replacing a 700r4 with a turbo 400 [Archive] - Team Camaro Tech

: replacing a 700r4 with a turbo 400


kapshots
May 7th, 08, 06:55 AM
I need help! I have a 85 camaro original trans was a 700r4 and now going to replace it with a turbo 400. Has anybody done this ? and what has to be done with the crossmember ?

sburdy
May 7th, 08, 08:11 AM
I don't know why you would do that!

I am replacing the PG in my 67 Camaro and the 400 in my 70 Chevelle with a 700R4.

With a 400 in your car it will be a dog off the line and you will loose overdrive and burn a lot more gas.

Keep the 700R4

If you do change it you will need a new cross member and drive shaft as the 400 is shorter than the 700.

kapshots
May 7th, 08, 10:21 AM
the 700r4 has 180,000 miles on it and the turbo 400 is a brand new TCI super street fighter.

KevinW
May 7th, 08, 10:38 AM
Get a built 700r4 to handle your horsepower, the th400 will involve too many changes to make the swap economical.

Rodder
May 7th, 08, 10:57 AM
http://www.thirdgen.org/techboard/transmissions-drivetrain/359853-th400-parts-list.html

emperor91108
May 7th, 08, 11:00 AM
Just have the 700r rebuilt for performance.

Fred Ficarra
May 7th, 08, 12:01 PM
Can't speak for the ease of the swap, but that 400 setup is similar to what mine is now. Be sure to budget for a NECKBRACE! Dog? NOT!

sburdy
May 7th, 08, 08:04 PM
GEAR RATIOS OF THE TH-7004R
FIRST GEAR SECOND GEAR THIRD GEAR FOURTH GEAR
3.06:1 1.63:1 1:1 0.70:1

GEAR RATIOS OF THE TH-350
FIRST GEAR SECOND GEAR THIRD GEAR FOURTH GEAR
2.52:1 1.52:1 1:1 N/A

GEAR RATIOS OF THE TH-400
FIRST GEAR SECOND GEAR THIRD GEAR FOURTH GEAR
2.48:1 1.48:1 1:1 N/A


You can see that the 700R4 would launch much harder with the steeper first gear.

One man's dog is another man thoroughbred.

Sorry man the numbers don't lie!!!!

kapshots
May 8th, 08, 11:29 AM
anybody want to buy a TCI turbo 400 never used never installed ?

Fred Ficarra
May 8th, 08, 01:47 PM
oops, messed-up, see below.

Fred Ficarra
May 8th, 08, 01:51 PM
There's numbers and then there's numbers. A TH400 is a BB trany designed to stand up to the pounding and torque that big blocks produce. As Hotrod Magazine said, if you've got a big-inch engine in front of a TH400 and want overdrive, don't replace it with a weaker 700R-4. Instead, consider an add-on overdrive such as from GearVendors. Hard to beat a TH400. Those gears are there for a reason. I'm no engineer so I won't go there but I sure wish I had something other than a 700R4 in my old 4X4. It can't take the load. It's on its third replacement behind a SMALL block! My TH400 has never needed a penny spent for repairs in nearly 40 years behind a very strong BBC. That number is even harder to beat. And I need a neck brace at the drags.

mike p
May 8th, 08, 04:51 PM
The value of overdrive is related to your axle gear and amount of highway use. The value of transmission first gear is related to your axle gear and engine power. Lots of racers use Powerglide or TH400 transmissions.

kapshots
May 9th, 08, 01:19 PM
The rear is stock for now and don`t plan on doing a whole lot of highway driving ,more of a weekend drag car

Fred Ficarra
May 10th, 08, 12:32 PM
Then skip the overdrive on your TH400.

kapshots
May 13th, 08, 05:28 AM
I really need to know what I would need to do to make this swap happen, The TCI turbo 400 super street fighter was bought for $650 brand new, that`s why I want to change it out, the stock gears in the rear will be changed at a later date . I do appreciate everybodys input so far

KevinW
May 13th, 08, 07:39 AM
Keith, I think what you are doing is not the norm for most of us. Since you plan to race this combo mostly, have you tried asking the question on a drag race forum? The 1/4 mile always finds the weakest link and once you replace the trans, I think the rear is the next weakest. :) Luck!

kapshots
May 15th, 08, 08:57 AM
Thanks Kevin I`ll give it a try
Im expecting the rear to take a dump on me when I drive it for the first time it has 180,000 miles on it.