PorscheDoc

In addition, check your wheel bearings, they can give you some really odd noises when they start to go bad. It is a bit of a pain, but pull both axles out of the rear, remove your calipers and spin the hubs by hand with the car in the air. See if they are making noise. I also like to pull the rotors off to do this. Once all of this is out of the way, you can feel the bearings grumble.

Torque on the axle nuts are 340ft/lbs.

Larry Herman

What I was trying to acertain was whether the tapping increase with engine RPM, and hence would slow on an upshift and then increase again in the next gear, or if it would just steadily increase with car speed, gettting faster as the car went faster under acceleration.

If it is the former, forget everything concerning the suspension, the problem is not there. If it is the latter, then look at the output shaft and outwards to the trans carrier bearings, suspension CV joints, etc.

I believe, if I understood Brinkley's reply to post #11, that it is the former and we should be thinking about engine or trans related componants that become stressed under load. Something in the trans, like an input bearing, could produce this tapping under load. I don't know what internally in the motor would tap only under load that would not just constantly tap otherwise except for maybe a rod bearing that is in intial stages of failure?

J richard

Don't assume that because a part is new it not defective, I'd still be looking at the cv joint.

The answer to larry's question is important, is the frequency of the sound vary with engine speed or road speed?

Brinkley

Boy, these a lot of info. Thank you very much.

Answer: the tapping increases as road speed increases but goes away if I push the clutch in and get off the gas.

Last thing to be replaced...I broke a half shaft at the last race. The shaft broke near the trans side cv joint.

Both shafts were replaced

Larry Herman

Ok then, forget everything about the motor, clutch etc and concentrate on items that are fixed to road speed; the output shaft, the ring & pinion (could be a chipped tooth), carrier bearings (could have damaged one from the half shaft flailing around), CV joints and hub bearings.

onefastviking

Based on that info I would first check part numbers to be sure you got the correct axles and that they are in the correct place, there is a left and right specific axle. If they are I would probably remove and inspect, especially at the rt side hub to make sure nothing is cracked or damaged. The wheel brg, ABS sensor ring, and misc other parts could have been damaged as well.

Brinkley

Well well... I looked at the two boxes the axles came in and the code number is 986 332 024 53 on both!

I was looking at a shop manual that I downloaded and thought that the 2000 Boxster S 6 speed had the same axles left and right?

If that's not correct then that might be my issue.

onefastviking

Opps, my bad, I had 5 speed stuck in my head.
I work on too many cars and occasionally they start to all blend together.

Brinkley

does that mean that the 6 speed from a 2000 S has the same shaft left and right?

Viperbob1

Yes on S both Axles were the same. As I said in my post and repeated, remove axles and check out everything there looking for any rubbing, bad bearing etc. If nothing, see if the stub axles have excessive play or can move around. Then pull side cover and check R&P, diff, bearings, races, etc,

Brinkley

Bob,
Thanks I didn't pick that piece of info out when I read it the first time. I'm going to pull the axles and inspect the cv joints and drain the trans and engine oils. While off I'm looking for wear marks.
I'm hoping that will prove or expose something.

J richard

An important distinction; does the noise go away when you let off the throttle without pushing in the clutch? Or only when the clutch is depressed? Aka loading and unloading of the drivetrain?

Did the broken axle stay in the hub or flail around? Think viperbob is on the right track, I still think you got a bad CV or a cracked axle flange.

onefastviking

So what did you find ? ? ?

Brinkley

Well....

I pick the car up Saturday to bring it home. When I do I will be able to confirm the noise is gone. But driving it around the shop parking area the noise is gone so once I open it up I'll be able to confirm 100%.

So...what did we do? So far we found a right side cracked header that was discovered by smoking each side with the motor off. A decent crack was discovered, taken off and welded. Back on, around the lot and where it was making noise before, it no longer did after the weld.

I'm cautiously optimist but I would have put big money on my ear hearing metal on metal not on air/exhaust escaping a crack. So tomorrow we see.

Brinkley

I tested the car and ran it up through the gears under heavy acceleration today and the noise is gone! All gears and all throttle positions.