rusted

Hi, I'm new here and have a technical issue.

Due to a mistaken repair manual, I over-torqued a caliper mounting bolt on my 1997 Jeep Grand Cherokee Laredo 6-cyl. I stripped the female threads on the drivers front knuckle. The bolt is a M8 x 1.25.

I read several posts about this problem, and solutions for it. The Helicoil option looks like it would cost about $40 for the kit and drill bit. I only need it for 1 bolt.

Autozone has oversized bolts, but they start with 1999 Jeeps, so they don't fit mine.

I also found a Metal Thread Insert, which is a plug with a male 1/2"-13 thread outside, and with a M8 x 1.25 female thread inside. This is a $3 part, and I have the tools to install it.

Anyone ever use this as a solution? Or any comments on either method?

Any help would be appreciated.

Jeep Driver

I have recommended here several times NOT to use a torque wrench for every bolt you turn.


YOUR post is the very reason I say what I say. But the other 'smart' guys here think I'm an idiot, I'm not the one with the problems.



To solve your problem-

I have no idea where you are located, however, if there is a PnP near you, you should be able to get another knuckle for about $20.


I'd recommend you replace the knuckle.

Jeep Driver

BTW, what brand of torque wrench did you use?

caged

x2

i wouldn't mess with helicoils or inserts on a braking component when it's much easier and cheaper to just replace the knuckle and never have to think about it again.

abodyjoe

stripped on on my sons jeep when he first got it. put a helicoil in it and its been fine for years now. couple sets of brakes have been put on and the helicoil is still there with no issues.

rusted

Yes, I don't normally use a torque wrench for everything, but in this case I thought I would do it "properly."

I should have known the spec was wrong, but my brain let me down. I never would have made it that tight if I was doing it w/o the torque wrench.

If I replace the knuckle, don't I have to do an alignment? My Jeep is very rusted, so every procedure is a risk that something else gets screwed up.

ehall

I used for my repair, very happy with it. Put red loctite on the insert, it will stay in place. Much less risk than banging on ball joints to switch knuckles, where a simple fix becomes a multi-day event. At some point you should replace the knuckle anyway, but this is perfectly acceptable fix until you get a round tuit

rusted

Thanks for the info.

I doubt if I would ever use the Helicoil again. At $40 for the kit and drill bit, seems pricey for 1 bolt.

The Metal Thread Insert costs $3.

My car is a 97 and rusting out underneath. I think it will be gone before I replace the knuckle. The tranny doesn't shift into high gear when its cold out. I don't want to lay to rebuild the tranny for the 3rd time.

Rust up here in Minnesota is brutal on cars.

El_Guapo

Helicoils are fine, Keenserts are fine. I've installed a whole lot of both. The keensert type (the 1/2-13 ones) are a little better as long as you leave enough meat around the hole to maintain strength during the drilling process.

When you drill it go slow with lots of oil, clean it out with brake cleaner then Loctite (red) the insert in there. When you go back together, use blue Loctite and a short wrench.

Jeep Driver

$3 fix is fine.........since your XJ is in it's last days anyhow.

Bustedback

I drilled out, tapped, and helicoiled all four caliper mounting holes to 5/16 18. I have one strip out, so I changed them all to a SAE bolt because I thought it would be easier to find if I'm out in a remote location.

rusted

Thanks! I can tell you have experience installing them. I'll go that route.

Any advice on how to keep the drill perfectly straight at 90 deg to the knuckle? I think I will only have 1 chance to get it right.

El_Guapo

I rarely use a guide, I step up bit sizes (in this case I'd go with a 9/32" then the 27/64") and the bit will use the existing hole to track itself with a good degree of accuracy. You will also be in better shape if you use just regular old 118 degree HSS bits with no split points, pilots or anything else like that.

When you are starting the drill, use short bumps of the trigger with minimal down pressure until the hole is established.

If you aren't too confident in that system, there are commercial guide blocks available or you can have a helper hold a scrap of pipe flat against the knuckle while you establish the hole.

rusted

Great info. Thanks again.

I'm old enough that I need to be comfortable before I start, so I don't paint myself into a corner (again).