Axle Pinch Bolts

[benorado]

Took my front and rear wheels off for tire replacement. Upon handsetting the two bolts that pinch the axle, one of them never set, just turned freely. I backed it out to discover some metal threading on the bolt. The torque for these is only 6Nm, but I never got to the point to setting the torque, as one of the bolts is stripped.

That's more than a little disturbing, because to my knowledge the front tire hadn't been removed since the factory set it. Anyway, the bike is less than a year old and I'm taking it to my service center. I told them what happened, they said they will *try* to see if they can warranty it.

That's why I'm posting this. I have searched several forums and such, haven't found anyone reporting this problem. I also do not have a trailer, so I have to ride with a single functional pinch bolt 120 miles to my nearest service center, hoping they can rectify this in under 3 days before I have to head back for work. Rubber side down.

 

[wsteele]

If you have enough spindle that you could put a star washer or a lock washer on it And tighten up the bolt I would try that to get to the dealer. Also you might try a bolt wth a nylon locking just a though to get there.

 

[SteveADV]

Andrew, what say you?

 

[Snowdog]

It needs to be Heli-Coiled. Take the bolt to the auto parts store and get the kit. It will then be better then the original threads. Get someone with mechanical experience to help you.

Did it fail when you took it apart or when you were putting it back together?

 

[yellasei]

your dealer should replace the fork under warranty or at least repair the thread. as already mentioned, a Heli-Coil or better still a WURTH TimeSert or similar repair. the only time i have seen pinch bolt thead problems is when they are corroded but this sounds like the thread has picked up on something and damaged.
i would push the dealer for a new fork leg under warranty though, good luck.

 

[benorado]

It came out fine, but when I put it back it did not catch thread, just freely turned. No torque, simply a hand tighten.

 

[benorado]

It needs to be Heli-Coiled. Take the bolt to the auto parts store and get the kit. It will then be better then the original threads. Get someone with mechanical experience to help you.

Did it fail when you took it apart or when you were putting it back together?

Never heard of HeliCoiled, but maybe I will give it a try, thanks in case BMW doesn't want to honor the warranty. Thanks everyone, great forum!

 

[Snowdog]

fixing threads

heli-coils have been used for many years in all sorts of machinery and are approved for aircraft use. They are very commonly used in aluminum to provide for stronger more durable threads. For your application they are cost effective and more then adequate. A good auto repair garage probably has experience with them, any good mechanic could put one in .

 

[benorado]

Never heard of HeliCoiled, but maybe I will give it a try, thanks in case BMW doesn't want to honor the warranty. Thanks everyone, great forum!

Thanks Snowdog. After researching heil coils, the only potential problem I can see with that solution is the overall size, and making sure that there is enough surface area left on the counter sink for the bolt head to catch on after widening the hole to fit the hell coil. But if the numbers work and BMW denies warranty (for contingencies sake) then that is exactly what I will do.

Thanks again everyone!

 

[r100cs]

I would check with your dealer before you initiate a heli-coil repair on your own. A repair might give BMW a reason to deny a warranty claim since it would conceal the original damage. If your bike is still covered under warranty I would let the dealer handle the potential claim and the logistics. While the risk involved in transporting the bike yourself after a "temporary repair" may be minimal, it is you who is assuming the risk. Ultimately it is your call.

 

[benorado]

I would check with your dealer before you initiate a heli-coil repair on your own. A repair might give BMW a reason to deny a warranty claim since it would conceal the original damage. If your bike is still covered under warranty I would let the dealer handle the potential claim and the logistics. While the risk involved in transporting the bike yourself after a "temporary repair" may be minimal, it is you who is assuming the risk. Ultimately it is your call.

Oh I am already there with you. Last resort is a self-repair, which actually doesn't bother me. The pinch bolts are a fail safe, and two is better than one. But the dealer won't initiate a warranty without looking at it first.

While it doesn't bother me to ride 120 miles to the dealer, it bothers me to ride 1,200 miles with a single pinch bolt.

In the end, should BMW decline warranty I will have no choice but to do a repair. Fortunately, I know an excellent fabricator (he fabricates EVERYTHING for our lifts at the ski resort for the past 20 years) who will assist. It's not something I want to do on my own, I don't work with metals everyday.

Fingers crossed BMW will acknowledge the pinch bolt should not strip under hand tension.

 

[Snowdog]

I went out and looked at my Sport to see the problems. Since the helicoil is a spring configuration it is larger then the hole it goes in. which means the hole would have to be enlarged about .040 " to get it in. The only way around that would be to fill the slot with some sheet metal so you could tap the hole length , and then it would still be a long run in for the coil. There would be plenty of meat left for the bolt head, although I might use a flat washer under it. It would be a challenge, but it is doable.
Probably what I would do, is drill the rest of the way through with an original size tap drill, and tap, and use a longer bolt.( most pinch bolts such as this would have the hole all the way through) I didn't check how much metal would be left to support the threads, but, you could also counter bore for a nut. AND, if you are neat, very few people would notice the change.
I know a lot of people would be flabbergasted at the thought of drilling their brand new bike, I am not one of those. I was drilling holes and cutting body panels as soon as I got my Sport home.
Or take it to your dealer , who might have screwed it up in the first place.

BTW, the unwritten law of garages, "the last guy to touch a bolt gets blamed for stripping the threads" No matter what your dealer says, he will be thinking that.

