Depends how "emotionally-involved" you are with the car. Cross-threading will only remove or reposition metal from within the hole. Retapping it only removes more metal. The threads on the bolt will likely be damaged too. All of this leads to less thread contact area and the likelihood the bolt will loosen later on its own.
The frustrating part is trying to convince the bolt to go in straight when it would be much happier going in crooked again.
I've used a trick that involves laying a piece of metal in the bolt hole to take up some space and make the bolts tighter, but I wouldn't recommend that for a brake part. At the very least, the stray metal could prevent the shoulder of the bolt from making solid contact with the mount. The bolt will be off-center too which will prevent the caliper from sliding freely. It makes a dandy repair for stripped holes in the firewall where you can't get behind it to put on a nut, but this is the type of "cobble job" that lawyers love to get their hands on. Even if the other guy was at fault for the crash, you and I know the makeshift repair had nothing to do with anything, but a lawyer will use that to convince a jury you had the most unsafe car in the world. I try to cut corners on my stuff all the time, but in this case, other than replacing the steering knuckle, the insert is the only professional repair. And if you're ever unlucky enough to have your car picked apart by an investigator, you will have no need to defend your repair.
Couple more comments just so we don't overlook something. The insert should be threaded in from the same side the bolt goes in. Starting a bolt where the Heli-coil tab was cracked off, and you can't see it because the caliper is in the way, makes it hard to start the bolt. Next, be sure none of the insert is sticking out from the knuckle. The last loop of the thread should be recessed at least half a turn so when the tightened bolt pulls on the insert, it won't stick out and prevent the bolt from making full contact. A little thread lock liquid between the insert and knuckle is a nice touch too.
Saturday, February 27th, 2010 AT 7:29 PM