Tranny swap question
Thread Starter
Drifting
Joined: Jan 2011
Posts: 1,853
Likes: 81
From: Hamilton Virginia
Tranny swap question
I have in my posession a 1985 th400 2wd tranny that came from a 2wd truck. Does anyone think this is usable in my 1976 vette ? Is there a gear ratio differance in these things when it comes to a car or truck ?
thanks for any info.
Mike
thanks for any info.
Mike
Drifting
Joined: Apr 2003
Posts: 1,323
Likes: 2
From: Castle Hills Texas
Why would you trade a three speed tranny for a three speed tranny? There is a ratio difference between the two trannies but it is small. I think a th400 is a th400, no different for a car or truck to my knowledge.
1st=2:48, 2nd=1:48, 3rd=1 to 1 (400)
1st=2:52, 2nd=1:52, 3rd=1 to 1 (350)
1st=2:48, 2nd=1:48, 3rd=1 to 1 (400)
1st=2:52, 2nd=1:52, 3rd=1 to 1 (350)
Drifting
Joined: Apr 2003
Posts: 1,323
Likes: 2
From: Castle Hills Texas
I see.... I think just about any tranny can be built to withstand big horses. There are plenty of factory 454 engines mated to th350 transmissions out there. I believe there are factory combos in Vettes like this.
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
Yes, the TH400 is stronger, but the 350 will also work. You want to measure the length of the tail shaft housing on the 400. I believe there were two lengths and the Vette used the short housing. Something to check into before buying and be certain.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
If you want to do much driving on the highway, now would be the time to put an overdrive [auto] tranny in your car. If you don't need the overdrive tranny, the 400 would be my preference for your BB engine. But, you will need to change some things in your drivetrain so that the 400 will mount up properly: different output yoke, different length driveshaft, different location on rear mount on crossmember, different brackets mounted to tranny oil pan. The simpler and maybe less costly approach would be to have your existing 350 rebuilt with stronger internal components. Then it would handle the power but you would require no changes during the installation.
Last edited by 7T1vette; Nov 3, 2011 at 11:41 AM.
Thread Starter
Drifting
Joined: Jan 2011
Posts: 1,853
Likes: 81
From: Hamilton Virginia
Cool. Thank you all for the replies. I already have the tranny, it was given to me as part of the 454 package. I will measure the check things before I pull the th350 thats in my vette now. If its not worth the swap and too much trouble I wont change it. We will see.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Just to be clear....I would not place your existing TH-350 trans behind the 454 engine unless it has been upgraded for more torque during a fresh rebuild. But, if you take the Th-350 to a transmission shop, a swap of your unit for a built-up 350 will not be that expensive...or they can rebuild yours with upgraded parts for about the same money.