New Brembo P4 30/34s @ 90 EUR Ea.


Hero member
Hi grant, can you point me in the direction of the correct adaptors?
Do I need to change the original Brembo master cylinder for this?

thanks in advance



Hero member
Idaho, USA
I would suggest that you try the 4-pot calipers with the original master cylinder before committing to buy one with a larger bore.  I like the feel/action of the original master just fine when combined with the new calipers. 


Staff member
NRW, Germany
Grant said:
You can buy adaptors on Ebay or others are available.
Attached is a photo of the adaptors on my bike.
I went with a 16mm m/c compared to a 15mm as standard.

The stock M/C may be nominally 15mm, but the piston is actually 15.8mm, just about exactly 5/8", as is commonplace in hydraulics.  Lever geometry can make a big difference.



Full member

The PS16 is *just* right with 2 P4s; a very common set-up on many 1990s Italian bikes, and I have it on my Moto Guzzi Sport 1100. I am happy with it, no chance of lever getting too close to the bar, but I would not use a smaller MC. Many upgrade their twin-P4 setups with Brembo RCS19s for more positive lever feel.



Hero member
As I just bought the bike, and was doing project planning, I wanted to know my options, Having now  found the master cylinder welded from a previous accident, the decision was easy , I just ordered a PS16 to replace the original  in the photo, so that with new callipers and discs, things should go pretty well, thanks for all your help,  New P4-30 Calipers are on the way, now I just need to find the mounting brackets. All original parts are heading for catalogued storage.


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Senior member
Well spotted Kristian, and thanks for posting the link.

As ever when swapping calipers, make sure the PADS are compatible with your discs.

Some suppliers of the P4 30/34 calipers send them out with pads meant for SS discs.  These will rip up your cast iron discs quickly.  And the replacement of discs will make the pads and calipers seem very cheap.
Check the pads when purchasing against your chosen pad manufacturers advice.


Hero member
if you need replacement disks in SS, Michael St?cker can sort you out:

Michael St?cker
Erbacherstrasse 62

D-64658 F?rth

Phone: +49  6253 - 86489

On his webpage he offers them for 140? (just the rings, the carrier needs to be kept and bolted onto the new rings; so - only available, if your disks are not made of 1 piece but of ring and carrier)


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ksoholm said:
One more find during my RGS brake upgrade research - Italy's Carpimoto has a great deal on Brembo P4s - fantastic outfit to do business with:


that is weird: he has different prices for different countries! If I click on the link above, it shows me the calipers for 90?. A pop-up window asks me if I want to change my location to Germany and if I click yes, the price goes up to 110?! With shipping costs, there is still a difference of roughly 17?/caliper. this makes me question how serious this seller is...  :'(


New member
I noticed the price difference between countries too - I just put it down to different sales tax rates (VAT)?

Mine were delivered quickly and look great.  Although the packaging wasn't the best - 2 loose calipers wrapped in bubble wrap, inside a box.  I was expecting them to be in a branded Brembo box with custom foam and the "Genuine Brembo" card that allows you to check them on the Brembo website (like when I got a pair of M4 calipers for my Streetfighter).

The packaging made me worry that they might be knock-offs, so I did some research on the company.  They are are listed as a genuine Brembo partner, listed on the Brembo website, and I found their warehouse on Google maps.

I'd be happy to use them again.  Their Master cylinder prices seem good and I'll keep them in mind if I go for a hydraulic cluch upgrade.

Merry Christmas y'all


I bought 3 calipers off them, just over 300 euros delivered.
I'll use them again.


Hero member
that is weird: he has different prices for different countries! If I click on the link above, it shows me the calipers for 90?. A pop-up window asks me if I want to change my location to Germany and if I click yes, the price goes up to 110?! 
  Same happened to me in England Lothar !
I have used the BMW 4-pot brembos on my Ceriani forked bikes - no fannying about  or extra expense with extra brackets - just a couple of small spacers - they work great with the original Ps15 m/cylinder too. -  got a few pairs on Fleabay for around 50 quid - Regards - Phil


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Hero member
Gerald said:
Hi Phil,

K 1100 4 pot calipers?

Hi Gerald- Got them from many different models. They were fitted to many of the nineties and early 2000's BMW's - if they look like the ones in my photo - then they are the ones - Regards - Phil