Rear axle

mtreid · 05-03-2016, 02:54 PM

I have a 1987 Porsche 930 with driveline lash(rear clunks when applying gas and letting off gas).I removed the rear axle assemblies and noticed rotational play in one of them, and will replace both. The flanges that enter the transaxle on either side also have some rotational play. Is this normal? Are they replaceable(could not find a part number for them). They appear to be held in place by one bolt.If they are worn would the corresponding inner teeth also be worn. I get the impression that if I replace just the axle assemblies I will still have the problem. Thanks for any help.

Discseven · Discseven's Garage

M... was immediately going to suggest slowly pushing the car in neutral but that was with the axles installed. The idea being to feel if the CV's were bad. If they were, there would be a binding feel to the car as it moved along. If a CV is exceptionally bad, it also makes a noise that sounds clunking-like.

I believe some year 911s had integrated axles and CVs so I checked '87. The '87 CVs are independent parts from the axle. My guesstimate from afar is one or more of your CVs is bad. It is possible to remove them from the axle... clean them and make an inspection. If bad, you could buy only the CVs. (If only one is bad, the suggestion is to replace them all at the same time.) If you go this route, get familiar with how CVs themselves are assembled and how they mount the shaft.

Concerning your flanges on the gearbox... as I recall there is a slight rotational play to them. Before you start taking your gearbox apart, my recommendation is to make a clear determination if one or more of your CVs is or is not the problem.

Trackrash · Trackrash's Garage

Sounds like a classic bad CV. At this point you are really going to have to reassemble and drive it to see if it is fixed.

There is a slight amount of play in the rear axle. But a large amount would be a concern.

I just jacked up one side of my car. It has a fresh 915. With it in fifth gear the axle flange on the jacked side will move about 1/4" when the wheel is turned back and forth. There is no noticeable play while driving.