Ok, many of you will immediately dismiss this idea as absurd, but for the rest of you...

How about taking a Toronado transmission (TH425) and removing all but the bell housing and drive chain area? If you mill the transmission housing down to the chain housing you could then -with additional machine work- bolt a T56 or other manual transmission to the chain housing. Put the input shaft of choice in the bellhousing and we then have a manual gearbox that can handle the power some of the turbo 3800s and V8s are putting out.

Thoughts (positive, negative or otherwise)?

edit: I admit the concept has been oversimplified, but what about the idea in general?

[This message has been edited by Xyster (edited 07-13-2011).]

If you use a chain setup,unless you spin the engine backwards, all the gears within the transmission would be loaded on their weaker side (input shaft would be spinning backwards). Other than that, it is a novel concept that does have some merit.

If the gears are cryo treated will the direction really matter?

thats alot of work. you might as well take a regular tranmission out of a front engine rear wheel drive car. that has a removable bellhousing make some brackets to mount the bellhousing up like the th-425 and add chains, differental of your choice ect. and have a solid steup that saves on space.

quote Originally posted by Niterrorz: thats alot of work. you might as well take a regular tranmission out of a front engine rear wheel drive car. that has a removable bellhousing make some brackets to mount the bellhousing up like the th-425 and add chains, differental of your choice ect. and have a solid steup that saves on space.

Interesting. I was under the impression that the bellhousing and main housing were all cast from one piece.

nope not all of them. iv ehad that idea for a long time but no money to try it out. there are some and dont quote me on which ones but ones that have the bellhousing attached by 4 bolts one in each corner. my dad had a 4 speed manual and i think it was a chevy trans that had a detachable bellhousing in his 40 ford pickup. ill try to do osme digging and see what i can find for you.

[This message has been edited by Niterrorz (edited 07-13-2011).]

quote Originally posted by Xyster: Interesting. I was under the impression that the bellhousing and main housing were all cast from one piece.

Sorry, I was refering to the TH425 being one piece.

oh ya those are all one piece. but if you look at some of the trans mounts for that they are like trans/engine adapters and transmounts in one. so coming up with a mount to relocate a detachable bellhousing should be that hard. its just trying ot figure out how to run the chain and if you decide to do a manual figure out the clutch fork are and blah blah blah.... its alot of work and money for research and goofups but hey it would be cool...

If you used three gears like car dealer did it would eliminate the reverse rotaion problem. There is little chance that the transmission attached to the 425 bell housing would cler the engine. If you took a huge bloock of aluminum and milled a matching bell housing made provisions for gears and spaced it out a little further than the 425's spacing for the transmission then yes it would work. I can tell you fron experience there is not alot of extra room for such a thing in a stock fiero. Nice idea thought

Well the C5/C6 Vette bell housing is about 5 feet away from the transmission input shaft, so pretty sure it's removable. The bell housing on the engine, torque tube, input housing, and transmission on the Vette are all separate pieces. If the Fiero were stretched, it would be much easier to do longitudinal setups. Then you could just use a Vette trans directly.

If you've got the money, a Porsche or Audi trans would probably be the way to go, though.

Your still going to need a front pump to build pressure to contol the clutch packs and a valve body. Cutting up a th425 is just not going to work that way. Since my
(Im cardealer) days of making a gear drive from the chain drive I have come up with a better way of using the reverse rotation method using the th425 but it will not work in a non streched Fiero. Im currently working on a 600hp (on 21 psi single turbo) 2jzgte mated up to a reversed rotation th425 to be put in my stretched 1988 Fiero based Lamborghini Diablo Roadster. As far I can tell no one has ever done this type of setup and for good reason, it just isnt that easy. I have tore apart th425's for 7 years now trying to figure out the best method to use it in a mid engine setup. And sadly the choices are few........

quote Originally posted by diabloroadster: Your still going to need a front pump to build pressure to contol the clutch packs and a valve body. Cutting up a th425 is just not going to work that way.

