Turbo Supra box behind a Gen 3 Chev

[Aussie Mike]

Hi All,

I've always been keen on doing unconventional things and I'm doing as much of the Cobra build myself as possible.

I'm toying with the idea of using a Toyota Supra Turbo gearbox behind the Gen 3 LS1 Chev. From what I heard from people involved with the Toyota Supra, these boxes can handle some big HP (600HP twin turbo etc).

I plan on using a lakewood or similar steel scatter shield and adapting it to suit the box. This won't be too hard, just machine up an adaptor plate and weld it in place. The 12" clutch plate on the Gen3 presents a more difficult task (different spline and larger diameter disk). I'm contemplating punching out the rivets on the center of a Toyota clutch plate and then making a solid center 12" disk to rivet it into. I would then re use the Chev facings on it or get new ones to suit. I can machine a new pilot bush out of some phosphor bronze or make a roller bearing pilot. The release bearing would probably just need a sleeve.

The Supra Turbo boxes (when you can find them) go for around the A$1500 mark for a good S/H unit (a new Tremec down here is around A$4000).

Has any one had any experience with these Gear boxes?
What do you think?
Am I insane?

Cheers

[Jim Gunther]

Originally posted by Aussie Mike
Hi All,

I'm toying with the idea of using a Toyota Supra Turbo gearbox behind the Gen 3 LS1 Chev.
What do you think?
Am I insane?

Cheers

In the kingdom of the blind the One-Eyed man is king!

In Oz, you're basically mainstream!

Hey, just 'funnin 'ya. I know zip about the Supra gearbox but, I'm REALLY intrigued by the Aluminum Chevy motor.
A lot of the U.S. Cobra guys would throw a fit - "the very idea" but I think it would really perforn in an FFR!!
Be well,
Jim

[Back in Black]

My brother was the first guy I ever heard of that put a chevy 350 (about 450 to 500 HP) in a Toyota 4 x 4 truck (~1979) He used a TH400 tranny, and the point I wanted to make is that the rear end held up for about 40k miles ! (Then he replaced it with a shortened Chevy rear) This was 40K of severe abuse!

If you have the stones, and the patience (I lack the patience part) then try it, and you can have bragging rights!

[Mike Braddock]

Mike,

I've seen several of these cars running at the track with 450-550 hp with no drivetrain reliability issues. Since you made reference to the "Toyota Supra Turbo gearbox ", I assume you mean either the 5 speed R154 out of the MkIII or the V160/V161 6 speed out of the MkIV ('93+)? But which one are you looking at? The V160 is heavier duty, but as expected, it's also a heavier box. If this is the one you're considering, have you made preliminary measurements on this box, as it's quite large and that might present some problems. It's also a pretty noisey gearbox. Lots of rattles--kind of sounds like ball bearings rolling around inside there . And yes, this is normal for these boxes.

The gear ratios for the V160 (3.82, 2.36, 1.68, 1.31, 1.0, 0.79) look pretty decent for the LS1, as you can see from the gear charts shown here:

http://www.mkiv.com/techarticles/getrag/v161/v161_2.jpg

What rear end are you running, or more specifically, what types of rear end gearset ratios do you have available? Since the spread between first and second is so tall, I think you'll end up with basically a 5 speed with a really short first gear.

Here are some sites that have information about this tranny (and the MkIV's in general), many of which you are probably familiar with:

http://www.mkiv.co.nz/
http://www.mkiv.com/

And here's some technical info on the tranny:

http://www.mkiv.com/techarticles/get...ecs/index.html

I've been considering using it for a future project as well. One nice, though often overlooked feature is the fact that is has a bolt on clutch (ie bell) housing, which the T56 6 speed does not. At least, the early T56's don't, I'm not sure about the newer ones.

As far as the clutch, why not just have your flywheel redrilled for a supra pressure plate and clutch assy? They make everything from stock to triple disk setups for that engine/tranny, so that might be an easier way to go. This is what makes these projects so much fun...the choices (and challenges) are endless ...

Good luck and tell me what you decide. Also, please let me know of any other info you happen across. Thanks Mike.

Mike

[750hp]

Mike,
The physical size of the 5 speed Supra box doesn't appear to be a problem. Rod Hadfield at Castlemaine Rod Shop www.rodshop.com.au will definitely be able to supply a bolt-in bellhousing/adaptor for the LS1 - Supra.

My worry would be how far back the shifter is.... I think my elbow would hit the rear firewall behind the seats when going for 2nd or 4th gears! I wonder if you can relocate it?

[Aussie Mike]

Thanks for the excellent info Mike.

