rotor options
 

hey guys i have been searching around on the forum and through this https://docs.google.com/viewer?a=v&q...oLpGsWdbG6HulA

i have a RC-51 front brake upgrade and i was told that the stock rotors dont fully engage the brake pad surface. first off is this true. Second what options do i have for replacements? i assume that i am looking for a 320mm rotor opposed to the sh's 296

i know i cant just buy a set of RC-51 rotors as the offset is different, and from the chart it looks like the cbr900 rotors are the same specs but the "oversize" rotors have a larger bore diameter.

i keep thinking about just doing a RC-51 front end swap... and be done with it but i just upgraded internals and brakes last year

choices....

You can't just swap on a set of 320mm rotors. The bolt pattern is different for one, and the calipers wouldn't line up on the stock hawk forks even if the rotors could be mounted.

who told you the pad surface doesn't line up??? New one for me?

I've got a CBR929 and the hawk, (929 has the same rotors as the RC-51), and there's no way those would fit on the stock front end/ wheel.

right thats what i said in the OP, i know i cant just slap a larger set on but i know there are options...

im not sure where i read it but i think it was somewhere in the bolt on brake mod thread

929 and RC51 rotors have the same bolt pattern and offset but are a different diameter (929 and 954 had 330mm whereas the RC51 had 320mm).....

Hmmmm, so all I would need to do is machine an adapter to move the caliper farther out if I used a set of EBC 929 rotors :nibble:

That's what I was saying with the BrakeTeck caliper brackets. Of course I'm not sure cause I don't have the rotors. I know I need the smaller hub diameter and bolt pattern so offset rmains the last issue.

The RC calipers are made for a larger rotor... That means that the pads have a wider arch... Larger rotor = larger circle = less sharp curve on the pad... It's that simple... So the only way to get a full alignment, are with larger rotors... And the only way to get that is by moving the calipers out to allow it... It can be done with adapters, but other than that it's impossible on stock forklegs... Doesn't matter what rotors you swap, they need to be larger diameter to get full alignment, and that's impossible...

great tweety thats what i needed, so it does sound like there are brake caliper adapters out there, then i can work on offset and alignment issues with the caliper mounting and away we go

Sure there are... And they are about as plentiful as other performance upgrades for the VTR... Unobtanium... Not to be found, unless you have a lot of luck... There was a pair sold a while ago on the forum... But that's about it...

But the "issue" you are trying to adress, is a misalignment of about 4-5 millimeters on the ends of the pads... Something that doesn't affect performance of the calipers, pads or rotors in the least... So why try to fit larger rotors on the stock forks to fix it? It seems a bit roundabout and counterproductive, since the forks are kind of dated tech... You have obviously upgraded the brakes by swapping in better calipers... If you swap in, or already have done so, new brake lines and master cylinder, you are already at the peak performance for the brakes... Bigger rotors aren't going to give you any measurable or percievable performance boost...

Infact, it's going to reduce performance with more rotating mass, so unless you match it to a set of nice USD forks, it seems fairly pointless...

good advice, i have the full RC brake upgrade and stainless galfer lines, ill just leave it how it is, i barely got to ride it with the new springs and fresh fluid this season... damn MN cold

Thread revival!!!

Hey Tweety, hoping you'll see this reply and be able to answer.

I don't understand your reply about bigger rotors not being beneficial. Let's establish a comparison and maybe you can help me understand:

Let's say we have a Superhawk with all the usual brake upgrades done. Calipers, pads, master cylinder, ss brake lines, etc. It brakes wonderfully, has good modulation and feel.

Now let's say you remove the stock size rotors, and install 320mm rotors with caliper adapter plates without changing anything else.

In my mind this is the same type of "big brake upgrade" offered in the car world. Big rotors and caliper adapter plates.

From everything i understand the increase in rotor diameter is like using a longer ratchet or wrench. The further out from the hub center that braking can be applied, the more stopping torque is applied to the wheel. Correct?

All this discussion is leading toward wondering whether swapping on 320 or 330mm rotors and caliper brackets would be a simple "big brake upgrade" for our Superhawks :)

James

Tweet said: "Infact, it's going to reduce performance with more rotating mass, so unless you match it to a set of nice USD forks, it seems fairly pointless..."

You will increase the unsprung weight and on the wheel (rotating mass)itself, which has more negative effects than adding the same weight to the chassis.

Thats a performance trade off, the two address different performance areas.
Unsprung or rotating weight added by way of a larger rotor does NOT negate the better braking effect from the larger rotor. the larger rotor DOES negatively affect other performs areas though, thus a performance trade off.

If the larger rotors weighed so much that the larger diameter rotor and its increase in braking performance was not realized due to the overall increase in mass.. THEN the larger rotors would be pointless.

Right i get all that... Not my question though.

Question is: it seems as if larger rotors were being discounted as a useless upgrade, when in fact on cars a "big brake kit" is known to show substantial gains in braking performance. It seemed as if there was a contrary opinion in this thread on the use of a larger rotor diameter as an effective upgrade.

I just wanted to talk about that aspect of the equation, not the unsprung weight increase.

James

Larger rotors are not the only option for better braking. I ran F4i calipers, SRJL pads and a radial MC from a Ducati Monster 1100 (and braided lines) and I assure you you'd be hard pressed to find a significantly better set-up without spending serious money (though for slightly more money, Zcoo pads and a radial Galespeed MC are a slight notch above). Of course, if you need more than being able to lock up the front at 75 mph with one finger, keep looking......

Yep, that makes sense, i've been reading a lot of the threads on leverage ratios and things.

Thanks for the response!

James

I think the main reason that the parts for larger brakes are discontinued are that the bike is old, with old tech... And the stock brakes aren't half bad, swapping to another caliper/master on the stock rotor makes them pretty good even...

Plain and simple, there were very few people forking out the money for the larger rotors back then, and they aren't made any longer, so the prices if you find them reflect that, not real world performance...

So because of that, you really get more bang for your buck by changing the fork, giving you better stability (an USD fork is less prone to flexing), better control (more adjustable), and more selection of calipers and pads to match the fork...

I'm not saying you aren't going to gain anything with a bigger rotor, but the money and fiddling will be about the same as a USD fork, and you're still stuck with all of the stock forks shortcomings...

In my case, I managed to bottom it out once or twice on stock springs, and then got fed up trying to get it right with stiffer springs and not well matched valves... End result, I just got myself a better starting point for fiddling with an USD fork, and never looked back...

Not looking for larger rotors, just replacement over OEM

What's the best bang for the buck?

FYI - I did the 6 pot Gixxer exchange some years back - made small diff., but they're still on, so I'm just looking for newer, lighter & better rotor - mine seem ok after 54k, but looking for upgrade.

EBC?

Galfer?

From the small sample of feedback I have received, the chinese rotors on Ebay are not that bad. I'm not sure if Arashi (i think that is the name of the co that stamps them out) makes one for our bikes or not. But they are half the price of EBC which are probably made in China anyway. Correct me on this if I am wrong.

I am going the route that Tweety describes and am moving my money into a fireblade front end. They are kind of hard to find in good condition, but they are out there. You want big rotors? 330mm. Good for my "compensation" issue. :)