Stripped threads in knuckle. Helicoil, tap out, or replace?

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May 3, 2004
Putting my FJ40, back together, I got the knuckle put back together.
As I am putting the caliper on I wound up stripping the threads of the upper bolt out of the knuckle.

The thread seems to be unusual. It's an M12 bolt, but I think it's a 1.25 thread. I have M12x1.5 and M12x1.75 taps but not the one I need.

I have another knuckle, but I had put the Trail Gear magnum studs (ARP 2000 material IIRC) in the 'new' knuckle and used high strength lock-tite with anaerobic activator on the knuckle, so I think those aren't going any where (old knuckle has OEM studs).

I am concerned that heating the studs to break the lock-tite will affect the heat treat of the studs (if any).
I suppose I can drill and tap the knuckle for a 1/2"x13 grade 8 bolt, or I can helicoil to the M12x1.25 threads. Would I be better swapping the knuckle or drilling/tapping the one thats installed? I probably have to tear it back apart either way...
If you can find the right helicoil I would go that route. Though the caliper bolts have a fairly substantial torque value (IIRC) they are primarily in shear rather than tension. Which ever way you go I would work with the existing knuckle. Good luck
If it were mine, I would heli-coil it. It probably is 1.25-thats what Toyota uses on their specialty high torque bolts it seems. Shouldn't be too hard to find a heli coil kit for that. Check ebay. I use red locktite when I thread a heli coil in so the threads stay put, has worked well for me. After the threads are in then put in your bolt. I like using heli coils better than drilling to a bigger size becuase it seems to be a cleaner repair.
It is 11 mm 1.25 up to 78. After that, it is 12mm 1.25. They do make an 11 1.25 helicoil and tap.

I swapped the knuckles out with FJ60 knuckles 5 years ago...
If done correctly (straight) a heli-coil will work fine.

It only takes ~300F to make loc-tite give up, well below what will change steel.
If done correctly (straight) a heli-coil will work fine.

It only takes ~300F to make loc-tite give up, well below what will change steel.
The locktight only hold the coils while you are screwing the bolt in and out. THe coil is steel on steel and will have the same properties of the bolt and threaded hole. Heat should not matter that much.
The Thread is 12mm x 1.25. The Helicoil will work good. The thing to watch when you fit them is keep the tap dead square on otherwise I makes the bolts hard to line up.
Its a landcruiser thing those stripping out. I have fitted heaps. I did 2 last week
If you have the kit you will never strip another one.

Another must is to remove the roter to do it.
Time-sert is a better choice than helicoil.
X2 on time sert over helicoil
After assembling the other side, I had the SAME problem. The threads wiped...
I even took the time to chase the threads with a thread chaser (bolt of the same pitch and diameter with a slot in the threads intended to clean the threads out) then cleaned with brake cleaner.

I am thinking that some time in the past, someone significantly overtorqued these knuckles...

I was going to torque in sequence 45-60-75 ft/lbs... I didn't even get to 45 ft/lbs before the threads wiped....
I guess the thing to do is to tap to the 1/2 USS. If that doesn't go, Time-Sert it is...

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