Brake Rotors - Wrist Twisters
 1Likes
  • 1 Post By mcromo44
 
Thread Tools Display Modes
post #1 of 14 Old 11-30-2019, 12:06 AM Thread Starter
Tesserarius
 
nathanktm's Avatar
 
Join Date: Oct 2013
Location: Floral Park
Posts: 625
Rep Power: 1
 

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 6

Brake Rotors

My rotors are all beyond the point where they should have been replaced. It's a struggle to remove calipers because of how ridged they are. I don't understand the differences between cheap and expensive rotors.

My question; What exactly is the science behind good and bad brake rotors?

I struggle to see what the difference is between a good and bad rotor. All the research I can find is about automotive brake rotors.
Essentially, drilled rotors really are more aesthetic than anything else, but do provide extra venting. Slotted helps expel brake dust and gas and possibly to bite into the pads.

For motorcycle rotors, I see that galfer's wave rotors "Keeps the brake system cooler by allowing air to pass over every point of a brake pad surface." Mr. galfer says they have better bite while keeping rotors cooler. Yet, you very rarely see them as stock on any performance oriented motorcycle, nor in any race setting. They do look really cool though.

Basically, I want some snazzy looking brakes, but I also don't wanna break the bank or lose any braking performance, and gaining performance would be nice. What blows me away is that even cheaper brake rotors are AT LEAST 200 bucks a POP, OEM is like 300 each from what I'm seeing.

Maybe LDH would know these answers as he actually probably sees what rotors work and what don't all the time, but I for sure have no clue what the difference would be between 200 dollar chinese ebay rotors, 400 dollar EBC replacement rotors, and 600 dollar galfer or OEM rotors.

nathanktm is online now  
Sponsored Links
Advertisement
 
post #2 of 14 Old 11-30-2019, 03:37 AM
Pilus Posterior
 
Join Date: Mar 2013
Location: Sacramento
Posts: 2,162
Rep Power: 1
 
I was shocked at the price a few months back when I was going to replace mine. I went metal to metal one day and stopped riding, got replacement pads (NON OEM) and they made awful noise. I replace them with OEM ones and took the rotors off the rim. I sat the rotor on a sheet of plywood and ran a drill based "paint remover" wheel on them. It looks like an ultra stiff brillo pad. I worked the heck out of the rotors and they came out pretty nice.

I measured them several times and I'm still well within spec.

This was discussed at length about March of this year, IIRC, LDH said the wavy rotors were crap. Most said that OEM brakes were actually very good, that's why I reworked mine.

I rebuilt the whole front end about a month or two ago... New tire, fork seals, oil, brake pads, brake fluid upgrade to DOT 4 and drained. Pretty much everything but the wheel bearings. If you take the rotors off, you can get to the back side with the surface pad.

It looks like this, but has a rubber backing pad. I spent quite a bit of time getting all the marks off the disks. 4 sides total, takes a good while. Then seating the new pads took a bit as they felt funny at first.

https://www.lowes.com/pd/3M-Paint-an...B&gclsrc=aw.ds

IDK about the groves/holes and cooling, I just trust so many people saying that OEM brakes on the 919 are great. I think I'd spend the money on a fork gold valve upgrade or a rear shock or PC III or something like that.

KarlJay is offline  
post #3 of 14 Old 12-02-2019, 08:58 AM
(Quintus) Pilus Prior
 
badmoon692008's Avatar
 
Join Date: May 2013
Location: Neenah, WI
Posts: 2,222
Rep Power: 1
 

Awards Showcase
Extraordinary Ride 
Total Awards: 1

Measure your rotor thickness and runout if you have the capability. I'd guess that they're well within spec still unless you have hundreds of thousands of miles or have misused/mistreated them in some way. The smartest thing would be to rehab and use your stock rotors, beyond that, you're just throwing money at something. It sounds like you're looking for looks as much as anything, and for street braking on a 919 you'll likely never have problems with the wave rotors and you'll get the cooler look you're going for.

