I know the pan has no inherent strength without the rest of the body. Even a VW pan isn't strong enough for anything beyond its 36hp. The guy who started this thread said custom tube frame. So Audi pan with running gear and tube frame with all the load paths figured out and triangulate triangulate triangulate. Lamborghini has wider and higher sills. Lots of room to tuck away monster frame rails. Plus you already have to have framework to mount the engine in the back. This is not that complex. I have seen plenty of modern pans with old bodies drop on them. There was a kit that took an impreza cut away a bunch of it including the roof, installed a full cage and dropped an RS200 replica body on it. Very similar to what I am suggesting. The only engineering here is the transfer box hung off the transaxle. That is gonna be a pain in the *****. The rest is not easy but not rocket science. As for a engine transmission and transfercase spun around backward you are talking custom driveshafts custom axles and a reverse rotation front diff out of something like an Explorer. 2 problems - all front diffs on awd and 4wd are open. No LSD. Also awd transfercase are rear biased. 66/33 to the front if it's backwards. It's gonna drive like an Accord. Do you have any solutions?

 

On a quick note yes 4wd front lockers and lsd but not the type you would need. Instant lock as soon as wheel spin occurs not the progressive type needed for tarmac.

 

You might be able to run reverse rotation ring and pinion on regular rotation diff and spin it backwards and then the helical cut would be going the right way but I don't know if it would bolt up. But then the lsd (1 way) will only lock up on deceleration. You could use a 2 way but it's not ideal for turning. You could avoid the lsd problem by flipping the diff upside down but now you've changed it from a low pinion to a high pinion causing the pinion to be drawn towards the ring. The exact opposite of what it was doing before. Don't know if diffs can handle the load doing a 180 and the pinion being high up away from the oil. Now flipped with a reverse rotation R&P should have it pushing away from the ring like it should but still the pinion is up away from the oil. The gear should be fine it's the bearing it rides on that worries me.

 

I might have a solution for the front rear bias problem with awd transfercase when turning the drivetrain backwards for mid engine placement. I repeat might. The trailblazer ss comes with a Torsen T3 transfercase with a Torsen center diff. Now look at this exploded view diagram of a 6spd FJ Cruiser center diff (very similar)


If you don't know how this works check youtube. The pinion bottoms out against the clutch plates, slows down and applies power to the opposite side. I'm thinking they get 33/66 front rear bias by using clutch plate material with a different frictional coeffcient on each side. If this is the case you might be able to swap the clutch plates from one side to the other to get back your rear bias. Here is the number for Torsen (585) 464-5000 if anybody wants to find out. Me I'm not building this and if I was I'd be sticking with my Audi idea. Not bad for a guy whose was called ignorant or that I have no idea what I'm talking about half a dozen time eh?

 

Hi Dr, in my shop we manufactured/assembled the ZF-25DS-1/2 and rebuilt these earlier BEFORE the ZF "blessing" to manufacture with ALL the OEM data, rights, tooling, machinery. (Roy Butfoy RIP)

I have never seen a 4WD "mid-engine" application, I would like to ?

As for the "locker" I would fit a Wiesmann. (Traction Products)

DO NOT run a pinion REVERSE as the Trust/Coast would be opposite.

WE had NO Problem with axle rotation as our Crown could be fit to either side of the pinion.

Lance, BTW we had Mangusta owners calling to STATE they had FIVE speeds in reverse AFTER fitting a Pantera Transaxle

 

Here is one from Nelson Racing Engines. 1967 GTO 2000hp AWD Mid Engine. It's been in the works for 8 years but it looks like it's finally coming together. NSFW total car ****.





Rough idea what one of those Weismenn diffs would cost?

 

Having built many chassis up from scratch,,, I guarantee that a hand built space frame is easier than trying to hatch together bits and pieces from a bunch of street cars.

Design the body, do a simple ladder frame , that fits in the body,
Several sources can build 9" differentials and independent housings, they can assemble them in either rotation. Look at how most SUV's do the front, they use a axle housing with the diff offset and a extension tube to get the CV joints the same distance from the wheels(CRITICAL). Use True-Track diffs in both ends. New process makes the transfer case for the E46 BMW 330's as well as the transfer cases for a slug of other vehicles. Get a BMW tcase from a pre 2006 and its a straight up torque split (60/40) rear/front single speed gear drive case elegantly simple no electronic BS to deal with. You'd build a plate to make the case a divorced unit if needed.

The NP242 is another option. It is a two speed but its not hard to get rid of the low range and is cool because you can lock it, or run it as a open diff. Again dead simple no electronics to figure out. they have survived 800 ft lbs of torque in some applications.

Another option is a simple chain transfer case like the monster trucks use, they use the chains and sprockets out of a regular transfer in a simple aluminum box housing or steel.

Want brute simple? The engine layout would be mid motor rear Tranny. chain case on back of transmission, driveline gets connected between the U-loints of the differentials, Chain case bolted on pinion side of rear diff. Put a jerico 4 speed behind the engine(Short), you can ditch the tail shaft for a machined part to match the chain box to the driveline/rear end. Both diffs end up offset with a extension housing to keep that motion center consistent side to side.

For outer hub ideas look at a spec racer ford. Fairly simple setup.


