Oversizing brakes [Archive] - Kiwi Biker forums

nathanwhite

28th August 2012, 16:34

Thanks to DucatiLover I have a donor ZZR600 caliper and master cylinder for my bucket now.

However as soon as I tried to work out placement I noticed that it's hitting the spokes. Seems the wheel is designed for a 2 pot caliper or something. Weird.

Anyho I'm wondering if spacing the disc out (properly or not) so the wheel can accomodate it would have any adverse reactions on the handling of the bike? I can't imagine ~300g extra further out on one side would be good.

F5 Dave

28th August 2012, 16:56

That's probably not weird at all, the calliper will be made for more offset on the disc or skinnier spokes & the wheel will be for a 2 pot slider calliper which was common on Kawis & Hondas of the 90s.

So offsetting the disc is an option, but you have to be very careful. Handling won't be affected worth mentioning, - but are you going to ask the bolts to act in shear alone? Not a good idea. Picture of the wheel without a disc would help. A turned spacer with a shoulder is likely the safe way to do it.

erm. . .a ZZR600 master cylinder will be a 5/8" bore most likely & designed for a 2 calliper system. you'll want a 1/2" or maybe 12 or posibly 11mm bore master cylinder or you'll be pushing it up hill. At which stage you question if you have the right calliper for an easy transplant, free or not. A late 80s/90s CBR400/600 one would work well.

crazy man

28th August 2012, 17:33

FJRider

28th August 2012, 17:49

Take the old caliper into a bike wreckers and find (a better) one that WILL fit.

nathanwhite

28th August 2012, 18:08

That's probably not weird at all, the calliper will be made for more offset on the disc or skinnier spokes & the wheel will be for a 2 pot slider calliper which was common on Kawis & Hondas of the 90s.

Tongue in cheek comment. I know they are designed for each other.

So offsetting the disc is an option, but you have to be very careful. Handling won't be affected worth mentioning, - but are you going to ask the bolts to act in shear alone? Not a good idea. Picture of the wheel without a disc would help. A turned spacer with a shoulder is likely the safe way to do it.

I'll go digging for a pic.

erm. . .a ZZR600 master cylinder will be a 5/8" bore most likely & designed for a 2 calliper system. you'll want a 1/2" or maybe 12 or posibly 11mm bore master cylinder or you'll be pushing it up hill. At which stage you question if you have the right calliper for an easy transplant, free or not. A late 80s/90s CBR400/600 one would work well.

Can you explain why a smaller bore on the master cylinder would work better? I'm still trying to learn all this stuff

for a kick of what type of bike of chassy is it going on?

Suzuki EN125. Have a look over in General Maintenance

crazy man

28th August 2012, 18:36

how close is the calaper to the spokes? l know on rs125 you have to remove metal of the calaper to clear the spokes on a after market rim

nathanwhite

28th August 2012, 19:02

how close is the calaper to the spokes? l know on rs125 you have to remove metal of the calaper to clear the spokes on a after market rim

I found some pictures!

<a href="http://s1066.photobucket.com/albums/u417/nathanwhite2/?action=view&current=IMG_6805.jpg" target="_blank"><img src="http://i1066.photobucket.com/albums/u417/nathanwhite2/IMG_6805.jpg" border="0" alt="Photobucket"></a>

and front wheel on the right

<a href="http://s1066.photobucket.com/albums/u417/nathanwhite2/?action=view&current=IMG001.jpg" target="_blank"><img src="http://i1066.photobucket.com/albums/u417/nathanwhite2/IMG001.jpg" border="0" alt="Photobucket"></a>

Spokes may not be the right word, but I don't know what else to call them.

bucketracer

28th August 2012, 19:27

http://i1066.photobucket.com/albums/u417/nathanwhite2/IMG001.jpg (http://s1066.photobucket.com/albums/u417/nathanwhite2/?action=view&current=IMG001.jpg)

Spokes may not be the right word, but I don't know what else to call them.

Yes, you are right, they are Spoke wheels, they have alloy spokes.

269022 wooden spokes

269023 wire spokes

koba

28th August 2012, 21:17

The EN I had for a short while had more than enough brakes.

Are you wasting your time/effort/money on this?

