flywheel bolted up fine from one to the other, the only other thing is the shifter will have to converted to a 3 speed set up and the detent set up, not a hard swap, go for it, the 400 can take a beeting.

[screamin340]

Thanks for the replies guys I know about the switch under the dash just forgot to post it. Ive had this car almost 2 years and this trans has NEVER been right. Ive set the TV system until I was blue in the face, Taken numerous pressure readings So i know the TV is set up right. It seems to be very sporadic<SP> sloppy shifts, hard shifts, late shifts, in OD by 25 MPH some times it dosent go into OD at all..and some days it works like a champ at this point im pretty discouraged. I got the 400 at a good price from a reputible source and its already been rebuilt I know about the weight the gear ratio and the lower power useage..I didnt just jump into this its been something ive been thinking about for a while..
You guys have been good to me in the past. Just wanted to see if I was gonna run into probs. thanks for the driveshaft/tailshaft info you guys rock

[Hippie]

Originally Posted by 71 c-10

my buddy did the 400 to 200r4 swap in his 75 vette. he didnt need to change the length of his drive shaft, his flywheel bolted up fine from one to the other, the only other thing is the shifter will have to converted to a 3 speed set up and the detent set up, not a hard swap, go for it, the 400 can take a beeting.

While the 200-4R and TH400 share the location of the rear mount and appear to be the same length the 200-4R is the same overall length as a short shaft TH350, the short shaft TH400 is about 7/8" longer. The TH350, 200-4R and 700R4 use a 27 spline output shaft and yoke the TH400 uses a 32 spline yoke. It would be possible to go from a TH400 to a 200-4R using the same shaft by changing the yoke although it wouldn't engage the tailshaft as much and I don't think I'd like that but I'm sure people do it all the time and get by with it. However if you're switching from a car that was originally equipped with a TH350 and still has the TH350 driveshaft you better shorten it for the TH400 swap or you run the risk of binding against the tailhousing. I switched from a TH350 in a '72 Chevelle to a TH400 and while I could have physically installed the 350 shaft by simply swapping yokes the first time the rear suspension made any significant movement bad things would have happened. I understand a Chevelle is not a Corvette and that may not be an issue with IRS but I'd still check the driveshaft fit up VERY closely. Now if screamin340's car was originally equipped with a TH400 and they kept the 400 driveshaft then all you need to do is switch it back to the TH400 32 spline yoke.