The Box I'm looking at is the R154 5 speed unit. From looking at your links and doing a bit more searching on this box I've only read good things. Some people quoting 500-600Hp. They also seem to be popular with V8 conversions into Toyota 4x4s and that seems like a punishing application to me.

The rear end ratio I'm using is 3.45/1 diff and the ratios in the R154 are 1 = 3.25, 2 = 1.95, 3 = 1.30, 4 = 1.0 OD = 0.75. From the spread sheet I've put these into they look like a good selection of ratios.

Hi Craig,

I spoke to Rod Hadfield about conversion kits and he can supply an alloy bellhousing to suit along with a clutch plate. I'm a bit paranoid about having the clutch trying to hang onto so much HP right beside my legs so I'm keen on using a steel scatter shield. It wouldn't worry me so much in a normal car with a steel floor and the motor and box a lot further forward.

Mike's suggestion of using an aftermarket Supra clutch is a good one. There seem to be quite a few twin a and triple plate setups available that would have less rotating inertia than the 12" Chev clutch.

The pic on Rod's site is a standard Supra box, the Turbo box looks like that one on sterroids and is about 10Kg heavier. Below is about the best pic I've been able to find.

I've been trying to get some measurements on the box especially the shifter location. It definitely isn't as far back as the BT56 and probably a little further forward than the rear position on a Tremec. I figure I'll make a bent forward shifter a'la the original Cobras if it's not to far back.

Cheers

[65hilly]

Originally Posted by 750hp

Mike,
The physical size of the 5 speed Supra box doesn't appear to be a problem. Rod Hadfield at Castlemaine Rod Shop www.rodshop.com.au will definitely be able to supply a bolt-in bellhousing/adaptor for the LS1 - Supra.

My worry would be how far back the shifter is.... I think my elbow would hit the rear firewall behind the seats when going for 2nd or 4th gears! I wonder if you can relocate it?

Just wondering where you got that info? I rang the Castlemaine rod shop, they said they didnt have a bell houseing for an LS1 to Supra gearbox, and said they wouldnt as that gearbox was really only good for 250hp? I was looking at this adaption myself as im fittling the LS1 into a 1970 capri. I have the standard auto 4 speed box, but would prefer a manual. although i have got a trans controller, that will allow full manual shift, so i could fit a paddle shift on the steering wheel. i guess my main issue is the size of the box, and i will have to cut the tunnel to fit it in. any ideas?

[Aussie Mike]

I cant see much point in doing the Supra conversion these days. I was looking at doing it when the T56 was still very expensive. Now you can pick them up for a couple of grand.

The T56 is a big gearbox but I'm not sure that you would need to do much to the tunnel. The box it deep and fairly long but when you think the main shaft is on the crank centerline it's not going to intrude into the tunnel much more than the Supra box. Given that, modifying the tunnel isn't a big deal compared to trying to match up different bellhousings, flywheels and clutches etc.

The bolt pattern for the LS1 is virtually the same as the small block chev. Only one bolt different I think.

Cheers

Michael

[Rog246]

Mike try Jeff Dellow @ Dellow automotive in Syderknee. He has a website etc and I know he does them. And my limited iinfo is yes they will take the grunt. I was also think of going down that path, but got a low K's engine & 6 speed complete when I didn't think I'd be able to.

Rog

[*Cobber*]

This is quite an old thread and R154's are getting thin on the ground now and prices are going up.

The R154's are very strong boxes but you need to do a mod to the first gear spacer to make them bullet proof (easy to do).

A cobra is very light and plenty of people run non turbo supra boxes W58's behind V8's with no problems too.

As above the T56 is now a good option and the Soarer and Supra boys are starting to use them because the R154's are hard to find.

[stephen low]

But for 65hilly it seems a current question and I too would suggest Jeff Dellow.

He supplied my bellhousing to mount my TKO to my windsor, that was after realising he had no immediate stock and arranging a casting to be done.

I'm sure Dellow's could provide something hilly!

[priobe]

Aussie Mike,

I am not claiming to be and expert or anything but my advice would be not to wast you time.

I have been in and out of the Toyota Supra tranny amongs other things and they are truely reliable. How ever they are delicate in the same manner. I had a supra done up with a 60-1 turbo running 20 psi boost , with a Haltech E6 programmer , amongs cams and other things. I would estimate my car putting out about 450 + hp others claim it was putting out more which why I am siding on the low side with out dyno results.

The tranny held up after a rebuild and when I was rebuilding it there was no aftermarket parts except those from the dealer. So it was expected to break again. This was a street car so it did not see abuse compared to a track car.

When I bolted the slicks on I worried about the tranny, which not too many times.

Also, the 7M motor generates low torque at low RPM this maybe an issue with having a LS1 motor.

Also, the 7M torque comes in gradual compared to a NA motor.

Best of luck