As the driving season is coming to a close for me, I'm starting to think about winter projects. It's becoming clear to me my trans is in serious need of some TLC. I have a spare trans lying around which I'm considering rebuilding myself. My questions to the Buick masters out there is is this something I can do myself? I have no problem tearing an engine apart but I've never done any work on a trans outside of a filter and fluid change. I know there are some specialty tools that will be required. Question two is I plan on rebuilding the engine also, but maybe not this winter. But when I do, it won't be a stock 455 rebuild. I would like to get it into the 500 hp/torque range. So what mods to the trans do I do to be ready for that? Or is that getting into a territory where it would be better for a pro to do it?
I just rebuilt my TH 400 myself for the first time. Theres tons of knowledge and experts on here and if you are somewhat mechanically inclined then you will be fine. You should definitely upgrade the sprag to a 34 element sprag, it has stronger holding power. You can install a transgo 1-2 kit or mod the separator plate and valve body yourself (explained in Ben's thread) to achieve a "free shift kit". Look into getting a custom built JW 9.5" converter, you won't be disappointed at all, trust me!! There's a bunch of free mods you can do to make the trans stronger and more efficient. I will try and post some links for you to get you pointed in the right direction. The first link is my build. I bought good quality parts, built my trans to handle whatever I could throw at it torque and HP wise the first time so I didn't have to do it again down the road when I get my other engine done. My engine build/goal is the same as yours to get the 500hp/tq range. http://www.v8buick.com/index.php?threads/rebuilding-my-th400.346849/ http://www.v8buick.com/index.php?th...-kit-and-a-few-easy-internal-upgrades.342929/ http://www.v8buick.com/index.php?threads/a-few-really-good-videos-on-th400-rebuild-stuff.346092/ http://www.v8buick.com/index.php?threads/th400-34-element-sprag.342788/
Thanks for the reply. The videos in particular were very educational. I wound up watching a bunch of YouTube videos. I think I will go ahead and rebuild one myself. For now I got a lot of research to do.
Whatever you do make sure your work area and parts are clean clean clean!! One spec of debris can clog a valve and then your into some real fun doing it all over again.
You have a nice case to work with. That's one with the extra thick ears, thicker pan rails, and stiffening web running down the center
Ben - what coded/production year(s) cases had these features? I'm looking at cores to build, and it'd be nice to start with a case like that..
I'm not sure I can answer that, I think they were early in production, 65,66,67. The one I have is a 66 Pontiac cas . But there are some easy external tells. The ears have extra webbing in them. I have a couple other pics to add but for reason lately I can only add 1 picture, then I have to wait and come back to edit Just did a quick look on craigslist and saw a long shaft Pontiac from a 74, it had this case. So no clue on production
I can say for sure the case I have is from 74 because it still has the plate with the date code on it.
I made some more progress last night. Some pictures: I got stopped because my 12 point socket wouldn't fit in the hole. You guys know what size that is again? I gotta stop at lunch to pick one up that I will grind down if need be.
I've been looking for some rebuild kits. This looks like a good one. https://www.oregonperformancetransmission.com/product/OPT-TH400-RBHP.html Though I'm not sure what some of the options are and if they are needed.
That kit is very similar to the one I bought. The red alto frictions and kolene steels are good for performance builds and can handle more than your average stock rebuild clutch parts.
It comes out. Pull out the pin, undo the nut off the stud and pull the stud back and the pawl comes off. Click on this link and it will show you a diagram. off.https://images.app.goo.gl/oPxjP6dwFGgRPumo8
Ben, I have looked at your modifications thread. Are those just for a full race application or would they work on a car that is just street? I mean for example I don't see me ever putting a trans brake on this car.
Nothing I have listed makes anything full race. I did race a trans built this way in a column shift car down to mid 11s and sure it would take more. Nothing done makes anything manual only. The only this you might want to do is not go to the full extremes on the drill sizes. Shift firmness is something that is very particular to heat person so I recommend starting small to see how you like it then go bigger if wanted. You can always drill more cant put it back on very easy
Because this is my first trans rebuild, I'm gonna be posting stuff I'm not 100% sure about. So to start: This is the manual shaft bore where the seal goes. At the bottom on the chamfer, you can see missing material. The bore where the seal seals is OK. So this is probably nothing to worry about, right? This is a closeup of the 'maze'. You can see a lot of the edges are missing a little bit of material. No where does this missing material go all the way across a flat. This is still good to use, right?
