Bad CV shaft
09-22-2005, 04:54 PM
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Bad CV shaft
Being on the PCA Technical Committee exposes me to a few additional "problems" that are sometimes unique. This is one that I have never come across and thought it would be a good idea to share with the rest of the 928 community.
"John - I wanted to make you aware of a mismanufactured halfshaft I recently found in my 1979 928. Please excuse the length of this, but I want you to have the whole story. About 5 years ago during a drivers ed event my instructor commented that he felt a vibration thru the passenger seat at speeds above 80 mph. We pulled off and checked the car, nothing was obviously loose or broken. The decision was that I had probably lost a wheel weight, so I was allowed to continue the event. Later at home, I tried all three other wheels on the right rear; with the rear wheels jacked up and running in gear, all the wheels would vibrate on the right rear, but not the left rear. Having eliminated the wheels and tires as the problem, I began asking for advice via PCA tech committee as well as other Porsche websites. I got lots of advice such as loose wheel bearing, loose suspension bushings and worn cv joints. I tried removing the brake pads and then rocking the wheel, no perceptible bearing looseness. I tried to move all the rear suspension joints, no perceptible looseness. I tried moving the halfshaft vertically and rotationally, no play felt in the cv joints. Rather than replacing any or all of the suspect components, I decided not to enter any more track events and to just use my car as a daily driver. Well - 5 years later, I noticed a cracked inboard cv boot throwing grease about a month ago. OK I thought, lets go for a new CV joint and boot. On this car, for some reason it has the original style separate stub axle and halfshaft on the left side, but the right side had the newer "unitized" stub axle and halfshaft assembly, where the outboard cv joint is welded on, not bolted. I pulled the axle out of the car and pulled off the damaged boot and cv off the inboard end. I was cleaning the axle in preparation for installing the new CV when I noticed that the end of the halfshaft is grossly off-center! The halfshaft was mismanufactured and causing my vibration problem! See the attached pictures for a view of the axle assembly, and a closeup of the end of the halfshaft. I have now backdated the right axle assembly to the original style by purchasing a junkyard stub axle and halfshaft, and installing two new cv joints and boots. I am looking forward to participating in drivers ed again. I wanted to make you aware of the problem I found, as it could happen to other model Porsches, not just the 928. I'll leave it to you to distribute this information to others in the Porsche community. "
The unitized axle assembly is marked LOBRO
3087 W-GERMANY 0600 928 332 030 30 followed by the VDO logo.
"John - I wanted to make you aware of a mismanufactured halfshaft I recently found in my 1979 928. Please excuse the length of this, but I want you to have the whole story. About 5 years ago during a drivers ed event my instructor commented that he felt a vibration thru the passenger seat at speeds above 80 mph. We pulled off and checked the car, nothing was obviously loose or broken. The decision was that I had probably lost a wheel weight, so I was allowed to continue the event. Later at home, I tried all three other wheels on the right rear; with the rear wheels jacked up and running in gear, all the wheels would vibrate on the right rear, but not the left rear. Having eliminated the wheels and tires as the problem, I began asking for advice via PCA tech committee as well as other Porsche websites. I got lots of advice such as loose wheel bearing, loose suspension bushings and worn cv joints. I tried removing the brake pads and then rocking the wheel, no perceptible bearing looseness. I tried to move all the rear suspension joints, no perceptible looseness. I tried moving the halfshaft vertically and rotationally, no play felt in the cv joints. Rather than replacing any or all of the suspect components, I decided not to enter any more track events and to just use my car as a daily driver. Well - 5 years later, I noticed a cracked inboard cv boot throwing grease about a month ago. OK I thought, lets go for a new CV joint and boot. On this car, for some reason it has the original style separate stub axle and halfshaft on the left side, but the right side had the newer "unitized" stub axle and halfshaft assembly, where the outboard cv joint is welded on, not bolted. I pulled the axle out of the car and pulled off the damaged boot and cv off the inboard end. I was cleaning the axle in preparation for installing the new CV when I noticed that the end of the halfshaft is grossly off-center! The halfshaft was mismanufactured and causing my vibration problem! See the attached pictures for a view of the axle assembly, and a closeup of the end of the halfshaft. I have now backdated the right axle assembly to the original style by purchasing a junkyard stub axle and halfshaft, and installing two new cv joints and boots. I am looking forward to participating in drivers ed again. I wanted to make you aware of the problem I found, as it could happen to other model Porsches, not just the 928. I'll leave it to you to distribute this information to others in the Porsche community. "
The unitized axle assembly is marked LOBRO
3087 W-GERMANY 0600 928 332 030 30 followed by the VDO logo.
09-23-2005, 12:44 PM
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It sounds like that axle was replaced at some time and the "new" replacement was defective ! Sometimes new parts do not work ! Like the Infamous Porsche green wire where a production run of the wires from the distributor to the spark box 1978-84 cars had a connector flipped over and miswired. They would sort of work and the car usually would run but very poorly.
