Using a Gm trans for drag racing

[Tireburner]

First off just want to say im building up a 87 hardtop supra for drag racing.
Have fully built motor forged piston and rods arp hardware through out. Fully ported polished head with Bc valve train and cams. Haven't picked a turbo yet but leaning towards gt42.

Anyway needing info On swapping in a Gm 350 turbo trans lots of guys have done this. Having hard time finding any info on this. I know Ati has adaptor kit anyone use this? Wondering if any other kits exist? Also wondering how people solved speedo issues and mounting issues clearance issues and what not? Which starter you use?
Really just looking for anyone that can give details about doing this.
Thanks hope someone can help

 

[foreverpsycotic]

ATI kit works well from what I have read/seen
NFI about speedo
hammer the tunnel out.

 

[suprahero]

dbsupra on here started a thread about it. You should be able to search his name and find the thread he started.

 

[suprahero]

Here it is. He didn't finish it I don't think, but it may help you get started. Good luck.
http://www.supramania.com/forums/showthread.php?t=79473

 

[VooDoo]

Im in the midst of mine now. If you get the ATI kit. it will really help on sourcing parts. It comes with the adapter, flex plate, and it will enable you to use the stock starter.
I will be installing the motor and tranny this week. As soon as I do I plan on doing a write-up on it. The main thing Im going to have issues with is the abs. I know joliroger on here has the setup in a truck and a car. Thats where I got my kit. Try doing a search for th350. there is info for speed-o. Can be rigged or custom made, your choice.

 

[Tireburner]

Sweet keep me updated. Did you build up Gm trans or put it in stock for now?
Can anyone give info on how much power they can hold stock or minor upgrades they need or major? Thanks

 

[VooDoo]

Mine is built. It has a reverse manual valve body. With a trans brake. Th350 can handle some power as long as it is done right. You get what you pay for.

 

[besttrans]

th350 has worked incredible for us. The only pain in the ass is beating up the tunnel to fit the bell housing. As for speedo i may have an idea for you. Give us a call anytime between 8-6pm et.

shawn cassady
best transmissions
413-736-9496

 

[Tireburner]

Hey besttrans do you make a adaptor plate ? If so could you pm pricing also does yours use stock flywheel ?

 

[VooDoo]

th350 has worked incredible for us. The only pain in the ass is beating up the tunnel to fit the bell housing. As for speedo i may have an idea for you. Give us a call anytime between 8-6pm et.

shawn cassady
best transmissions
413-736-9496

I may give you a call for this idea. If you don't mind.

 

[joliroger4]

Any speedometer shop can make you a custom cable. You just have to send in a core with the toyota gauge cluster end on it since no speedometer shop can get this end new. Then let them know the length you need and have them install a TH350 type end on the other side. Then you will need a 1:1 90 degree th350 speedometer adapter to come right off the transmission so the cable does not hit the tunnel. The trans should have a 22 drive gear and 7 driven gear and this will put your speedometer very accurate with a 3.91 and stock sized tires. Stock 3.91 speedo gears have a .3125 ratio, the TH350 ratio I just spec'd will yield a .3181 ratio.

 

[besttrans]

We do have a few adaptor plates in stock, I get $300 for them. you retatain the stock starter and flywheel. We recomend a precision converter. Thanks

shawn cassady
best transmissions
413-736-9496

 

[Tireburner]

How much do the converters usually run price wise for precision's ?

 

[VooDoo]

Expect to spend $1,000. That's what mine cost. And make sure you use new converter bolts. They should send them with the converter.

 

[Tireburner]

So voodoo your using ati adapter kit and running a precision converter ? why not use the ati converter? Just curious is all thanks

 

[VooDoo]

Sorry I mis understood what you were asking. I am using the ATI converter. Didn't realize you were asking price for a specific converter. I would expect the same though.

 

[Tireburner]

Lol no worries just trying to get everything straight on what is needed and costs and what not.

 

[dbsupra90]

my precision converter made to work with sean's plate was ~$700

i was in the same boat you are, and here were my thoughts:

ati- cost a lot more ($700 vs $300 for shawn's). however, you do get a nice flexplate.

ati- you have to completely cut to fit. shawn's plate- ready to bolt on with the exception of trimming for water pipe.

ati- have to use their converter. it is 8" and $1000-1500. shawn's- can use precision 9.5" converter and made to work with his plate for $700. also, midwest makes a converter that will work but more expensive.

ati- sfi approved. shawn's is not.

ati- back to flexplate. theirs is bolt on. shawn's you will have to modify the stock.

not sure on the ati, but on shawn's you can run studs on the starter, which makes it a breeze to r&r.

hope this helps!

db

 

[VooDoo]

Agreed 100%. Lucky I bought mine cut. You can run studs on the ATI as well. Either Kit will work and you should be happy in the end.
Here is a pic of mine on the motor.

Was planning on putting in my motor and transmission today. Well after looking at my transmission. I don't even have a place for my speedo to hook up. Guess he just put a cap on it seeing how I told him it was a going to used for dragracing.
Am I correct?

 

[upgradedsupra]

ATI kit here, trans good for 1K plus...

TH350 built. P Affontis IIRC ran the same trans in his Supra running high 7's back in the day.

Duane