i am just wondering how hard it is to put in a shift kit in a thm 400 transmission. what exactly does this do for the tranny.
It makes the trans give you snappier shifts and is actually better for your trans longevity than if it is left softer shifting. It will also give you a nice chirp under hard throttle when you shift. It is kind of a pain to change if it is in the car and if you don't fell comfortable having trans fluid running down your arms while laying on your back then don't try it. When you remove the valve body the small ball bearings can also go every where causing lots of cursing! There are two good kits. One is the Trans-Go that may even come witha video if you get it from Summit. The B and M is also good. the B and M has a stronger valve spring that I don't think the trans -go has. This requires removing the inside C clip on the verticle valve that will want to snap out when it releases possibly hitting you in the face. Wear safety glasses! Trying to get the spring then valve then clip all in while laying on your back can be an excersise in severe frustration. Anyone who has tried this will know what I mean. My advice is buy one and pay someone to do it. Only about any hours work for a good mechanic.
Do yourself a huge favor. Either take the transmission out of the car and attach it to your engine stand, turn it upside down and then install the kit. OR Buy the kit of your choice, take it to a reputable shop and have them install it. Those little check balls are nearly IMPOSSIBLE to get to stick in place long enough to get the valve body back in place. Without them, the trans won't work and will get burnt to a crisp inside of 25 miles. I didn't even get out of my driveway and back. I even used the lithium grease as suggested to have them stick. Didn't work well enough.
I did mine laying on my back but would not do it again. I used vaseline on the balls and it worked first time. I dont know if the vaseline is better than the lithium or maybe I just got lucky.
No it actually decrease horsepower to the rear wheels by increasing pump pressure but it is such a small amount that you probably would not see it on a dyno.Not all shift kits for the th400 increase line pressure but just about all transmissions will perform better and last longer after installing a kit. B&M kits are fairly easy to install but dont address some of the reliability issues that the TransGo kits do. Poston sells one that is also easy to install and you dont change the pump pressure regulator spring.
No, but it will increase the amount of time that power is applied to the wheels. Traction is another issue, a chirp is fine but much more than that and you loose potential acceleration time. Word to the wise...a new shift kit and positive traction must be treated with respect (especially in a curve or in the rain). :Smarty:
