Need help. Stripped threads on front caliper mount

[Spanky Pete]

I was rebuilding my front brake calipers, and when I went to reinstall the right caliper, I noticed one of the bolts was longer...not a OEM bolt. I didn't think much of it. Tightened the lower stock bolt to 90lb, then went to tighten the upper, longer, non-stock bolt and...it slipped. Bolt just spins in place. Now I know why someone had used a longer bolt last time.

I am hoping to get some feedback here on the best way to repair stripped threads. It looks like I will have to remove the rotor to get at the mount.

 

[-Spike-]

Helicoil.

 

[sdog]

Same thing happened to me, except at speed when applied the brakes. PO must have buggered something up. Anyhow, I just went up a size in hardware and drilled and tapped, now I tighten those bitches waaay up. I don't recommend a helicoil there, IMHO.

 

[Cruiser804]

Had the same issue, bought a used knuckle from cruiserparts.net for 75.00.

This is a pretty important mount. I would err on the side of safety.

 

[-Spike-]

I don't recommend a helicoil there, IMHO.

Any reason why? They are generally considered to be stronger than the original tapped steel. Have you had experience that indicates otherwise?

 

[earl]

Same thing happened to me. I would've helicoiled it, but there just happened to be a parts FJ80 locally so I swapped knuckles.

 

[Hulsty]

Both mine in the RHS side have been helicoiled by the PO. Only problem is that they were done to a course thread, which can loosen more easily than the original fine thread.

 

[sdog]

When i think Helicoil, i use it on aluminum or other areas where drilling and tapping is not the most desirable. Spark plug holes is my first thought. On aircraft engines, for example, every plug port is supplied with a Helicoil from the factory because of the effects on aluminum of the temperature affected cylinder heads. On the knuckle, i feel that there is PLENTY of meat to facilitate drilling and tapping. Worked well for me. What do i know. Install a Helicoil.

 

[-Spike-]

When i think Helicoil, i use it on aluminum or other areas where drilling and tapping is not the most desirable. Spark plug holes is my first thought. On aircraft engines, for example, every plug port is supplied with a Helicoil from the factory because of the effects on aluminum of the temperature affected cylinder heads. On the knuckle, i feel that there is PLENTY of meat to facilitate drilling and tapping. Worked well for me. What do i know. Install a Helicoil.

Hey, not picking a fight, just looking for your experience. Sounds like you're saying tapping the hole out for a larger bolt is easier. I wanted to know why you wouldn't use a Helicoil, if you had trouble with them. Apparently not. Personally, I'd rather use the stock fasteners so there's no confusion later, but that's just my opinion.

 

[Spanky Pete]

Wow, sounds like this is a common issue, is it because of the fine threads and high torque specs?

I like the idea of replacing the knuckle except that I could see it happening again, or going to the trouble of locating a used knuckle just to find it has been stripped too.

Has anybody tried time serts? ++ TIME-SERT Threaded inserts for stripped threads, threaded inserts, thread repair stripped sparkplug's, Ford sparkplug blowouts, threaded inserts threaded, repair stripped threads, stripped threads, inserts threaded inserts, Ford spark plug repair,

I don't have any experience drilling and tapping, but I might give that a try. just don't want to screw it up.

 

[-Spike-]

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I'd be concerned about the flanges, unless they have some way to countersink them. I can't see them having any advantages over Helicoils (or any similar wire coil insert).

I don't have any experience drilling and tapping, but I might give that a try. just don't want to screw it up.

It's not difficult, getting the tap in straight is the most challenging thing.

 

[Spanky Pete]

I am looking at the FSM and it looks like there is more to pulling the rotor than I thought. I am not really looking to do a front end rebuild right now, but maybe this would be a good time. It is going to be tough convincing .

Anyone perform thread repair with the knuckle on the axle and the rotor still mounted. It looks like maybe there is enough room, if the wheel is cocked all the way to the left.

 

[gotmud]

I'd be concerned about the flanges, unless they have some way to countersink them.

