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Author Topic: YZ front brake caliper on the rear of a 250R DIY  (Read 2350 times)

Offline oilinthegas

YZ front brake caliper on the rear of a 250R DIY
« on: July 09, 2014, 02:29:18 AM »
I was doing some maintenance the other week and found some issues with my original 86 rear brake caliper. A used one on ebay goes for quite a bit and I remembered reading a while ago that a 2000ish YZ caliper was a simple swap. It is still a 2 piston caliper but itís a little smaller because it doesnít have an e-brake built into it. I learned itís not a direct bolt on but it isnít too hard either as long as you have a couple hours and some tools. I ordered a used YZ125 front nissin caliper and bracket but any 250 400 426 should work. I immediately found that the bracket would not fit between the 250R brake stay and rotor.


I did some measuring and made a quick drawing of some of the modifications I would have to make. The yz bracket would need to be machined so that it would fit closer to the brake stay and sit where it should centered over the brake rotor. The CTC distance on the yz caliper bracket was 102mm whereas the original 250r was 107mm, so I would have to drill a new hole on the brake stay 5mm closer to the front mount.



I ended up milling about .118Ē (3mm) off the face of the treaded mounting holes highlighted with red marker. You could do this with a grinder or belt sander if you are very carefull and measure again and again until you get your desired thickness.



Next I plunged a 5/16 end mill 5mm from the original rear bolt hole on the brake stay, 5/16 is almost 8mm so if you do it right your M8 bolt fits very nice. (you could use a drill bit or maybe a dremel or something if you needed to. I also made a small relief cut on the brake stay to make sure there was not going to be any interference with the caliper.

After the cutting I just lubed the caliper and installed it with new yz125 pads. All together it was less than 30 bucks and I think it looks a bit better.




Offline JesseA420

YZ front brake caliper on the rear of a 250R DIY
« Reply #1 on: July 09, 2014, 09:34:01 AM »
that is great mod for the price!!
Quote from: Hawaiiysr;66760
Yup i sucked the head. taste like dirt.

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Offline pinned250r

YZ front brake caliper on the rear of a 250R DIY
« Reply #2 on: July 09, 2014, 10:00:55 AM »
Drill and a little shaving. I like it.

Thanks for the great write up, really detailed and easy to follow. Thanks again!
I ride PINNED! Therefore, no bdt in this household.

Offline mx250r91

YZ front brake caliper on the rear of a 250R DIY
« Reply #3 on: July 09, 2014, 12:29:55 PM »
Very cool! I like the slimmer caliper, that should help with clearance between the silencer at max travel.

Offline enri330r

YZ front brake caliper on the rear of a 250R DIY
« Reply #4 on: July 09, 2014, 08:23:40 PM »
very good mod looks great! thanks for sharing and taking the work!