Disc brake front master piston travel length?

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Onder

Onder

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Can some kind soul give me the length of travel of the piston in the front brake
master cylinder?
 
98 views and nobody knows? Well neither do I which is why I asked!
 
The only one I can measure has been modified, the figure would be of no use.
 
what kind of travel do you expect?
empty cylinder, full travel ,until it bottoms out.
Full of fluid until there is a bit of resistance or a few thousand PSI with the rubber lines bulging like doing a screaching stoppie?
Modified 1/2-13mm sleeved down is quite a bit different hydraulic travel don't you think????
 
I think it is about half an inch in my Lockheed master cylinder. But it would be different in others - it depends on where the hole is in the bottom of the reservoir and also the ID of the bit where the piston fits. I use a master cylinder which is intended for use with one calliper, to operate two callipers. So the distance the piston travels is twice as far. When the Lockheed master cylinder is used to operate only one disc, you probably need to grab it harder. I only use one finger to operate my front brakes. The other fingers always hold the twist grip. With two carbs and a quick action twist grip, the spring load is quite high. Little things like that can make a difference.
Is the question you are asking related to the lever travel ?
 
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An original AP master, according to AP :

Weight 520
Bore Size mm (ins) 15.875 (0.625")
Stroke mm (ins) 16.0 (0.638")
Hydraulic Connections Outlet Thread 3/8" x 24UNF
Reservoir Capacity 50cc. When re-filling reservoir reform internal bellows as flat as possible prior to re-fitting
Repair Kit CP5678-1RK
Lever Part Number CP2233-18

So the lever pressure, for me, is way too high. I want to go to a 13mm or 1/2" but not sure if the travel will be
sufficient. One disk, using the CP2696 caliper.

Of course, need to find a good master after all failure here could be painful.

And full disclosure, it isnt for a Norton but a Rickman.
 
Well dont disagree with you but it is staying a single fore and aft. It isnt for racing just an old street bike. Changing a master is no big deal
putting on new hubs and rims a bridge too far.
 
A 1/2" bore master cylinder works perfectly with that caliper. I have a Honda/Nissin type on my 750 Tiger which is far better than the original 5/8" fitment. You could even go to a 12mm for a little more travel/feel.

Martyn.
 
Differnce between 12mm and 1/2" is pretty small hard to believe you could feel that difference. But Im not doubting you.
The problem is 14mm masters are nearly free but 13 , 12 seem to be mostly Italian and costly. 11mm more common because
they use them for the clutch. Would not your Honda master be a 12mm, not half inch?
Imperial stuff is dear anymore. World turned upside down.
 
Onder said:
Differnce between 12mm and 1/2" is pretty small hard to believe you could feel that difference. But Im not doubting you.
Click to expand...
Actually, you probably could as it is about 11% difference (reduction) in pumping volume ..
12mm x 16mm stroke = 1810mm³
12.7mm x 16mm stroke = 2027mm³

I use an 11mm Nissin master cylinder from a Honda scooter (oh the shame of it) which is connected to a two piston Yamaha V-MAX Sumitomo (redeemed myself) caliper with 38mm diameter pistons which gives 24:1 ratio, the lever is rock solid not spongy at all, and the brake is very good on an RGM floating disk. I think the CP2696 has 38mm pistons as well, which is why I mentioned it.


Cheers,

cliffa.
 
Thanks, Ill have a go. I dont mind experiments that are a small outlay it is the pricey ones that cause me to pause.
 
Oooops. My error here. AP-2195 I think is more likely and are smaller, cannot go measure right now. They have three ribs and one port .
 
The squish depth measures .120" , same as DD quoted, so this must be a stock head.
I can give a pretty accurate number for piston above deck.
I have an original mk 3 barrel and pistons here, standard size 15,000 miles on the bike from new, disassembled by a bike breaker.

Glen
 
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