1983 310 with a blown transmission

[scotdo]

Well I just had a new 454 put in and now the tranny goes
I would like to upgrade to a 4spd (overdrive?) if possible
Anyone know if there's a good option?
Thanks

[idroba]

The original THM 400 in the '83 310 was and is a classic workhorse transmission, and generally last and last and last.

In 1982 GM developed the THM 700 R 4, which is an overdrive 4 speed unit. They had nothing but problems with it for years, and although they finally improved it to the point it didn't fail as often, it was still a miserable substitute for a THM 400.

I would stick with the original if it were my unit (and I had an '83, 310). You could put a better Torque converter on it when rebuilt though. I believe there is an Allison which will substitute for the original. A friend did that to his '81 280 with the diesel.

[HowieE]

The 700R4 was noted rated to TOW in overdrive so I put a Gear vendors splitter behind it set over and towed in 3rd. over.

I would suggest considering the 400, stronger trans, with a splitter behind it. That will give you 5 usable forward gears. 1sr, 2nd, 2ndover, 3rd, and 3rd over.

If you really want a neat setup put a BD Torq Loc in and lock the convertor in any gear over 35 mph. Pulling long hills in 2nd over with the convertor locked at 55 or better.

[Waipio Rim]

There are a few threads here on changing transmission types, they have convinced me that it is definitely not for the faint of heart. Here is one: http://www.airforums.com/forums/f159...old-69221.html
Our 310 came with a newly rebuilt TH400 that has performed flawlessly for five years. I do wish for an overdrive now and then, but I think HowieE has the right idea.

[shepherd57]

idroba which Allison did your friend use the 5 speed or the 6 speed. Any chance he might share the information on the swap.

I have the Allison 545 4 speed in my 32.5 and I would like to swap in the 5 or 6 speed.

[idroba]

Originally Posted by shepherd57

idroba which Allison did your friend use the 5 speed or the 6 speed. Any chance he might share the information on the swap.

I have the Allison 545 4 speed in my 32.5 and I would like to swap in the 5 or 6 speed.

It was an Allison torque converter as I recall, not an Allison transmission. He used it with the THM 400 transmission.

Although he is still with us, he is in his low 90's now and probably could not help much with what he did to make the change.

My memory is also hazy on what he told me he did, but Allison and torque converter stick in my mind pretty hard. I do know the THM 400 was retained.

[tevake]

you could consider just rebuilding the 400 trany. and add an overdrive with the extra cash that a trany swap would have cost you.

did you post about the engine replacement? I would like to learn more about that process and the choices involved.

cheers Richard