Tony

Killing time in the airport the other day i came across this and bought the magazine

I had never really seen how the TT system was set up in the Vettes. It appears to be a true "drive shaft" with in a tube and NO SUPPORTING bearings along its length.

Notice the rubber coupling that both dampens vibration and i would imagine absorbs any change in drive train length behind it. NO TBF?!?

We have some pretty resourceful minds on here....anyone think about how this could be applied to the 928?

Issue i see is our drive shaft length. If one could mount this coupler to the flex plate, then some how have the other half attached where the stock pinch collar is located, we would be away!!


If our TT were to be a similar dia Im sure we wouldnt need TT bearings either to support it?
Anyway, tossing it out for discussion.

Tom in Austin

Interesting they use shafts of 2" dia and up, wonder if they're hollow and what they're made of? The flex coupler makes perfect sense to allow some fore and aft movement.

hacker-pschorr

This past July during my first weekend working for Corvette racing team, I found myself in a discussion about what to do about the C5/C6 torque tube failures (like the above) because installing solid mounts is a popular upgrade but that almost guarantees the transmission or differential will fail (I cannot remember which was more likely as a result of solid mounts). They were also discussing the various issues with the transmission since one guy in the group lost 2nd and 3rd that day.

I jumped in, explained how the 928 torque tube is setup, issues with TBF, the super bearings, Mike Simards theory on the 5 speeds etc.... They were very interested, and a fabricator / machinist in the group said he would like to get his hands on a 928 torque tube to see if it could be reverse engineered to copy the design for the Corvette (he was most interested in some kind of support bearing system).

It appears to me when the weak link in their chain (rubber coupler) is "fixed" they move the problem to the transaxle. The 928 has a more robust transmission sending the pressure to the crank (at least with the automatics) resulting in TBF.
With 5-speed 928's this pressure is taken up by the transmission which has been theorized to be one of the reasons why track driven 928's have issues, which is what Mike Simard is working on.

So unfortunately the grass isn't always greener. I suppose a coupler like the above could be used to act like a fuse saving the engine. The Corvette guys we were racing with are not big fans of the design.


It was sure an eye opener sitting around that "campfire" the first night. Everyone talking about half-shaft failiures, wheel bearing issues (we always have spares along), what a bitch the clutch is (far worse than the 928), timing chain failure breaking valves, ABS modules failing, transmission issues, oil issues including starvation..... Here I thought this whole time the solution to a reliable 928 was installing as many parts as possible from a Corvette?

blown 87

I can not count the number of them (they are called Gazebo's in the trade) I have replaced on MB's and BMW's, hundreds and hundreds of them.
But they do make different sizes of them, and the bigger ones like out of a M5 can hold a lot of power, just a thought and any driveline shop can weld new ends on them for the bigger ones.

JHowell37

Looks very similar in concept to a rag joint.

Mike Simard

The 928 manual TT doesn't have the auto problem because it terminates in the pilot bearing and has allowance for movement. What I've worked on is giving support to the input shaft to prevent gear breakage. I don't worry about that in my car now after my mods.

The poor 'gazebos' in the vette! They must handle all of the tortional funk because the driveshaft is rigid. There's an advantage in the 928 shaft being spindly, it can absorb alot of tortional vibrations.
These large diameter driveshafts have been a problem in all of automotive history, I don't understand why you would use one when you have a tube housing that a small shaft could be used in. I'd guess that it's cost and to prevent bearing noise complaints.

Black Sea RD

Yes, we studied the C5 Corvette drivelines carefully when we were coming up with our 928 products. Thought we would find a great new idea being used in the new Corvettes with a new transaxle system. Surely they had improved the driveline design after all these years.

What we found was their driveline had more problems than the 928 driveline. They can also suffer TBF with their automatics and after a torque tube change must follow a protocol to not let that happen.

Our TTs are a good design, they are just aging. That and Porsche should have done a better review of the drive shaft pullout/TBF problem in their automatic equipped 928s.

But those problems have been taken care of for the future.

By the way I thought those rubber devices are called "guibos" which is an incorrect takeoff of another word given to them from their inventer and manufacturer.

By the way, there is a new style aftermarket rubber/aluminum coupler called a "six shooter" and which is also mentioned in the Corvette article posted by Tony. Supposedly it cures the problem of the rubber joint coming apart.

Cheers,

blown 87

Yankees

Mike Simard

Wonder if you could repair a gazebo with some duck tape?

hacker-pschorr

I'm pretty sure JB Weld is in the Vette shop manual in the drive-shaft section.

blown 87

Been lots of 928 TT's "Fixed" with the loctite version of JB weld.

the flyin' scotsman

so Im reading this thread in all seriousness and theres the duck again.

Now all Python followers knows the witch weighed the same as a duck and floated as wood but didnt introduce any TT discussion but again they were in mediveal times.

hacker-pschorr

In other words, Greg doesn't float?

the flyin' scotsman

Never met the guy...perhaps he looks like a duck or maybe from Peking?