iloveporsches

Not a bad idea until the CV joint wears out or the shaft snaps

inactiveuser92616

i was just thinking about a longer term solution to this... rather than relying on bolt shear strength and the friction of the plates (and you could probably make a roughened/friction enhanced plate treatment) how about machining interlocking teeth between the halves? (like a dog ring, without the slop) This would require new parts to be made, but the reliability could be worth it. straight teeth might work, even stronger would be an undulating pattern.

Thoughts?

FSAEracer03

Bonedeaded? The point that got across to me was that the bolt's shear strength doesn't matter, but that the tensile strength is the only determinant. If I was wrong, sorry... but that's how the post sounded.

The shear and tensile strengths are indepedent of each other, Adrial. The chalk twisting case, though involving shear, isn't the "textbook" case. It fractures at 45 degrees, like someone said, because of it's brittle grain structure. Other brittle materials such as cast iron fail the same way.

A good "textbook" case of single shear involving only one bolt would be the rear shock bolt on 944s. The bolt has all it's loading placed in one location of the bolt. One side of the location has a downward force from the shock; the other side of the location has an upward force from the trailing arm. One face for each force... single shear. Suprisingly enough, single shear is actually a real no-no in the field when dealing with serious load-bearing items. I'm surprised they didn't stick with the 924 CGT shock mount, which apperently was in double shear.

Pshh... I'm going to be a hair stylist!

FSAEracer03

I hate to go OT, so I apologize, Rage.

Re-animator, could you possibly send me info and pics of the C32? I'm interested to see what you got done to it. I'd pm you, but it says I can't.

EDIT: Patrat... now that's thinking. Interlocking teeth, or a cam-system, would spread the load out a lot better and probably cure the bolt shearing problem for Rage. Then he'd have to worry about chucking the CVs themselves ...and the gears, and the pinion and the...

rage2

Great discussions! Just one comment regarding the bolts, safety wire, and backing out. The bolts were inspected about a week prior to failure. None of them backed out at all. There wasn't any sign of movements from the bolts.

Re-animator - I have a few tricks for the C32 / SLK32 motor... the renntech kit claims 394hp, I was able to squeeze 419hp out of it .

special tool

how is the Honda coming along?

jimbo1111

the 3 times that I snapped the cv joints I was shifting from 1st to 2nd while going down hill. The tires bite much harder when going down hill. They don't break loose as easily. Avoid down hill hard shifts where ever you can.

toddk911

So what allows other makes and models to be able to withstand hard launches and clutch drop burnouts, etc. ????

Re-animator

Perhaps Audi engineers from yesteryear couldn't foresee the inevitability of an aftermarket 400 HP 951.

DivineE

They don't! People with other highly tuned cars like all the Jap tuners just seem to break things like gearboxes so often they are used to it! The 944 is so tough that when something does go wrong its a big issue.

Well thats how I like to see it. Backed up with some witness of watching 1/4mile runs and seeing countless EVO's and Pulsar GTI's pulling off the track with transmission issues!

Ben

iloveporsches

It wouldn't be any noticible "looseness. You couldn't spot the difference between being torqued to 50 or 25 ft-lb (not su"re what the correct number is for the CV bolts) with your eyes, or even feeling it. But that 25 ft-lb, times 6 bolts, could make a big difference in the clamping/ frictional force between the plates. Now, if you checked it with a torque wrench, that's another story.

Skunk Workz

I've seen Supra's pulling brake-boosted launches with 800+RWHP day after day after....with stock gearboxes,stock CV's,stock bolts....only thing that broke (once) was the trans-shaft...or what ever you may call it (the one between the 'box and the rear housing)...if they can make it stick...why shouldn't the 951's?

Hmm...I see a market for improved transmission components...

toddk911

Not to mention muscle cars.

rage2

It's simple. Those cars came from the factory or is upgradable with much beefier components . It'd be nice to have an affordable aftermarket gearbox and CV's/axels solution for our cars though.

Got my car back today... time to start the bolt death countdown!

Skunk Workz

What would you consider to be an affordable price to pay for a gearbox with much tougher 1st and 2nd gears,and the option of using bigger,stronger bolts for the CV's,as they obviously are a problem..? I have no choice but to make beefier components for the box,(or what else may fail in the drivetrain...) or else the engine I'm working on is no use...would be cheaper for each,if I have several sets made,instead of a one-off. But then again,if there is no market for it,why bother making 10-11-30 sets....