Topic: Stripped M6 holes on fork lower

[70CB750]

What do you do with those?  Drill it and tap it for M8?  Or hellicoil?

There are three holes for brake bracket, the bottom is M8, the top two are M6 and the M6s I trust for now, but I would like to fix them before too long.

I have a left lower in good shape, but it is also a problem of inspection sticker.

Ideas/solutions?

[ekpent]

Can you tap up to the next non metric size or don't you want to mix that in.

[70CB750]

Can you tap up to the next non metric size or don't you want to mix that in.

Neat idea!  SAE could be right there in between M6 and M8, I will check it when I get home.

I could also replace the lower and get a new inspection or carry the paper with me   - anything is cheaper than brake bracket getting loose while breaking.

[martin99]

1/4 BSF will tap straight into the M6. Have used this fix on the odd camtower bolt thread with success in the past.

[70CB750]

Regular coarse 1/4"-20? 

Looks like that's the easiest way to go with some flanged bolts.

Thank you!

[754]

Why not helicoil? Fix it right.
 The difference between 6mm and 1/4 inch is only 16 or 20 thousandths.  ..a 1/2 mm or less, so that will not be strong enough.

[Ewan 500K1]

got the same issue here .. I'm helicoiling ... got the M6 kit for 8.50 UK poundsoff ebog

[Fritz]

Had the same problem.

V-Coil might be a cheaper alternative to Helicoil. I've used both and have not seen any difference in quality:

http://www.newark.com/v-coil/04010/thread-repair-kit-m6x1-0/dp/74M7201?in_merch=Popular%20Hand%20And%20Workholding%20Tools

[Ewan 500K1]

Had the same problem.

V-Coil might be a cheaper alternative to Helicoil. I've used both and have not seen any difference in quality:

http://www.newark.com/v-coil/04010/thread-repair-kit-m6x1-0/dp/74M7201?in_merch=Popular%20Hand%20And%20Workholding%20Tools

This is the one I Used , cost £8.45 over here = $13.56
http://www.ebay.co.uk/itm/310678382294?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

It works fine

[70CB750]

Thank you, I am pretty sure I can find it in our local hardware store.

[Tews19]

I have 2 sets of K1 lowers that I don't use and an early K0 lower with the hard to find lip..

[70CB750]

Thank you, these are later forks, went that way for dual brakes - T bracket style.

[mysta2]

The idea of mixing sae with metric makes me cringe, possibly showing my OCD.

Helicoil, re-thread, v-thread(which I've never heard of) is the only right way to do it. Here in Texas I've seen the kits at most chain auto parts stores. Aircraft are exclusively built with these things, there shouldn't be any strength concern. If you can manage it, get a preload-able installation tool instead of the split ones, but you should be able to manage with any, especially with ones as big as M6s. Pre-loaders just make them really hard to mess up.

[Duanob]

helicoil works great. I've had to helicoil three of my exhaust studs all with great success. I bought a kit off of ebay that had all the stuff I needed, 6 helicoils, a drill bit and a set tool.

[LesterPiglet]

Got mine welded (free) and retapped to original. Pity they were the wrong bottoms for my 550.

[754]

I would helicoil before welding..much stronger thread and less work involved.

[LesterPiglet]

There were cracks right to the outer Frank. Hey it was free. 
If the meat is there, yeah rethread. Doesn't matter what size as long as it works.

[robvangulik]

I'd helicoil them, if you got parts from a PO with mixed SAE and Metric threads you'd curse him.....