Carl Fausett

No. The CF diriveshafts get their torsional strength from diameter, often 4, 5, and even 6" across.
There is no room for that in here.

I also beleive the torsional loading was engineered to soften damage to the drivetrain, like the use of springs in the center-hub of the clutch. You would not want the driveshaft to be rigid, IMHO. The shock loads on the transmission would be too high.

Tony

very nicely done!
just when you think what else can be done................

James Bailey

Very pretty....wonder how it would polish up

DR

Hmmm, so you like to polish "tubes", eh??

HI JIM!! Hope you are doing great!

Dave

Imo000

So there is a 25lbs difference between the empty aluminium and empty steel TTs?

dr bob

Now I'll need a nice lightweight polished billet sleeve for the steel autobox torque tube.

The next gen of these will be an extrusiion with both inner and outer fins on it. The bearing holders will index in the iner fins, while the external finns will help disspate heat. Anodized in your choice of colors with polished faces on those outside fins. I could put strips of LED's in the upper fins to show off the polished heat shields under the car too. Wahoo!


Like most things 928-specific, there just isn't a huge market.

PorKen

The walls of the stock steel tube are surprisingly thin. The tube will absorb some of the energy of a severe impact by crushing/bending.

I have a TT from an '83 auto that was driven under the back of a semi trailer. The trailer's bumper crushed the front of the engine, pushed it down, and sheared off the intake manifold. (Didn't reach the cab.) The TT is compressed and bent a few degrees, about 1 foot back from the engine. (The engine and trans mounts sheared off as they were designed to do.)

Given the wall thickness, I reckon there is some flex in the stock tube as well.

Carl Fausett

Good information, Porken.

Good thread to all!

Brad W

So since the Corvette has a TT with the trans in back, what is it made from? I would think aluminum and we know the Vette has a lot of flex.

dr bob

It's OK for the car to flex, so long as the forces causing the flex aren't applied to the tube. Regular motor and rear trans mounts isolate the frame enough to "protect" the tube from excessive torsional stress as thge frame moves around.

I'm thinking harder and harder about the extruded aluminum tube. Ribs would limit flex, help with torsional rigidity. So what would break off while the tube is still intact? Bellhousing ears?

James Bailey

I believe that steel assembly being weighed still has the big cast iron vibration dampner inside while the "race" tube has none. After all if you solid mount the engine and transmission and are O K with THAT level of vibration it probably makes no difference !

Jerry Feather

This is a false concern since although the T6 alloy will go dead soft when it is welded, it will age harden itself back to about 98 percent of its original hardness in about 24 hours and then over time all the way back.

Black Sea RD

The C5 and later Corvette TT is very different from the 928 TT. It's much bigger, beefier and uses a drive shaft "tube." It has rubber connectors at each end of the drive shaft to reduce drive line shock loads.

Carl has given racers another way to reduce sprung weight from the 928. Looks very beefy in it's own right and should handle itself just fine in a track 928 with a proper roll cage as he suggests.

The only exception we have is with the chosen bearing units. We think our aluminum units would be a much better fit in this beautiful aluminum TT.

As far as weight, we have a customer 5 speed TT rebuilt with three aluminum Super Bearings and no vibration dampener and it weighs about 43 pounds.

The 5 speed TT gutted weighs in at approximately 27.6 pounds

The 5 speed drive shaft weighs about 12 pounds

Cheers,

jon928se

I agree - Steel or alu TT if you solid mount the motor and trans the TT will start to contribute some stiffness to the unibody, quite how much will depend on how much the body twists and how stiffly the motor and trans mounts are connected to the body.

I'm guessing a little OK a lot by judging thickness from pics. But I would think that the tube is more than adequately strong and stiff for normal or track use. I'ld reserve judgement on the welds between tube and endplate without more info.

Re what would break off while the tube is intact - my thoughts are the bolts would pull the threads out of the trans/bellhousing.

My concern (and Carl's quite sensibly) if one were to use the tube in a non caged car for road use would be exactly how the original tube is supposed to react in the event of crash, (I'm not clear on that) and does the Alu tube perform similarly. It's no beyond the bounds of possibilty that it could perfom better.

Imo000

That's what I was trying to find out. If the dapener was left out from the aluminium TT, then it's not really a 25lb savings, is it?



Carl, What is the weight difference between the two empty tubes? Any other deleted/changed parts have no relevance on what the TT is made from. Or am I missing something?