Th 400
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 43
Likes: 0
Th 400
I have discovered my 71 TH 400 Transmission is in need of an overhaul or replacement. Looking at Summit and Jegs rebuilt units.....want to spend about $1500 or less. Any advice or experiences with these transmissions?
2026 Loser of the Year
Joined: Sep 2013
Posts: 36,573
Likes: 7,015
From: New Or-leens Loo-z-anna
I wouldn't know about those vendor's transmissions.......I have bought other parts from them that are quality parts. If you are able to turn wrenches you can buy a very good rebuild book with illustrations to rebuild your TH400. You would have to disassemble your trans. completely to make sure no major damaged has been done......then buy a quality rebuild kit and do the work yourself.
A new torque converter would be a good choice also to prevent contaminating your new/rebuilt transmission.
Wait for experienced members to reply.
A new torque converter would be a good choice also to prevent contaminating your new/rebuilt transmission.
Wait for experienced members to reply.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
While the Turbo 400 was an excellent transmission back in the day (and still can be of course) the addition of an overdrive transmission may well bring a new level of enjoyment to you Corvette. There are a couple of threads regarding swapping out for an overdrive automatic in the C3 Tech/Performance Forum going on right now.Good luck... GUSTO
Racer
Joined: Jun 2012
Posts: 252
Likes: 25
I agree with GUSTO14. Get a rebuilt auto with overdrive. This website has two that are within your budget. http://www.monstertransmission.com/H...on_c_4044.html
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Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
If you want to keep your car with the 'original' equipment, have a local trans shop rebuild YOUR transmission (don't 'exchange' it). If you don't care about originality, swap your THM-400 out for a THM-200R4 overdrive unit. That may run you up to the $1500 you have, but it will be SOOooo much easier on the engine, quieter, smoother, and more economical than that old gas-guzzling 3-speed auto trans. Nothing wrong with the THM-400…it's super durable; but it is very inefficient and doesn't offer you an overdrive range nor a lockup clutch.
I made the change and I love it. Great for highway driving (2100 rpm @ 70mph).
I made the change and I love it. Great for highway driving (2100 rpm @ 70mph).
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
My '72 vert was a Muncie 4 speed, and in the DC region I shifted from 2nd to 4th in traffic....yes it was that bad.....3rd was rarely used 350 engine 336 rear ratio......
here in Florida a couple years later it was OVERdrive or fuggetaboutit.....so in went a 700 which is a poor match to the car....so went over to a 200 4r that I rebuilt myself with Trans Go shift kit and good quality soft parts.....mounts with stock driveshaft, but you will need a new cross piece and smaller output yoke.....like fits a thm350
I had to widen the tunnel on pass side, but it was a slim Muncie car so doubtful you will need do that.....
here in Florida a couple years later it was OVERdrive or fuggetaboutit.....so in went a 700 which is a poor match to the car....so went over to a 200 4r that I rebuilt myself with Trans Go shift kit and good quality soft parts.....mounts with stock driveshaft, but you will need a new cross piece and smaller output yoke.....like fits a thm350
I had to widen the tunnel on pass side, but it was a slim Muncie car so doubtful you will need do that.....
Racer
Joined: Nov 2006
Posts: 435
Likes: 7
From: Wake Forest NC
B&M makes a rebuild kit with kindergarten instructions. I'm not a pro and I rebuilt mine. The hub seals were the hardest things to install, but it went all right. Shifts tight.
http://www.summitracing.com/parts/bmm-20229/overview/
http://www.summitracing.com/parts/bmm-20229/overview/
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 43
Likes: 0
th400
I agree with GUSTO14. Get a rebuilt auto with overdrive. This website has two that are within your budget. http://www.monstertransmission.com/H...on_c_4044.html
Regards,
Police Copter
Race Director
Joined: Mar 2003
Posts: 11,608
Likes: 780
From: Eustis ( Area 51 Bat Cave ) Fl
Originally Posted by Mikeski View Post
I agree with GUSTO14. Get a rebuilt auto with overdrive. This website has two that are within your budget. http://www.monstertransmission.com/H...on_c_4044.html
I agree with GUSTO14. Get a rebuilt auto with overdrive. This website has two that are within your budget. http://www.monstertransmission.com/H...on_c_4044.html
just wanted to thank you regarding your heads-up about Monster Transmission....looks like the best way to go for my 71 a rebuilt th400 for about $1300 with a good warranty. it has a new stroked 383 in it and it sounds good but the transmission needs attention now. will let you know how it works out thanks again.
Regards,
Police Copter
Regards,
Police Copter