Bert

28th August 2012, 21:28

nathanwhite

28th August 2012, 21:34

The EN I had for a short while had more than enough brakes.

Are you wasting your time/effort/money on this?

I concur koba. that setup doesn't look that different to a RG50 setup... never had an issue with them...
new pads and you will be away laughing.

#1 wouldn't it be awesome to have 4pot calipers?
#2 I have already rooted one caliper and cannot have another stuck one. This was offered to me so I thought I might give it a shot.

I'll have a look into rg50 calipers also

Bert

28th August 2012, 21:40

#1 wouldn't it be awesome to have 4pot calipers?
#2 I have already rooted one caliper and cannot have another stuck one. This was offered to me so I thought I might give it a shot.

I'll have a look into rg50 calipers also

#1 maybe... but not needed.
#2 really; they hard to stuff up what's actually wrong? seized? stuffed seal? hammer???
(but if new one free then all good)..

Rg50 caliper = rocking-horse shit. there will be some around...

nathanwhite

28th August 2012, 21:53

#1 maybe... but not needed.
#2 really; they hard to stuff up what's actually wrong? seized? stuffed seal? hammer???
(but if new one free then all good)..

Rg50 caliper = rocking-horse shit. there will be some around...

erm. Stripped inner thread on the caliper of the pad retaining bolt due to drilling the bolt out because it was seized. :Oops:
2nd caliper also has a seized bolt, but I'm not going to drill that

speedpro

28th August 2012, 22:20

RG50 brakes aren't up to it on a faster bucket on a faster track. A good mod is to fit a NZ250 disc if you can find one. It has the same bolt pattern as an RG50 and the same offset. Then you just need to extend the caliper mounting plate. I still found the Vesrah redback pads overheated and cracked all over and lost chunks. The red paint also got scorched off at places like Wanganui. Even the bigger disc turned blue but at least it kept working.

A 2-pot caliper with both pistons on the same side has the same braking pressures as a 4 pot but may be slimmer on the wheel side. I found the RG50 caliper to be OK. Having said that I now use an early RS125 master cylinder and caliper onto an early 2KT FZR250 disc.

Big brakes may not provide more ultimate braking capability but may require a lot less effort to use making the bike easier to ride fast.

Henk

28th August 2012, 22:31

erm. Stripped inner thread on the caliper of the pad retaining bolt due to drilling the bolt out because it was seized. :Oops:
2nd caliper also has a seized bolt, but I'm not going to drill that

Break out the Dremel, make a hole in the pin on the inner side and keep it place with either a split pin, R clip or lock wire?

ac3_snow

29th August 2012, 00:42

Can you explain why a smaller bore on the master cylinder would work better? I'm still trying to learn all this stuff

Apparently that is what I have inadvertently put on my bike, a larger diameter bore, twin disc master cylinder with a single disc front. It makes the brake lever ridiculously hard, and needs very little pressure and movement to apply the brakes hard.

edit; you end up with twice the required pressure/fluid going through one caliper.

ducatilover

29th August 2012, 01:11

Apparently that is what I have inadvertently put on my bike, a larger diameter bore, twin disc master cylinder with a single disc front. It makes the brake lever ridiculously hard, and needs very little pressure and movement to apply the brakes hard.

edit; you end up with twice the required pressure/fluid going through one caliper.

Personally I don't think it's going to be an issue and neither the caliper or master are renowned for being exceptionally powerful. They work well, but I do very much doubt this is going to be a problem :yes: If nathanwhite wants I can always unbolt one line from my splitter on my ZX6 (same brakes) and try it, if I lock up/flip/die, then it's awesome

nathanwhite

29th August 2012, 08:07

Apparently that is what I have inadvertently put on my bike, a larger diameter bore, twin disc master cylinder with a single disc front. It makes the brake lever ridiculously hard, and needs very little pressure and movement to apply the brakes hard.

edit; you end up with twice the required pressure/fluid going through one caliper.

Ok that makes sense.

Personally I don't think it's going to be an issue and neither the caliper or master are renowned for being exceptionally powerful. They work well, but I do very much doubt this is going to be a problem :yes: If nathanwhite wants I can always unbolt one line from my splitter on my ZX6 (same brakes) and try it, if I lock up/flip/die, then it's awesome

Yea but you have the weight and speed of a 600. My 125 would do 1/3 the speed and probably weigh 1/2 as much.

nathanwhite

29th August 2012, 13:29

Break out the Dremel, make a hole in the pin on the inner side and keep it place with either a split pin, R clip or lock wire?