Love is the feeling you get when you like something as much as your motorcycle - Hunter S. Thompson
I just mı̸̸̸̸̸̸̸̸̸̸̸̸̸̸̸̸̨ade you wipe your screen.
-2009 Suzuki GSX-R 750 Race Bike
-2007 Honda 919
-1995 Nighthawk 750 (Tboned)
-1983 KZ 440 (Sold)
badmoon692008 is offline  
 
post #4 of 14 Old 12-02-2019, 07:17 PM
Old, Bold rider
 
robtharalson's Avatar
 
Join Date: Jan 2007
Location: Aurora, Colorado
Posts: 2,356
Rep Power: 1
 
Garage

Awards Showcase
Donation Veteran Community Leadership 
Total Awards: 3

There is a very good reason why motorcycle discs are drilled: originally the rotors were solid, and worked pretty well ... unless it's raining. In that case the water spins off the center of the rotor carrier(s) and onto the rotor(s), and when the brakes are applied the pads hydroplane for several revolutions, then as the rider tries to get some reduction in speed by squeezing harder on the lever the water is pushed out of the way and the brake locks up, usually resulting in a crash. No fun. The holes in more modern rotors are usually made to overlap slightly to make sure the pads are scanned completely to vent gases and water into them which then escapes as soon as the holes leave the contact surface of the pads. In this way there is a maximum amount of metal for the pads to grip.

Looking at the Galfer rotors it looks like there is about 30% less metal for the pads to bear against, resulting in less braking force for the same amount of pull at the lever (air is a lousy braking surface). This requires more pull which builds up heat in the rotors, eventually causing warpage and a significant decrease in braking power. In the real world they may look cool, but that's the only positive that can be applied to them.

As was said before you can take down the ridge with the careful use of a relatively fine grit sanding wheel on an angle grinder without cutting into the actual braking surface, that is as long as they are not to the minimum thickness.

Rob

If it has already been done, it is safe to assume it is possible to do it.
On the other hand, if it has not been done never assume it is impossible to do it.
------- Rob --------
robtharalson is offline  
post #5 of 14 Old 12-04-2019, 05:59 PM
Tirone
 
Join Date: Aug 2018
Posts: 11
Rep Power: 1
 
Best Source for Disk Brakes

If you have problems with your rotors, then you need to talk to these guys: https://truedisk.net/

Unquestionably, THE best source to solve your problems. Have used them extensively. You will not find better. A call or e-mail is free.

Best, MyCB919.

MyCB919 is offline  
post #6 of 14 Old 12-05-2019, 01:24 PM Thread Starter
Tesserarius
 
nathanktm's Avatar
 
Join Date: Oct 2013
Location: Floral Park
Posts: 625
Rep Power: 1
 

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 6

That's a nice site. I might have to try it, thanks.

nathanktm is online now  
post #7 of 14 Old 12-05-2019, 05:50 PM
Pilus Posterior
 
Join Date: Mar 2013
Location: Sacramento
Posts: 2,162
Rep Power: 1
 
Quote:
Originally Posted by MyCB919 View Post
If you have problems with your rotors, then you need to talk to these guys: https://truedisk.net/

Unquestionably, THE best source to solve your problems. Have used them extensively. You will not find better. A call or e-mail is free.

Best, MyCB919.
I never realized anyone would turn motorcycle rotors. I searched for it and everyone said "buy new ones" without considering the price.

How much does this guy charge? Used to be about $20/each to get something turned.

KarlJay is offline  
post #8 of 14 Old 12-05-2019, 08:15 PM
McTavish
 
mcromo44's Avatar
 
Join Date: Oct 2007
Location: Calgary
Posts: 5,655
Rep Power: 1
 
Quote:
Originally Posted by KarlJay View Post
I never realized anyone would turn motorcycle rotors. I searched for it and everyone said "buy new ones" without considering the price.

