Clutch Master Cylinder Size

SandPebbles

SandPebbles

Junior member
Location
Madison, CT U.S.A.
Good Afternoon,

I would like to confirm the size of my clutch master cylinder.  The bike is a '74 3C and the hydraulic
clutch conversion was done by the previous owner. 

The master cylinder is a Brembo with the clear, attached and round reservoir.  The numbers
at the bottom are 10.2729.01.

I measured the diameter of the piston at 15.85 mm (at the greatest diameter).

Is this indeed a 15 mm Brembo?  I just want to be sure before I purchase the rebuild kit.

Thanks for all your help.
 
If you're measuring the steel part of the piston, a diameter of 15.85mm indicates a 16mm bore master cylinder. The rubber seals that go on the piston would be 16mm + diameter.

Try measuring the bore of the cylinder to be sure.

16mm M/C kits are a bit hard to find these days. Good luck.
 
15mm Brembo master cylinder repair kit. Fits rear master cylinders on all integrated disk brake models from 1976 through 1997, and fits original front master cylinder on 850T and disk brake Eldorado. (actual 15.84mm) - I assume (probably wrong) that the guts of the clutch M/C is the same as for the brakes?

Available from:-

http://www.mgcycle.com/product_info.php?products_id=753

or

https://store.bevelheaven.com/brake-related-parts/brembo-15mm-lrd-brake-m%7Cc-kit-fits-round-reservoir-70s-80s-front-rear-mcs/

or

http://www.stein-dinse.biz/Brembo/Supplies-spare-parts/Bremszyl-Rep-Satz/Mastercylinder-gasket-kit-PS-15-big-Model::29.html
 
15.88 is 5/8".  A surprising amount of hydraulics are still done in imperial, including Nissin master cylinders up to quite recently.  It's even cast into the body on those models -  ' 5/8" '.
 
For some unfathomable reason, perhaps only known to Senore Brembo himself, PS15 denotes 15.8mm piston size.

The clutch M/C piston has a small plastic inlay where the lever bears on it, apparently to prevent rattle and stiff action of the lever.  Missing from the brake side, probably for safety reasons.  Otherwise, both repair kits are identical.

piet
 
When I fitted 320mm floating discs to my Jota I fitted matching pairs of Lockheed adjustable ratio master cylinders and there fantastic and much much cheaper than Brembo items.
These units work really well and I strongly recommend them if your looking for an alternative.

and they look good as well!
 
OK. I stand corrected. It just seemed logical to me that anything measuring 15.88mm would be a 16mm M/C.

To further confuse the issue, I recently had to fit a piston kit to the rear M/C on my Benelli. I measured the piston and cylinder bore and it was near enough to 16mm (don't remember the exact measurements, but may well have been 15.88. I bought a 16mm piston kit and it fitted perfectly. The box the piston kit came in was labelled Brembo 16mm.


Cam
 
Gentleman,

Thanks for all your replies.  The fact a 15 mm master cylinder has a 15.88 mm piston comes as no
surprise to me as I become more familiar with Italian manufacturers!

RCGBOB44, I have a AP Racing (Lockheed) brake master cylinder from their classic range that I have
considered about using.  It has the integral, cast reservoir and looks the part.  According to their
website, they no longer have the matching clutch master cylinder to match in the classic range.

So I then looked at AP Racing's adjustable ratio master cylinder range, CP3125 family.  Their website only
offers a brake master cylinder, but I did find the left-hand clutch version mentioned by Harris Performance in the UK. 

Any clarification or vendor ideas for the clutch master cylinder (either classic or adjustable ratio) would be
appreciated.  I am still deciding on which path to take...Brembo or AP (if available).

 
sfcpiet said:
For some unfathomable reason, perhaps only known to Senore Brembo himself, PS15 denotes 15.8mm piston size.
Click to expand...

As per Steve, Piet.  Many hydraulic fittings are still sized imperial.  For example, taps sold in here in France are ?", ?" etc  :o.

SandPebbles said:
The fact that a 15 mm master cylinder has a 15.88 mm piston comes as no surprise to me as I become more familiar with Italian manufacturers!
Click to expand...

Not surprising at all, and nothing to do with the nationality of the manufacturer - see above  :D.

Ciao

Craig
 
Ventodue said:
As per Steve, Piet.  Many hydraulic fittings are still sized imperial.  For example, taps sold in here in France are ?", ?" etc  :o.

Not surprising at all, and nothing to do with the nationality of the manufacturer - see above  :D.

Ciao

Craig
Click to expand...

OK, Craig, get your point.

But, why the fuck didn't they state so on the M/C?  If they use imperial dimensions, why state a metric size?  Too much of the red at lunch?

piet
 
Definitely not an Italian thing, as I mentioned Nissin m/c's on Yamondasakiukis etc up till fairly recent times have imperial measurement, but at least it is stated on the cylinder! :)
 
sfcpiet said:
But, why the fuck didn't they state so on the M/C?  If they use imperial dimensions, why state a metric size?  Too much of the red at lunch?
Click to expand...

:D  :D  :D

"Just to piss you off ..." ?  Or maybe the piston is 15mm and the bore 5/8?  I'm guessing here, you understand.  So I'll shut up ...
 
You must log in or register to reply here.
Back
Top