Fancy New caliper doesn't fit

[Tom]

So anyway i got that "great deal on the 4 piston "Braking" caliper on ebay only to get my bike back from the mechanic, try to fit the caliper . . . and of course it doesn't fit.

The mounting holes line up perfectly, but. . . the pads rub on the float pins and the disc does not line up with the centre of the caliper.

The pads rubbing is ok, i ground off the inside of the pad so it doesn't hit any more. But now i have to sort how to get the disc to line up. I can't move the caliper in cause it hits the spokes, so my options are to space the disc out from the hub with washers by anout 2mm(sounds dodgy) OR . . . there are 2 metal plates that go between the pads and the pistons, if i put both plates between the outer pad and pistons and no plate between the inner pad and piston i might be able to line it up. Is this too dodgy?

Should i space the disc off the hub OR use the plates to move the pads in the caliper OR junk the whole idea and buy a new one?

Any help is appreciated.

Oh yeah, here's the first photo of the new toy (pleanty of work still to be done though)

http://img5.picsplace.to/img5/9/IMGP0749.JPG

[Flash]

The bikes look like the shit!!

I have seen to many brake failures in my time on Dh mtbikes because of silly things like this. So I would be against it, the further out the disc is the more load is on the bolts that hold it and spacing the pads will probably cause wear on the piston and the bore on the one side because there is a lot more leverage on the one pad that is coming out further, but Muzz and or Neil my have a bit better idea on a motard

[Wobbly]

If you can space the pads apart the right distance and still have it functional, that might be good enough, but I'd just check that you're not going to be in danger of popping one of the side's pistons out when your pads wear a bit. Maybe try just clamping the pistons on the disc with no pads, or using a couple of bits of scrap wood trimmed to the minimum worn pad thickness.

The other alternative is to space the disc out, but just using spacers sounds a bit dodgy. You're effectively increasing the leverage point of force on to the bolts that secure the disc to the hub, and there's a lot of shearing force transmitted into them, so I'd be extremely suspect of doing anything like that.

The alternative would be to locate an offset caliper carrier that matches the hub diameter/bolt pattern and the button arrangement on the disc, as long as it doesn't cause the disc to foul the fork leg. I'm guessing that the matching Braking disc for this caliper is that sort of arrangement, but whether the button pattern on one of those matches the one on your existing disc or not is a good question. You may be able to find a worn out one somewhere, but its not the normal sort of thing you see crop up on ebay very often.

So I reckon your best bet is trying to work out whether offsetting the pad location will work reliably or not or, failing that, find yourself a matching Braking disc and hock your existing disc on ebay or similar. Pain I know, but maybe the best bet.

Bike is looking good though :up:

[shane]

why dont you machine it down where it bolts on thats what i did to mine ,i filled the face down 1mm which moved it closer to the fork ,much better than spacing the disk over .....

[banshee]

Rod from awsome disc in ringwood top bloke could probably off set your disc carrier or something like that im sure if you had some measurement off disc or just a heap of measurement in that general area he could do something and he is very cheap and does some wicked work (mention VSMR for him to realy look after you)

[Tom]

Thanks for the help, i think i'll try to space the pads out this weekend to see if it works. If that doesn't work i guess i'll make up a spacer for the disc (not washers, but a disc that matches the hub)I'm not giving up on this one yet.

One more question. . . being a 4 piston caliper, with 2 pistons on each side, will the pistons naturally align themselves (a little bit) with the disc? i.e. will the pistons on one side just push in further than the ones one the other side until they seat on the disc?

Also, can you use a master cylinder from a sports bike (i.e. 2 front calipers like a CBR or GSXR) on a motard with just one caliper? or do you need one designed for a single caliper bike? I noticed that the brembo radial cylinders for sports bikes are 19x21mm cylinders and the motard ones are 16x18mm.

It's pretty cheap to get second hand master cylinders from bike wreckers for CBR600's and GSXR's and sounds like a better deal than spending a fortune on a brembo set up.

[shane]

the supermoto Brembo radial master is 13 x 13

[Wobbly]

Don't go too big on master cylinder, but yep you can get 13mm road bike master cylinders from wreckers pretty cheap. I'm waiting on a brembo one from an aprilia rs125 myself, which cost me 20 quid from the UK. I had a play with a 16mm m/c on the standard caliper and it was crap, due to the m/c having w-a-y too little leverage ratio on the lever compared to the fluid volume it was trying to pump...

[Tom]

The stock XR650 master cylinder is 1/2 inch, so what is the advantage of going to a 13mm one?

i though the idea was to get a bigger cylinder to go with the bigger caliper. I would like to get a much firmer feel on the lever, so i'm getting a braided line when i get this caliper working, should i just stay with the stock master with braided line and 4 piston caliper or is there an advantage to a 13mm or 16mm sports bike cylinder?

[Muzzard]

I'm with Shane on the flycutting of the mount to align the disc rather than space pads or the disc from the hub...
Tom bike looks real nice mate,
;) Good job all round...

[shane]

its the feel a 13x13 radial brembo is very plush you can do a race using only one finger you dont get any arm pump ,the stock ones feel like wood little feel and lots of arm pump ,comes down to want you are using the bike for and how much cash you want to spend ,also the crf master was way to small for the gp brembo caliper you could not get any leaver when trying to bleed it up

[Tom]

Can't cut the mount, as the caliper needs to go the other direction (towards the wheel, not away from it) I tried putting spacers between the caliper and the mount to move it towards the wheel. This worked in getting the disc to line up. . . but then the spokes hit the caliper. So i'm back to moving either the pads or the disc (or grinding the back out of the caliper so the spokes don't hit. . . but that sounds really dodgy!)

[shane]

why dont you do what you just said ,then offset the wheel to get clearense you can also grind a little off the back of your caliper you say it sound dogy but take a look at some pics of the factory bikes if its good enough for them its good enough for us mortals

[Tom]

I'll look into it, but where it's grinding is right on the back of the pistons, and i'm sure they've made that bit as thin as possible already to not hit the spokes when it's mounted normally. If i grind a bit off it (need to take off atleast 2mm) i'm pretty sure i'll end up in the piston chamber.

I think that the best solution would be to space out the disc, but it's also the hardest. Worst case scenario, i'll sell it to someone with a CRF450(pretty sure that's what it's made for) and buy myself one that fits properly.

[banshee]

You are in sydney just find someone who makes discs and get them to off set it how ever many mm it needs it will look a heap better and i would rather that than washers and i dont think it would cost that much.