Front Rotor Runout

[Ryanthegreat1]

Getting tired of the terrible front brake lever feel and in consistent bite point I decided to check the runout on the front rotor. I thought it might be runout related because I could pump the lever up to a nice hard brake but as soon as the wheel rotated the lever would be mush again.

Got out the measuring tools and put the bike on the stands to find I had 0.010" total runout!

I could not find a spec in the service manual for allowable runout so I did the best I could. Used a 30" piece of 2x4 as a soft pry bar and worked the runout down to 0.0015"

Have to say this is the best the front brake has ever felt even since new. I have a track day tomorrow to go put some abuse on the rotor. If rotor warps again I will be in the market for a floater.

 

[Ryanthegreat1]

Well the first 2-3 braking points were amazing. Once the rotor build of some heat it all went pear shaped. By the end of a 20 minute session the rotor looked like a piece of bacon and the lever would go clear to the bar.

In the pits while everything was hot you could see daylight between the rotor and pads. The gap could be squeezed out but as soon as the pressure was release the daylight gap would return.

Time for one of them swanky 320mm floating rotors.

 

[Maddog Reynolds]

My 2015 road bike's disc did that. I hadn't been heavy on the brakes at all, but I had to brake to walking speed from 70 for sheep and it was slightly warped ever since--not enough to push the pads back badly, but just enough to feel uneven braking when I used them gently. I bought the Powerparts 320mm disc (made by Galfer) and it's much nicer. I've since hammered it pretty hard a few times and it's perfect. And it's a bit lighter, with all those holes

 

[Ryanthegreat1]

That is good to hear! I have one on order from Hard Racing. Can't wait to have confident braking again.

 

[isaac_]

And let me tell you... it's possible to Endo this bike on a 320mm rotor + stock master cylinder. [emoji23] emergency braking in a race is how I found out.


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[Ryanthegreat1]

Nice to know it has the power!

I need something that is consistent and some what easy to modulate.

The stock solid rotor was a challenge to ride once it went all bacon on me.

 

[Kootenanny]

And let me tell you... it's possible to Endo this bike on a 320mm rotor + stock master cylinder. [emoji23] emergency braking in a race is how I found out.

Yeah, that's nice to know. Gonna have to look into that--got EBC HH pads on order right now (to run with the stock rotor), but I like the idea of the 320mm rotor.

Used to practice endos on my Buell, because the 'Bolt will definitely lift the back end off the ground during emergency braking. Never felt out of control, but...felt I should know how it feels for when it does happen. BTW, the Firebolt also only has a single front rotor (but it's an inside-out, perimeter mounted ZTL brake, so doesn't really compare...).

 

[Ryanthegreat1]

The EBC HH pads will 1 finger stoppie with the stock rotor until you warp it. Have to turn off the ABS to get a proper stoppie.

Those HH pads were also VERY loud until they fully bedded in.

 

[green_bread]

The EBC HH pads will 1 finger stoppie with the stock rotor until you warp it. Have to turn off the ABS to get a proper stoppie.

Those HH pads were also VERY loud until they fully bedded in.

Can confirm both of these statements. My pads gave a nice loud "HERRRRRRRRR" when I was coming to a stop for a while. Its fun to try to imitate the sound with your mouth for the people around you in pit lane. Haha!

Not a one finger stoppie, but very effortless with two fingers on the lever:

 

[Kootenanny]

The EBC HH pads will 1 finger stoppie with the stock rotor until you warp it. Have to turn off the ABS to get a proper stoppie.

Yeah, keep forgetting about the ABS. I've never owned a bike with ABS before; so far, it seems seamless; I'll probably leave it alone unless anyone can give me a good reason to bypass it. (Also, there's a way to turn it off temporarily, right?)

 

[Ryanthegreat1]

Yup, there is a hidden button on the cluster you can hold before you start the bike that will turn off ABS.

For a street bike I have not found a compelling reason to remove the ABS. Properly bled you can get a nice firm lever if your rotor is not bent.

 

[Kootenanny]

Yup, there is a hidden button on the cluster you can hold before you start the bike that will turn off ABS.

For a street bike I have not found a compelling reason to remove the ABS. Properly bled you can get a nice firm lever if your rotor is not bent.

Yes, so far it feels pretty good--I haven't really noticed the ABS. Brakes are perhaps a bit weak, but the EBC pads should help with that.