Ok that was fun.. cheers.

 

Even if you use a front diff in the back it's still spinning the wrong way. Any ideas on where you can source a reverse rotation diff without spending a fortune?

 

All you need to change is the gearset, Randys/Yukon and others carry them.
High pinion*Pinion is above the axles) 4x4's use them..

The current ford SUV's use a nice independent diff in the rear...


Back to the top for the Jurrasic thread...

 

Just for the same of clarity I shouldn't of said reverse rotation diff. What I meant is that the diffs input from the driveshaft is reversed. Even though the driveshaft spins backwards the wheels spin the right way. Randys carries something like this? With a one way lsd rather than a two way lsd? I called but they are closed till Monday. Thanks.

 

Called Randys and they don't have a diff that will work. Gonna shoot Wiessman a email. Don't expect it to be cheap.

 

Well, if you're looking for cheap, this whole project just circled the drain.....

 

Lol you again. Still bringing nothing to the table I see. How's the box?

 

Oh you meant reverse as in swap directions! LOl
You could do that by flopping a rear end side to side so the pinion is on the opposite side of the ring gear from normal, you need some mods internally to the diff so it will lube correctly and you'll need reverse rotation gears in the diff to load correctly. This has been done a lot with the VW tranny in spec/sports racers, they flip the transaxle over so they can use it in a mid-engine layout. requires some internal work but not rocket science. Many guys have made the mistake of stuffing the ring in a vw trans from the wrong side and ended up with 4 speeds backwards..

BTW not sure if you realize this but the C5 chassis is almost useless as a base frame, because of the way they build the roll structure and pan if you change it the thing will have zero strength.. again,,, a hand built space frame chassis with a glass body is the way to go if you want a drive-able super car, ALMS prototypes would be your model. And there are several kit bodies that you might be able to use as the base skin.

 

Just for the record I didn't start this thread. I'm just trying to come up with solutions as this idea keeps coming up on the forums. I was told in a previous post that flipping the diff won't work as the thrust/coast would be backwards. Probably wouldn't want to use something cobble together behind a stout LS anyways. Weissman does make diffs that will work but didn't give me a price. I'm GUESSING 4k a piece. Still going to need axles and driveshafts as well. This will get expensive quick. Plus no definitive answer on a transfercase with the right front rear bias. I'm standing by my original idea of using Audi components and a custom transfer box as a easier and cheaper solution.

 

Quick question, I see mention of tcases that have different rear/front bias. Some are 50/50 and some are 60/40. Obviously in the 50/50 case you run the same diameter tire rear/front, but what is done when using a 60/40 case? Do you have to use some math and then try to search for a wheel/tire combo that works???

I'm a virgin to the AWD scene.........but have also wondered how the GTR guys get away with running different height tires front/rear. What is the split on those cars and how does this work???

 

GOOD QUESTION!!! As far as I can tell Nissan is in league with Lucifer and has a caudre of Crowleyites sprinkling the blood of the innocent into the transaxles of those demonic drag weapons.

So to summarize I don't have a clue.
Overdriven gears, clutches and computers is a uneducated guess but I will find out and post as you have piqued my interest.
Sorry for the delayed response but it's been 12-14hr days at work.
To be continued......

 

I've looked and not found much on the R35's front rear split of its GR6 transaxle. It does have a final drive ratios of 3.700 rear and 2.937 front. Which means it runs as a rear wheel drive car until the rear tire start to slip then the computer starts locking the clutch to the front wheels in the transaxle. Overdriving the front wheels means you can hang the tail way out and still catch it as on full clutch lock the front tires would be spinning 25% faster than the rears. So to answer your question - if the rear tire is bigger than the front but less than 25% bigger it wouldn't matter in a drag race. For a good explanation look up how the Focus RS drift mode works. Same idea but in reverse.
As for front rear bias 40/60 split it has nothing to do with the size of the tire you have to run. It's how much power is being sent to the front or rear. They do this with the angle of the gear input (not all). A simple explination would be this - you have a motor winding up a rope that is pulling two different guys on toboggans up 2 different hills. One hill is steeper than the other so he would use more of the motors power to be pulled up. The other guy uses less. But they would be going at the same speed. Same thing but with gears.

 

The R35 uses a clutch pack to send drive to the front....so it can either be full rwd or 4wd as desired.

There may be some internal gearing prior to the clutch pack that enables the large difference between front and rear diff ratios.

And as for flipping diffs...gearboxes upside down. It's a fairly common thing so despite it probably not being ideal, it does work.
Maybe if the setup was really pushing big numbers it might be more of a concern

 

I doubt there would be gearing before the clutch packs for two reasons
1. Why add complexity when you could just have a higher front diff ratio. Which it does.
2. You wouldn't want to spin the clutch packs any fastest than you have to. Faster you spin it the more mass it has exponentially and the harder it would be to control. Its the law of inverse square.

As for flipping the gearbox like a Porsche or VW thats a transaxle and won't work for this application.
Where would you source "flipped" diffs that won't have the thrust-coast and the helical R&P backwards? Besides Weissmans? I am calling Currie tomorrow as their diffs are used in mid engine Ultra4/KOH buggies. Maybe a solution.