What do you need that for on a manual transmission?

quote Originally posted by dobey: Well the C5/C6 Vette bell housing is about 5 feet away from the transmission input shaft, so pretty sure it's removable. The bell housing on the engine, torque tube, input housing, and transmission on the Vette are all separate pieces. If the Fiero were stretched, it would be much easier to do longitudinal setups. Then you could just use a Vette trans directly. If you've got the money, a Porsche or Audi trans would probably be the way to go, though.

I like the Vette transmission idea. It is already setup for remote inputs (vs direct input like a more conventional rwd manual) and a diff can be bolted directly to the back of it with no need for extra machine work.

I have toyed with the Porsche gearbox idea, but, I am hoping to keep the wheelbase a short as possible.

quote Originally posted by Xyster: I like the Vette transmission idea. It is already setup for remote inputs (vs direct input like a more conventional rwd manual) and a diff can be bolted directly to the back of it with no need for extra machine work. I have toyed with the Porsche gearbox idea, but, I am hoping to keep the wheelbase a short as possible.

Which is why I suggest the Porsche/Audi options over the Vette. The axles on the Porsche trans connect up just behind the bell housing, like you can see on RRunner's IMSA race car, here:



The engine there protrudes pretty far forward, but might not be as bad with a V6? You'd need to cut out the bottom of the trunk, too, though.

The design of this Porsche trans is pretty much as you describe, except it puts the gearbox behind the axles, instead of under the engine.

quote Originally posted by dobey: What do you need that for on a manual transmission?

I guess I dont understand what he is talking about. Nothing new, I rarely understand anything......

quote Originally posted by dobey: Which is why I suggest the Porsche/Audi options over the Vette. The axles on the Porsche trans connect up just behind the bell housing. The engine there protrudes pretty far forward, but might not be as bad with a V6? You'd need to cut out the bottom of the trunk, too, though. The design of this Porsche trans is pretty much as you describe, except it puts the gearbox behind the axles, instead of under the engine.

I am surpised I forgot about RRunners car. I had been following his build on cardomain for quite awhile and have always admired it. The Porsche transaxle will probably be the way to go. It will be easier to locate than a TH425, cost less over all without the machining, and perhaps even leave a little more room for a twin turbo setup.

Also, the trunk of the car that would receive this is damaged so removing the bottom half won't be an issue. Oh, and the engine will be a 3800 so the firewall will be violated a little less.

Well the 425 was a decent idea while it lasted.

I don't think the Vette trans will work.. Unless I'm mistaken, the gear selector shaft would run right through where the clutch should go:

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Currently in the middle of my 88 + 3800NA swap

quote Originally posted by aaronkoch: I don't think the Vette trans will work.. Unless I'm mistaken, the gear selector shaft would run right through where the clutch should go:

The gear select could be moved easily.

quote Originally posted by aaronkoch: I don't think the Vette trans will work.. Unless I'm mistaken, the gear selector shaft would run right through where the clutch should go:

If I understand the original idea correctly, it wouldn't matter, because the clutch would still mount to the flywheel, and the TH-425 bell housing would need modified to have a throw out bearing of some sort for using the clutch. Then the rotation would reverse going into the Vette trans that was mounted backward, which would then use the TH-425 diff to reverse again and drive the wheels in the correct rotation. I don't think there's enough room to go this route though. But I think that is basically what Xyster's idea was with the original post. You could substitute the C5/C6 trans for any other manual trans with removable bell housing. But a Porsche or Audi trans would be a much better option, I think.

quote Originally posted by dobey: If I understand the original idea correctly, it wouldn't matter, because the clutch would still mount to the flywheel, and the TH-425 bell housing would need modified to have a throw out bearing of some sort for using the clutch. Then the rotation would reverse going into the Vette trans that was mounted backward, which would then use the TH-425 diff to reverse again and drive the wheels in the correct rotation. I don't think there's enough room to go this route though. But I think that is basically what Xyster's idea was with the original post. You could substitute the C5/C6 trans for any other manual trans with removable bell housing. But a Porsche or Audi trans would be a much better option, I think.

Correct and after being reminded of RRunners car, I agree with the Porsche transaxle part too.