Um, the 944 used an Audi FWD transaxle. The same as in a Passat (Audi chassis). This same transaxle is used by the Lamborghini and GT40 replica builders. LSD is easy, an Audi v8 rear differential can be bolted in. Rebuilding the torque tube is relatively easy and the bearings are under $100. Since it is steel, shortening the outside to allow room for the adapter plate and new bell housing isn't impossible for the average enthusiast.
I don't know why you're making a mountain out of a mole hill here. 944's are scrapped all the time with bad motors and no one wants the torque tubes as they are too ungainly to ship. Sounds to me like you need to stop talking and get yourself some parts and start playing with them.
For a start though, look up Audi 016 on the GT40 replica sites and then hit up porsch-hybrids.org board to learn about adapting various bell housings to the nose of the tube.
carguy123 wrote:
thatsnowinnebago wrote:
You do it like this
Can't view it. It says my count must be 3 or more to even view it. Could you copy & paste?
Oh yeah, sorry about that.
See if this works instead. Different forum, same pictures.
petegossett wrote:
...the polar moment of inertia. A shaft has all it's mass much closer to its center-line than a flywheel. Therefore it takes less energy to accelerate/decelerate than a flywheel.
No, I get that, though I admit my example made it look elsewise.
You're still talking about rapidly changing the rotational speed of a shaft at every shift. There HAS to be reprecussions of that extra mass, even if it is of relatively small diameter. Also, in any gear that has reduction (usually 1st-3rd), the torque tube is going to be spinng faster than a tradtional driveline.
Basically, my assumption is that this design trades gaining a bit of extra rotating mass (and rotating that mass faster in low gears) for better overall weight distribution.
well, depending on where the clutch is.. you can run a lighter flywheel to make up for it
No matter where the clutch is you can run a lighter flywheel to make up for it, or is there anything to make up for? You no longer have a driveshaft so this might be a swap with little detrimental issues.
I don't remember the numbers, but IIRC the stiffness of a rod/tube goes up geometrically with an increase in the diameter so it makes me believe that on a low hp (165-250ish) with a length of 4' or less you might be able to use a lightweight alum driveshaft and not have to worry about the bearings which could be a fail point and also a source of drag. You'd still want an outer tube to contain it in case of a failure on either end, but I have an idea about that. A driveshaft has to transmit power after the torque multiplication of the lower gears with no ill effects so all(!) until you get up to big truck lengths. I'd have to contend with is the increased rev count which means a balanced driveshaft would be a must.
Trying to figure out what kind of tranny to shop for. Is the 6 speed Audi/VW huge when compared to the 5 speed? In the Subie world there is a huge difference in size and weight between the 5 speed and 6 speed.
I've passed at least a dozen 2.0T Passats today, do any of them come from the factory with an LSD and how do I tell which ones? What else comes with the longitudinal engine?
I'll be spending some quality time the porsche-hybrids site once it gets dark and I can quit working in the yard and come inside for long periods of time with. I looked into Porsche & Audi stuff a year or so ago and it was so very pricey. At that time I was thinking of bolting the bellhousing directly to the transaxle. The transaxles alone were more than many engine & tranny combos. It seems the transaxles are used for a lot of stuff so demand is high and so is the pricing. I'm hoping that doesn't translate into higher prices in the VW world. I'll have to see if there are any local yards that have any of those unloved torque tubes laying around. Who knows, they may pay me to take some off their hands. ;)
The Subie tranny could be used, but LSDs are an issue and there's a lot of transmission behind the axle line. I'm hoping the VW ones are shorter. The drawing of the 944 someone posted seems to show the linkage is located on top the the transmission whereas the Subie is mounted behind so that's a big plus in the favor of the VW.
Well I haven't been able to locate a VW transaxle to get a price or dimensions/pictures. None of the places I've seen who might sell the trannies have a clue as to whether they come with LSDs or not. They also want an exact year model as their computer systems key off year and model of car, not model of transmission.
I was able to get some dimensions from the S2000 motor and the 280 Z motors I have laying around.
The centerline of the crank (attachment point of torque tube) is about 8.75" from the very bottom of the stock oil pan. The Z motor is about an inch higher.
The centerline of the stock S diff on a lowered S is 9.5" I'm presuming the input on the VW tranny will be at a similar height. This tells me that the torque tube will sit slighty higher in the chassis than I desired, but not so high as to be an issue. I wanted to put the shifter on top of the torque tube and that is still doable.
Now I need to get some dimensions of the engine output of the rotary and the Subie engines. I'd really prefer them because they are lower and more compact, but I'll probably end up using and S engine simply cause I have one.
