Replacement Master Cylinder

[Fred the Zed]

My 78 Z1R has an underslung AP rear caliper fitted. I've serviced the original master cylinder but I'm not sure its the best combination for performance. Sure, you can feel retardation when applying the back brake but I think it might need something more modern and perhaps of a better master cylinder vs caliper ratio.
The bike is fitted with Tarrozi rearsets, not standard footrests.

Any ideas on the best way to upgrade?
Fred

[Fred the Zed]

Anyone used one of these kits?

https://www.webike.co.uk/products/1522926.html

Fred

[Robw]

Used a zrx 1200 rear master cylinder on my AP Lockheed brake for the Lawson and a brembo one on my endurance bike.
Rob

[Fred the Zed]

Used a zrx 1200 rear master cylinder on my AP Lockheed brake for the Lawson and a brembo one on my endurance bike.
Rob

What size MC was it and did you fabricate a bracket to suit?

Fred

[Robw]

Sorry, I don't know what size, I have Kipkawa rearsets fitted to the Lawson and the zrx fitted perfectly. The spacing between the bolt holes seems pretty standard, a zx7r will be the same as well I expect.

[KWACKERZ1]

just use an AP One to match the caliper they are available
https://www.apracing.com/products/motor ... nders.aspx

[Fred the Zed]

just use an AP One to match the caliper they are available
https://www.apracing.com/products/motor ... nders.aspx

Hmmm
The Z1R back brake lever pivots a rod that pushes up into the MC. The AP rear MC requires the action to pull down. Not sure I want to be fabricating a linkage to reverse the action. Thanks for the suggestion though. What it did reveal was that AP rear master cylinder has a 5/8 bore. I need to see what the standard master cylinder size is to see what the difference is.

Cheers
Fred

[Robw]

Just checked some spare rear brake master cylinders and they are 14mm. Which will be sufficient for your brake.
Rob

[Fred the Zed]

Just checked some spare rear brake master cylinders and they are 14mm. Which will be sufficient for your brake.
Rob

Thanks Rob

[Fred the Zed]

Just checked some spare rear brake master cylinders and they are 14mm. Which will be sufficient for your brake.
Rob

Hi Rob

Just done some maths, taking into account that the bike is now wearing a rear AP 2696, a 1/2" rear master cylinder would give more power and feel.

Cheers

Rich

[Robw]

Mine has the same rear caliper, only reason I have a 14mm one fitted is that at the time it fitted and worked. It is good enough to lock the back wheel up if needed, but I very rarely use it as the bike spends most of its time on the track and I only use the front brake.
Rob

[Fred the Zed]

Mine has the same rear caliper, only reason I have a 14mm one fitted is that at the time it fitted and worked. It is good enough to lock the back wheel up if needed, but I very rarely use it as the bike spends most of its time on the track and I only use the front brake.
Rob

I hear you. Back in the day when I raced in the Hornet Cup, I swapped the 14mm front master cylinder for one off a VFR / Blackbird which was 12.7mm. Just that small difference made the front brake much more effective (if I remember correctly, I worked it out as about 18% more powerful). It made a big difference and I could overtake on the brakes a bit more easily... the Hornet Cup was (ahem) a little competitive to say the least... so any little advantage that could be squeezed out was useful.

I think its less relevant with the back brake - I only used that for keeping the front end down, I wouldn't pretend that I had the skills to use it to back a bike into a corner. On the road its perhaps more relevant so I'm interested in making the most of the braking potential. At the moment, the front is significantly out performing the rear, so I just want to balance it up a bit.

Have you seen the caliper vs master cylinder ratio chart that was circulating on the forum recently? If not, I'll post it up as its really useful.

Cheers
Fred

[Fred the Zed]

Mine has the same rear caliper, only reason I have a 14mm one fitted is that at the time it fitted and worked. It is good enough to lock the back wheel up if needed, but I very rarely use it as the bike spends most of its time on the track and I only use the front brake.
Rob

Hi Rob

What make is your rear master cylinder and did you have to make up a mounting bracket? If so, do you have a template that I can copy?

Fred