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2008 yz125 caliper deflection

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Did a lot of searching but haven't found the specific answer...

Wondering there is a stiffer caliper than what comes on the 08 yz125.

On a bench test there is a significant amount of caliper deflection that directly corresponds to lever travel.

You can see/measure the actual caliper cast body move.

I'm suspecting that the lighter weight caliper introduced in '08 has less material where it counts. (where caliper wraps to support indirect /inboard pad) Does anyone know of a stiffer bolt on caliper.

Just to save time, this is not a bleeding/air issue or a ballooning hose issue.

Proved out by: clamping the pistons directly to body with a vice = no sponginess,(caliper deflection taken out of the equation), THEN using a parallel machined block as dummy pads there is considerable caliper body deflection witnessed.

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There is deflection, for sure. BUT, I am not convinced its a real problem. If you run a pad with higher grip, the pressure needed for "grip" or friction, is less. This makes deflection less, by default. Thats the issue with Yamaha brakes in general. You can get the power, problem is you need both hands, a foot, and a penis or two pushing the lever to get the power.

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haha i have two penis' so that would be one way to skin the cat lol.

Seriuously I was thinking of going to high mu pads as a solution, and from the sounds of your advise it could be enough, I did not know the coefficient of friction of these yamaha pads was considered to be on the low side.

I will order some EBC high friction pads and see what I think.

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haha i have two penis'(i) so that would be one way to skin the cat lol.

Seriously I was thinking of going to high mu pads as a solution, and from the sounds of your advise it could be enough, I did not know the coefficient of friction of these yamaha pads was considered to be on the low side.

I will order some EBC high friction pads and see what I think.

I use one finger on the brake, but I mount my lever very far inboard for a lot of leverage (and travel), the pull does not require much force.

It's an ergomic problem, and I'm wasting travel via caliper deflection,I will try the high friction pads it may be enough to satisfy me. I like to race with one finger over the lever even as I modulate the throttle. In order to have the lever close enough to the grip I can't get ideal stopping force in emergancy situations.....

It's pretty amazing the amount of travel and lack of force in the spongy zone really made me think there was air until I proved it was caliper deflection. (i've already modded the M.C to minimize m.c piston travel to the resevoir feed port. I use set/stop screw (everyone should do this).

FYI people should also check that the pad backing plates are indeed flat as this can cause excessive take up travel. (pistons retract far because of warped pad backers)

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I dont know if the yam pads are low friction or not. I do know they suck compared to Honda cr pads...the best I've found so far. MX Josh told us the ktm pads were better yet, but needed mods to work.

Honestly there is no way we could make those stock calipers not flex, right?

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ha , hmm yes. of course there is always deflection, impossible to eliminate it.

In my usage less deflection would help. But there may be no easily fitted stiffer caliper options.

it's just amount of how much and if it is causing a problem in a particular situation. In my case it would be nice to reduce it and I know the 08 came equipped with lighter calipers... may be deflecting more than other calipers at a given clamping force.

in any case thanks for awarness that yamaha pads are not highly regarded, this is good news as better pads may make the setup acceptable.

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I run a 2008 CRF front brake (complete system) on my 2002 YZ250. On my 2010 YZ250 I have the complete OEM setup. I wouldn't say the CRF brakes are really a lot better if both systems are in new condition. Just switching to Honda pads is an upgrade, but once you do that, I don't think there's any advantage to swapping in the Honda parts.

The 2008+ YZ brakes are better as a system than the older YZ brakes for sure.

The older Yamaha caliper is bigger, so is the standard CR/CRF caliper. I think Yamaha only switched to save weight and took the opportunity to optimize the piston designs too.

I do the same trick to increase braking power, I move my brake M/C inboard about 1/8 to 1/4 inch farther than stock. I find that a small amount makes a noticable difference, while also protecting the lever in a crash. Although I don't have an issue with lever travel.

If you need more braking power, perhaps a larger rotor is the best solution for you. They make a big difference. If you upgrade to a 270mm rotor from the 250mm, you're adding 8% more mechanical advantage to the system. That's 8% more braking power without adding any lever travel. Braided stainless lines will also reduce your lever travel a small amount.

As for the caliper deflection, I'm sure every caliper has some. It's a neat topic for discussion, I always find the details and tech investigation very interesting.

If you really want to find the most rigid caliper put a pressure guage on the bleeder port and bring it up to a range of specific pressures while you use a dial indicator to measure the deflection at each of those pressures. Those data points will show a nice "deflection curve".

Keep in mind: at a given line pressure you will see different pad/rotor clamping pressure based on the diameter (area) of the pistons. Because of this, you'll have to factor that out by doing a little math if the piston diameters are different.

Ultimately you could compare each of the following calipers:

-KTM (Brembo)

-Honda CR (Nissin)

-YZ 2008+ and YZF 2007+ (Nissin)

-YZ 2007- and YZF 2006- (Nissin)

KTMs now are regarded as having the best brakes. Honda CR/CRF brakes are always great, and their pads are awesome.

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ha , hmm yes. of course there is always deflection, impossible to eliminate it.

In my usage less deflection would help. But there may be no easily fitted stiffer caliper options.

it's just amount of how much and if it is causing a problem in a particular situation. In my case it would be nice to reduce it and I know the 08 came equipped with lighter calipers... may be deflecting more than other calipers at a given clamping force.

in any case thanks for awarness that yamaha pads are not highly regarded, this is good news as better pads may make the setup acceptable.

As far as easily fitted solutions... you said it yourself. Yamaha put a lighter, probably flexier, caliper on in 08. Try putting a 2006-2007 caliper on.

I don't really get all the fuss about the Yamaha brakes. I have a 2006 YZ250 and 125 and a 2007 CRF450. To me, they all feel to have about the same stopping power. If anything, the Yamaha brakes seem a little firmer at the lever with a little more aggressive initial bite. The Honda feels just as strong but smoother.

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