$93 mistake or poor design?

[Joncon11]

While installing my rear wheel I ended up in a bit of a jam. While torquing the caliper bolts (18 ft lbs?), I heard a distinct snap on the last bolt. Almost every thread in the mount bracket had pulled out  . So I ream the hole and cut new M9x1.0 threads ( next size up from stock) and set out to look for a new bolt only to find nobody on the planet sells a bolt that size, including Fastenal. I could go up to M10x1.25 but then I would have to drill the caliper too, I don’t want to do that. So I ordered a new mount bracket and 2 new bolts from Bikebandit. So my question is this; is it poor design ( steel fastener, aluminum part) or is the 18 ft lbs I got from the C14 Wiki section wrong? This is the third rear tire change so maybe it could be metal fatigue?

[mike-s4]

10 rear tire changes on my 08 and no metal fatigue here.
Anyone else change your tires? Kaw dealer?

[Joncon11]

It’s just me removing and installing the wheel. I was amazed at how soft the caliper bracket metal was, 6061 T6 would be my guess. I guess i’ll dial the torque down for the new one. Maybe I pulled the torque wrench to hard and to fast

[philipintexas]

Have you always been the one to r/r the wheel? I suspect some ham-fisted mechanic may have damaged it previously. Have you considered a Heli-Coil thread repair?

[Joncon11]

Have you always been the one to r/r the wheel? I suspect some ham-fisted mechanic may have damaged it previously. Have you considered a Heli-Coil thread repair?

I thought about a heli-coil, but I run a bit nervous. That bracket is a high stress part that I don’t want failing. A replacement was surprisingly cheap so I went for a new one. I am the only one I know of that has disassembled the rear wheel, though I can not account for what was done at the dealer before I took it home.

[Stubby]

I have found in my past ( both dirt bike and street bikes ) that steel fastener, aluminum part is not a good combo at times I have put a dab of grease on the steel so as not to get it to gall up with the aluminum. Not sure this is what happened to you just my past experience.

[jjsC6]

Have you always been the one to r/r the wheel? I suspect some ham-fisted mechanic may have damaged it previously. Have you considered a Heli-Coil thread repair?

Heli-Coils are the best option - although if the new part is relatively cheap I can understand going that route.

[aspire61]

Hi all:

i just changed the rear tire myself two months ago. I've always removed the wheels and taken them to the dealer for a tire change, then re-assembled. Contrary to most people i dont use a torque wrench for small jobs. I know a lot of guys who torque everything- even their spark plugs, but .....  For those hex bolts i just applied threadlock and snugged it up. I'll check it once in a while, but i trust it. I agree that it was most likely damaged before you removed the bolt. 18 lbs torque is nothing.

mat

[Rhino]

I do all my own tire changes and haven't had a problem yet (knock knock knock).

[katata1100]

My Katana 1100 had cam towers stripped by ham fisted dealer mechanics, if you F them up.
Anyhow, I'd second what everyone else says and helicoil it. If you don't feel comfortable doing it yourself, find a machine shop in your area, probably won't cost more than $25 or so, take just a second.
Machinists are like wizards and a good machinist can do a good helicoil job with one eye open and both hands tied behind their back!

[basmntdweller]

Properly done, a Helicoil in aluminum is considerably stronger than the original threads!

Matt

[T Cro ®]

Properly done, a Helicoil in aluminum is considerably stronger than the original threads!

Matt

Absolutely!

[katata1100]

Properly done, a Helicoil in aluminum is considerably stronger than the original threads!

Matt

A machinist told me that that too, said that aircraft parts will be helicoiled for that reason.

[Joncon11]

I do agree that Heli-Coil is a viable option and if I wasn’t able to find the part I’m sure I would have done that. Yes, Heli-coil is common practice on aircraft and most of the time guidelines for their use in the aircrafts structural repair manual, I have used them many times on the helicopter that I work on. I do use loctite and clean the threads every time I put the wheel back together.

[Just Krusen]

Have you tested your torque wrench to see if it reads correctly?  Some are off even when they are new.  I have one that is off by 13#s at 80.  I don't know where you can get it tested but we have a gauge to check ours on at work.

Also if you had any oil on the threads the torque setting will be too high.

That said, the only time I have ever stripped out threads was with a torque wrench. 

[Joncon11]

Have you tested your torque wrench to see if it reads correctly?  Some are off even when they are new.  I have one that is off by 13#s at 80.  I don't know where you can get it tested but we have a gauge to check ours on at work.

Also if you had any oil on the threads the torque setting will be too high.

That said, the only time I have ever stripped out threads was with a torque wrench. 

Yeah, I tested it at work when I got it, it was spot on.  I didn’t have grease on the bolt but it did have loctite on it. Just one of those fluke things I suppose.

[T Cro ®]

Yeah, I tested it at work when I got it, it was spot on.  I didn’t have grease on the bolt but it did have loctite on it. Just one of those fluke things I suppose.

In my opinion liquid Loctite on clean threads will act a lot like oil thus I will reduce the amount of torque I use to at least the lower end on the spectrum. Another thing to consider is don't use one wrench to cover all bases. Torque Wrenches are at their absolute worst in the lower 20 percent of their range. You are much better off with a wrench dialed up into the middle 2/3's of its range.

[lather]

I've removed the rear wheel about 14 times but have never removed the rear caliper bolts...why do that? I remove the whole caliper bracket, one big bolt 47 ft/lbs.

[stevewfl]

ebay the part

[Joncon11]

In my opinion liquid Loctite on clean threads will act a lot like oil thus I will reduce the amount of torque I use to at least the lower end on the spectrum. Another thing to consider is don't use one wrench to cover all bases. Torque Wrenches are at their absolute worst in the lower 20 percent of their range. You are much better off with a wrench dialed up into the middle 2/3's of its range.

Good point, I was taught to stay away from the upper and lower 10%. My wrench will accommodate that. I agree with the loctite thing, I think if anything it would reduce the heat built up by running the fastener in.