I have a question for members knowledgeable about the Turbo 400: I purchased a rebuilt BA transmission and believe I was told that it was essentially stock. It wouldn't chirp the tires like a BB, but would still be fine for my non-stage 455. That is what I was looking for. Being curious, I removed the pan and valve body to see what might have been done in the rebuild. The obvious mods were removal of the accumulator piston servo spring and drilling out the 1st and 2nd gear apply holes to .156" in the separator plate. I don't know if anything has been done to the 1-2 primary accumulator valve as I have not removed it. One thing I did notice was that only 2 check balls were installed. The instructions for the B&M Shift Improver Kit call for 3 check balls to be installed. Are 2 check balls vs. 3 a common modification? The attached .pdf shows the two check balls installed and those missing. The circled location is where the third ball should be according to B&M. Also, there is no wire from the spark control pressure switch to the electrical connector that mounts through the case. View attachment GSX BA Oil Passage Check Balls.pdf So, am I good to go or should I add ball #3, drill out the spacer plate holes to 3/16", add the spark control wire, or do anything else to improve performance/ reliability? I don't need a race transmission, but one that will "chirp" the tires. Thanks to all for their input. Art B
Art, your PDF link didn't work for me. I am curious , as I have a TH400 w/ a shift kit in it. I can't remember or find paperwork for it, and I have no idea if the builder used a B&M or TransGo kit. As JW will probably tell you , people use all kinds of "tricks" to improve their shifting/shift points and end up butching a perfectly good trans. Be interested in seeing your diagram. Jim/Rott
Good Afternoon Das Rottweiler: Sorry for the slow reply....spent some time in the hospital. Thanks for your response. The pdf was just a photo of the case oil passages showing where the check ball are. You can find the same picture in the instruction manual for the B&M Shift Improver Kit # 20260. It is available on line. The TCI 400000 kit instructions show the same illustration, just not a clear. OK, the trans I bought is a '70 BA that was rebuilt to BA specs. and not BB. No reason to doubt that. Since the pan was grungy, I removed it to clean it up. As I had seen a few videos on YouTube, I decided to take a closer look. I carefully disassembled the valve body making sketches as I went. The valve body had a little gunk in it went through the parts washer. During the reassembly, I found two valves that were not assembled according to the Shop Manual illustration. That was easy. I hope I didn't undo something that was done intentionally. However, the illustration shows 2 springs in the 1-2 accumulator valve assembly for the BA and only one for the BB. Mine had no springs and a set screw slipped in as a spacer.. WFT? I'm sure there are dozens of ways builders assemble there for a specific application. While the BB illustration shows only one spring, there is no mention of anything in its place. So, I will source and install the two springs. This wasn't a totally stock rebuild as the 2-3 accumulator valve had the spring removed (common modification) and the 2nd and 3rd gear apply holes had been drilled out to .0.156" in the spacer plate. This is also part of the B&M kit modification for street use. Back to the check balls. My BA had only two installed in positions 5 and 6 as shown in the B&M instructions Figure 11. B&M says put balls in position 4-5-6. The TCI 400000 instructions call for ball in positions 1-2-3-5 and 6 shown in the B&M instructions . So are 2 check balls acceptable? I don't claim to know anything about the T-400 except it does what it is designed to do through oil pressure, speed and vacuum. Any recommendations or advice on my situation for a mild shift upgrade is appreciated. Thanks. Art B.
Art, NP on the slow response, hope you are feeling better . I will Google B&M as well as TransGo shift kits and see what comes up. Automatic Transmissions have always been Voodoo to me. Always had a reliable Tranny Shop build them for me. Jim/Rott
In reality all you need is one (1) check ball in the, what's called, the "bathtub" spot on the very rear of the separator plate. I don't know about the springs. As you are doing you will have to do more research on the subject. There are many ways & methods to modding TH400's. Everyone has their own. Tom T.
Tom: Thanks for the reply. I figure that if I start with the stock valve assembly in the valve body, I can't screw anything up. From there, the modifications described the B&M, TCI or TransGo kits, I should be OK. Now, if there are specific parts supplied, that could be another story. I have no idea if the valve body gaskets and separator plates, for example, are the same as stock or have their own tweaks. I suppose the more I poke around the more tidbits I'll pick up. I won't do anything that jeopardizes the BA case or internals. Have a great week. Art B
