Going to reactivate this thread...maybe something has changed in the meanwhile.. I recently aquired a 71 OW TH400 out of a Buick (VIN is Buick) but unfortunately the previous rebuilder removed the valvebody and installed a different one for the former customer ou:. Now I have a rebuilt OW but without a valvebody. Is there a kit or someone who can calibrate a TH400 valvebody to behave like an OW or BB valvebody? My 67 442 used to do the 3-1 at speeds below 30mph and this really rocked
No, there is not. There are some valve bodies that are better than others. I don't know which ones. Mark DeConti (DCM422) would be able to answer that better than I.
I may as well chime in and say I fixed mine years ago and snaps down to first from third fairly consistently at lower speed. My original problem is I had a bad wire going to my solenoid. I have never rebuilt my TH400. Only a shift improver kit from B&M years ago. It is such a tight shifting trans. These TH400's amaze me.
The switch on my car works fine. But the currently installed TH400 is from a 75 Cadillac... Instead of swapping the valvebody I'd rather find a good one to go into the OW. Going to ask Mark as Larry suggests
Larry, are you saying that cars will have one or the other, or can they have a hydraulic-activated kick down AND the electric one triggered by the gas pedal? Thanks! Best, Ranger Aiken, SC
They can have both. Lots of things affect how easy it is to get it to do that. Gearing and converter stall play a part. My current combo won't do it very easily in 3rd gear, but with the GV engaged, it is easy to get it to do it hydraulically.
Larry, Thanks. Well, what would happen if they have both (trying to figure out if mine, in fact, does) and the electronic gas-pedal doesn't work. Would they hydraulic one still allow it to downshift? Best, Ranger Aiken, SC
Like I said, it really depends on the gearing and converter, and maybe even the modulator setting. The tighter the converter, the lower the numerical gearing, the easier it will do it. Get it into high gear at about 40 MPH, and slowly push the gas down about 1/2 way. It should downshift before the gas pedal switch activates.
While I have nothing radical, modifications of the governor and modulator can make the trans more responsive. And probably lower the max 3-1 shift speed. The time for the downshift can be reduced by opening up the right valve plate hole. Bruce Roe
