I'm studying up for my first DIY transmission build, and it's a TH400 for my 900 HP street/strip naturally aspirated 1970 Chevelle. I'll be building it from scratch without any TH400 core, and I have a new aftermarket Reid case for drag racing. HERE'S MY QUESTION: Do you guys have any tips or tricks to offer me for checking and/or adjusting the travel properly for the rear servo piston, to achieve the correct rear band apply so that reverse works properly? But also so that the trans brake will hold at the starting line on the drag strip before the launch? None of the videos I've watched really get into that and I'm not sure that I really have my brain wrapped around that part of the build. I even bought the Kent Moore tool but I'm not really understanding this diagram from page # 74 and 75 in the ATSG manual. Maybe once I bolt this fixture tool to the case, it will shed some light on how to use it. Maybe there's a better way instead of using the tool? I was considering the adjustable kit from Sonnax. But any tips would be appreciated. I also welcome any other warnings or tips that might address any common or potential trouble aspects of DIY TH400 builds. Thanks in advance. BTW, I plan on leaving out the OE stock type plastic "silencing" ring. I'm told it often breaks apart into pieces in drag racing applications. I couldn't find any source for a metal ring or kevlar.
This is the only video I have found on this..... 400/4L80 servo check - YouTube EDIT: maybe this is one of those things that I just won't fully understand until I go to do it and I'm in the middle of the process.
Looking at Jake's video again, it seems that the method he's using simply ensures that the piston and pin fully engages the rear band without the piston being bottomed-out.
