Is it worth to swap in a TH400 with overdrive? My '72 Riv does not have overdrive. I would like better mpg and shorter gears. If this is a good idea, specifically what trans should I look for? I would want something I could pick up for a couple of hundred off of craigslist or something.
A T400 is a 3 speed auto, it doesn't have overdrive. If you want overdrive you can invest in a 200-R4 or you can install a Gear Vendors overdrive set up. L8
if you were to go with a 200 4r then you should build it up to handle such a big car. it can be built up to handle anything but its gonna cost you some :dollar: as already you can go with a th400 with a gear vendors OD but its gonna cost you :dollar: but its gonna be bomb proof. randy:beers2:
I thought I saw some ads on craigslist for th400's with overdrive, I guess I got confused. It's good to know that I can stick with what I've got. Thanks!
You can add overdrive to a TH400 but I doubt you will keep the car and drive enough miles to recovery the cost of the addition.
Ads could have mean't a couple of THM400 OD "types" The GM 4L80E or the remote possibility of a THM400 with an older type Warner OD adapted to it. There used to be a set of prints available years ago that showed how to machine and fit them together to make one unitized assembly. We built a couple but didn't like some issues such as no engine braking in OD -just free wheeled when off the throttle- and no park if left out of OD when parking-had to use the parking brake as a manual trans car. The previously mentioned options(Gear Venders or a THM200R4) will probably be your easiest but probably not cost effective. Jay
Stock, a 4L80E (which is basically a TH400 with overdrive and 75% of the parts are interchangable) can handle your riv. I did this conversion in my '70 rivi. It takes work. When you consider engine wear when running down the highway having lower gears like 3.42s and the cost of fuel...it doesn't take long (two years depending on miles driven) to recover the cost. Consider reading up on the following: http://www.v8buick.com/showthread.php?t=157013 or http://www.v8buick.com/showthread.php?t=166567 to form your own opinion and make a choice. good luck -Chad
My buddy who does trannies is planning a double 400 set up. He saw it in a magazine and can't get it out of his head!! back to back or something. He was saying something about getting a true 10 speed auto in his vert. 2 400's with gear vendors od. Anyone ever hear of this?
I have heard of putting two TH400s back-to-back, but never with a gearvendors OD. However I've never really understood why you would do it - I have yet to hear of an application where the right combination of transmission mods (on a single TH400) and rearend ratio cannot cover every possible situation. Unless he wants to do it for the sake of doing it. -Bob C.
That's exactly it!! He just wants to be the first. He had a procharger mounted to a 455 like 10 years ago. I believe he did this before anybody had it. He is a mad man!!!!
With that long of a transmission (two TH400s + GV), you might not even need a driveshaft at all. Just hook the output of the GV to the rearend pinion! -BC
He did explain how it went but I forget cause it was a long time ago he brought this up. But I'll ask him about it.
I do drive my Riv everyday. Gas is 4-5 gallons for a 50 mile commute. I'm saving for another car, but trying to improve this one at the same time. I'm pulling the trans to install a new converter and flexplate, thought that there might be an easy way to get overdrive. This guy has overdrive: http://www.buick-riviera.com/fastbill.html
