Ok, this friend of mine has a 93 LT1 that is fairly built with forged pistons, ported stock heads, a descent comp cam, a 2800 stall, a 150 shot of nitrous and a 700R4 to back it up. He is having problems with the trans and was asking a local shop about the cost of a trans. This shop is dead set on selling him on a TH350 that they have to replace it.

I know there would be a few probs with it, but just wanted to get the general idea of a few things.

1. drivability with a TH350 on an Lt1. This car is not a DD, but it will be driven occasionally and on the track often and to and from it. Prob weekend driving as well.
2. what RPM have yall seen at the traps with this trans and a 3.73/3.42 gear?
3. what RPM will you see while cruising. i know it should be the same as the rpm from the 700 in 3rd gear since it is 1:1 ratio (iirc).
4. would you recommend the 350 or build the 700R4?

I do believe the 350 will also have to have a diff driveshaft? What else would be some problems? They both use a kickdown cable, so thats there, but the 350 he is getting will not have lockup. Im not sure if that would throw a code or not for the TCC circuit, or if he can have that deleted from his chip/computer. Also will he have to move the trans crossmember/get a new mount?

I like the 700 for its drivability and the car is already designed around it. The driveshaft wont have to be changed. I have built a few descent 700s and i like them alot, esp when you have a spare 4l6x to swap parts out of. heh.

Thanks

 

First of all that stall is WAYYY to small for that build.

I'd say get the TH350 built and swap it in.

Here is something that might answer some of your questions:
https://ls1tech.com/forums/automatic...questions.html

 

well that is what he has in it right now. he will be going up to a 3200-3400 i believe. i forgot about the torque arm as well.

 

Make it a Yank SS3600.

 

A competently built 700 will do the job, gives you a better first gear and the option of lockup.

Problem is few shops seem to be able to build them well and it is NOT a matter of fancy parts. It is a matter of proper setup not just stabbing all the parts in which is what most shops do.

IMO the three speed trannies should be left ONLY for dedicated track cars. Even just to and from the track without OD and lockup besides being annoying puts undo wear on valvesprings and such.

 

i like the turbo 350's myself. i'm sure theirs different opinions on streetability. i run a th/350 with a tci streetfighter 10" convertor (around 3000-3300 stall speed). i have 3.08 gears in my chevelle (its efi lt1 powered). it has gotten 18.5 mpg driven easy. i had a stock th/350 with a shift kit in my t/a for 3 years and ran 6.4s in the 8th, with no problems. other things to consider is getting the speedo to work, shifter and as mentioned drive shaft. also, you'll need a trq. arm bracket unless you have an aftermarket trq. arm. the crossmember can be reused by sliding it forward and using the back bolt holes in the crossmember in the front holes of the body.

 

well after seeing the extensive cost/parts involved in the swap and the cost of a descent 700 rebuild, he is sticking with the 700.

 

rebuild the 700 and add a 3500 stall with a tranny cooler.....profit

its the same build i did last year and i just put it in the car 2 weeks ago and its amazing. im not a track buffer but if i do take it there it will hold . jus my opinion

 

I wouldnt go with a 700 if the choice was between it and a th350. You can get a long tail 350 so you dont have to mess with the driveshaft. Strength wise 350 is stronger and cheaper.

 

I just got a TH350 not too long ago. We'll see how that goes. I've been through 2 4L60's up till now.

 

better first gear in a 700R4??? it aint an impala dude, these cars need less first gear.

 

lol true.

I am running 3.42s with my TH350 but will be also running a 28" slick with a 200 shot lol. Should be fun. Stall speed is around 3700.