DavidBoren

I have been looking at transmissions lately. I thought I was dead set on a TH400, but I think I want overdrive. I still want a purely mechanical transmission, so I have been looking at what the 700r4 can reasonably be built to handle.

I have heard of rockcrawlers switching their TH350's 2.52 first gear for the 700r4's 3.06 first gear to get better crawling ratios.

If the two different transmissions' first gear planetaries are compatible, can I have the TH350's 2.52 first gear in a 700r4?

I have seen the 200r4, and I like the gear ratios it brings to the table, but I do not trust it behind a 500rwtq naturally aspirated motor. Especially one shifting above 7000rpms.

Anyone ever switch the 700r4 first gear for either the TH350 or TH400 first gear? Is it even possible?

Any help or information will be greatly appreciated.

DavidBoren

I have seen the 2.84 first gear planetary for the 700r4. And while it is definitely closer to what I am looking for, I am specifically hoping to be numerically lower than 2.6 for first gear. This may be wishful thinking, but I figure it never hurts to ask if anyone here knows about using Th350 or TH400 first gear in a 700r4.

mrvedit

I'll just say that the 2.84 planetary is the only option I have ever heard of. The Sonnax part is about $600.
Why do you not want an electronically controlled trans? Don't you have a PCM?

DavidBoren

It's going to have a reverse pattern FMVB, with engine braking. Just for a fun driver.

The 2.84 planetary is not at all a bad option, I was just hoping for something closer to the TH350/TH400 first gear ratio.

MY_2K_Z

iTrader: (1)

I'm sure the 700r4 can be built to handle some power but i personally have had 3 fail behind bone stock 250hp motors they are just weak to begin with. I would go with a th400 as they are pretty stout from the factory. I went 4l80e just for ease of retaining factory speedo and all that nonsense. But if I was doing a swap into a fox or something I would go th400 all day.

DavidBoren

See, I was really looking at the TH400, but with a lot of highway driving I would need to run 3.08 rear gears. And the detroit locker I want in the back specifies 3.23 or lower (numerically higher). I could run the minimum 3.23 rear gear with the TH400 and still be reasonable cruising down the highway.

But overdrive would allow me to use the 3.42-3.66 rear gears that I want to run with the locker.

I am not going to boost this, so I was thinking a 700r4, a monster in a box, and some TCI goodies would bring it up to the challenge. The monster in a box SS package is rated for 650, which I will not even be trying to surpass.