Differences between the TH350 and TH400

[6spdg37s]

So my 83 Monte SS has a th350 in it (factory) now my question is, (don't know alot about old school transes)

Is the setup of the th350 and th400 interchangable. In other words, I would like to run a built th400 but I want to get the 5.3 im going to build in the car and running/moving first and drive it a little then deal with upgrading the trans, but I don't want to have to re-purchase , torque converter, flexplate, and manual converter lockup switch.

is there a benefit of going with a TH350 versus a TH400??

thanks,

John

 

[SoFloG]

Stronger transmission, converters are the same, kickdown is different

 

[6spdg37s]

same mounting setup? location for the crossmember? or do i need to change ?

 

[pontiacgp]

stock 350 is lighter and weaker but uses less HP than a stock 400

350 - 2.52 1.52 1.00
400 - 2.48 1.48 1.00

 

[SoFloG]

stock 350 is lighter and weaker but uses less HP than a stock 400

350 - 2.52 1.52 1.00
400 - 2.48 1.48 1.00

Less "parasitic drag"?

 

[565bbchevy]

same mounting setup? location for the crossmember? or do i need to change ?

The 400 is longer and would need a different or modified crossmember and the 400 will also use a shorter driveshaft (assuming both short tail trans)and a larger yoke..

 

[pontiacgp]

Less "parasitic drag"?

GM
PG 18 hp
TH-350 36 hp
TH-400 44 hp

 

[6spdg37s]

The 400 is longer and would need a different or modified crossmember and the 400 will also use a shorter driveshaft (assuming both short tail trans)and a larger yoke..

that is awesome amount of info I thank you !

 

[axisg]

A little more info for you. The 83ss would have come with a 350c aka "lockup" trans. No OD but lockup function was a step up on the th350. The lockup function was controlled by the CCC System. Vacuum Modulator controlled the shifts

If you prefer to run a th400 it will fit comfortably in a gbody. You mention a lockup switch but the th400 is not a lockup trans nor does it have OD. Mounting pad is the same as 2004r crossmember, and short tailshaft trans is within 3/4" of the same driveshaft length ( but you will need a different yolk swapped on the end ). You will need all the th400 kickdown linkage to make it work.

So you already know anything that came from the factory will not handle power levels over 300hp without an upgrade ( hence why you want a th400 ). The 200-4r with upgrades will fit in place of the 350c in there now. It will give you all the performance needed, with decent shift points and OD. There are loads of threads here and on the net showing what is needed for the swap. In short you can reuse your driveshaft but will need a factory shifter, factory crossmember, and 2004r TV cable to make it work

Good luck

 

[6spdg37s]

A little more info for you. The 83ss would have come with a 350c aka "lockup" trans. No OD but lockup function was a step up on the th350. The lockup function was controlled by the CCC System. Vacuum Modulator controlled the shifts

If you prefer to run a th400 it will fit comfortably in a gbody. You mention a lockup switch but the th400 is not a lockup trans nor does it have OD. Mounting pad is the same as 2004r crossmember, and short tailshaft trans is within 3/4" of the same driveshaft length ( but you will need a different yolk swapped on the end ). You will need all the th400 kickdown linkage to make it work.

So you already know anything that came from the factory will not handle power levels over 300hp without an upgrade ( hence you want for a th400 ). The 200-4r with upgrades will fit in place of the 350c in there now. It will give you all the performance needed, with decent shift points and OD Loads of threads here and on the net showing what is needed for the swap but in short you can reuse your driveshaft but will need a factory shifter, factory crossmember, and 2004r TV cable to make it work

Good luck

can I re-use the factory driveshaft with the th350 as well?