Stripped knuckle

homebrew · Aug 9, 2009

While replacing the calipers I somehow stripped out the knuckle where the caliper bolt fastens. I tried tapping it but its beyond that. Looking for solutions to fix this. Would that chemical thread repair stuff that they sell at the parts stores work? TIA

Chrisc321 · Aug 10, 2009

Yikes. Since it is involving a safety issue (brakes), I would head off to the nearest junkyard.......

bmfm64 · Aug 10, 2009

you can heli coil it... lots of threads about doin it that way...

ehall · Aug 10, 2009

smart fix is replacement knuckle from a junkyard, should be $30 or thereabouts

Tim_MN · Aug 10, 2009

Heli-Coils or other similar brands are perfect for fixing that. We use Heli-Coils as called for by the Military Specifications noted on the blue prints for some Aluminum and Magnesium US Government parts we make in the shop.

The Heli-coils are hardened steel and the resulting threads are stronger than the original threads.

johnnyc · Aug 10, 2009

Yup, I have one Heli-Coil in each of my knuckles. No problems for about 5 years now.

homebrew · Aug 10, 2009

What size bolt did you use Jonny? I've never used the helicoils before.

WB9YZU · Aug 10, 2009

Popular is the Helicoil. You simply re-drill and tap the hole at the size specified, then install the coil. You buy the Helicoil for the bolt that you will be using. If in doubt, take a retainer bolt down to the NAPA and have them set you up.

Not having a Helicoil kit, I ground down a couple of nuts and welded them in place on the inside of the knuckle.

The bolts don't actually hold the brakes in place, they just locate the caliper. All the rotational force is transmitted from the pad directly to the knuckle.

Ron

88 Wagonman · Aug 10, 2009

Zuki-Ron said:
Popular is the Helicoil. You simply re-drill and tap the hole at the size specified, then install the coil. You buy the Helicoil for the bolt that you will be using. If in doubt, take a retainer bolt down to the NAPA and have them set you up.

Not having a Helicoil kit, I ground down a couple of nuts and welded them in place on the inside of the knuckle.

The bolts don't actually hold the brakes in place, they just locate the caliper. All the rotational force is transmitted from the pad directly to the knuckle.

Ron

Did you really just say that? Of course they hold the brakes in place. They don't hold the pad or piston to the knuckle but they secure the assembly to the knuckle. Would you feel comfortable with c-clamps "locating" them? Of course not, you need the bolts.

Welding nuts to the nuckle may work, but my vote is also for the JY knuckle.

homebrew · Aug 10, 2009

Zuki-Ron said:
Popular is the Helicoil. You simply re-drill and tap the hole at the size specified, then install the coil. You buy the Helicoil for the bolt that you will be using. If in doubt, take a retainer bolt down to the NAPA and have them set you up.

Not having a Helicoil kit, I ground down a couple of nuts and welded them in place on the inside of the knuckle.

The bolts don't actually hold the brakes in place, they just locate the caliper. All the rotational force is transmitted from the pad directly to the knuckle.

Ron

I thought about putting a nut on the back side. I'll give the helicoil a look.

johnnyc · Aug 11, 2009

homebrew said:
What size bolt did you use Jonny? I've never used the helicoils before.

Pretty much what Ron said. You use the original bolts. You just buy the Heli-Coil kit for that size, which I want to say is M8. I don't remember. The instructions will tell you what size drill bit you will need. IIRC, it was an oddball size that I didn't have. So I had to buy the drill bit too.

If you feel uncomfortable using the Heli-Coil, you can do it as a temporary fix until you get a new knuckle. But I have no such qualms, because as Tim said, Heli-Coils are widely used by the military and in the aircraft industry.

Chrisc321 · Aug 11, 2009

johnnyc said:
But I have no such qualms, because as Tim said, Heli-Coils are widely used by the military and in the aircraft industry.

I have been an aircraft mechanic for 11 years and have never used a helicoil on an aircraft... I have used a bunch on cars though. Helicoils are considered a "patch" in aviation, and are widely frowned upon by both mechanics and the FAA. Not so bad for automotive, though...

Stripped knuckle

homebrew

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Chrisc321

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bmfm64

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ehall

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Tim_MN

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johnnyc

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homebrew

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WB9YZU

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88 Wagonman

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homebrew

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johnnyc

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Chrisc321

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