Rear end "clunk"

Fellow board members.... We have collectively written a small novel on the subject of a distinctive "clunk" in the butt of our beloved P-cars. While there are many possible causes for this problem, I have finally found my "gremlin" after about 4 months. I took the car to Stuttgart house in NC, they went through the entire rear of the car. The noise finally was diagnosed as loose inner stub axles. Unfortunately, it had somewhat galled the splines, and I will ahve to think about re-building the diff during a future trans re-build.

If you have a clunk, and it is not the CV's, sway bar mounts, or swing arm bushings. I suggest you check the inner stub axles ASAP.

I hope my pain saves a few others... Geez the way I sacrifice myself for you guys....

I had bad service from a company here in New Zealand that "fixed" the gearbox. They had multiple attempts at fixing the graunch between first and second. Anyway it escalled into me taking them to court and I lost. He managed to convince the judge 911 gearboxs are meant to graunch. After the last time he had a shot at fixing it, it came back doing a ker-thud sounding noise after I have moved forward about two meters/yards. The mechanic has a habit of not doing up nuts and bolts properly - His name is Richard Gillies of The Chequered Flag. I suspect it may be the same as what you have dicsovered. I also read about a similar thing in an old copy of 911 and Porche World. Did your car go thud after a yard/meter or two, or was it something different?

Bill,

This seems to be similar. Mine would mostly do it when going from reverse to Fwd or vice versa. Definately only 1 or at max, 2 clunks. Occasionally, it would also give a clunk if you tossed the car from side to side hard (like a race car warming the tires). I'll ask my wrench today how he thought to look at the inner stubs, and get back to you.

Originally posted by scott matre:
Fellow board members.... We have collectively written a small novel on the subject of a distinctive "clunk" in the butt of our beloved P-cars. While there are many possible causes for this problem, I have finally found my "gremlin" after about 4 months. I took the car to Stuttgart house in NC, they went through the entire rear of the car. The noise finally was diagnosed as loose inner stub axles. .

scott-

are the inner stub axles just the axle shafts joined to the transaxle? or is this something else? (i have a minor 'clunk' under hard cornering only...)



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Adam Nitti
ajnitti@mindspring.com
www.adamnitti.com
'85 911 Carrera Coupe

Adam,

As I understand it, the inner stub axles would be the flange that the inside CV joint bolts to. There is a nut in the middle that holds the flange into the diff.

If you have Bruce Anderson's book, look at the top picture on page 236. It shows the circular 6 bolt flange, a nut is clearly visible in the middle.

Good luck, hope it solves your problem.

I suppose, if semantics is the game, you could say there are two sets of 'stub axles' ... the inner set, though usually called output shafts or flanges, fit into the differential and ring gear carrier, and are retained by a bolt. The outer set, are actually an extension of the outer CV-joint flanges, and are held together with the rear wheel hubs by a 30 mm nut. Both sets are splined and can, of course, make odd noises when loose and allowed to wobble in use! So, in conclusion, both sets of stub axles, or specifically, any ONE of these can make expensive noises ... if left to wobble!!!

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Warren Hall
1973 911S Targa

ok.. i see now. just opened my bentley manual, and it labels them as being just inside the outer cv joint; not the inner. if you stick with the bentley terminology, they slip inside the wheel hub. how would these things go bad, though, and how do you determine whether or not they are bad? scott, do you know for sure that your problem dealt with the inner cv joint?

thanks!

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Adam Nitti
ajnitti@mindspring.com www.adamnitti.com
'85 911 Carrera Coupe

[This message has been edited by adamnitti (edited 12-19-2000).]

[This message has been edited by adamnitti (edited 12-19-2000).]

[This message has been edited by adamnitti (edited 12-19-2000).]

Adam, the flange/stub axle that I'm talking about is actually inboard of the inner CV joint. Look inside the inner CV, to the flange it bolts to. Let me say again, my problem did NOT exist within the CV/axle unit. Rather, the drive flanges coming out of the either side of the differential/transmission.

thanks for the clarification, scott- i'm gonna check mine out...

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Adam Nitti
ajnitti@mindspring.com
www.adamnitti.com
'85 911 Carrera Coupe