Odd noise when running the car "in the air"

Folks,

As you may recall, i just did a ton of maintenance type work on my track boxster S, including a complete clean/grease/boots of the drive-shafts.

The car is 20" in the air on very solid 45-degree blocks.

Before i put it down, i started it, wheels off, put it in gear and... that's not right.......

clunk, bang, chug. Brain re-engages, no big deal, that's traction control going haywire and applying the brakes. Check. Yep. Turn off rudimentary TC.

One more time. This time much better, but some cyclical noise, and still the occasional TC light flashes (despite being off, huh?).

Turned each wheel by hand. Seems smooth, a little "chug, chug" with one spot being slightly stickier than others, but nothing rough. Shaft moves freely. No noise, aside from slight brake drag (the brakes are wearing a tiara). They ave been sitting for 6 weeks, no great surprise.

Maybe its just in my head. Maybe when i drive it all will be well. But here's the questions:

1. " is this TC behavior normal?" I can run my Audi fast on a lift, no issues, PSM on. (in fact that's how i warm it up to service auto tranny)
2. Can anyone think of anything i should check, aside from "everything" whcih, within reason, I have?

TIA,

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

Not sure about TC in the 986's. With PSM in the 987, even when you turn it off, it will still be there in the background just in case you mess up big time. The manual says even with PSM off, if one wheel starts slipping, it will activate.

Its was the first year offered and does very little.

But yea, apparently it likes to intervene, welcome or not.

The track guys go crazy trying to turn it off on newer cars. Apparently the only way it can be done also kills ABS, which few want to do.

(pull the ABS pump fuse)

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

You can turn off the accelerate forward traction control but you can't turn off the active brake fake differential thingy.

The whole thing is frankly annoying. What a PITA on the track - its mostly ineffective except at slowing me down at inopportune times

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

Source [www.renntech.org]

It probably won't work but according to this cars equipped DSC (i.e. not yours) can disable ABD by holding down the DSC switch for 3+ seconds.

[collision.enterprise.alldata.com]

It will re-engage if it feels like it, on or off.

This is not only pre-PSM, its pre-full TC. Very rudimentary.

Incidentally, many of the issues exist on track below 60 mph; low speed, tighter turns are where it becomes highly annoying.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

"in the air" as the half shafts droop and this puts the CV joints in a bad position. It could be possible they could be so out of position they could bind. The CV joints have a limit to how much deflection they can handle.

My advice would be to stop doing the "running in the air" at least with your Porsche. I'm not sure it is a good for your Audi but at least it reads like the Audi doesn't "complain".

.. but:

1. it does not appear to be much worse than normal ride height
2. as noted, they turn, by hand, smoothly - so the CVs do not appear to be binding

This is in fact the method specified by the factory for doing a tranny service for Audi.

But yes, it is possible. And the CVs in 986S models are already at quite an extreme angle.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

Any chance you have a wheel bearing starting to go? Had to replace a few on my 986S.

i think ti continues to be the ABS/TC intervening. Wheel bearings on these cars slowly get noise, whiny and may deviate microscopically under high load - enough to make the rotor interfere with the rock shield ( about 1/32"). But they wont cause this.

Thanks, though

And yes,i suspect both my left wheel bearings are wearing. We sports car guys mostly turn right :-)

Grant

gee-lenahan-at-gee-mail-dot-com

... whcih is a big deal since getting the car up and down 20-something inches on piles of lumber is qutie a task, btu makes me feel safe under it.

Anyway, it drive great. i did have a "burning" smell that worried me, btu its neither brakes nor driveshafts, and i KNOW for SURE that the car leaks oil from one sensor on the driver's side, above the exhaust. So i'm confident that's what it is. Or liekly and hopeful :-)

Brakes are cool, driveshafts are cool, no thumps, bumps or squeals. No ABS or TC lights. I think its just iver-sensitive when the two wheels spin at vastly different rates FYI - in the air, the left side whel spins while the right remains stationary, so as a % rotational velocity, its a nbig delta, whcih I'm sure terrifies whatever little brain is in there ( and doesnt realize we're also stationary).

So, awaiting final testing (called a serie sof real drives) i pronounce the car well. And absent a problem, it shou;ld be in the best shape its been maybe ever.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

I think its the old, tired diff... lots of play and some noise.
(which i know needs help, whenever the transmission gets either replaced or rebuilt)

Grant

Grant

gee-lenahan-at-gee-mail-dot-com