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In the vicinity of 250 pounds. In the greater scheme of things it was not a problem; I had a 520 cubic inch big block Ford with a 6-71 supercharger, which required a transaxle that could take the torque.



Absolutely. I ran into the same "weight cascade" that led Colin Chapman to design the Lotus Seven, except the other way. An 800hp motor required an appropriate transaxle, differentials, halfshafts, hubs, brakes, tires, chassis... I was figuring an all-up weight of around 3300 pounds, which wasn't out of line, considering... that little oopsie about the double final drive reduction saved me from building something I probably didn't really want. I sold off most of the pieces, which was probably one of the smarter things I've done in my life...

When I was scanning piles of old 35mm prints last month I found some pictures of the Kelmark project. The car ran, but the (apparently drunken) previous owner had smashed the windows out and jumped on the roof. The gelcoat was still holding everything together, so I didn't figure it would take too much to fix it. It was sitting on a VW pan at the time. I think the guy just drove it until it wouldn't move any more - there was no clutch cable, the throttle cable was broken and it had a piece of cigarette pack holding the throttle open a bit, and the passenger side rear wheel bearing was... gone. Oh, and big metal chunks fell out of the transmission when I pulled the plug. All of no consequence since I just wanted the body, which was also fully wired, etc.

The chassis looks twisted in the picture, but it wasn't. 2x4x.090 rectangular tubing. I had some S-10 4wd cartridge hubs and halfshafts and big blocks of 2024 aluminum to whittle the uprights from.

The Cadillac transaxle came with a little 425 smog-era engine instead of the mighty 500, or I might have considered going with the Cad. I had some big block Ford bits on hand, so I built a big stroker. There's a picture of a 350 Chevy piston turned sideways, sitting in the 520 Ford's 4.440" bore.

I had some 17x9 wheels custom made, to take 275/40-17s, which were exotic back then.

Besides the gearing problem, the Kelmark was set up for 14" wheels in front and much larger 15" wheels in back. The 17s didn't look right, and there really wasn't enough clearance in front.

Some years later I realized I'd been a fool for being so hung up on the mid-engine layout. I could have scrounged or adapted a Porsche or Audi 4wd setup, and I had a rusty but running Maserati Biturbo sitting alongside the shop. The Biturbo engine would have fit nicely in place of the VW engine, and though it wouldn't have been the psychotic road rocket a supercharged big block would have been, it would have been a whole lot nicer car to actually drive on the street.

How about the way Bugatti did it in the Veyron ?

It would be possible to do something very similar with standard garden variety off the shelf SUV parts, and these come in a wide variety of size/strength at a not totally unreasonable cost.
The mid engine could be placed either at the back or at the front.
If the engine is to be placed at the back, both diffs just need to be turned upside down.

That's standard Lamborghini for many past models. Mitsubishi L200 4WD is the same for locost result.

That was my original plan. It curled up and died in the harsh light of reality-as-we-know-it.

I never found any combination of reasonably-available transfer case bits that would work. The Lamborghini box is all custom stuff, spur gears on a narrow centerline. Even then, it's wide. The Diablo is wider than the Kelmark to start with, with a huge center console and Lotus-width seats, to make it all fit.

Any number of layouts would have been simple, had it not been for the annoying problem of accomodating a passenger more than a foot wide...

I got an idea what about a rear mid engined locost with subie parts. now the problem with most locost is that the engine in a subie drivetrain sits in front of the axel, but if you flip it!!! the engine well sit behind the rear axle! awd traction with a fully build wrx motor
best regards,
Jacob R

That is very true.
Most simple primitive off road transfer cases either lock the front and rear tail shafts together (solid), or have some type of centre differential that splits torque evenly front/rear 50/50.
There are also now available a vast number of ingenious schemes using viscous couplings, clutches, even active computer control. But they mostly all have characteristics sending most of the torque to the wrong end for a rear mid engined 4Wd road car.

My own preference is for an epicyclic torque splitter that is biased towards the rear, maybe 32/68 F/R.
This system is used by BMW, Jaguar, Hummer, and (in Australia) by GMH.
The transfer case I am using is the New Process 124 which is gear drive 32/68 split, without a low range.
This is ideal for a front mid engined car, but would not work with a rear mid engined car.

