Hot Rod Forum : Hotrodders Bulletin Board

Hot Rod Forum : Hotrodders Bulletin Board (
-   Transmission - Rearend (
-   -   T-400 torque converter questions (

ChadGresham 02-10-2011 05:30 PM

T-400 torque converter questions
I am looking at torque converters for the THM400 transmission, and am wondering if any of you chevy guys have put a locking type converter in your tranny, or do they make locking types for that transmission? B&M has a wide selection of torque converters but none say if they are locking or not? has anyone installed one of these and know whether they are locking or not??

ericnova72 02-10-2011 05:49 PM

The TH-400 transmission never had a lock-up feature, that I know of. The trans has to be a lock-up type to use a lock-up converter.

potvinguy 02-10-2011 09:11 PM

400: no. 350:yes.
The TH350C was a lockup TC/tranny combo. But there never was a lockup 400.

SSedan64 02-10-2011 09:52 PM

I think Chris at CKPerformance was talking about doing Lockup TH400's on the Forum. It's been a while can't remember what ever happened. These would be Custom as none came factory w/Lockup.

ChadGresham 02-11-2011 10:39 AM

So there are no aftermarket torque converters that i can get for this transmission that lock up?

ericnova72 02-11-2011 12:21 PM


Originally Posted by ChadGresham
So there are no aftermarket torque converters that i can get for this transmission that lock up?

That is correct, because this transmission is not designed for a lock-up converter. There would be no provision in the valve body, case, or input shaft for the hydraulic lock-up fluid path.

ChadGresham 02-13-2011 01:47 PM

Ok thanks, i figured that but i had my hopes kinda high in consideration of gas mileage.. Has anyone ever swapped a thm400 for a 700r4? including the display on the dash for p,r,n,d... i wonder if that would be very hard to do?

1ownerT 02-13-2011 03:50 PM

A lock up converter is only going to net a couple hundred rpm's, not enough to make any real difference in mileage especially considering the cost vs mpg gain.
A 700r4 could be swapped but depending on the application you may be giving up a stronger trans.
Depending on the vehicle there are some companies that make replacement shift indicator displays.

ChadGresham 02-15-2011 04:55 PM

That is true, i know that the 400 is the toughest one available for a 1986 truck. I bought a new torque converter seal which was my main problem, just a small trans fluid leak, and a new torque converter as well just in case the old one was slipping and causing bad gas mileage.

msilveira 02-15-2011 05:20 PM


Yes. There is a "switch pitch" converter that came in TH-400s in Buicks, etc. in the 1970s. Likely hard to find.

Good luck,

Matt ;)

All times are GMT -6. The time now is 07:50 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.