944 drivetrain questions
12-01-2018, 01:03 AM
#1
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944 drivetrain questions
Hello all!
Big track car project coming this spring and my buddy and I wanted to get some of the in depth planning done ahead of time.
Firstly what are the measurements for a 944 input shaft? (Spigot, spline, and diameter)
Is the ‘bell’ for the torque tube removable?
how much torque can the factory drivetrain handle?
is there a recommended strengthened gear set for he 944, or a recommended swap? (We have looked into the corvette trans, but it could be less expensive to rebuild the stock trans after all the fab required to swap)
with our build, we are keeping the transaxle for better FR balance but swapping in a vq35 from a Nissan because it’s cheap and reliable with a large aftermarket.
Thank you!
James
Big track car project coming this spring and my buddy and I wanted to get some of the in depth planning done ahead of time.
Firstly what are the measurements for a 944 input shaft? (Spigot, spline, and diameter)
Is the ‘bell’ for the torque tube removable?
how much torque can the factory drivetrain handle?
is there a recommended strengthened gear set for he 944, or a recommended swap? (We have looked into the corvette trans, but it could be less expensive to rebuild the stock trans after all the fab required to swap)
with our build, we are keeping the transaxle for better FR balance but swapping in a vq35 from a Nissan because it’s cheap and reliable with a large aftermarket.
Thank you!
James
12-01-2018, 01:27 AM
#2
Generally, the weak point is the transmission. Although, the torque tube can require noticeably more frequent servicing if you're above 500 hp.
The AOR-code Turbo S trans is good for maybe 450 hp. The 968 trans, which requires a few other modification to fit a 944, is probably good for about 700? Although I don't know if many have tested its limit. The 924 G31, which also requires modifications to fit a 944, may also be good for around 500, as Porsche used a variation of that transmission in its 924 GTRs.
The 01E, on which the 968 box is based, has been used in AWD applications with over 700 hp. Understand that most of those aren't track cars but people do a lot of hard launches with them. Champion Motorsport used it in 500hp AWD touring cars that did a standing start at every event.
You'll likely experience issues with axles as well. If you're running over 500 hp you may need to investigate better axles. I don't know if there is an available alternative to the CV joint setup. On some 924 GTRs Porsche used titanium tripod axles with U-joints and rubber isolators.
With a high horsepower or high grip car you should also carefully choose front axle components. If you have an early 944 (or any 924) is has a hollow LF spindle which is trash; the set should be swapped for a solid pair. There are different thickness spindles, and aftermarket options for A-arms and hubs.
Someone else should chime in with your other questions.
12-01-2018, 01:28 AM
#3
Rainman
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1" x 23 spline, i forget the pilot snout size...
the front bell yes, the rear bell has to be cut off.
driveshaft no issues, 944 turbo gearbox is good for 500+ tq/hp but at this age they all could stand to be refreshed
there aren't really any aftermarket gear sets, anything out there would be mega-buck custom. 951 stock is very strong, 951S is even stronger
VQ35 - are you sure it'll fit under the hood? a 944 engine from crank center to top of manifold/etc is barely 15" high. most 60* V6 engines are over 20" there...
width/length is not a problem.
the front bell yes, the rear bell has to be cut off.
driveshaft no issues, 944 turbo gearbox is good for 500+ tq/hp but at this age they all could stand to be refreshed
there aren't really any aftermarket gear sets, anything out there would be mega-buck custom. 951 stock is very strong, 951S is even stronger
VQ35 - are you sure it'll fit under the hood? a 944 engine from crank center to top of manifold/etc is barely 15" high. most 60* V6 engines are over 20" there...
width/length is not a problem.
12-01-2018, 09:42 AM
#4
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Regarding axles and CV joints, you may wish to upgrade these to chrome moly items.
XSCHOP on here offers the axles and the CV joints can be found on eBay - https://www.ebay.com/itm/Empi-98-508...e/112735960406
As always, as you up the ante and start adding extra strength to accommodate more power, something else reveals itself as the weakest link/fuse.
XSCHOP on here offers the axles and the CV joints can be found on eBay - https://www.ebay.com/itm/Empi-98-508...e/112735960406
As always, as you up the ante and start adding extra strength to accommodate more power, something else reveals itself as the weakest link/fuse.
12-01-2018, 12:39 PM
#5
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If you want to go racing, but are even remotely concerned about cost, why not just get an early 2000s Camaro? GM probably misplaced more Camaros in a single year than the entire production run of 944/951s, making them cheap and easy to get parts for. And a car like that is hard to kill, which is what you want in amateur class racing.