ldamelio

I was helping a friend do brake pads on a 981 GTS yesterday. The car is tracked moderately (about 8 - 10 days a year) and had caliper bolt studs in place - supposed to be torqued to 54 ft-lb.

When removing the nuts on the front left side studs, it took minimal effort and they were clearly below recommended torque. We did the pads on that side and the calipers stud nuts re-torqued normally. We were using a well-calibrated torque wrench with the settings double-checked.

On the left side, the bottom nut was clearly loose. When we went to retorque that one, the stud backed out of the hub carrier and was clearly stripped and had no Loctite on it. I had a spare caliper bolt on hand. We put that back. As we started to get torque on it, it felt like it was not tightening any more, so we stopped before reaching the 63 ft-lb that a caliper bolt requires. The top stud and nut were secure so he could drive home OK.

I suspect that whoever put in the studs and did the brakes last didn't use correct torque and skipped the Loctite. I don't think the calipers have been off and on this car that many times for the hols to strip from normal wear and tear. Any other thoughts as to cause?

Are there any possible fixes for this (retap, helicoil, both) or does this hub carrier likely need to be replaced?

Kitc2246

First I suspect the threads were damaged before the caliper studs were installed. It is too easy to damage the aluminum threads with the steel caliper bolt. Porsche recommends new bolts each time for corrosion. I know many who carefully clean the threads and the bolts and reuse. You can drill, tap and install a helicoil.. It can be done with the knuckle on the car, but it is hard to make sure the drill hole is perfectly vertical. I did this on an old 09 Boxster. Made sure the first thing I did to my 2013 Boxster S when I bought late 2019 was the brake caliper studs, third radiator and 911 coil pack heat shields. You can buy used knuckles, but disassemble and reassemble is not easy. You need a good quality ball joint breaker. You will then need a front end alignment. Unless you are experience in doing this I'd check with a couple of Porsche independents who have done this before.

dps214

Loctite isn't a factor in the threads stripping unless the stud was backing out first. Incorrect torque maybe. As the other commenter said, you can try putting a helicoil in but it's going to be hard to do on vehicle. If the knuckle is coming off anyway, it shouldn't be too much more expensive to just replace the knuckle with a good used unit. That's the route I took when one of my caliper studs stripped out last year.

Kitc2246

If you go the used steering knuckle route make sure you check the mileage since you are getting a used wheel bearing.