 

[Snowdog]

Oh I am already there with you. Last resort is a self-repair, which actually doesn't bother me. The pinch bolts are a fail safe, and two is better than one. But the dealer won't initiate a warranty without looking at it first.

While it doesn't bother me to ride 120 miles to the dealer, it bothers me to ride 1,200 miles with a single pinch bolt.

In the end, should BMW decline warranty I will have no choice but to do a repair. Fortunately, I know an excellent fabricator (he fabricates EVERYTHING for our lifts at the ski resort for the past 20 years) who will assist. It's not something I want to do on my own, I don't work with metals everyday.

Fingers crossed BMW will acknowledge the pinch bolt should not strip under hand tension.

Good idea to get someone experienced to help you.

 

[benorado]

The

I went out and looked at my Sport to see the problems. Since the helicoil is a spring configuration it is larger then the hole it goes in. which means the hole would have to be enlarged about .040 " to get it in. The only way around that would be to fill the slot with some sheet metal so you could tap the hole length , and then it would still be a long run in for the coil. There would be plenty of meat left for the bolt head, although I might use a flat washer under it. It would be a challenge, but it is doable.
Probably what I would do, is drill the rest of the way through with an original size tap drill, and tap, and use a longer bolt.( most pinch bolts such as this would have the hole all the way through) I didn't check how much metal would be left to support the threads, but, you could also counter bore for a nut. AND, if you are neat, very few people would notice the change.
I know a lot of people would be flabbergasted at the thought of drilling their brand new bike, I am not one of those. I was drilling holes and cutting body panels as soon as I got my Sport home.
Or take it to your dealer , who might have screwed it up in the first place.

BTW, the unwritten law of garages, "the last guy to touch a bolt gets blamed for stripping the threads" No matter what your dealer says, he will be thinking that.

So funny you should say that. I was wondering why they didn't just do that from the factory (drill all the way through, counter a steel hex nut), but I'm not a motorcycle engineer. At least not that I've been told.

I'm skeptical on the ability to do a solid repair, drilling through might be the ticket, and apply the same soft 6Nm torque on a STEEL threaded coniguration. Imagine that.

 

[Snowdog]

A lot of machinery and vehicles have the hole drilled all the way through. In manufacturing, it makes it easier to drill , tap, and clean, as the chips have another way out. I have repaired many with a longer bolt. Critical threaded holes in aluminum usually have heli-coils ( someone mentioned sparkplug holes, a good example).

Telluride? Shouldn't you be riding a snow machine?

 

[Skutorr]

Actually, spark plug holes do not come helicoiled...that's just for a repair. Fasteners into aluminum such as cap screws require as a general rule a minimum of 11/2 times the fastener diameter in thread depth for anything other than minimal torque, and usually utilize a cap screw with fewer threads per inch and different thread pitches than your typical steel cap screw into steel or cast iron.

Aluminum can not take the repeated torqueing and R&R that harder materials can, and is more susceptible to galling. That's why it's a good idea, when possible, to upgrade to installed studs and nuts. If studs would work, but aren't used, it's STRICTLY economics, nothing else. Fewer parts, fewer labor steps.

 

[benorado]

A lot of machinery and vehicles have the hole drilled all the way through. In manufacturing, it makes it easier to drill , tap, and clean, as the chips have another way out. I have repaired many with a longer bolt. Critical threaded holes in aluminum usually have heli-coils ( someone mentioned sparkplug holes, a good example).

Telluride? Shouldn't you be riding a snow machine?

Yeah, we close on the 5th, just got snow last night. I'm ready to trade my telemarks for two wheel therapy, Moab is perfect for mountain biking right now!

 

[benorado]

Actually, spark plug holes do not come helicoiled...that's just for a repair. Fasteners into aluminum such as cap screws require as a general rule a minimum of 11/2 times the fastener diameter in thread depth for anything other than minimal torque, and usually utilize a cap screw with fewer threads per inch and different thread pitches than your typical steel cap screw into steel or cast iron.

Aluminum can not take the repeated torqueing and R&R that harder materials can, and is more susceptible to galling. That's why it's a good idea, when possible, to upgrade to installed studs and nuts. If studs would work, but aren't used, it's STRICTLY economics, nothing else. Fewer parts, fewer labor steps.

In quantity those are the rules I am sure, for longevity it just is a bummer.

 

[Colin J Monteith]

I recall back in 1969 along with a friend we bought a Mini that had been used in the Monte Carlo rally. My friend was a mechanic and to bring some life back into the engine we had to use some heli-coils. The engine in rally form was about 160hp but when we got it it was testing at less than 70 because of engine condition. About a weeks worth of work and amongst other things some heli-coils and it was close to 160. We could not afford replacement parts of what at the time was a totally non standard engine so some "borrowed" heli-coils from my friends work did the trick at the right price!

 

[Snowdog]

Actually, spark plug holes do not come helicoiled...that's just for a repair. Fasteners into aluminum such as cap screws require as a general rule a minimum of 11/2 times the fastener diameter in thread depth for anything other than minimal torque, and usually utilize a cap screw with fewer threads per inch and different thread pitches than your typical steel cap screw into steel or cast iron.

Aluminum can not take the repeated torqueing and R&R that harder materials can, and is more susceptible to galling. That's why it's a good idea, when possible, to upgrade to installed studs and nuts. If studs would work, but aren't used, it's STRICTLY economics, nothing else. Fewer parts, fewer labor steps.

There are probably more aluminum heads manufactured with heli-coils in the spark plug holes then you might think.