Hollow Caliper Bolts?

Tonight I removed the front wheel from my 05 FJR (to have a new tire installed) and realized the bolts holding the calipers to the fork tubes are hollow, you can see right through them. Does anyone have an idea why these bolts are hollow and not solid. I would think solid bolts would be stronger.

Heat disipation?

I think they are hollow to reduce unsprung weight. May also be the bling factor.

I remember a physics class that showed that a hollow tube is stronger than a solid tube. The example given was the human bone. We did pressure tests and found it to be the case too.

But, that was also 20 years ago, and I've been wrong a bunch in the past and I'm certain to be wrong again in the future.

The cylindrical shape is best for compression. I think the stresses on this bolt are different.

If hollow bolts were stronger I would expect to see rod bolts and things like that hollowed out.....not.

I would bet they are hollow for mass savings. Sort of pointless but a bling item that marketing can talk about that cost little or nothing since they were probably making them for other applications where it really mattered.

Probably to make it easier to drill out and remove when some Yahoo with his Mil Spec torque wrench leans on it too much.

You know we can't leave good alone.

Skippy

jestal said:

If hollow bolts were stronger I would expect to see rod bolts and things like that hollowed out.....not.
I would bet they are hollow for mass savings. Sort of pointless but a bling item that marketing can talk about that cost little or nothing since they were probably making them for other applications where it really mattered.

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I think the stress points are different for rod bolts. More likely mass (unsprung weight--minimal ounces?) coupled with the "common parts bin" approach (read: $$).

Remember that the brake calipers for the Gen 1 FJR were straight from the R1. My take would be weight reduction.

My vote is for weight reduction as the number one reason.

reducing unsprung weight, hidden benefit: easy to drill through sides and safety wire them!

So that traffic coming from the side can see oncoming traffic just before they remove your front end. Safety first!

J Claybrook

Diktator for Life

NHTSA

Thanks for the replys. I had considered most of those reasons, but could not really justify any of them. Carry over from R1 technology makes sense, but the weight reduction with hollow bolts versus solid bolts would miniscule, but I guess it all adds up. Anyway, the new tire is on and I'm back riding.

Thanks again.

jrd14 said:

...but the weight reduction with hollow bolts versus solid bolts would miniscule, but I guess it all adds up.

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The key is in the additional part of the statement. It is weight reduction in the unsprung weight. Think just the wheel, brakes, and part of the forks that go up and down with them. The bolt weight is a lot larger percentage than that of the overall bike.