monoshock front brake caliper replacement

[Matt Chapter]

So I was out on a bit of a tour of the hill country yesterday, finally made my way home as the dark and rain descended... and along the way, my front brake lever gained the ability to touch the grip.

Made it home fine, not even too wet.  This morning, pulling the lever causes brake fluid to drip from the caliper.  Last time I had it apart I noticed the piston was causing wear on the inside of the caliper, figured I'd replace the caliper next time I went into the brakes.  I've seen others mention the brembo f08 as a replacement on the dual shock R65, will it work for the mono? Or do I need an f09?

My current caliper is a brembo 2H5 48; what motorworks describes as "the large caliper for the factory single disk".  I've got a 14mm master cylinder installed.

[Barry]

A brembo F08 has 38mm pistons  and the F09 has 48mm pistons.

You need to measure your caliper piston size although A 2H5 48 sounds like it has 48mm pistons which would be a much better match for the 14mm master cylinder than an F08.

[mrclubike]

I think you Need a F09 also 
MG cycles is a good source for the Brembo calipers
http://www.mgcycle.com/index.php?main_page=index&cPath=110_350&zenid=fc9102dc0e98ed694002e8177984db1f

[Matt Chapter]

Bit of an update, I decided to go with a new rotor, ordered the BMW F09 brembo from MG cycles.  Here's some photos of the new rotor.

The old rotor (from Spiegler) seems ok, so I'm keeping it on the shelf. https://photos.app.goo.gl/JvaEWYyYvjgLAnCe6

New rotor all mounted up.  The hardware that came with the Braking rotor wouldn't fit so I reused the Spiegler pucks and fasteners with some locktite.
https://photos.app.goo.gl/BjvUNaYRpTXmZVSX7

For whatever reason I can never figure out how to embed photos from my google albums into posts here.

I'm still waiting on the F09 caliper, apparently they have a lead time of 2-4 weeks.

[georgesgiralt]

Hello,
A long time ago, I had an ATE caliper totally seized on one side. beyond repair.
I decided to put a set of Brembo instead and tried to keep the remaining ATE on the shelf. Some time after that a friend of mine needed an ATE caliper and I thought to give it to him. Alas the caliper was destroyed because of internal corrosion.
So you have to do something on this caliper before storing it if you want to reuse it later on...
Just my 2¢

[Matt Chapter]

Alas the caliper was destroyed because of internal corrosion.

I'm keeping the rotor on the shelf.  Not sure what I'll do with the caliper yet.  I think I could have rebuilt it and been back on the road already, but haven't taken it apart to know.  Once I've done the swap I'll make a decision on that.

[mrclubike]

Here you go

[Matt Chapter]

Here you go

you downloaded it, shrunk it, and uploaded it to the forum server...

i wish i could hyperlink stuff from my google photos album, bbcode doesn't seem to support it

[Matt Chapter]

Update: The replica F09 calipers mgcycle offers don't fit my R65.  The one that matches the part number mounts to the rear of the fork, but mine mounts on the front side.  The opposite side (which would mount to the rear of the fork) has the ears in the correct places, but the offset is incorrect.  So although they sell BMW F09 calipers, they don't have the one for my bike.

I got the seal kit and rebuilt them tonight.  I took a picture of the wear inside the caliper, I'm still not happy about it but I think it will work.  During that operation I realized I need to rebuild the primary cylinder.

What a hassle.

Here's some photos of the new rotor, my caliper compared to the caliper mg cycles sells, and the wear.

https://photos.app.goo.gl/wJCgggytxBUKM7Bv9

[mrclubike]

I wonder if you need the standard F09 and not the BMW specific one
Because  the one you need mounts  on the outside of the fork leg (holes not threaded)
The one you got is suposed to mount behind the fork leg (threaded holes in caliper)

Max shows a different F09 for pre and post 06/88

34 11 1 454 185       BRAKE CALIPER, LEFT - D=48 (to 06/88)

34 11 1 454 186       CALIPER RIGHT - D=48MM (from 06/88)

[mrclubike]

I will bet this is the one you need
I would call MG and find out for sure

BMW wants over $700 for one of these

[mrclubike]

Is the wear only the anodizing or can you feel it with your finger nail 
I don't think it will hurt anything as long as the piston is good and it does not bind

[Barry]

I agree, minor wear on the caliper bore is not an issue, it does nothing but guide the piston and it's only the piston which must have a good finish where it contacts the seal.

[Matt Chapter]

@mrclubike I've talked extensively with MG cycles.  My calipers are threaded ears, and the caliper ears go inboard the fork ears on the front of the fork legs.

MG offers two F09 calipers (right and left behind the fork), in two threading options (BMW threaded, and guzzi non threaded).  They say the caliper castings are otherwise the same.

Interestingly, I found those part numbers via fiche as well, and 34 11 1 454 185 is for the wrong "side" since my caliper mounts in front of the fork leg.  I thought that perhaps the right side behind fork would fit, and it would mount up, but its offset doesn't match the rotor.  One of the pictures in my album shows the right side caliper and mine aligned at the mounting ears. The rotor slot is off by a centimeter or more.

It's possible I have the later caliper, which would be something to try, but I think my next move after the primary cylinder rebuild is new pistons, if necessary.