disc break mount bolts ruined or wrong size?

matt fairclough

I have recently swapped my avid elixir 5 brakes for shimano slx onto the same mounts and discs.(got this done at the lbs.)
After a particularly rocky descent today I noticed the front mount bolts had worked themselves loose and where making a terrible noise.tried tightening them but the threads seem to be knackered.any ideas if this is just a case of new bolts(or different size) or could it be the holes in the mount?
also,could this have damaged the forks in any way and caused them to leak oil?

cooldad

The bolts are the same size, but Avid might be longer to get through the Avid washers.

The bolts are steel, the mounts are aluminium (assuming post mount) so most likely if anything has stripped, it's the mounts. Which is a problem.
But without more info impossible to say.

nicklouse

matt fairclough wrote:

.(got this done at the lbs.)

Take it back to the LBS.

matt fairclough

Yes,I intend to do that first thing in morning..there did seen to be a bit of swarf(if that's the right word)
on the bolts,but impossible to say if that has come from inside the mount..

matt fairclough

any thoughts on the last question about the forks?

cooldad

Leak, no, damaged yes.
Swarf on the bolt would indicate the mounts are stripped.

poah

matt fairclough wrote:

I have recently swapped my avid elixir 5 brakes for shimano slx onto the same mounts and discs.(got this done at the lbs.)
After a particularly rocky descent today I noticed the front mount bolts had worked themselves loose and where making a terrible noise.tried tightening them but the threads seem to be knackered.any ideas if this is just a case of new bolts(or different size) or could it be the holes in the mount?
also,could this have damaged the forks in any way and caused them to leak oil?

is it a 180mm adaptor by any chance?

matt fairclough

yes its 180mm..

Giraffoto

As a glimmer of hope, if the bolts that appear wobbly go into an adapter that's still securely fastened to the fork, you may only have a busted adapter.

matt fairclough

tried the old avid bolts,they go in fine,but 1 is slightly to long..
anyway,i'll see what the bike shop have to say for thereselves..

matt fairclough

he's just confirmed its the lower fork holes that are worn.. :x
he's managed to set up the brake with new bolts though and everything seems fine..for now.
will it get worse over time or is it not that big a deal,if so,will it be a matter of new fork lowers
or can the holes be re-cut?

cooldad

Worn? Bullocks. Sounds like they managed to strip them. Especially if swarf came out when you loosened them. They don't just wear.

If there's enough metal left they can be helicoiled, if not likely trashed.

The Rookie

Things wear when there is movement by design (such as at bearings or on your tyres), the bolt doesn't move in the hole so cannot wear it unless it's been fitted loosely and the bolt not tightened, or the bolt over tightened and stripped the threads.

I'd take it back and ask him to sort it properly!

poah

matt fairclough wrote:

yes its 180mm..

a shimano caliper won't sit flush with an avid CPS 180 mount and the bolts are too long without the CPS washers

FishFish

matt fairclough wrote:

tried the old avid bolts,they go in fine,but 1 is slightly to long..
anyway,i'll see what the bike shop have to say for thereselves..

Well I hope that the LBS believe that in doing this it was not you that stripped the thread.

Good luck.