How much does this guy charge? Used to be about $20/each to get something turned.
The depicted rotors have not been turned.
The surface finish is clearly from grinding, and not turning.
It looks Blanchard ground.
Much superior and more suitable a process than turning, re disc brake rotors.

mcromo44 is offline  
post #9 of 14 Old 12-06-2019, 12:41 AM
Pilus Posterior
 
Join Date: Mar 2013
Location: Sacramento
Posts: 2,162
Rep Power: 1
 
Quote:
Originally Posted by mcromo44 View Post
The depicted rotors have not been turned.
The surface finish is clearly from grinding, and not turning.
It looks Blanchard ground.
Much superior and more suitable a process than turning, re disc brake rotors.
Didn't know anything about that process before now, I wonder how much they charge?

KarlJay is offline  
post #10 of 14 Old 12-06-2019, 09:17 AM
McTavish
 
mcromo44's Avatar
 
Join Date: Oct 2007
Location: Calgary
Posts: 5,655
Rep Power: 1
 
Quote:
Originally Posted by KarlJay View Post
Didn't know anything about that process before now, I wonder how much they charge?
$45 per rigid rotor, +5 for floating rotors.
Going by info found in the link that is.
For good work of that nature, the price is very good and definitely an indication of having a volume based system of work and order handling.

mcromo44 is offline  
post #11 of 14 Old 12-06-2019, 09:28 AM
McTavish
 
mcromo44's Avatar
 
Join Date: Oct 2007
Location: Calgary
Posts: 5,655
Rep Power: 1
 
Quote:
Originally Posted by KarlJay View Post
Didn't know anything about that process before now, I wonder how much they charge?
Blanchard grinding stems from Blanchard Machine Co's invention of the Blanchard Grinder over 100 years ago.
It was a brilliant invention that offered fast grinding that was good enough for the actual application, without having to instead use Precision Grinding which was pokey slow in comparison, and unless the application needed true Precision Grinding, provided machining accuracy overkill.

I'm not current re engine work of today, but back in the 60s and 70s, race heads and block head decks would be Blanchard Ground after having been milled.
My assumption is that gasket-less head/block engine designs would need precision grinding.

Fascinating stuff, eh?
Islandboy likes this.

mcromo44 is offline  
post #12 of 14 Old 12-06-2019, 12:22 PM
"Whose ABBA ZABBA?"
 
Bigdaa's Avatar
 
Join Date: Jan 2006
Location: Goleta, California
Posts: 17,128
Rep Power: 1
 
I picked up an aftermarket rotor for my KLR rear for $69.
It was purely garbage in quality and material. I ended up using it as a target.
Bought one off a stacked KLR and got a free caliper to boot.

ďIn my opinion, the M1 rifle is the greatest battle implement ever devised.Ē
General George S. Patton
Bigdaa is offline  
post #13 of 14 Old 12-07-2019, 12:26 PM Thread Starter
Tesserarius
 
nathanktm's Avatar
 
Join Date: Oct 2013
Location: Floral Park
Posts: 625
Rep Power: 1
 

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 6

I checked and it would seem that I wouldn't be able to resurface my rotors. The fronts are at 3.25mm minimum thickness (3.5mm service limit) and the rear is at 4.0mm, which is also the service limit.

nathanktm is online now  
post #14 of 14 Old 12-07-2019, 01:15 PM
919 Rider
 
Islandboy's Avatar
 
Join Date: Dec 2016
Location: Flinders island
Posts: 2,213
Rep Power: 1
 
I'm thinking of buying these, for spares.Tourmax. Made in Japan. Price is right.
Keep in mind they are stainless.
I've no idea what these are like. I've used Tourmax spare parts before and haven't had an issue.

https://rover.ebay.com/rover/0/0/0?m...2F113760016060

Islandboy is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Wrist Twisters forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome