TH400 in 70 Vette
Thread Starter
4th Gear
Joined: May 2017
Posts: 4
Likes: 0
TH400 in 70 Vette
Hello
My sons and I are starting to put our 70 Vette together. We are putting in a 540 that makes 580HP and 707TQ on pump gas. We have went back and forth on doing a TCI TH350 or TCI TH400. Right now the car has a 350 and 700r4.
Other than a driveshaft change to go with the TH400 (the TH350 we will use a 9" tailshaft to be the same length as a 700r4) and the electric kick down.
What else would need to be done to get a TH400 in the car? The TH350 seems like an easier bolt in but people have told us to go TH400..
Thank you,
Doug
My sons and I are starting to put our 70 Vette together. We are putting in a 540 that makes 580HP and 707TQ on pump gas. We have went back and forth on doing a TCI TH350 or TCI TH400. Right now the car has a 350 and 700r4.
Other than a driveshaft change to go with the TH400 (the TH350 we will use a 9" tailshaft to be the same length as a 700r4) and the electric kick down.
What else would need to be done to get a TH400 in the car? The TH350 seems like an easier bolt in but people have told us to go TH400..
Thank you,
Doug
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Electric detent and driveshaft are just about it. The vacuum for the modulator is on both the 350 and 400, just in different locations.
A 350 can be built to take quite a lot of hard use, and uses less HP than a 400 (lighter internals). I built a 350 for a guy a few years ago that was racing a GTO with a 455, and I've built a 400 for a guy that had a 505 in a Camaro. Both still running as far as I know.
A 350 can be built to take quite a lot of hard use, and uses less HP than a 400 (lighter internals). I built a 350 for a guy a few years ago that was racing a GTO with a 455, and I've built a 400 for a guy that had a 505 in a Camaro. Both still running as far as I know.
Thread Starter
4th Gear
Joined: May 2017
Posts: 4
Likes: 0
Sorry for the delay in response. Right now I am going to go with the TH400. I called TCI and they recommended it. I did call a guy from EBAY - Maddogtrannys is his ebay name and he sells race 700r4 when I called him and was ready to buy (before this post was written) he said he didn't know if his 700r4 would hold up and said TH400 would be better than a 700r4 he could build me. looked on monster transmissions site and their site was limited in the 700r4s for this kind of power.
so I am going with the TH400, really wanted the overdrive with the 3.70 rear, but may go to 3.08 or something if I start getting this car on the highway.
I liked the 700r4 for the interstate for sure and that is a big plus. just don't want to get it in and it break from the power. I also wonder if I keep street tires on it and don't do a lot of hard driving my thoughts were a 700r4 may make it for a long time.
planning to buy the transmission this week so all info it welcome
Thank everyone for the help I will post some pics soon
Doug
so I am going with the TH400, really wanted the overdrive with the 3.70 rear, but may go to 3.08 or something if I start getting this car on the highway.
I liked the 700r4 for the interstate for sure and that is a big plus. just don't want to get it in and it break from the power. I also wonder if I keep street tires on it and don't do a lot of hard driving my thoughts were a 700r4 may make it for a long time.
planning to buy the transmission this week so all info it welcome
Thank everyone for the help I will post some pics soon
Doug
Pro
Joined: Jan 2016
Posts: 502
Likes: 103
From: Reno Nevada
I have a TH400 in my garage that I just took out of my Big Block Car. It is built and ran fine when I took it out. Because you are going back new, I would probably rebuild it, but it could be run as is. $100 plus whatever shipping. Will likely save you $$ and you will know what is in it if you have someone rebuild it for you. Just a thought....
Thread Starter
4th Gear
Joined: May 2017
Posts: 4
Likes: 0
I have a TH400 in my garage that I just took out of my Big Block Car. It is built and ran fine when I took it out. Because you are going back new, I would probably rebuild it, but it could be run as is. $100 plus whatever shipping. Will likely save you $$ and you will know what is in it if you have someone rebuild it for you. Just a thought....
Doug
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Safety Car
Joined: Oct 2015
Posts: 4,782
Likes: 223
From: Lebanon Pa
Doug, The TH400 is pretty easy to rebuild, buy a good manual and a rebuild kit... Also upgrade the sprague to the 34 element,the sprague is the weak spot... Good luck..
Last edited by Jeffs82c3; May 25, 2017 at 12:05 PM.