Stripped Brake Caliper Bolt Hub Threads

[thstone]

Ohhh Noooo! I was in the process of changing my brakes (pads and rotors) and found that the upper caliper bolt on the front right wouldn't torque properly (it would tighten and then turn more, tighten and turn more, etc). Damn, I knew this wasn't good.

Removed the caliper and found that the threads inside the hub were stripped. My first thought was "who worked on this last?". Uh. It was me.




Two choices - I could replace the hub or try to repair the threads. I tried using a thread tap but they were already too far gone to be chased properly so I ordered a kit called Time-Sert in the proper size. The kit was kind of expensive ($96) but it was still cheaper than replacing the hub.

Amazon Time-Sert M12x1.5




The kit came with everything you need and five inserts. It was easy to use with very clear instructions. Here is the repair process:

Drill out the hole. The drill and countersink bits in the kit were too big for the chuck on my drill so I used a 3/8" socket bit in the drill and a socket to fit onto the end of the drill shank.




Drill out a counter sink....




Tap the new threads. I used a ratchet and socket to carefully run the tap into the hub by hand.

[thstone]

Screw in the insert and you're back in business!




I also ordered new caliper bolts. The new bolts came with a star pattern rather than the old hex pattern. Good thing that I already have a full set of star sockets!




The caliper bolt torqued up properly and here it is, all done! Took me about 30 mins. I took my time and tried not to screw it up (really wanted to avoid the time to replace the hub!).

Ready for pads!

[husker boxster]

Nicely done!

You might have a candidate for a rent-a-tool.

[tommy583]

I had a caliper bolt break of in the hub a few years back. Took it to my indy, he couldn't get it out either. I ended up getting a hub from Woody.

[Starter986]

Great job!!!!!

Everytime I pick up a new tool, the last one being the power bleeder, I tell her it will pay for itself the moment it touches the car.

+1 on the rent-a-tool. With reasonable to/from postage it'll pay for itself many times over.

Cheers!

[BYprodriver]

Time-serts work very well, many went into the Shelby Series 1 frames in 1999.

[Qckslvr]

Originally Posted by BYprodriver

Time-serts work very well, many went into the Shelby Series 1 frames in 1999.

We use them at my dealership all the time on blown out spark plugs. Saves the customer a ton of money. But you have to install them right, or they can also spell doom.

[specboxCO]

For us racers that change the rotors frequently, I can highly recommend getting a stud kit:

Brake Caliper Stud Kit - Cup Car Style-Rennline, Inc.

If you have a contact at the dealership you can buy the PMNA cup car parts instead for a little cheaper.

[steved0x]

Yeah I've got the Tarett studs, makes it sooooo much easier when taking the caliper off.

[thstone]

Originally Posted by specboxCO

For us racers that change the rotors frequently, I can highly recommend getting a stud kit:

Brake Caliper Stud Kit - Cup Car Style-Rennline, Inc.

If you have a contact at the dealership you can buy the PMNA cup car parts instead for a little cheaper.

Thanks! I counted and found that I've pulled the calipers at least 15 times - so far. Its only a matter of time until another hub thread strips out again. I'll see if House Automotive can get me the 996 Cup studs and swap out the bolts the next time that I do the brakes.

[Van914]

Plus 1 on the Tarett studs. Really great quality kit.
Van

[lkchris]

Porsche specifies these screws be replaced, not reused every time they're removed.

[jaykay]

Originally Posted by specboxCO

For us racers that change the rotors frequently, I can highly recommend getting a stud kit:

Brake Caliper Stud Kit - Cup Car Style-Rennline, Inc.

If you have a contact at the dealership you can buy the PMNA cup car parts instead for a little cheaper.

......this is what I was going to post. So this kit is has some serious value any known down sides?

[Quadcammer]

Originally Posted by jaykay

......this is what I was going to post. So this kit is has some serious value any known down sides?

To get over the studs, you put some pressure on the hard line, potentially bending it

[itsnotanova]

Originally Posted by Quadcammer

To get over the studs, you put some pressure on the hard line, potentially bending it

Only a small bolt holding down the bracket.

[BYprodriver]

Originally Posted by thstone

Thanks! I counted and found that I've pulled the calipers at least 15 times - so far. Its only a matter of time until another hub thread strips out again. I'll see if House Automotive can get me the 996 Cup studs and swap out the bolts the next time that I do the brakes.

Stomski Racing tools has a great kit for fixing this. I love the piston circlip injector.

[Quadcammer]

Originally Posted by itsnotanova

Only a small bolt holding down the bracket.

True although that littlr bolt likes to crossthread also

[Burg Boxster]

Originally Posted by lkchris

Porsche specifies these screws be replaced, not reused every time they're removed.

Pretty much every car manufacturer today recommends replacement, not just Porsche.

If they are one time stretch fasteners, then yes it makes sense, well, except for being stretch fasteners to begin with. Otherwise, it's definitely a belts & suspenders approach b/c the stresses on them are more compressive than tensile... well, except on my F150 which specified 150 lb ft. of torque along w/ loctite blue - LOL.

[steved0x]

Originally Posted by Quadcammer

True although that Little bolt likes to crossthread also

They make a stud for that too, and that stud is fiddly to get the bracket over. I'm moving the caliper studs over, but still debating on moving those bracket studs

[itsnotanova]

You guys must have some bad luck. I've taken off and reinstalled somewhere around 200 of those caliper bracket bolts. I never had any cross thread. I'd probably just drill and tap a new bolt if I did cross thread one.