What are the difficulties in installing a th400 in an '84 vette? Do I need a different cross member and does anyone make one? How will it affect the computer, etc. Thanks for any help,

 

Try to do a search, there are a couple of guys that have changed over to a 350/400 tranny. I can't remember off hand who has done it.

 

I just did one. I put a TH400 in an 86. Alot of issues have to be addressed. I installed A TH400 with a 2800 stall convertor. No electric lockup capabilityanymore. You have to convert to the pulse type of speedometer gear/transmission which did not come on the TH400. Or you could solve that by putting in a mechanical speedometer guage. I opted for a manual downshift with no kickdown. You could possibly fabricate a mount and adapt an electric kickdown switch to the throttle linkage. That will give you kickdown if so desired. So on this particular installation that I did, you have to downshift it manually with the new aftermarket shifter assembly. But that is okay since we will be shifting this thing manually anyway for street and strip duties. There are many choices in shifters out there for the TH400 application. And you need to fabricate a mount for the C beam on the rear of the trans tailshaft because the vette has no crossmember. The C beam is the only support for the rear of the trans. And lastly, you need to fabricate a driveshaft since the rear trans yoke and driveshaft length are completely different. I almost forgot that you also need to adapt the trans cooler lines since the arrangement is a little different.
It is not impossible, but it is a little more complicated than the usual type of conversion. But if you don't need an overdrive and desire a rock solid trans for street and strip duties, this is a good option.
:cheers:

 

Thanks for the info, I have a th400 manual valve body reverse pattern, and a pretty well built 408 ready to go, just bought an '84 with 149,000 on the clock, and I'm trying to learn what I can before I get started. Do you have any pictures of the mount that you made? Thanks for the info...

 

Unfortunately, I did not take any pictures. However, if you install the trans and hold up your c beam where it should go, you will see what needs to be done. You wil need to take off the tailshaft on the TH400 and weld a piece of aluminum stock with holes to match the ones on the c beam. I strengthened it by utilizing the bottom mount holes in the tailshaft also. It was not that hard. Most welding and machine shops could perform the job. You will also need to align everything and fabricate a driveshaft. Make sure that there is sufficent play for expansion.

:seeya