I need info on 944 trans strength

vwhammer · 10-25-2009, 02:39 PM

Ok I am using a plain old 944 5 speed trans in my V8 rabbit project.

Many people that may or may not know what they are talking about have mentioned their concerns about the strength of said transmission.

Does anyone have any real numbers as to what kind of power they have put through such a transmission?

Mine will have a limited slip diff, an oil cooler and will only be in a 2200 LB car but does anyone see any problems putting 300 HP through one?

speedracing944 · speedracing944's Garage

300 HP through a NA tranny? It won't last long, only long enough for you to save up for a 944 turbo tranny. If you shift gently you can get a 944 turbo tranny to withstand 400 ft/lbs of torque.

If you drive the 944 NA tranny gently you might get about 5000 - 10000 miles out of it. If you bang through the gears, speed shift or drag race you will ruin it in a hurry.

What are you using the car for?

Speedy

Tervuren · Tervuren's Garage

Its a crap shoot IMO, I don't recommend it if you know you are going to be putting that much power through it. Some units are stronger than others, and you won't know what you've got until you break it!!!

vwhammer · 10-25-2009, 07:07 PM

Well poop!

I have no intentions of shifting it "gently" and I will drag race it.

As for the general purpose of this car all I can say is that it will be used for a little bit of everything.

It will see track time, both road course and drag strip and I will, on more than one occasion, beat the crap out of it on the street.

Does anyone have any pics of the difference between the NA 944 and the turbo 944 trans.

What are the primary differences and will the turbo unit bolt up to the NA torque tube?

HondaDustR · 10-25-2009, 07:36 PM

Both turbo and NA trannies have the same bellhousing bolt pattern. The big difference is the turbo has a taller final drive ratio. The turbo S transmission has 1st and 2nd hardened and has an even stronger final drive.

v2rocket_aka944 · 10-26-2009, 08:31 AM

i had an NA box on my car for the first 3 years i owned it. i beat the hell out of it, lots of hard launches, 5000RPM clutch drops, powersliding, etc, and it took it all without any issue. still shifted great, no weird noises.

one day i was driving home from school on the freeway cruising the whole way at around 65mph, got about 60 miles and heard a clunk, pulled over, clunking the whole way. somehow on the freeway i had grenaded my ring and pinion. flatbedded the car home and swapped my spare 951 trans in that night.

if youre worried about strength i have another spare NA trans you could have for $250 plus shipping

flash968 · 09:34 AM

guys who have done the 968 engine swap against that box have blown it up - a V8 is sure to

we blew up 2 turbo boxes with a blown 302 against them before we switched to something stronger - lol - then we twisted the heck out of the car once we finally got that working - too much torque for the car - i told the guy not to make a drag car out of it, and that the chassis was too soft, and the IRS rear was a bad idea, but he was determined

it was one failed component after another trying to get the thing to hook up - in the end we cut the car up into bits and pieces and threw it away

HondaDustR · 10-26-2009, 01:02 PM

Quote:

Originally Posted by v2rocket_aka944

i had an NA box on my car for the first 3 years i owned it. i beat the hell out of it, lots of hard launches, 5000RPM clutch drops, powersliding, etc, and it took it all without any issue. still shifted great, no weird noises.

one day i was driving home from school on the freeway cruising the whole way at around 65mph, got about 60 miles and heard a clunk, pulled over, clunking the whole way. somehow on the freeway i had grenaded my ring and pinion. flatbedded the car home and swapped my spare 951 trans in that night.

I lost one myself the same way, minus the ricer beating.

Only mine died at 25 mph rolling down a small road pulling out of a parking lot. No abuse here, although I'd spin the wheels in the rain now and then. The other thing that probably was bad that happened to it a couple times the night before was accelerating out of toll gates and hitting the metal drain grates just after full clutch engagement. The momentary loss and regaining of traction doesn't help.

Quote:

Originally Posted by flash968

we blew up 2 turbo boxes with a blown 302 against them before we switched to something stronger - lol - then we twisted the heck out of the car once we finally got that working - too much torque for the car - i told the guy not to make a drag car out of it, and that the chassis was too soft, and the IRS rear was a bad idea, but he was determined

What was the something stronger?

flash968 · 10-26-2009, 01:17 PM

played with a modified ZF from a pantera for a bit - better, but kept snapping shafts - ended up completely refitting with a BW and a 9" - that got it to hook up really well - lifted the front end off the ground 2 feet and when it came back down on 3 wheels it stayed there like that - completely twisted the car in the process

i knew it would happen though - the chassis is too soft for big torque

the problem is the lower frame rails and suspension mounting points - it required a complete tubular reinforcement package on the next car to get the chassis strong enough to do launches, but the added weight of all the extra stuff made it less than what we wanted - interesting project, and it turned low 10s, but frankly the small block vega did better

we were only putting out about 450 ft/lb and about 500hp too

tooms351 · 10-26-2009, 01:24 PM

I say go for it, but always have a spare standing by. breaking stuff just means you're having fun. Don't side step the clutch from a start and change the fluid, it should last a while. check out Hybrid9s.com, I've been running 425hp for the last two years, street, DE and solo with no problems yet.

