TH400 into a manual L68
Thread Starter
Racer
Joined: Sep 2015
Posts: 309
Likes: 71
From: South Florida
TH400 into a manual L68
Due to mobility issues, I can no longer drive a manual. I'd like a 68-70 L68 or L89 convertible, but factory automatics are rare.
Is it possible to swap a TH400 without perminent modifications? I would want to return the car to stock when I'm done with it.
Luke
Ps: my 60 was built with a PG.
Is it possible to swap a TH400 without perminent modifications? I would want to return the car to stock when I'm done with it.
Luke
Ps: my 60 was built with a PG.
Last edited by 64luke; May 7, 2016 at 09:48 PM.
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,482
From: Southbound
Cruise-In II Veteran
FWIW: the TH400 requires a bump out panel on the passenger's side of the tranny tunnel in order to fit the transmission and a removable cross-member. The AIM shows where the tranny hump was cut and how the bump out was bonded in.
Note the bump out panel where the passenger's left foot would be.
Manual tranny car with no bump out.
Note the bump out panel where the passenger's left foot would be.
Manual tranny car with no bump out.
Last edited by Easy Mike; May 8, 2016 at 09:47 AM.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
If you do not remove the engine it will be impossible. The 4 speed cars did not have a removeable crossmember and it is impossible to get the turbo 400 in without a removeable cross member.
Melting Slicks
Joined: Feb 2006
Posts: 3,105
Likes: 96
From: Sunrise FL
At some point the TH350 was used, its smaller and may fit?
BUT what I would do:
Search for a later C3. The "newer" C3s had a higher percentage of auto as time went on.
They are basically the same car, with different engine power. But being Chevies, many inconspicuous and subtle changes can be made to get whatever you desire. And put back to original if desired.
Just ask on this Forum
BUT what I would do:
Search for a later C3. The "newer" C3s had a higher percentage of auto as time went on.
They are basically the same car, with different engine power. But being Chevies, many inconspicuous and subtle changes can be made to get whatever you desire. And put back to original if desired.
Just ask on this Forum
Last edited by mikem350; May 8, 2016 at 01:27 PM.
Racer
Joined: Dec 2008
Posts: 297
Likes: 19
From: arlington TX
Hi,
I did the 4-speed to auto conversion on my 74 pictured in my signature. Put in a TH350 and it went in with no cutting, etc. Driveshaft was the same length, u-joints and yoke were the same as the T-10 I took out, the 350 went in with the fixed (4-speed) cross-member with a little 'persuasion' and the mounts lined up. The tunnel was a close fit, but no real problem. Flywheel, shifter, cooler lines have to be figured out, but it is doable. The TH400 is a bigger,heavier transmission. But the 350 (properly rebuilt with a few performance parts) will handle just about any stock or mildly modified engine. My engine (361ci) had about 510hp and raced regularly with no problems. Good luck.
I did the 4-speed to auto conversion on my 74 pictured in my signature. Put in a TH350 and it went in with no cutting, etc. Driveshaft was the same length, u-joints and yoke were the same as the T-10 I took out, the 350 went in with the fixed (4-speed) cross-member with a little 'persuasion' and the mounts lined up. The tunnel was a close fit, but no real problem. Flywheel, shifter, cooler lines have to be figured out, but it is doable. The TH400 is a bigger,heavier transmission. But the 350 (properly rebuilt with a few performance parts) will handle just about any stock or mildly modified engine. My engine (361ci) had about 510hp and raced regularly with no problems. Good luck.
Last edited by wzschirnt; May 8, 2016 at 01:53 PM. Reason: add text
