A question for those who went 5-Speed to GM Auto Tranny.

[SupraOfDoom]

I'd like to hear your thoughts on how you like it? I'm talking in terms of performance and fun factor, do you have any regrets? I know there aren't many of you guys out there so hopefully I get some comments. If you had the choice to go with a rebuilt R154 or GM Auto tranny which would you choose? My ideal candidate will drive his car a lot, but also have drag racing in mind.

 

[Sil]

Let me know if you want a turbo 350, might have a buddy with a spare one laying around.

 

[suprabad]

If you had the choice to go with a rebuilt R154 or GM Auto tranny which would you choose? ...have drag racing in mind.

I haven't done it yet but it's no brainer...TH350 is way beefier and common as potatos, can be built anyway you want it, and most importantly (if you want to drag-race) you can build it with a trans-brake. Not possible with an A340. I've spent a small fortune on Toyota A340's and they can be ok, but with no trans brake...you're fucked at the drags.

As far as a R154 goes, it's a pretty good 5 speed, but an automatic with a trans brake (every thing else being equal) will leave a car with a stick at the line like it was tied to a stump.

I can hardly wait to do this swap. I'm just trying to decide what motor I'm going with next.

 

[foreverpsycotic]

What is his HP goal?
What is his 1/4 goal?
How much highway driving?
Look into the 700r4 if he is going to be running under 700whp, it has the same benefits of the autos (can use a transbrake) AND has the added benefit of a 4th gear. A built one will probably run around $1400.

 

[SupraOfDoom]

My entire goal is to beat my best friends GT35RS, 13B-RE powered FC. I don't think I'll need an auto to do it, but the more I do it the better. I'm looking at the bigger GT40R's for this since my car weights more. I'm guessing he will be in the 11's some where when he is done tuning.

 

[shawnsmkiii]

are there any write ups on how to swap to gm auto? i've tried searching but no luck.

 

[mdr40z]

are there any write ups on how to swap to gm auto? i've tried searching but no luck.

There's not but it ain't rocket science; there's basically two diff adaptors, the first uses the Toyota bellhousing, the other uses an adaptor plate at the block. If I had to do it again I suppose I would try the plate at the block that uses standard GM torque convertors, that was my biggest pain in the neck. The only other thing is the lower gearing, another gear would be nice or use a gear vendor$ overdrive unit. I don't know of anyone who does an adaptor for a 700r so I don't think that is a viable option. Have fun.

 

[Facime]

cant a 700r4 have the same bolt pattern as a th350? I mean they both go behind some of the same motors.

 

[fstlane88]

Let me know if you want a turbo 350, might have a buddy with a spare one laying around.

Could ya ask him how much he wants for it for me?

 

[Sil]

cant a 700r4 have the same bolt pattern as a th350? I mean they both go behind some of the same motors.

Not all th350's are the same, there were variants for Chevy's, Pontiacs, Buicks, Olds and Caddies. but there were also universal bellhousing versions that fit all the blocks. A good auto trans shop should be able to fab something up for you if you don't mind paying for it. If you're buying a 700r, make sure you get a 30 spline count tranny, the lesser count ones sucked for making power.