st 400 transmissions

[35chevcoupe]

Anyone familliar with the st400 trans ? are they pretty much the same internally as a turbo 400 ?
I,m just wondering how much power you can put in front of them .

[WkillGS]

I only know a little about them.... I rebuilt one in 1984 or so! Yes, they have TH400 internals. Might want to upgrade the intermediate sprag and I believe sometime in '66 they added a snap ring to keep the center support from moving around. I think the earlier case can be machined for it. Later valve bodies can be swapped in for better control.
'64 ST400 used a different case, valve body, and didn't have the switch-pitch converter. 65-66 units are preferred.

[GreatScat1965]

I'm not a trans guy but I can say with certainty that you can but a late model valve body/HD parts including a sprag and in my case a late model pump to convert to fixed stall. I don't know what if any mods had to be made to the case but Internally my ST400 is no different that a later model TH400. At least that is what I was lead to believe from my trans guy. (Case mods are needed for trans brakes) I know it has a TCI valve body, Coan converter and the HD parts I think may have came from Rossler. It's been several years since Vince Janis did my trans so some detail are a little fuzzy. You might want to contact him if you are in the Midwest.

Jerry

[35chevcoupe]

Thanks Walt and Jerry ,   good to hear they take a lot of the same parts as the th 400 .
I know the th 400 can take some pretty serious HP .

[Brian]

I have a complete nailhead ST400 out of a 66 Riviera I would love to sell if you are looking for one.  Took it out of a car in 1989 and it has been in the barn ever since.  The engine in the car had thrown a rod, so the trans was running and working when that happened.  After sitting all these years, it will definitely need a rebuild.  I have the flexplate that goes with it too. 

[35chevcoupe]

Brian , I have one now but might be interested in another for a spare .
Getting it here reasonably is the problem .