Hollow Caliper Bolts

[dan]

Tightened the upper caliper bolt on my 2006 yesterday @ 28 ft/lb and the bolt stretched and broke. Anyone seen such before? Used an ez-out to remove the part still in the threads. Praise be tne bolt was hollow which raises the question of why the hollow bolt? I would assume a solid bolt of the same material should be stronger. All reasonable replies are appreciated.

 

[Ignacio]

Praise be tne bolt was hollow which raises the question of why the hollow bolt?

Reduce unsprung weight.

Snapped bolt at 28? I wonder if your torque wrench is off or you're not using it as designed.....

 

[dan]

Yeah...When I asked about the hollow bolt at the yamaha shop we all laughed when the weight saving angle came up. It was suggested that I could purchase a titanium brake set that is made for thr R1 at $1400.00 and that shaved off all of 2 lbs. I have used the offending torque wrench many times on the same bolt(s) whilst pulling the wheel for multiple tire changes over the years.

 

[wheatonFJR]

Yeah...When I asked about the hollow bolt at the yamaha shop we all laughed when the weight saving angle came up. It was suggested that I could purchase a titanium brake set that is made for thr R1 at $1400.00 and that shaved off all of 2 lbs. I have used the offending torque wrench many times on the same bolt(s) whilst pulling the wheel for multiple tire changes over the years.

...and it finally gotcha. :huh:

 

[kaitsdad]

The bolts are hollow for heat dissipation. Over time the bolts will stretch - and will break. Cheaper than new fork lowers. Buy new bolts.

 

[wfooshee]

Damn engineering knowledge! taking all the guesswork out of "I know why it does that!" No fun at all.

 

[dcarver]

Really, KD? Heat dissipation?

Does it really matter on an FJR with an average peep rider?

 

[dan]

I'm going with KD's take on the reason as to why the bolts are hollow and his suggestion about replacement which has already been implemented.

 

[dan]

Really, KD? Heat dissipation?

Does it really matter on an FJR with an average peep rider?

Makes more sense to me than weight savings.

 

[kaitsdad]

Really, KD? Heat dissipation?

Does it really matter on an FJR with an average peep rider?

Makes more sense to me than weight savings.

Simple, really. Under extreme braking conditions (most peeps on this forum, moi included will never experience this) the brakes (rotors, calipers) can become incredibly hot - and that heat not only affects the functioning of the calipers, but if you consider that the calipers mount to the fork lowers the risk of cooking the forks exists. Hmmm.... light weight fork oil, seals, upgraded suspension cartridges...o-rings....lots of heat. Not a good mix.

So - something as simple as hollow bolts reduces the heat transfer to the forks.

Average rider? Might not make a lot of difference - or does it?

 

[Chuck35]

T would think that hollowness would also prevent damage to the forks due to overtorque...

 

[Afast03nNJ]

What's a torque wrench?