70rivme Posted April 18, 2020 Share Posted April 18, 2020 As my '70 Riv is on it's way to getting the engine put back in with TA headers and hopefully no more oil leak, I am rolling the idea around of rebuilding the original Turbo 400. My 1st instinct is to shelve it like I have with the original differential and engine, but I think on this go around I will use the original trans. I like to bring my Riviera counseling here first and then if necessary I will try V8 Buick, but for now you are all stuck with my question. Has anyone rebuilt their own transmission and do you have any suggestions on kits and/or upgrade parts? My newly rebuilt 455 is supposed to have 450ish HP and 550ish ft/lbs. I wanted to get it dyno tested to know for sure but the builder kept telling me that it would be quite expensive and is not necessary so i am at the mercy of what he told me. I guess since it is still out of the car I could find someone to dyno it, but that will have to be later. Anyways I know a TH400 can hold up to alot in stock form but I want this to be a one and done project. What do you all say? Thank you! Link to comment Share on other sites More sharing options...
EmTee Posted April 18, 2020 Share Posted April 18, 2020 2 hours ago, 70rivme said: I want this to be a one and done project. I think that you answered your own question... Link to comment Share on other sites More sharing options...
70rivme Posted April 18, 2020 Author Share Posted April 18, 2020 8 minutes ago, EmTee said: I think that you answered your own question... You lost me already, what did I already answer? Maybe I missed something. Link to comment Share on other sites More sharing options...
RivNut Posted April 18, 2020 Share Posted April 18, 2020 Is the dyno run "expensive" because the builder doesn't want you to know he didn't reach your goal? A 'built' 200-4R overdrive transmission is a bolt-on behind a Buick Big block. You can run 3.73 or 3.91 gears and still have an above average road gear. A 3.91 with a 200-R4 will give a 2.62 final drive. Link to comment Share on other sites More sharing options...
EmTee Posted April 18, 2020 Share Posted April 18, 2020 Ha - I was trying to be a bit of a smart a$$... It sounds to me like you'd prefer to only deal with one repair cycle -- so doing the transmission while the engine is already out makes sense and saves you from having to deal with a transmission rebuild a year or two from now. Good news is if the trans was functioning fine before, all it should require is new seals and friction discs. Anyone who knows what they're doing can rebuild the clutches with a few extra friction discs and firm-up the shifts to compliment the engine build. Remember, these transmissions handled 455 GSXs with 500 ft-lbs out-of-the box... 1 Link to comment Share on other sites More sharing options...
70rivme Posted April 18, 2020 Author Share Posted April 18, 2020 6 minutes ago, RivNut said: Is the dyno run "expensive" because the builder doesn't want you to know he didn't reach your goal? A 'built' 200-4R overdrive transmission is a bolt-on behind a Buick Big block. You can run 3.73 or 3.91 gears and still have an above average road gear. A 3.91 with a 200-R4 will give a 2.62 final drive. Honestly I do not know how much a dyno run costs and i would like to believe that when a reputable engine builder tells me something that he is honorable and is telling me like it is. Buuuut, the "expensive " part has crossed my mind to be perfectly honest but like I said. I like to think on the side of honorable. As for the 200-4R, I like where your head is at! I am in possession of a 200-4R and have contemplated installing but I think there is a little more to it than just putting it in the car and calling it a day. At this point my search for a numerically higher differential set up is stalled as I cannot find anything higher than the 3.08 I installed in it and I would like to just get the Riv on the road before I start making further changes to it. There is nothing set in stone as of yet, but the 400 trans just seems to be the easiest route for now. I just got done clearancing (hammering) the TA headers to fit on the left side and they will be sent out this week for the Jet Hot treatment so there will be plenty of time to think about this I guess. Link to comment Share on other sites More sharing options...
70rivme Posted April 18, 2020 Author Share Posted April 18, 2020 (edited) 31 minutes ago, EmTee said: Ha - I was trying to be a bit of a smart a$$... It sounds to me like you'd prefer to only deal with one repair cycle -- so doing the transmission while the engine is already out makes sense and saves you from having to deal with a transmission rebuild a year or two from now. Good news is if the trans was functioning fine before, all it should require is new seals and friction discs. Anyone who knows what they're doing can rebuild the clutches with a few extra friction discs and firm-up the shifts to compliment the engine build. Remember, these transmissions handled 455 GSXs with 500 ft-lbs out-of-the box... I kinda figured you were trying to give me a smart ass comment, but wasn't completely sure if I did miss something or not. Trans worked great before removing it and even worked great with the new engine in front of it for a very short while before the removal. Definitely needs a higher stall though. I am going to rebuild it myself, something that i haven't done in a loooooong time. Just need some tips and tricks that will strengthen any weak points and hopefully enhance this 455 even more. Edited April 18, 2020 by 70rivme (see edit history) Link to comment Share on other sites More sharing options...
