AlanC

My 2000 has developed a fairly severe driveline vibration which feels like it is coming from directly below the shifter.

Does not occur constantly, but seems to happen between 2500-3000 RPM. Clutch in or out does not affect it. Happens both in neutral and in gear.

Does this sound like torque tube bushings?

Car is making around 500 RWHP. If I need to rebuild the torque tube, should I upgrade to the 12mm version? Which bushings are recommended? Any other things to consider when rebuilding?

Thanks!

Alan

torkman15

My 2000 is heading down that same road since the LS3 install. Vibration is more noticeable every time I drive her hard. The torque tube parts seemed tight when I put the LS3 in but I should have put new biscuits in when I had it apart...

Good luck, Tom

0Mike Yeager@Eastcoast Performance

Hi Alan & Tom,

Yes you guys need to replace your torque tube couplers...What happens alot of times is everything is good and tight, then you go with more power or a better clutch then the driveline gets shocked alittle more...then these under lying things pop up...

We have the exact German Made Couplers much less than GM's prices...The 10mm & 12mm couplers are on sale for $89.99...They must say made in Germany, if not they are China made, and then thats another whole problem...

Just keep in mind we have done 100's and 100's of these cars over the years...

Please call me anytime I will be glad to help...

UniqueDoug

This part really stood out to me.

Is the dynamic of what is happening within the torque tube changing under these varying driving conditions?

If the torque tube was "bad" at 2500-3000 how could it clear up at higher rpm's?

Have you had any new mods/parts installed before this started??

AlanC

To clarify, I don't think it completely clears up at other RPMs, but it is most noticeable around 2500-3000.

It started as a minor vibration that I felt sometimes, then the other day I was slowing down to a stop and pushed the clutch in and my engine was idling at 3000 RPM (a whole 'nother story in itself) and the vibration really got bad.

I took the opportunity to test some different situations while it was doing this, like pushing in the clutch and letting it out, shifting into and out of neutral, etc. and nothing seemed to affect the vibration.

Once my engine settled down and was idling normally (around 900 rpm) the vibration mostly subsided. Once I was moving again, I could feel the vibration, but it wasn't as severe.

I'm not exactly sure why the vibration didn't subside with the clutch engaged. You would think that when the clutch is engaged (pedal depressed) the prop shaft would begin to decellerate and the vibration would change. I guessing this could be due to the minute amount of friction that exists when the clutch is engaged and this keeps the prop shaft spinning with the tranny in neutral. Does this sound plausible?

My engine is extensively modified. It is a 406 stroker. I'm running a Fidanza aluminum flywheel with the LS7 clutch. Everything from the torque tube back is stock with approximately 65K miles on it.

I ordered a tranny jack this morning and I'm planning to rebuild the TT with new couplers and bearings. I'm also going to check out the clutch while I'm in there just to be on the safe side.

UniqueDoug

From my very limited experience, could it be a clutch/flywheel balance issue?

AlanC

Possible, but I had the the clutch/flywheel balanced prior to installing it, and it has been fine for at least a few thousand miles prior to this issue starting up.

The vibration is dramatic enough that I think it would have to be something major that changed the balance of the clutch/flywheel, like losing a PP bolt or something.

UniqueDoug

That sounds more realistic. I just had my torque tube rebuilt and the old couplers were showing wear but not too bad for a '99 with 100k. When a problem just comes out of nowhere like this it almost seems like the bolt theory is more accurate.

WKMCD

FWIW: When my TT bushings went bad it felt like I was running over rumble strips when under light load - off a stop sign, etc. I replaced them with the German bushings and all was good. I recently did some further upgrades and RTK56 installed the RPM poly bushings. I'll never worry about them again.

cantrelmitl

I was thinking you have to swap out the torque tube also to use the 12MM couplers if you have the original torque tube. I have a '99 and my torque tube was a 10MM, when I went to replace, I upgraded to a Z06 torque tube and 12MM couplers. The 97-2000 are 10MM and 2001 to 2010 is the 12MM.

Not sure exactly the type vibration, but I roasted my flywheel and clutch on a launch. It was a very expensive lesson and I had a vibration at low RPMs (1800 - 2500), but I also had vibration at start off. Of course, it was evident that it was roasted right off the bat once I redlined 3rd and 4th before finishing the 1/8 mile. If no hard launches, couplers are suspect. Wouldn't have said anything about this till I saw you had a aluminum flywheel.

Also, is it possible you are picking up some excessive drone due to a possible bad gasket or exhaust mount issue on your LTs? Can also cause some vibrations. The RPM range is right in the range for this type symptom with different header/catback combos.

If it's your couplers, you might want to consider the RPM kit that come with couplers and better bearings. I agree with above the couplers when really torn are very apparent, you know something is really messed up. Good luck with your efforts.
Mike C

AlanC

Thanks for your comments.

I really don't think it is the clutch. I know what clutch chatter feels like and this doesn't feel like that.

This feels more like a u-joint problem to me (if we had u-joints).

I do appreciate the suggestion about the exhaust leak. At first I thought it could be an exhaust leak, but after the latest episode it seemed too violent to be that. I'm running Kooks headers and off-road h-pipe. I was thinking if it was leaking right where the header meets the h-pipe, it would be roughly in the area the vibration is coming from, but it seems too severe to be that now.