flash968 · 10-26-2009, 01:34 PM

yeah- it's not the HP but the torque that presents the problem - we had it come on big at 2k

i suppose if you kept your foot out of it, it would hold up, but then what's the point of that?

pretty sure we could have gotten down into the 9s with a bit more work, because we had a lot to go on the engine, but with things already snapping and twisting, it seemed silly, especially since we had a bug, a vega, and a pinto that already ran faster - the 944 was just too danged heavy

krystar · 10-26-2009, 02:45 PM

besides, if yer gonna be dragging it. u should do this

PORSCHE 924 SETUP FOR SBC CHEVY DRAG ~ RACE CAR

flash968 · 10-26-2009, 02:57 PM

yup - that's the sort of thing we were doing - full on drag car - should have started with a 924, but he really wanted to do a 944 - no worries - it was his money

tooms351 · 10-26-2009, 03:04 PM

yea I definately wouldn't drag race and try to launch it with slicks! but with street tires walking outta the box, rolling starts or road racing shouldn't be a problem. The 944 is a great street car, if ya wanna drag race get a ranger or s-10

vwhammer · 10-26-2009, 03:08 PM

Well the car is not being built to drag race but I live near a track or two so I will probably take it there simply to get some numbers as to what it can do in the quarter mile.

It will not hook and launch like a purpose built drag car would so I do expect a fair amount of wheel spin.

Perhaps a look at the project will give you some idea what I am building.
motorgeek.com :: View topic - Hammer built V8 Rabbit project

I have put a lot of thought and research time into this project so I could build it on a budget to do what I want it to do.
However I do not want to put any money and time into trans that may only last a couple thousand miles.

I guess what it boils down to is a simple question.

What trans will bolt to the NA torque tube and handle 300 HP and 300 or less ft-lb in a 2200 LB car that may see a fair amount of abuse?

And what does a trans like this cost?

Matt Monson · 10-26-2009, 03:09 PM

vwhammer,
Are you going to rebuild it first or just throw in a "good used" box? When they are fresh they are pretty durable little gearboxes. The problem is if you grab any old takeout with an unknown history you don't know what happened to it in it's previous life.

Aside from rebuilding it the other two things you can do to avoid grenading it are to stay away from pucked clutches and don't go to wide on the tires. You would rather have those things slip at the limit than put it all through it.

Lastly, if you are talking about using a factory LSD on it, forgot about it. Those things are throw aways. It will start acting like an open differential about a week after you put that v8 against. That differential isn't any good for anything more than a doorstop.

matthewb · 10-26-2009, 03:28 PM

I personally think there are a lot of people here speaking without experience. The 944 turbo transaxle will bolt up to the n/a torque tube and it is much stronger. As someone else did say there are plenty of us running these with v8's in them without any trouble. I also disagree with the "LSD is junk" bit. I am running a stock LSD and have been for about 15,000 miles and I spin both wheels quite frequently on dry and wet pavement and mine still works great. It even gives me some chatter in regular turns. Maybe the other guy just had a bad one.

As for the differences, the turbo ring and pinion is way bigger than the n/a. I didn't believe they would do it either but I have torn them down personally and am now a believer. I think some of the bearings are larger as well.

I should be putting out HP and torque in the upper 200's very close to three and am still doing fine. I am currently building up a stroker motor so maybe next spring I will be ready to tell you it can take more. Plenty of the ls1 guys are putting way more through it than me without trouble. Bottom line... I say go for it.

Good luck

Matt Monson · 10-26-2009, 05:47 PM

Quote:

Originally Posted by matthewb

I personally think there are a lot of people here speaking without experience. The 944 turbo transaxle will bolt up to the n/a torque tube and it is much stronger. As someone else did say there are plenty of us running these with v8's in them without any trouble. I also disagree with the "LSD is junk" bit. I am running a stock LSD and have been for about 15,000 miles and I spin both wheels quite frequently on dry and wet pavement and mine still works great. It even gives me some chatter in regular turns. Maybe the other guy just had a bad one.

You're welcome to disagree with me both about the strength of the gearbox and the performance of the LSD, but you might want to check my credentials before you accuse me of talking without experience.

So, humour me. Jack up one side of your car, and put a socket and torque wrench on one of your lugs. Check the breakaway torque on your LSD. Post back.

matthewb · 10-26-2009, 06:35 PM

I did not look into you credentials yet and I am sorry if I sounded rude. I didint mean to be that way. I guess everyone has their own experience with them. I am simply speaking from my own and from the experience of the other people I know. Please don't think any less of my future input here.

What do you expect I will find when I do this test. I would estimate it is only maybe 10 foot pounds or so but it sure does seem to get the job done and I am currently running a v8 against it. I may get around to doing that little experiment someday.

matthewb · 10-26-2009, 06:39 PM

Matt it looks like most of your recent posts relate to Porsche cars other than the 944.