stripped threads in nosewheel fork

[prkaye]

I cross-threaded and stripped the threads in the hole in the nosewheel fork where the allen-screw goes in for attaching the wheelpant and holding the towbar. There's obviously no room for a nut between the fork and the tire. My initial thought was I need a new fork, but someone suggested that something called a heli-coil might work well as a repair. Thoughts?

 

[bret]

Yip, those work, and the threads will be stronger also. You can buy a kit from Napa

 

[rzbill]

There are a couple of techniques to fix it.

1) Have it welded and retap it.
2) Helicoil. I am not a big fan of helicoils. Feel free to google. They take a special tap and an installation tool due to the design of the wire coil insert. The outside thread (the tap) is not a standard, however, your local auto parts joint may be able to supply everything you need. Plus there is not a specific part of the helicoil that actually locks it into position. Only friction. They can come out.
3) Solid insert. There are a number of these and they generally differ by how the insert is 'locked' into place in the parent metal (your fork). Some use "keys", some use an external nylon pin that works like a nyloc nut. In this case I would recommend a key locking insert. One brand name is Keensert (may be the originator, not sure).

Here is a LINK to keensert type inserts from Mcmaster carr.
I like solid inserts because they generally use standard taps for the outside thread and the keys you pound in ( for the key type) at the end make it a permanent installation. *** EDIT*** Mcmaster shows an installation tool. If I was doing hundreds, sure but it is not really needed for one. The insert should thread in by hand before whacking the keys.

 

[prkaye]

if I go with a helicoil, any tips for the specifications of what part to get? The fork is just under 3/8" thick there, so I figure I need a helicoil of that depth. Anybody know what the thread on that allen screw is?

 

[Auburntsts]

Before you do anything else, I'd run a tap in the hole. You might find this repairs the threads.

 

[Mike S]

If it were mine, I would go Helicoil.

That being said, I have used this stuff in the past for automotive repairs with good results. No idea if it would work for the nosewheel problem you have, you might research it to see what the applications it covers are.

 

[terrye]

There are a couple of techniques to fix it.

1) Have it welded and retap it.

The nosewheel fork is 6061-T6 aluminum. If you weld it, the weld metal and the heat affected zone will not have the same temper as the parent material. It will be much softer and much easier to strip the threads. I would recommend a Helicoil or equivalent thread insert.

 

[Carl Froehlich]

Another option is to drill and retap to the next larger caps screw. McMaster has the needed cap screw.

Carl

 

[andyrv]

Helicoil

I put a Helicoil in mine almost 2 years ago and still good today. If I recall correctly I was able to do this repair on the airplane with the wheel in place.

I have this item in my Amazon history for the full repair kit but please check the nosewheel drawing to verify the size: Helicoil 5528-6 3/28-24 Inch Fine Thread Repair Kit

Ace hardware has the hex head bolts.

Andy

 

[868RM]

threads

I put heli-coils in before I ever put the fork on. Dia. of bolt same as thread depth in aluminum is not good.

 

[Bavafa]

And what's wrong with tapping it with new threats. This serves only to hold one side of the bracket and does not have to exactly the same size bolt or threat pitch, right?
Am I missing something so obvious?

 

[RV7A Flyer]

And what's wrong with tapping it with new threats. This serves only to hold one side of the bracket and does not have to exactly the same size bolt or threat pitch, right?
Am I missing something so obvious?

Towbar not fitting a larger head on a larger bolt? Just thinking out loud...it may not be a problem.

 

[prkaye]

thanks!

Thanks guys! I'm going to try to source the correct Helicoil part and give that a try