The only way I can think of doing a rear mid engined car, would be to use one of the primitive fully locked up transfer cases, and fitting a clutch between the front driveshaft and the front diff.
The rear diff of the very common Honda CRV already has such a clutch fitted within the diff housing.
And there are other very similar systems used on less common vehicles.




http://www.awdwiki.com/en/honda/

I have not really looked into this idea in any real depth, as my own mid engine 4Wd project has the engine at the front, which is a lot easier to do.

I am just thinking and mumbling out loud here, but the above 4WD link is full of ideas and some really interesting hardware.

Click on the topics listed at the left hand side of the above 4WD Wiki link, there is some really interesting hardware around if you are prepared to search it out.

The only problem then is that you have 1 forward gear and x reverse gears...

can you not flip the tranmission? if not then dont

Flipping a diff upside down is the only practical way to reverse vehicle direction, while keeping the diff gears turning the correct way.
Drive and coast sides of the diff gears are cut a totally different shape.
As long as the pinion turns the direction it was designed to turn, just about any diff will work right way up, or upside down.
You just need to be careful of pinion bearing oiling if you run upside down, but most (?) diffs will be o/k in that regard.

But as we all know, the Subie font diff is located inside the transmission. Flipping the whole transmission would place the gear lever underneath the gearbox, and underneath car !
And that creates a very interesting new problem to fix.

The Subie box can only really be used the way Subie intended it to be used, there is not much else you can really do with it.
Reversing the engine rotation means the front diff gears will also rotate backwards, and the front diff gears won't last long.

Adapt a Honda engine to your Subaru transmission. ..

_________________
"There are times when a broken tool is better than a sound one, or a twisted personality more useful than a whole one.
For instance, a whole beer bottle isn't half the weapon that half a beer bottle is ..." Randall Garrett

Incorrect, there are kits to covert the 5-speed boxes to reverse rotation, everything else stays the same. Usually for VW van conversions.

For a diff, the R34 Skyline GTR happens to run a hitachi R160 front diff (case built into the engine) with reverse-cut gears which would swap directly into a Subie R160/R180 case, allow it to spin backwards without having to flip the diff (oiling issues) and having to worry about engaging the wrong side of the gear teeth.

Yes indeed, the Skyline R34 GTR uses a high pinion reverse cut R160 diff with a ratio of 3.54.

In fact I have one right here with me right now, so I am very familiar with that particular GTR diff.
It also has a conventional spline and thread on the end, and a big nut, to fit a conventional diff drive flange which is driven by the GTR transfer case through an external front prop shaft.

However the Subie R160 diff has the pinion located on the end of a very long shaft that extends right to the rear of the gearbox, where the centre diff is located.

The GTR and Subie pinion shafts are totally different, even though the actual crown wheel and pinion gears themselves might both be dimensionally correct to properly mesh.
I wish you luck in fitting a GTR pinion into a Subie gearbox, the GTR pinion shaft is totally the wrong shape, and far too short.

This ain't easy !!!!




By the way, I originally planned to use an R34 GTR front diff in my own 4WD project, which is why I happen to have all the parts here, but have now decided to use a Dana 30 front diff instead.

The new build is shaping up to be RWD/mid engine, but as I've mentioned before, if an AWD Subaru fell into my hands - even an old carbureted four - I'd jump on it. Just transplant the driveline in its original configuration, reshape the nose cone as needed, and let the engine fly in the wind like some of the old British cycle-cars. It'd have a sort of hammerhead look.

The 305hp WRX is just under 3400 pounds and is pretty sprightly. Shave off two thousand pounds of "road-hugging weight" (as the Ford ads used to brag about) and it would be even more fun.

Depending on where you put the radiator, you'd have most of the original engine bay available for luggage, fuel, your rock collection, etc.

Aw, shoot. :\ I actually hadn't considered that, touche. Well, I guess the options are a custom shaft, or some frankenstein of the 2. Got pics you could share, by chance?

What's the weight of the dana 30 diff?

edit: I see they're mostly solid axles, not independent susp., how are you working around that?



Except the engine would stick wayyy out in front of the axles since the output is from the transmission, behind the engine. Basically one of the deadly sins as far as handling is concerned.