How about using Brembo rear caliper up front?

[pekka]

Hello all,

I've been toying with the idea of using the Brembo 32mm dual piston rear caliper as the front caliper on my 1980 XS. I like the looks of the smaller 2-piston Brembo compared to the 4-piston. And I think it looks more "period correct".

The stock XS single piston caliper has piston area of 1134mm2 and the Brembo has about 1608mm^2. That should give a nice improvement on the braking force. I'm now running a 12mm master and FZR600 disk and those should also work with the Brembo.

Any reasons why the rear caliper could not be used as front caliper?

Thanks,

Pekka

 

[jd750ace]

Check the swept area. A lot of pressure on 60-70 percent of what a disc is designed to have swept could cause heat or warpage issues. I don't have much more to add except I have a rear dual pot brembo off a BMW 1200 that is made for a much narrower swept area than anything I have except my SV650, and the Tociko that is on there now is an over-dog of a caliper on that bike to begin with. I believe it is dual 28's or a 28 and a 32.

 

[pekka]

Good point on the swept area. According to this: http://cdn.carpimoto.com/Images/Products/Pdf/20-5161-43.pdf the pad width is 39.9mm and height 34.5mm. XS pad is around 55x50 mm (http://www.bits4bikes.co.nz/images/products/6072.jpg). Hmm... Thats a LOT smaller. 1377mm² vs. 2750mm². Need to do some measuring and calculations...

Pekka

 

[pekka]

........

 

[retiredgentleman]

An important consideration is the ratio of the master cylinder piston area to the total caliper piston area.
Have a read on this from Michael Morse:
http://www.vintagebrake.com/mastercylinder.htm

 

[CDNTX650]

Why not just run a 2 piston front....its a bit smaller. Mine is from a monster s2r800.

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[pekka]

Why not just run a 2 piston front....its a bit smaller. Mine is from a monster s2r800.

For the looks and because I want an "opposing piston" caliper instead of a floating one.

Pekka

 

[pekka]

retiredgentleman: I've read that page a few times. A 12mm master should be good for the dual 32mm pistons. At least way better than the stock 14mm with a single 38mm piston.

The swept area (or pad height) of the rear caliper is about the same as with the 4-piston front. And the stock XS (measured wit a tape measure from my brake rotos) is about 38mm. So no problem there. The pad area "only" contributes to heat distribution and since I'm not racing this should not become an issue.

Thanks for the replies.

Pekka

 

[pekka]

Interesting ebay find:

http://www.ebay.com/itm/2-Piston-Mo...Parts_Accessories&hash=item4173d0675f&vxp=mtr

http://www.ebay.com/itm/2-Piston-Br...005&prg=9209&rk=2&rkt=6&sd=281049762219&rt=nc

Real Brembos or replicas (or actually fakes because they have the Brembo logo)? My guess is fake. Good price though...

Pekka