EmTee Posted April 18, 2020 Share Posted April 18, 2020 (edited) I still have my grandmother's '56 Chevy that I drove in high school. Back in the mid/late 70's I replaced the original 265/Powerglide with a 327/TH-400. There was an older transmission guy who used to stop by my best friend's father's gas station. He sold me a valve body for the TH-400 that he said he modified based on an article in Hot Rod magizine. Sorry, but I don't know what issue,but probably early to mid 70's. Anyway, the performance change was night & day! The deeper my foot is in the throttle, the harder it shifts. Light throttle, well-behaved (but firm) -- foot to the floor yielded tire chirp on 1-2 shift. Whereas stock it only held 1st gear until 6000 RPM, the modified valve body would hold first until something exploded. He told me at the time that the modifications mainly involved leaving out certain balls and springs, I don't remember for sure, but I don't think there was any drilling or other permanent modification made to the valve body. The car isn't currently on the road, but it's on my list to get it recommissioned so I can experience that again... Edited April 18, 2020 by EmTee (see edit history) 1 Link to comment Share on other sites More sharing options...
RivNut Posted April 18, 2020 Share Posted April 18, 2020 The TH200-4R has a dual pattern bolt pattern on the bellhousing. The 67> TH400 bolt patterns for BOP and Chevy. The converter bolts to your flex plate and the transmission bolts to your block. You might have to work with the length of the driveshaft but the transmission mount bolt holes are very close. The biggest thing you'll have to deal with is the TV (throttle valve) cable which controls upshifts / downshifts / EVERYTHING. If it's not installed/adjusted correctly, you can fry the transmission by driving the car a few feet. The cable is connected to the carb linkage. The TH200-4 is the transmission used in the 87 Grand National GNX. Some of those cars are now modified to put out over 1,000 horsepower. Something to think about anyway. Link to comment Share on other sites More sharing options...
70rivme Posted April 18, 2020 Author Share Posted April 18, 2020 4 hours ago, RivNut said: The TH200-4R has a dual pattern bolt pattern on the bellhousing. The 67> TH400 bolt patterns for BOP and Chevy. The converter bolts to your flex plate and the transmission bolts to your block. You might have to work with the length of the driveshaft but the transmission mount bolt holes are very close. The biggest thing you'll have to deal with is the TV (throttle valve) cable which controls upshifts / downshifts / EVERYTHING. If it's not installed/adjusted correctly, you can fry the transmission by driving the car a few feet. The cable is connected to the carb linkage. The TH200-4 is the transmission used in the 87 Grand National GNX. Some of those cars are now modified to put out over 1,000 horsepower. Something to think about anyway. This is good info. I know everything in the front will bolt up but honestly thought the trans mount was quite a bit off and the difference in overall length required a slightly different length driveshaft. I also think the trans output splines are a different count if my memory is working correct. Back in my heavy automotive days I have seen what a misadjusted TV cable is capable of. No Bueno! Link to comment Share on other sites More sharing options...
KongaMan Posted April 18, 2020 Share Posted April 18, 2020 If it ain't broke don't fix it. If you go looking for problems, you'll probably find (or create) one. 2 1 Link to comment Share on other sites More sharing options...
70rivme Posted April 19, 2020 Author Share Posted April 19, 2020 9 hours ago, KongaMan said: If it ain't broke don't fix it. If you go looking for problems, you'll probably find (or create) one. Words of wisdom right there!!! This is deja vu as I have spoken similar words to a friend doing similar work. Link to comment Share on other sites More sharing options...
XframeFX Posted April 19, 2020 Share Posted April 19, 2020 The TH400 is a vintage transmission but I know of plenty of places that can do it in my area. So shipping a heavy item like this should be minimal. Based on this, if a rebuild is in order, I would farm-it-out. Since these shops don't see many TH400s, they will rebuild yours with your parts and not be building several TH400s in the same production run. Something you don't want. But the big places can test them. For me, no need to go to a production place. There are a few specialty places that will take it on with knowledge on TH400 upgrades such as Trans Go shift kits and center supports. Search for a Jim Weise write-up on the TH400 from trishieldperformance.com (V8Buick.com). He mentions the 1965 to 1970 TH400s being the better transmissions. He has good info on it. Two years ago, I removed a 1966 BOP ST400 just to strip it of the switch pitch torque converter and front pump assembly. If it was a nailhead ST400, I would've purchased the whole transmission! Now thinking I should've bought the whole unit. Good choice on the TH400. John B. Link to comment Share on other sites More sharing options...
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