squirrel_hunter Posted May 16, 2020 Report Share Posted May 16, 2020 So while we're all still lockedup I don't have a lot to do on the my YSR project bike as with the workshop out of action I can't play with the big machines to finish the rearsets I'm making so I've reduced myself to playing with Fusion360 in my spare time. But the way I've set my desk up means that I keep seeing the front end of the YSR and it got me thinking... Basically the only thing that I've not really modified is the front brake setup, yes it will have a HEL line, and a full rebuild, but its still running the OEM master cylinder and single piston sliding front caliper. So having recently completed a Brembo conversion on the Grom I wondered what could be done along those lines with the YSR. All that was needed on the Grom was a new caliper, a longer line, and a conversion bracket for mounting surely something similar for the YSR would be possible? Now I'm no engineer but I've been reading build threads for some time and picked up on a few things. For the caliper all I need to do is pick one and ensure that it mounts in the middle of the disc, that the pad area should match up, and there is clearance for anything around, then all I need to check is that the radius of the caliper matches with the disc via the conversion bracket, and one other thing that I'll come back to. The first question to answer though is what caliper to use. And my first thought was what about the same as the Grom a Brembo P2 34, it works well for that bike, why wouldn't it here. Now I could have taken one off the Grom but that would be a pain, thankfully I have what I believe is an OEM caliper that came with an interesting swingarm I'm intending for another project so I took that off and offered it up to the YSR. Though as a side note I'll not be using this caliper as it appear to have had some modification of sorts. Can't tell if that grind is intentional or not, but I'd say thats scrap. Anyway using a bit of card I've drawn a rough pattern of what the mount could look like. With the caliper lined up in the middle of the disc there looks to be clearance around, the closest object being the hub bolts at the back but with some rough measurements it looks to have about 3mm clearance. The pad area looks roughly the same as the discs swept area and I think I can get a good point of contact by pivoting the caliper via the bracket. The next thing for me to do is to make a mockup bracket but that will have to wait for the workshop to reopen so while I wait I thought I'd throw the idea out to the hive mind to see if there is anything I'm missing or should be considering? Now the only other think I can think off that I'm yet to address is the ratios. I know that the master cylinder and the caliper need to have some sort of match, but I don't know what that is, nor do I know what the OEM ratios are or even the Brembo. So any idea how I would find out or calculate this? And then with those numbers, what would good look like? Quote Link to comment Share on other sites More sharing options...
Evilchicken0 Posted May 16, 2020 Report Share Posted May 16, 2020 The caliper and pad look ok (to me anyway). Usually the bleed nipple is at the top of the caliper. For the ratio look at the bike that used the caliper, it looks like a rear and look at the master. Or contact Mode Performance, they're brembo specialists and might help. Quote Link to comment Share on other sites More sharing options...
squirrel_hunter Posted May 17, 2020 Author Report Share Posted May 17, 2020 Yes, nipple to the top. The P2 having the ability swap nipple and banjo positions is something I didn't know when I first did the conversion on my Grom, but is very useful and is one of the reasons I'm looking at this caliper. I'll do some more research to find the m/c size, I've got the original dissembled so taking measurements won't be a problem hopefully it will be close to 13mm then. But as an idea it looks like I'm not far off the mark, the mockup is where the next action will be... 2 Quote Link to comment Share on other sites More sharing options...
TLRS Posted May 17, 2020 Report Share Posted May 17, 2020 That bracket on the fork looks positively weedy.. There ought to be info about what sort of ratio you would want to aim for. Caliper piston size / mcil piston size / leverage ratio. 1 Quote Link to comment Share on other sites More sharing options...
Mark/Foggy Posted May 17, 2020 Report Share Posted May 17, 2020 Is a very light bike, If you make that plate out of aluminium plate and is all bolted together will work fine. I'd be choosing a piece of 8mm plate, you need to think about how is all going to line up. I say 8mm minimum because it may help if you tap threads in the plate because you cannot get a nut on the back. Consider tapping the plate and fitting a half depth nut if you can. Material choice ..... well I'd start by looking for 7075 Aluminium, but seems to be hard to find just now, maybe a trip from China. 6082 should be easy enough to find on That site. Both of these materials are strong enough to do the job and if you need a tread tapped in them it will be easy and secure. When you have a plate mounted to the fork, using shims to adjust the run of the disc in the centre of the caliper is fine, or even a big thick stand off spacer if you need to. Quote Link to comment Share on other sites More sharing options...
rossm Posted May 18, 2020 Report Share Posted May 18, 2020 Ratios to your hearts content here https://www.vintagebrake.com/mastercylinder.htm Quote Link to comment Share on other sites More sharing options...
squirrel_hunter Posted May 18, 2020 Author Report Share Posted May 18, 2020 I was thinking 10mm 6082 for two reasons, firstly I think I will need to take it down 1/2mm at the fork bracket side to line it all up so should still have plenty of material to tap a thread into, and secondly I think I have some left over in the workshop. I was intending to leave the disc in the standard position and use the bracket to line things up, but thats another consideration, will have to see what happens once I get a test bracket cobbled together... And that link to the ratio chart is great, thanks. 1 Quote Link to comment Share on other sites More sharing options...
squirrel_hunter Posted May 25, 2020 Author Report Share Posted May 25, 2020 As an update I fabricobbled a prototype bracket as I found some 10mm bar I didn't remember I had here. Did the caliper mount first as I know the measurements for that and then cut out a hole for the body. Then I took the bracket back to the bike to line up the mounting holes. This gave me an interesting problem to solve, how to offset the caliper body from the disc equally so I could mark the holes. I checked against my Groms conversion and there was 3 - 4 mm distance between the disc and the top of the caliper body so using some zipties taped to the edge of the disc to make up an offset I could rest the caliper on them and then mark the hole centres for the final mount. And it all looks about right. However the centre line of the caliper body is not in line with the centre of the disc, its not the easiest thing to measure but sticking a washer behind the bracket makes it look good. So that means I need to take the caliper mount side down by about 2.5mm, that shouldn't be to difficult to do once I get back on the mill. But its not pretty, the bracket needs a bit of improvement which I'll fix in the CAD as the lower mount doesn't have much meat, however considering I only have a Aldi special pillar drill, a 64mm hole saw, and a grinding wheel on a Dremel here I'm pleased. I'll order some wider plate ready for when I can make a proper one and get on to working out if the stock master cylinder is going to work with this new caliper. 2 Quote Link to comment Share on other sites More sharing options...
TLRS Posted May 25, 2020 Report Share Posted May 25, 2020 Looking pretty good considering the diy factor! If it’s 10mm thick the thing looks meaty enough to me. They use plates like these for rear suspension brackets on much heavier bikes.. Quote Link to comment Share on other sites More sharing options...
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