Prolink front mc options

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Prolink front mc options

Post by Warwick Biggs »

My '82 Prolink has a David Silver front brake master cylinder fitted operating the stock 4 piston calipers.

My first question is where is the tiny return pressure hole? I ask because my brakes are dragging and it could be a blocked return passage but I can't see it in my mc without pulling it apart.

Second, what is the piston diameter? On the Silver web site it is shown as 15,8 mm but the casting on the bottom of mine is '14'.

Third, what is a good second hand replacement from the wreckers that has a good ratio for the stock 4 piston calipers? Some years ago at Eastern Creek I was told by a knowledgeable CBX owner that a mc from an early model R1 worked well. Most of the modern bikes that run Brembos and the like seem to have significantly larger diameter pistons and the adjustable ones seem to range from 18-20 mm. I don't believe these would work at all well with my calipers. There is a ratio chart available on the web but I would like to hear from those with actual experience of different diameter pistons. Mechanics will say there is a world of trouble fiddling with ratios but that sounds like regular territory for CBX owners!

I should add that my usage is racing.

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Re: Prolink front mc options

Post by CBX-tras »

One of my first upgrades ever (many years ago) was to use a Kawasaki Concour m/c (made by Nissin). Radial design, providing superior braking power to the stock calipers. Upgrade to braided lines too. Anyone using 40+ year old lines is on borrowed time.

I still use these m/c's today but usually paired up with 320mm rotors and Brembo monobloc calipers that give you one finger power brakes.
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Re: Prolink front mc options

Post by NobleHops »

Rick, there are two conical depressions in the front MC beneath the reservoir, into the cylinder itself. The smaller is the return, It *might* be possible to clear the return EDIT without removing the reservoir with a strand of wire plucked from your least favorite wire brush, held in needle nose pliers. Use a strong flashlight and remove most of the fluid from the reservoir first. Failing that, I can get a reservoir off in about 10 seconds without harm - grab it firmly and rotate it 25 degrees or so, put two large screwdrivers underneath the main reservoir and carefully pry up. It should wiggle off, although you want to be in good control of it when it does. That oring that seals it to the body is worth replacing, with Honda OEM.

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Re: Prolink front mc options

Post by Warwick Biggs »

Thanks fellas. Do you know what bore diameter the Kwacka MC is?

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Re: Prolink front mc options

Post by Syscrush »

Rick, what are your goals? Do you want more power, or less lever travel? Grippier pads can give you both, but any other change will be a tradeoff between those two factors.
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Re: Prolink front mc options

Post by CBX-tras »

Warwick Biggs wrote:
Thu May 05, 2022 4:50 am
Thanks fellas. Do you know what bore diameter the Kwacka MC is?
The Kawasaki m/c and most sport bikes have a bore of 11/16". The radial design (developed by Brembo, years ago) provide more pressure with less effort than standard "push the piston" design.

They can be used on any caliper, single, double or multiple pucks.

Just like chicken soup, no down side. Except when used on stock lines. The added pressure may cause an aneurysm on the old rubber.

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Re: Prolink front mc options

Post by Larry Zimmer »

To answer your primary question, it is a 15.8mm (5/8 inch) bore in the stock master cylinder. Why English/SAE units in a Jap bike -- dunno! Larger bore size will reduce travel and reduce braking. Conversely, smaller bore size will increase travel and increase the braking effort. (Reduce lever effort.) As Phil said, a trade-off. All that with the stock calipers.
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Re: Prolink front mc options

Post by Warwick Biggs »

I would like more power and above all improved feel. I could just buy another master cylinder like the one I have and keep the existing one as a spare after cleaning it. But for the same money I could get a radial Brembo mc.

I have braided lines and sintered HH pads working on turned down Honda VTR rotors. There are a number of second hand 19 mm Brembo mc's available from wreckers that I thought would not work with the Prolink calipers because of the larger bore but are you suggesting they will work because of the radial design?

