Kymasabe

Thank you all for the answer on my seized caliper. Replaced right front caliper and hose, this morning, as well as both front rotors and pads. Here's the problem: Caliper bolts to...knuckle? I don't know what to call it, so am going to all it the knuckle for the sake of this thread. Someone I'm sure will correct me if I'm wrong. Anyway, right side went back together without a problem. New caliper came with new bolts, everything went on nice and tight. Left/drivers side, got the caliper back on and went to tightenen the bolts...upper bolt got nice and tight, lower bolt got snug, but when I went to tighten it, it stripped. I pulled the bolt out and there was some material on the last 3 threads. I had two extra bolts from the other side, so I put in one of the old bolts I had, same thing, snugged up, went to tighten and it stripped too. Pulled it, last three or four threads looked rounded and shallow. Put my last bolt in, snugged it and stopped there. I don't have a shop manual so I don't know what the torque spec is supposed to be. And, now I'm worried that the knuckle is stripped or damaged/weak. Should I be ordering/replacing a new knuckles and 2 new caliper bolts?
(pic is of my morning project before I boogered up the drivers side)

jordan96xj

Its really common. The threads in the knuckle aren't particularly hardened, they are just the same material as the knuckle. With age, moisture, and corrosion they get pretty weak and strip out when you go to tighten the caliper bolts. You can get away with the stripped bolt being "snug" for a bit. But I wouldn't leave it that way.

Simply get the appropriate sized helicoil kit from a auto part store and repair the stripped hole. The helicoil will be stronger than the original hole/threads.

I had the same. But ended up replacing the knuckles as part of a front end rebuild before I got around to installing helicoils. But if I had done the helicoils, I would have pre-emptively done all 4 of them.

Kymasabe

Thanks for the reply, I feel better knowing this is common and that a helicoil will fix it. I forgot about helicoils, has been a loooong time since I used one. I just ordered new caliper bolts and booties from RockAuto, will wait 'til the bolts arrive so I can match up the correct helicoil kit and get it done !
Thanks again.

00t444e

I had the same issue and fixed it with a helicoil. You will have to tap it for the next size bigger to put the helicoil in.

dzywicki

Been there, done that. I was able to get by the first time by using a regular bolt of the same size/thread pitch from home depot. The threads on the OEM bolts are soft and not very deep. The new bolt grabbed pretty good and lasted for awhile. Eventually I used a threaded insert like everyone else.
If you want the quick route, you can look for black magic brakes. HE sells a knuckle saver kit with all the parts. I didn't go that route, since I only needed it for one hole.

Kymasabe

Questions about the helicoils though. When I drill and tap and insert the helicoil, do I do everything from the front of the knuckle (wheel side) or do I have to do everything from the backside of the knuckle ??
And, I think someone said to use Locktite as well. Do I use blue (which I have) or should I go get some of the permanent red ??

dzywicki

IIRC I worked from the wheel side since I did not remove the knuckle for repair. I used red loctite. I don't think it matters much ehich side you work from since the hole goes all the way through.

I used these guys:
If you go with these, skip the installation tool. It did not work well and I just used a bolt with a jam nut to put it in.

Kymasabe

They look pretty good, beefier than the wound wire of a helicoil. I really like Time-Sert's but they're WAY outside my budget.

jordan96xj

When placing the insert, most people use a dab of red loctite on them. I have heard from some that it doesn't make that much difference, but I do it any way. (I can see why they say that though, because the insert kind of "packs" into the newly tapped threads and gets very snug, I doubt it would ever back out even without the loctite).

On the knuckle, don't forget that you will want to clean up any portion of the insert that is protruding from either side of the repaired hole so that the surfaces remain flush.