I'm getting geared up to have a th350 built and plainly I'm nearly ignorant when it comes to automatic transmissions. Hopefully you can answer a few questions for me. The engine I'm building developes in the neighborhood of 550 hp and I'm running 3:70 gears in a 9" ford rear and my torque converter will be in the 3500 stall catagory.
First of all, Are there different th350's? (is there a more desireable year or any other specific difference that would be a better choice for a starting core to build a high performance trans.)?
Secondly, This will be going in an 89 Iroc and the computer and all of its related wiring will be removed. Will this need a lock up or nonlock up converter, also will a kick down cable be an issue or does a th350 even have one?
Lastly, I;m going to buy all Transgo parts for this rebuild. Could you tell please tell me what parts I need to order for a complete rebuild with performance and reliability in mind.
Thanks in advance for all of the help
Sincerely, Bruce (70GTO)
First of all, Are there different th350's? (is there a more desireable year or any other specific difference that would be a better choice for a starting core to build a high performance trans.)?
Secondly, This will be going in an 89 Iroc and the computer and all of its related wiring will be removed. Will this need a lock up or nonlock up converter, also will a kick down cable be an issue or does a th350 even have one?
Lastly, I;m going to buy all Transgo parts for this rebuild. Could you tell please tell me what parts I need to order for a complete rebuild with performance and reliability in mind.
Thanks in advance for all of the help
Sincerely, Bruce (70GTO)
There are some differences but generally they are all the same. The TH350 is just a plain 3 speed tranny. The TH350C offered in the mid 80's had a lockup converter that was controlled by the computer for better fuel economy. You don't need a lockup converter.
The TH375B was offered in 74-76 in Buicks. If it doesn't have a dual bellhousing bolt pattern, you can't attach it to a chevy however all the internals can be swapped over to any chevy case. The Th375B has the maximum allowable clutch plates in the forward, intermidiate and direct clutches.
You'll only need a kickdown cable if you plan on driving on the street and want the tranny to "kick down" when you push down on the gas peddle. For a race only tranny the kickdown would never be used.
Stuff to buy:
First of all buy the book Turbo Hydra-matic 350 Handbook from HPBooks. Don't start thinking about rebuilding automatic trannys without a proper manual. Buy a good rebuild kit with new seals and clutches. To improve the strength of the TH350 you need to buy an aftermarket intermedite roller clutch (sprag) from places like B&M plus the aftermarket direct drum for it to mount on. This is the weakest link in the TH350.
If your engine is really going to put out that much power then consider going to a TH400 instead. It's a stronger and better designed tranny.
The TH375B was offered in 74-76 in Buicks. If it doesn't have a dual bellhousing bolt pattern, you can't attach it to a chevy however all the internals can be swapped over to any chevy case. The Th375B has the maximum allowable clutch plates in the forward, intermidiate and direct clutches.
You'll only need a kickdown cable if you plan on driving on the street and want the tranny to "kick down" when you push down on the gas peddle. For a race only tranny the kickdown would never be used.
Stuff to buy:
First of all buy the book Turbo Hydra-matic 350 Handbook from HPBooks. Don't start thinking about rebuilding automatic trannys without a proper manual. Buy a good rebuild kit with new seals and clutches. To improve the strength of the TH350 you need to buy an aftermarket intermedite roller clutch (sprag) from places like B&M plus the aftermarket direct drum for it to mount on. This is the weakest link in the TH350.
If your engine is really going to put out that much power then consider going to a TH400 instead. It's a stronger and better designed tranny.