I had a number of experts looking at my brakes at the track today and we worked out the sliders were fine and the fluid was returning and the problem was in the calipers themselves. Probably the rubbers on the pistons turning over and shredding. It is not overheating so provided the track is dry I will still race and recondition them when the new pistons arrive.

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Re: Prolink front mc options

Post by CBX-tras »

You probably have the typically crud buildup between the caliper and the square shaped seal which will prevent the piston from retracting. Caliper rebuilding is the required fix. I've never seen that seal "turn over" but, I've seen hundreds of calipers (and master cylinders) with this condition.

If you install one of those 19mm Brembo's, you'll experience a vast improvement.

Brake bleeding tip - Upon reassembly of the caliper, wrap the bleed screw threads with teflon ribbon, 2 to 3 wraps. Then with the m/c full of fresh fluid, suck the fluid through each caliper with a hand pump vacuum to get the majority of the air out of the system. Then pump/pressure bleed as usual to get a hard lever.

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Re: Prolink front mc options

Post by Larry Zimmer »

Do keep in mind, that if you go to the 19mm m/c using the stock calipers, your lever effort will increase by about 40% for the same stopping power. Certainly a shorter lever travel. BUT, a measurable lever pull increase.
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Re: Prolink front mc options

Post by CBX-tras »

Larry Zimmer wrote:
Fri May 06, 2022 12:12 pm
Do keep in mind, that if you go to the 19mm m/c using the stock calipers, your lever effort will increase by about 40% for the same stopping power. Certainly a shorter lever travel. BUT, a measurable lever pull increase.
Larry, not with the radial design, actually less.

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Re: Prolink front mc options

Post by Larry Zimmer »

AH!!!!
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Re: Prolink front mc options

Post by cross »

CBX-tras wrote:
Fri May 06, 2022 8:42 am
You probably have the typically crud buildup between the caliper and the square shaped seal which will prevent the piston from retracting. Caliper rebuilding is the required fix. I've never seen that seal "turn over" but, I've seen hundreds of calipers (and master cylinders) with this condition.

If you install one of those 19mm Brembo's, you'll experience a vast improvement.

Brake bleeding tip - Upon reassembly of the caliper, wrap the bleed screw threads with teflon ribbon, 2 to 3 wraps. Then with the m/c full of fresh fluid, suck the fluid through each caliper with a hand pump vacuum to get the majority of the air out of the system. Then pump/pressure bleed as usual to get a hard lever.
And this would be the one for '08-'22 Kawa Concourse?
Does the Prolink brake cable banjo and bolt size match kawas?

Thank you
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Re: Prolink front mc options

Post by CBX-tras »

cross wrote:
Tue May 10, 2022 4:07 pm
CBX-tras wrote:
Fri May 06, 2022 8:42 am
You probably have the typically crud buildup between the caliper and the square shaped seal which will prevent the piston from retracting. Caliper rebuilding is the required fix. I've never seen that seal "turn over" but, I've seen hundreds of calipers (and master cylinders) with this condition.

If you install one of those 19mm Brembo's, you'll experience a vast improvement.

Brake bleeding tip - Upon reassembly of the caliper, wrap the bleed screw threads with teflon ribbon, 2 to 3 wraps. Then with the m/c full of fresh fluid, suck the fluid through each caliper with a hand pump vacuum to get the majority of the air out of the system. Then pump/pressure bleed as usual to get a hard lever.
And this would be the one for '08-'22 Kawa Concourse?
Does the Prolink brake cable banjo and bolt size match kawas?

Thank you
Sasha
Yes, for size and thread pitch but, you may need a slightly longer line from the stock length.

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Re: Prolink front mc options

Post by Warwick Biggs »

I have ordered a new set of stainless pistons, a seal kit and a 16 mm Brembo master cylinder off an ST4 Ducati.

I will let you know how it turns out.

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