Axle bolts sheared. Is this common?

[MYTOY986]

I was driving home the other day, and heard a "pop". then there was a weird vibration. At first, I thought I had blown a tire, and pulled over to check it out. To my surprise, the tires were fine. So I got back in, and went to pull away. Nothing! The engine revved, but the car just sat there.
I had just had the transmission fluid change when I had the IMS bearing replaced. So the first thing I thought was possibly a broken line. but no fluid leaking.

I had it towed back to the shop that had done the work. The verdict? Sheared axle bolts. The tech told me he had done "quite a few" in the past few months.

I'm a bit confused. I haven't really heard of this being a common failure. Am I just missing something? Are the bolts that attach the axles to the transaxle really aluminum????

[dad911]

Originally Posted by MYTOY986

.......I had just had the transmission fluid change when I had the IMS bearing replaced. So the first thing I thought was possibly a broken line. but no fluid leaking.

I had it towed back to the shop that had done the work. The verdict? Sheared axle bolts. The tech told me he had done "quite a few" in the past few months.

I'm a bit confused. I haven't really heard of this being a common failure. Am I just missing something? Are the bolts that attach the axles to the transaxle really aluminum????

Not aluminum. They can shear if not torqued properly, start to loosen, then bang, or possibly shear if over-torqued and stretched?. I hate to say this, but IMHO the shop that dropped transaxle to change IMS likely didn't torque properly. Which may be why he's done "quite a few"

M8 bolts, driveshaft to transmission flange should be torqued to 29 ft-lb and be re-torqued after a few hundred miles.

[JFP in PA]

Originally Posted by MYTOY986

I was driving home the other day, and heard a "pop". then there was a weird vibration. At first, I thought I had blown a tire, and pulled over to check it out. To my surprise, the tires were fine. So I got back in, and went to pull away. Nothing! The engine revved, but the car just sat there.
I had just had the transmission fluid change when I had the IMS bearing replaced. So the first thing I thought was possibly a broken line. but no fluid leaking.

I had it towed back to the shop that had done the work. The verdict? Sheared axle bolts. The tech told me he had done "quite a few" in the past few months.

I'm a bit confused. I haven't really heard of this being a common failure. Am I just missing something? Are the bolts that attach the axles to the transaxle really aluminum????

Most likely, the bolts came loose and then sheared off. When reassembling one of these cars, both the bolts and bolt holes need to be clean (spray brake cleaner works fine), then Loctite and torqued to specs, otherwise the become loose and shear off.

[MYTOY986]

Kind of what I was thinking. He lost me when he said the bolts were aluminum. I need to learn to do more research before picking a shop to do work on my car.

[JEC]

How many miles since your IMS bearing replacement?
I have a couple hundred miles on my 2004 S since replacing the IMS bearing, clutch and flywheel.
The S does use larger bolts. They are not a replace each time used Item like the fly wheel bolts. As I recall they were torqued to 60 ft lbs.
Most bolts in the Boxster have a specified torque and over torquing can be just as bad as under torquing.
The cylinder nuts on aircraft engines are a good example.
Years ago when I lived in my hangar at Flabob airport (Riverside, California) we had a guy that would fly in with his homebuilt Great Lakes Bi-plane. It had a inverted in-line engine out of a Spanish built Jungman. I asked him what the torque was on the cylinder nuts. He said that he just tightened them up with a wrench. On his way home after one of his trips he had a cylinder depart and he ended up in the top of a tree in Pasadena.

[MYTOY986]

I had the IMS done maybe 450 miles ago. picked it up 2 weeks ago. and drove it to Butler PA and back. (I'm in Alexandria VA) since then just a couple of trips to work and back. Thank god all I ended up with was a tow back to the shop. Beats the hell out of anything having to do with Pasadena! Oh and did I also mention, I had the car back 2 days and it threw a P1128 code? If it ain't one thing it's another!