So I'm getting ready to set up the 425 Nailhead and trans into our 54 F100. I've had the motor and trans for years, and removed them from a rusted to death 65 Rivera. The entire time I had the motor and trans I assumed the trans was of the switch pitch variety since I pulled it from a 65, but never really checked. After looking it over yesterday, I realized it is not. It appears to be a 64 only ST400, non switch pitch. After some research, I have not found little info on the 64 only trans and can not find answers to some of my questions about this thing...… -With it being non SP, can I use a regular TH400 converter in it? -With the weird 64 only valve body, can I put a later 400 valve body in it? -With the original valve body having a detent gate of PRNDL what shifter can I use with it? Power Glide? -Are the standard TH400 rebuild kits enough to rebuild this thing? save for the weird valve body which I'm sure needs a special gasket. -Any info on a home spun shift improvements with the original valve body/separator plate? I'm sure a TH400 one wont be right for the original valve body. -Or should I just go find a switch pitch or adapt another trans to it, and not mess with this odd ball one year only thing? Any input would be appreciated. As I have to decide what im doing trans wise before I set up motor and trans mounts in the truck. Thanks Jason
Check out centervilleautorepair.com. Good article on nailhead transmission options and info on the 64 ST400 as well as switch pitch models.
one of the best on the east coast guys. E-mail, telriv@yahoo.com or telriv@msn.com Phone, days, 8Am-6Pm, M-F, (203) 324-6045 Snail mail: Tom Telesco C/O Classic & Muscle Automotive 465 Glenbrook Rd. Stamford, Ct. 06906-1820
If it is a 64 ST400, you have to use a non-switch pitch convertor. I knew the 64 Buick 400 were non-switch pitch, but I didn't know they had a PRNDL selector pattern. I just pulled out my old Motor's Automatic Transmission Manual and the 64 does have the PRNDL shift selector pattern. The oil schematic also shows that it applies the intermediate band in second gear. On the later 400's the band is only applied if you put in 2 (PRND21 selector pattern). It also states that you can get the car into manual second by moving the selector to L when you are above the low downshift point. The 400 isn't a bad transmission to overhaul. The forward clutch piston takes a little finesse to get it to go back in the drum. The reason is that it has 3 lip seals and the inner one is the opposite of the other two. A lot of vasolene and some gentle twisting will get the job done. Also, keep track of all the check balls in the valve body. We have two transmission supply houses in Portland so I've never had a problem getting parts.
Thanks for the info. Yeah its not a switch pitch, and that's fine. I believe I can use a standard th400 converter in it, but have not verified that yet. I think my biggest concern at this point is a shifter, weather I can use one for a power glide or if I need an actual 64 Buick shifter. My thoughts are I want to make sure that the gates in the shifter will line up with the gate locations on the valve body.
My limited understanding based on previous experience with my 64 Riviera and the ST400: -With it being non SP, can I use a regular TH400 converter in it? I believe the converter is the same as any regular T400 style. -With the weird 64 only valve body, can I put a later 400 valve body in it? I don't think you can, but there is not really a big need to change it out if it is working. -With the original valve body having a detent gate of PRNDL what shifter can I use with it? Power Glide? I think the trans shift arm is same as regular T400, so a std T400 shifter should work, you just can't pull it down past second gear position. A PG shifter may also work, as long as the shift arm puts the trans into the right gear position. -Are the standard TH400 rebuild kits enough to rebuild this thing? save for the weird valve body which I'm sure needs a special gasket. That is my understanding, the internals are the same, just the different valve body. -Any info on a home spun shift improvements with the original valve body/separator plate? I'm sure a TH400 one wont be right for the original valve body. No ideas here, I am sure there are methods but a trans expert would know. -Or should I just go find a switch pitch or adapt another trans to it, and not mess with this odd ball one year only thing? No reason to bail on the ST400, it is tough enough to find nailhead pattern cases. Any input would be appreciated. As I have to decide what im doing trans wise before I set up motor and trans mounts in the truck. Even if you later change to a SP400, or a 65-66 ST400, the mount locations should be the same and you can use what you have for setup and getting it running and driving.
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