Now this idea, I like. I might even try it too.

FastFred

29th August 2012, 14:55

Personally I don't think it's going to be an issue and neither the caliper or master are renowned for being exceptionally powerful. I can always unbolt one line from my splitter on my ZX6 (same brakes) and try it, if I lock up/flip/die, then it's awesome

The piston on a dual caliper master cylinder is a bigger diameter (area) than on a single caliper master cylinder unit.

If you use a dual caliper master cylinder on a single caliper because of the laws of hydraulics it is likely to feel hard and wooden and have less breaking effect for the amount of squeeze you apply at the handle bar.

Master cylinder piston to caliper piston size is like gear ratios the smaller the driving gear (or Master cyl piston area) compared to the driven gear (total caliper piston area) the greater the torque amplification of the gears or hydraulic squeezing amplification of your hand pressure between the brake pads.

ducatilover

29th August 2012, 22:31

Ok that makes sense.

Yea but you have the weight and speed of a 600. My 125 would do 1/3 the speed and probably weigh 1/2 as much. I've only got 200kg wet :bleh:
And I don't ride that fast

The piston on a dual caliper master cylinder is a bigger diameter (area) than on a single caliper master cylinder unit.

If you use a dual caliper master cylinder on a single caliper because of the laws of hydraulics it is likely to feel hard and wooden and have less breaking effect for the amount of squeeze you apply at the handle bar.

Master cylinder piston to caliper piston size is like gear ratios the smaller the driving gear (or Master cyl piston area) compared to the driven gear (total caliper piston area) the greater the torque amplification of the gears or hydraulic squeezing amplification of your hand pressure between the brake pads.

I am very much aware of the theory/physics. But I'm very, very familiar with ZZR brakes. The set that's on mine now had 6 seized pistons out of a total eight, effectively making it a dual caliper master running a smaller twin piston unit and from what that was like, I'd be willing to say it'll perform okay solely because the master is not a big ginormous grunty one,

There's a reason people throw the calipers/master way from them
Thankfully mine work pretty well, but mine's also 200kg wet.

F5 Dave

30th August 2012, 10:15

. . .Can you explain why a smaller bore on the master cylinder would work better? I'm still trying to learn all this stuff
. . .
Fred has it mostly covered, but think of it as 'leverage'.

The reason a bigger disc works well is there is more leverage on the wheel, a tiny disc has considerably less.

Similarly the lever ratio of a drum brake, the longer lever at the hand & at the drum will have more 'advantage'. Only trade off is that you need to move the lever longer, but it is much easier, just as a longer ratchet handle undoing a bolt is easier.

Hydraulic system is same principle. A larger ratio (so small lever piston to big calliper piston area) will give huge 'advantage'. the trade off is more lever travel.

This is where people get it wrong. They know a knackered line feels soggy & mistake the travel for weak. Too big a master cylinder makes the ratio less & thus feels wooden. But you have to use more pressure to do the same work. If the brake is powerful enough it can still lock the wheel of course.

Somewhere in the middle there is a sweet-spot of ample power & enough travel for 'feel' but not too much so it comes to the bar.

I like to minimise air in the system, maximise rigidity (braided helps here) & maximise lever travel (some master cylinders need a lever mod to get a another cm travel + adjust so only 1mm clearance, yet still fit a human hand). Then you can run a smaller cylinder than often possible.

F5 Dave

30th August 2012, 10:24

RG50 brakes aren't up to it on a faster bucket on a faster track. A good mod is to fit a NZ250 disc if you can find one. It has the same bolt pattern as an RG50 and the same offset. Then you just need to extend the caliper mounting plate. I still found the Vesrah redback pads overheated and cracked all over and lost chunks. The red paint also got scorched off at places like Wanganui. Even the bigger disc turned blue but at least it kept working.
. . .

Those redbacks (NR5) aren't available any longer, but where the only pad that worked on the RG50 discs & were great. But as you found out you could over stress them away from Kart tracks.