marksportcts

What do all you racer's and tuner shops using for the CV and halfshafts? Factory, GKN Motorsports, custom, ect?

Huntley Racing

GKN shows the listing but doesent sell them so forget that. We have had them made for the realy big cars but most get away without them.

John Anderson

So far the stock shafts, and CV's seem to hold up just fine...Although, I've never launched my 951 with micky soft sided sticky tires at 5ooorpms! But on the track, I have not really heard of the issue coming coming up. I know there are a lot of hefty 951's out there and suspension, brakes, tires are the main concern...

So, unless your putting down, over 500hp at the tires and launching at every red light...your fine. I'm making 400+hp and over 500 tq at the wheels and have been runniong the stock parts for years.

Hope this helps!

Jon-D

John: That's great to hear, actually. I was getting kind of troubled thinking about just how much HP/TQ the 944 drive-shafts can actually handle. Windward Performance seems to believe that ~350 HP is the breaking point as quoted on their website:

[quote] TECH TIP: Your 944 turbo's transaxle (Manufactured by Audi) cannot tolerate over 350 H.P. (real world) without breaking. Oddly enough, all 924 models have a stronger Porsche-manufactured transaxle. <hr></blockquote>

You can read that quote here: <a href="http://www.windward-perf.com/944turbo.html" target="_blank">944 TURBO</a>

I don't plan on putting down anymore than 350 HP at the rear wheels, anyway, so I don't see any problems. Half-shafts and CVs aren't the hardest of repairs or replacements to make, either. I just love seeing all kinds of ricers in the shop for busted 'shafts, though. Makes me burn with pride for german engineering.

- Jon

Danno

Were the axles the same on the 924s with the Porsche gearbox vs. the 924s with the Audi gearbox?

Jon-D

Don't know. The website doesn't state; however, it to reason that the Porsche shafts would only come with the Porsche boxes, but who knows? Of course that raises the question of 924 vs. 924S. Would the 2.5L 924S (with the same gearbox as the 944) have weaker half-shafts than it's earlier 2.0L cousin? That, I cannot answer.

- Jon

Luke

I have heard a Firehawk guy say that that quote is totally bogus. The 924 trannys cannot withstand any where near as much as a 951's ? <img src="confused.gif" border="0">

Ahmet

I believe the early 924 5 speed transaxles (the only ones MADE by porsche in the entire front engined series) are the strongest of the bunch.

Broadfoot racing used an 89 turbo transaxle in one of their race cars (the red GT3 car) for over an entire season, including spinning it in 3rd gear (off pavement--&gt;on pavement, back off) which fried the stock clutch. I think the car had 400+hp at that point with race tires, and the transaxle was still fine. This car also had the stock CV joints (the updated style) which also held up fine.

So I would think the transaxle is strong enough, along with the rest of the drivetrain. Then again I snapped an axle a couple of days ago (axle shaft, not a cv or anything) launching the car on some pretty crappy 225/50/16 tires... The axle looked original though, and the car's from chicago with 179k miles on it, so chanses are it was at least partly fatigue.
Ahmet

Luke

over1g,

do you have an open diff? <img src="confused.gif" border="0">

Ahmet

Yes, why?
Ahmet

Jon-D

over1g: That's awesome to hear. I knew Porsche wouldn't put junk on their cars and any sports car drive-shaft that busts at 350 HP is a junk shaft. Kudos to german engineering... AGAIN!

- Jon

rage2

I went through 3 sets of CV joints (one set used, one set new, one set rebuilt) in one of my boy racer years, like John said, launching at every light, drag strip every weekend. This was before my big engine mods too, nothing but an Autothority Stage 2 chip. I even chipped a few teeth off 1st gear after about 2-3 years of abuse.

I just replaced my CV joints with GKN OEM's (broke another about a month ago), we'll see how they last. The last set had a few launches on them. Also, my car makes a little over 400ft-lbs torque at the wheels, so that can't be good for the CV's either.

I'm also going to be trying out drag slicks this year, god knows how the drivetrain's gonna hold up =).

Danno

Ahmet's failure puzzles me.... I have never, ever heard of anyone snapping an axle. Plenty of CV joints yea, especially when they're worn, but axles? Did you find any odd markings on the axle? Like chips or dents? Was there any bends in it? I'm going to compute the torsional strength of one of these things... and I'll bet it's HUGE!

Luke

I snapped an axle in my audi 4000s last week. So it's not a "power" thing. That car has about 70hp. It DOES happen Danno. Fatigue and heat cycles. Im sure it's more common on open diff cars. (like mine used to be)

Weak dampers combined with dryin' cv joints in an extreme "plunged" position

I think the force that ultimately snapped the shaft came from the weight of the car, and not the engine danno.

Ahmet

Danno, I'm planning to clean the short piece of this axle, along with the cv joint to put on my desk. I'm going to take pictures, let me know if you're interested in seeing them. This kind of worries me though, if a CV axle can just break, what does that say about the rest of the chasis, an axle is one thing but a control arm or spindle breaking at high speed under load wouldn't be pretty... BTW, did you ever get that e-mail I sent you?

Also, yes my car's shocks are very very dead and on a good launch it definately squats quite badly. I don't even have enough money to buy that rebuild kit right now after clutch troubles with my other 944... Anyway, I don't know if the squat's an issue but I wouldn't think so, since it's within the movement range allowed by the CV joints themselves. Luke, why does an open diff transaxle stress the joints more?
Ahmet