Replacing original brake m/c with square Brembo

N

Nick

Full member
Hi,

I'm going to replace the original m/c on my '81 Jota with a square brembo type found on more modern Ducati's. The aim is to get a similar feel to that on my RGA Jota which I'm told runs a PS14 (which are rare). I'm sticking with the P08's.

I know the idea is to decrease the bore of the master cylinder however I've been advised that when using the square m/c I should go for a 16mm as the lever pivot point gives an improved feel. Has anyone done this and what is the correct size square m/c?

Many thanks

Nick :-)
 
Nick said:
Hi,

I'm going to replace the original m/c on my '81 Jota with a square brembo type found on more modern Ducati's. The aim is to get a similar feel to that on my RGA Jota which I'm told runs a PS14 (which are rare). I'm sticking with the P08's.

I know the idea is to decrease the bore of the master cylinder however I've been advised that when using the square m/c I should go for a 16mm as the lever pivot point gives an improved feel. Has anyone done this and what is the correct size square m/c?

Many thanks

Nick :)
Click to expand...

The newer M/Cs also do not suffer from the friction between lever and piston. Slightly more sophisticated push-rod design.

piet
 
If it has a lever span adjuster as opposed to just a free-play adjuster like the original ones that great addition as well.
 
Hmmm thanks guys but I'm not really any further forward.

Anyone fitted a square block (without a span adjuster) retaining the original P08s, got more feel and can tell me which bore size to go for?

Cheers

Nick
 
As the pivot difference isn't too great, I'd go for 14mm for starters, nothing much to go wrong. Reckon the benefit from a 16 will be marginal, at best, when compared to the present PS15 (actually 15.8mm!). After all, the old PS14 is just about ideally paired with the 08s.

piet
 
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FWIW
I changed to a Nissin square master from a Honda CBR 1000 SC21 many moons ago.
Works very well for me with the P08 calipers and EBC brake pads.
Gerald
 
Hi Rob, just to clarify have you run a square 14mm Brembo master cylinder with the standard P08? I know that a PS14 is the best combination but that's using the original style of m/c. As I'm going to change to these square m/c I think the best bore size with this configuration might not be 14mm?
Thanks
Nick
 
Nick,

The pivot to actuating point length is almost identical between the early round reservoir PS12/13/14/15 and the newer square reservoir PS11/13/15/16 (my supplier doesn't list a 14mm!). Doesn't matter if the lever is equipped with the span adjustment facility or not. The old version even has the disadvantage that mechanical advantage decreases as the lever travels further through its arc due to the contact line moving on the face of the piston.

If you do find a square Brembo PS14, it will work slightly better than the old PS14.

Lots of Nissin M/Cs on fleabay from all manner of Jap bikes that will work just as well, for a far lower outlay... just keep in mind most jap brake equipment makers use M10x1.25 thread for their hose connections instead of the M10x1.00 that Brembo generally used.

piet
 
sfcpiet said:
... just keep in mind most jap brake equipment makers use M10x1.25 thread for their hose connections instead of the M10x1.00 that Brembo generally used.

piet
Click to expand...
And in keeping Brembo used 10x1.25 for their master cylinders on standard Yamahas (mine is from an R1 front, R6 rear).
 
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