I don't do any hard launches. I do some road course HPDE type events, but that doesn't involve any hard launching.

I'm pretty committed to pulling the driveline at this point, so we'll see what it looks like once it is apart.

Thanks everyone for the replies and information!

Alan

cantrelmitl

Roger that,
BTW, RPM has a Father's Day Special on new drive shafts, $849 for a 3" prop shaft w/ billet ends. I'm thinking that would be cheaper than you could get a 2001+ driveshaft (12MM) unless you got a bud that works with GM, plus never have to worry again. Just a thought.
Mike C sends

AlanC

Since I don't do any drag race hard launches, at this point I'm thinking I'll rebuild it with the (good, made in Germany) stock type couplers and the upgraded bearings.

How does everyone feel about keeping the 10mm shaft? Do I really need to upgrade to the 12mm version at my power level if I'm not drag racing?

cantrelmitl

I would make that decision after seeing what was up with the torque tube. If it is really hosed and the couplers are really messed up and you have any marks showing that a few of the sleeves ground into the end of the drive shaft, I might upgrade as the drive shaft could have possible gotten whipped out of alignment. I upgraded mine due to my plans for increasing RWHP and the explanation from two vendors concerning the 10MM couplers backed up with different searches on the issue. BTW, I already had everything apart for an engine replacement and it seemed like the perfect time to save on labor costs.

It would be messed up to replace the couplers only to end up putting undue stress back in the same spots and rip your couplers again. That's just my two cents.

Do a search on torque tube and coupler damage. You will see a lot of threads to include a really good one from Lou G explaining what can happen if the couplers get messed up and you really get on it. Also, reports of shredding bolts at different RWHP ranges, some due to abuse and others due to using the same coupler bolts as before. Since you sound like you are doing this yourself, I would do a look see and go from there. Hope this helps.
Mike C sends

0Mike Yeager@Eastcoast Performance

Hi Alan, No you do not need to upgrade to the 12mm setup, but if you wanted to, we can do it for you...You do not need to replace the input & out parts of the shaft, only the prop shaft itself and the couplers...

We have the CarbonFiber Driveshafts for only $899.99 right now, w/Billet Aluminum Ends...Each one is tested to 800 ft/lbs/tq..these will hold up to 1580 ft/lbs/tq before failure occurs....LG Motorsports run them in all there race cars and High HP Street cars...

Anyway I am sure you dont need this upgrade at all, We have instock everything you need so your corvette will be good for another 12 years...

2 Updated 10mm German Made Couplers
3 HQ Upgraded Bearings
$349.99
+freight

LMK...thanks Mike Yeager

lionelhutz

I'm confused by your description. If you clutch in and stick the car in gear and it still vibrates around 2500rpm then it's not the torque tube shaft or couplers. It's the clutch or or something ahead of the clutch.

Peter

AlanC

Yes, I agree that the symptoms are confusing. I took the car out for one last test drive over the weekend before I start tearing into the drivetrain.

The problem was mostly non-existent when the car was cold.

After driving a mile or so, the vibration became noticeable.

It seemed to be most pronounced under load. With the clutch in and the transmission in neutral it gradually subsided. With the transmission in gear and the clutch in, slowing to the stop seemed to make it go away as well.

These symptoms seem to reinforce the idea that it is related to the prop shaft, although I plan to check out the clutch while I'm in there as well.

I'll keep you posted.

argonaut

Hi Alan - I have a little experience on this issue: I have a 99 I purchased used. It has had a nasty vibration right about at the 3500 RPM point. Its most noticeable when doing a hard acceleration out of a corner or from a stop. Back when I first got the car, I read all the same advice - replace the couplers - and thus I did so. When I got the prop-shaft out, I was sort of disappointed to see that the couplers were fine...no visible damage. I noticed the rubber donut in the middle was damaged from impacting the interior wall of the TT. It seems, when put under serious load, the prop shaft can flex. The donut is there to keep it from flexing too much. I spun the prop shaft on a lath and noted that it was not perfect, i.e. it was bent the tinniest amount. Being stupid and not knowing too much about Vettes with a trans-axle (as opposed to say a Mustang) I put the prop-shaft back in, along with new couplers, figuring the vibration must not be the shaft but rather the clutch assembly. Of course the vibration didn't go away. Hmmm I thought, it must be the clutch. So I replaced it (I wanted a different clutch anyway, for other reasons) and to my dismay the vibration still existed.

So, after talking with a few folks I came to the conclusion thats its a bent prop-shaft causing the vibration. So...my advice is be prepared to put in a new shaft. When you get the shaft out and see the couplers...hopefully the issue will be obvious. If its not, I'd recommend you get the shaft tested and see if you need a new one. I wish I'd done that, it would have saved me a bunch of money.

lionelhutz

Check the shaft for run-out. The car may have been over revved and damaged the shaft.

It's more an rpm thing than load causing it. Every drive-shaft will become a "skipping rope" above a critical rpm. This is one reason why long drive-shafts (such as pick-up truck shafts) are 5" or 6" in diameter and the main reason why the newer C5 shaft is a larger diameter.

Peter

0Mike Yeager@Eastcoast Performance

Hey guys, if any of you need anything please dont hesitate to call us, we have everything instock all the time...

thanks for all the orders...