Can anyone with 140mm rotors and flat mount calipers help?

BlueDynamo

I'm about to install a Shimano BR-RS805 caliper to my frame as part of a build and was wondering if someone who has 140mm rotors and flat mount calipers could help?

Page 50 of the Shimano instruction manual (http://si.shimano.com/pdfs/dm/DM-BR0008-08-ENG.pdf) indicates that when using 140mm rotors with flat mount calipers that the bolt that secures the caliper to the chainstay should not require a washer.

The washer only appears to be required if using 160mm rotors (page 51).

Page 44 details the length of the bolt required based on the frame thickness. The bike manufacturer has confirmed to me the length of bolt required so I'm assuming I've got the correct one (see photo below).



If the washer that is supplied with the bolt is not required does anyone have any idea how to remove it from the bolt? The threads seem to stop the washer moving along the bolt.

cycleclinic

the washer being above the caliper will cause no problems if used.

BlueDynamo

thecycleclinic wrote:

the washer being above the caliper will cause no problems if used.

Not sure I understand? The bolt is installed from the underside of the chainstay so the washer is always below the chainstay and caliper.

bbrap

BlueDynamo wrote:

thecycleclinic wrote:

the washer being above the caliper will cause no problems if used.

Not sure I understand? The bolt is installed from the underside of the chainstay so the washer is always below the chainstay and caliper.

On my flat mount the bolt goes through the caliper and threads into the chainstay/fork.

BlueDynamo

bbrap wrote:

BlueDynamo wrote:

thecycleclinic wrote:

the washer being above the caliper will cause no problems if used.

Not sure I understand? The bolt is installed from the underside of the chainstay so the washer is always below the chainstay and caliper.

On my flat mount the bolt goes through the caliper and threads into the chainstay/fork.

That's true on the fork but the instructions definitely show the caliper bolt going through the chainstay first on the rear. What flat mount calipers do you have on the rear?

bbrap

BlueDynamo wrote:

bbrap wrote:

BlueDynamo wrote:

thecycleclinic wrote:

the washer being above the caliper will cause no problems if used.

Not sure I understand? The bolt is installed from the underside of the chainstay so the washer is always below the chainstay and caliper.

On my flat mount the bolt goes through the caliper and threads into the chainstay/fork.

That's true on the fork but the instructions definitely show the caliper bolt going through the chainstay first on the rear. What flat mount calipers do you have on the rear?

805's

veronese68

The washer is not between the caliper and the frame it is directly under the bolt head so will not affect how the caliper fits. The only way the washer could create a problem is if it is so thick that the bolt is not long enough, or so wide there is not enough space. I doubt that either is the case.

tsarouxaz

these bots are meant to be used with is built in washer. that is why it is built in the bolt! never use tightening bolts without washers!

dj58

BlueDynamo wrote:

Page 44 details the length of the bolt required based on the frame thickness. The bike manufacturer has confirmed to me the length of bolt required so I'm assuming I've got the correct one (see photo below).



If the washer that is supplied with the bolt is not required does anyone have any idea how to remove it from the bolt? The threads seem to stop the washer moving along the bolt.

They are captive washers and are not designed to be removed. I think you are confusing them with the thicker spacer type washers, item (B) shown on the illustration at the top of page 51, of installation instructions.

BlueDynamo

Thanks to all that have responded.

DJ58 wrote:

BlueDynamo wrote:

Page 44 details the length of the bolt required based on the frame thickness. The bike manufacturer has confirmed to me the length of bolt required so I'm assuming I've got the correct one (see photo below).

[img]https://s31.<span%20class="skimlinks-unlinked">postimg.org/59i02z1hj/IMG_0449.jpg</span>[/img]

If the washer that is supplied with the bolt is not required does anyone have any idea how to remove it from the bolt? The threads seem to stop the washer moving along the bolt.

They are captive washers and are not designed to be removed. I think you are confusing them with the thicker spacer type washers, item (B) shown on the illustration at the top of page 51, of installation instructions.

Yes the thicker spacer type washers are the confusing bit. They don't seem to have been supplied with the hydraulic disc brakes and calipers so it is a good job that my rotors are 140mm diameter and I don't need these spacers!

It now looks like the bolt lengths that the frame manufacturer advised I required are incorrect so I'll have to order the next size up.