Bill Curlee

I disassembled my 02 ZO6 torque tube last night and when I pulled it out of the tube,, plastic chips came out of the inside of the tube.

Upon closer examination, EVERYTHING looked perfectly normal except the plastic ring in the center of the propeller shaft. Prior to disassembly, the torque tube showed ZERO issues or noises.

The ring was worn down on 1/2 of its diameter. All the rubber couplers looked perfect and the bearings roll smooth and silent and do not have any slop.

So,,, how can the plastic ring wear down on only ONE AREA???? I spun the shaft and it spins straight. No wobble. The couplers do not flex or distort when I examine them by hand.














The ONLY thing that I can see that would cause this is if the shaft wraps when torqued. I have ne rubber couplers. Do you think they would eliminate the issue?


Please help me figure out how this can happen and what do i need to do to fix the issue. Thanks for any and all assistance.

Bill

lionelhutz

What rpm do you spin it to?

It's my understanding that every drive shaft will begin to whip like a skipping rope above some critical rpm and that's the reason why a longer shaft or a higher speed application (for normal transmission to rear-end drive shafts) needs a larger diameter tube.

Nt sure how you would fix it though.

Peter

Eric D

with Peter. The center ring is there for over-rev protection of the propshaft to torque tube. If you haven't noted any issues I would be tempped to put it back together as is. I don't know of any way to replace the center ring without effecting other things.

Update: From the manual, The propeller shaft tube has an overspeed limiter, snubber, that prevents permanent propeller shaft damage as a result of a downshift above recommended speeds.

Measure the propeller shaft runout.
8.1. Mount the propeller shaft in wooden V-blocks or between centers on a fixture.

8.2. Check the runout of the propeller shaft in multiple locations, including the barrel ends, using the J 7872 .

8.3. If propeller shaft runout exceeds 0.3 mm (0.118 in), the propeller shaft is bent and should be replaced.

Inspect the snubber - manual transmission - for wear or a flat spot on the outer edge.
Check the runout of the snubber.
If the runout of the outer edge of the snubber exceeds 2 mm (0.79 in), replace the propeller shaft.

Bill Curlee

6850 RPM and its transmitting 450 RWHP and over 400 TQ. I sat there an hour going thru every scenario I cold muster up on how that happened and all I could figure was it was wrapping under load.

Its never given me an issue so,,,,,,,,I guess i just reassemble it and give her hell.

I have the entire drive train out and installing mods. The tranny is getting a 60/60 up grade, the rear-end is receiving C6 ZO6 output shafts, DTE Bellview heavy duty clutch pack springs (the long output shaft spring was broken) and DTE spider gear cross shaft.

Clutch is upgraded to SPEC duel disk with a TICK Master cylinder.

I was trying to cure a sticky clutch under full power. When I pulled the clutch I was very surprised to see that the clutch disk, pressure plate and fly wheel was in very good condition. All my problems came from the slave cylinder and or master cyl.

I will get her all back together and let ya know how the torque tube holds up.

Thanks

Bill

corvettebob1

I believe LG has a fix for this, it's a carbon fiber shaft that will not whip like the stock one does at high RPM.

Eric D

Added some info to my above post from the manual. From your photos it looks like the snubber runout would be less than the .78" max they allow. You would still need to check the shaft runout as well.

Blue Angel

I wouldn't be putting it back together with the WORN snubber on it, since it is worn exessively in one place it will throw the shaft out of balance.

There's nothing wrong with the Corvette that money won't fix!

Question: What keeps the driveshaft centered? If there's no hard centering mechanism for the shaft then it's likely the bushings alone that center it. Since they're made of rubber and designed to flex, I'd say that snubber is likely a wear item and would need periodic replacement.

On that note, my '02Z has ~108k miles on it and the torque tube has never been apart...

Bill Curlee

Well,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,, Here’s what I found out after a little "QUESTIONING" last night.

I asked my Son, if he had ever mechanically over-revved the car and he said, "I may have". Then my wife admitted that she MAY HAVE.

So,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, with that knowledge,,, ,and the fact that I NEVER HAVE over revved it,,,,,,,,,,,,,,,,,,,, it’s going back together AS IS. Under MY control, everything should be FINE.

So,,, LESSON LEARNED,,, When your car is out of your control and being driven by someone else, you NEVER know what is happening to it regardless of who it is driving your car.

Thanks for all the great info.

Bill

lucky131969

I would at least check the runout on the snubber Bill, just so you have a baseline number.

Eric D

Funny no one pointed it out, but the manual in its conversion mm to inches is wrong. shaft runout, .3mm should be (.0118) and for the snubber, 2mm should be (0.078 in).

Bill Curlee

The main prop shaft is .004 on the big end and .003 on the small end. The plactic snubber is FUKED! Its half mssing on one side.

Im not too worried about now that I KNOW what caused it. I know that it happensed prior to my second set of mods. Ive had the engine apart after that and there' new valves, springs, pushrods and no piston damage and or smiley marks.

I feel good that it will be fine. Just like finding the cause of my hydro lock issue (leak in the runner floor), at least I can feel better that it's not going to be a problem.

BC

Fast Cop

Thats why you NEVER let it out of your control!!!!!!!!

MVP'S ZO6

so, its safe to say then the out of roundness of The propeller shaft tube overspeed limiter, snubber, is doing its job and theres nothing wrong with bills car?

Blue Angel

Can you get a new snubber on there at least?

LoneStarFRC

No. It's bonded permanently.

It appears this problem is over-rev on downshift related.

BLOWNBLUEZ06

Mine moved down the shaft 1/2"

The problem also appears when you start to make large amounts of power. I had a really nasty vibration in my car at WOT. I thought it was wheel hop. Turned out to be that I exceeded my Textralia Exoskel's holding ability.
Months after upgrading that to a triple, I had another nasty vibration, but a little different feeling than the clutch. Turned out to be the prop shaft had seen enough power and abuse from me. Ended up with a custom 3.5" prop shaft with billet ends from the driveshaft shop. No more issues.

LoneStarFRC

Was your particular snubber chewed only on ONE side or was it just possibly defective and moved down the shaft?

Bills' shaft had the obvious signs of contact only on one side of the snubber.

Eric D

One side snubber contact is typical in an over-rev occurrence. The whole purpose of the snubber is to keep the shaft from bending to the point that it will no longer return to its original shape. This is a shaft speed (rpm) issue, not a horse power issue.

BLOWNBLUEZ06

I had one side shaved off too, but it didn't appear to be as severe as Bill's case. It went just past the raised edge on one side. I didn't put up with the vibration for very long. Only long enough to decide it was the prop shaft or couplers.

BLOWNBLUEZ06

So you're saying if a person is applying 450ft lbs torque through the prop shaft at 6kRPM vs. 750ft lbs of torque at the same RPM, it makes no difference and would produce no worse effects? My guess would be that it would tend to make any warping worse under the additional stress, but I'm no engineer.