Each size comes with a drill, countersink bit, tap, and install tool. No experience on caliper mounts, but I've done a ton of 22R cylinder heads lately for the exhaust manifold studs. So far, so good.

 

[tirewater]

Any reason why? They are generally considered to be stronger than the original tapped steel. Have you had experience that indicates otherwise?

I second timeserts.

I'm not a big fan of helicoils, albeit it's been a few years since I've used them. The insertion tools break, the spring tab that the tool connects to breaks before the coil is fully installed, they come out when you remove the bolt, etc... Perhaps they're better now, but for long lasting applications timeserts are a much better alternative.

OP, you're lucky you stripped the threads. Better to find out the problem on the jackstand rather than on the road.

I'll stress the importance of using a torque wrench in these applications. I surmise that people use too much torque when installing the caliper because of fears of having the caliper come off. The end results are stripped threads and more pain & headaches. If you don't have a torque wrench, well - try not to over tighten bolts & use blue locktight to prevent bolts from backing out.

 

[toyteg08]

I am looking at the FSM and it looks like there is more to pulling the rotor than I thought. I am not really looking to do a front end rebuild right now, but maybe this would be a good time. It is going to be tough convincing .

Anyone perform thread repair with the knuckle on the axle and the rotor still mounted. It looks like maybe there is enough room, if the wheel is cocked all the way to the left.

It's not a full on repack. You don't have to get into the knuckle. That's the messiest, suckiest part. Just pull the hub off, and if you have to or still want to, repack the bearings. When I replaced my rotors, I pulled the hubs off really carefully, and didn't mess with repacking the bearings; just slathered some more grease in and around them and put the hubs back on.

Jon

P.S. - I should note that I just did a knuckle repack and birfield swap last year, so the grease in there still looked good.

 

[GXO]

I had similar happen to me when I rebuilt my front end the 3rd time. The knuckle threads let go. I just bought new knuckle housings. Safety first. If you can source them used so be it.

 

[jfz80]

We did this about a month ago.

Helicoil kit was 95 bux that had that size, the individual piece was special order only (dont remember the $)

used knuckle was 60 (and it came with birf/axle/spindle/steering arm/ etc)

 

[Spanky Pete]

After some tine to sit on it, I decided to replace the knuckle and do a front end rebuild. After an exhaustive search of local salvage yards that turned up virtually zero 80s, I went with cruiserparts.net for the knuckle and Kurt at cruiser outfitters for the rebuild kit and hub socket.

Getting the garage ready and reading up here. And this all started with a brake pad change.

 

[informationjunky]

Wow, sounds like this is a common issue, is it because of the fine threads and high torque specs?

I like the idea of replacing the knuckle except that I could see it happening again, or going to the trouble of locating a used knuckle just to find it has been stripped too.

Has anybody tried time serts? ++ TIME-SERT Threaded inserts for stripped threads, threaded inserts, thread repair stripped sparkplug's, Ford sparkplug blowouts, threaded inserts threaded, repair stripped threads, stripped threads, inserts threaded inserts, Ford spark plug repair,

I don't have any experience drilling and tapping, but I might give that a try. just don't want to screw it up.

Yes, I used this to fix the threads on my old 60. IMHO it is prefered to helicoils. Your drill out the old threads, tap for insert and have original thread size hole afterwards.

 

[Sea Knight]

Re-Tap to SAE

Both mine in the RHS side have been helicoiled by the PO. Only problem is that they were done to a course thread, which can loosen more easily than the original fine thread.

'97 FZJ 80. I had to do an emergency repair to the PS front knuckle earlier this week. The caliper bolt and knuckle eye were stripped and I didn't have time to pull the knuckle for a heli-coil fix. I retapped the knuckle to 1/2" and used an SAE grade 8 bolt, with coarse threads. Also used a split lock washer when I bolted up the caliper.

Is this coarse thread bolt likely to cause me a problem down the line? I've checked the new bolt a couple of times, after 100 miles or so, and so far it's staying put. Need to do an axle rebuild within the next month, and I'm trying to decide whether my fix is good enough, or should I replace the knuckle housing?