Radial Master Cylinder Source?
 

Guys

Where is the best / cheapest place to look for a Brembo Radial Master Cylinder & P4 Calipers?

I am running a 748 BP and therefore think they are 40mm fork bottoms. To move to P4 would i need to change them for 64mm? If so any ideas where these can be sourced. I am sure I saw some billet ones recently but can't think where now!

Cheers

Chris.

P4 only come in the later 65 mm fork mounting as I understand.
If you're changing your fork bottoms, why not just go straight to radial calipers?

Either check ebay or speak to the uk importers, http://www.gprdirect.co.uk/
I've used them a couple of times for parts and spares, and also a service on one of my Brembo radial m/c, and they always provide good service.

As for radial m/c, I just bought a brand new one off ebay for £145, or again check GPR.

Whats the major difference between radial capipers and P4?

Are these P4? Calipers

No, they appear to be the 996 SPS standard calipers.

I took those off my 996 SPS and replaced them with the P4's - big improvement (in conjunction with cast iron floating discs).

BC

No, those are Goldline calipers which have 4 pistons, but two pads per caliper. They come in 40mm and 65 mm mounting.

40mm calipers have one pin holding the pads, in the middle:

You can also see that the two mounting points are at the "back" of the caliper.

65mm calipers use two pins, one over each piston:

You can see that the mounting points are much further apart.

P4 calipers only come in 65mm mounting but use 4 pads per caliper:


For all three type above, the bolts that hold them into the fork are fitted sideways in - ie, laterally mounted. The problem with this is that braking forces are applied over a very restricted area, the point between the mounting bolt in the fork and the bolt in the caliper itself. This can cause flexing if the load exceeds the amount of force that this area can carry.

Radial calipers are mounted radially - that is that the bolts go through the caliper and into the fork bottom in a radial arrangement. This helps to spread the load over a great area, ie, the full length of the bolt, as the force is now aligned with the bolt rather than in a shearing pattern. Thus radially mounting calipers are stronger, flex less and look more trick...

This is a radial caliper - note how the bolts don't go in sideways...

Thanks Antonye

So I would be best to go for some P4 calipers? Anyone got any for sale?

Then i need to find some 65mm fork bottoms! Any ideas?

Cheers

Chris

To be honest, the best thing you can do is get some decent pads in there first, as this can improve the feel of the brakes no end. Its all down to personal choice but I prefer Carbonne Lorraine SBK3 pads as they have excellent initial "bite" on them.

Second cheapest is to replace your lateral master cylinder with a Brembo radial, as this will increase the amount of "feel" (feedback) you get from the brakes. Again this helps your feedback of the brakes so it doesn't feel like two wooden blocks in your calipers instead of pads!

If you still find all that inadequate, then think about replacing the calipers and fork bottoms!

Good write up Antonye, thanks for that article / reminder :)

By the way, make sure that you have braided hoses as well, as the original rubber-covered hoses can degrade and bulge under pressure, which reduces the pressure being sent to the calipers so you get reduced braking effect.

Replacing the hoses is another cheap and easy job to do if its not been done already.

P4 callipers fitted straight onto my 1998 748BP I should check the bolt spacing on yours, I thought 748's were all the same.

Mike