Brake upgrade question?

[KTM21]

I came across a new 4 pot brembo caliper on ebay for £55 but I'm not sure if it will work with my bike. The bolt spacing is 65mm which is the same as my bike but the bikes that come with this caliper from factory use a 320mm disc. My bike has a 300mm disc. Does this matter?

Here's a pic of the caliper:

 

Here's a pic of my 2 pot caliper:

[Tango]

There's a few things you need to consider......A 4 pot caliper will be deeper than your 2 pot, so you need to check the clearance between the rear of the caliper and your wheel spokes......and also that the gap that the disk runs in is not offset on the 4 pot. The 4 pot will also need more fluid movement to operate the pistons.....so your Master Cylinder may not be suitable. And the fact that the caliper is normally used on bikes with a 320mm disk, the pads may not be centralised on the disk.

Unless you know of someone who has used one of these calipers on your type of bike I'd be inclined to give it a miss.....

[eastanglianbiker]

as tango says the spacing and offset will be different as you calliper has no rear pistons and even if it did work to lose 10mm off the braking area is a huge amount it wold mean only half the surface area would be in use of the pad or maybe less so got to agree dont bother it would be more hassle than its worth if it fitted at all

[Stu]

summed up in one post

[KTM21]

as tango says the spacing and offset will be different as you calliper has no rear pistons and even if it did work to lose 10mm off the braking area is a huge amount it wold mean only half the surface area would be in use of the pad or maybe less so got to agree dont bother it would be more hassle than its worth if it fitted at all

But why would you lose 10mm of pad contact? The caliper would be mounted from the same place as the 2 pot is now.

[eastanglianbiker]

because it is designed for a 320mm disc and yours is only 300mm making it 20mm smaller making it less contact surface area

[Stu]

mounting point is irrelevant

its the position of the pads against the disc

with a 20mm smaller disc you are going to lose 10mm of contact patch if the positioning is the same

[Joeman]

Hang on guys,

If you increase disc size by 20mm you would need to space the caliper out by 10mm.

If reducing the disc size by 20mm, the caliper would need to move in 10mm

In this case the mounting is correct for the disc size so as long as the position of the pads relative to the mounting is the same as the old caliper you won't lose 10mm of unswept disc.

[KTM21]

Hang on guys,

If you increase disc size by 20mm you would need to space the caliper out by 10mm.

If reducing the disc size by 20mm, the caliper would need to move in 10mm

In this case the mounting is correct for the disc size so as long as the position of the pads relative to the mounting is the same as the old caliper you won't lose 10mm of unswept disc.

What I was thinking just couldn't explain it

[Stu]

thats what I was getting at in my post!

just worded shite

if the caliper mounting points are the same on both bikes for arguments sake lets say the top mount is 300mm from the centre on the donor bike then your disc would be too small and lose 10mm of braking efficiency your mounting would need to be 290mm from centre to compensate