Brake Rotors - Harley Forum

flathead512 · #1 07-23-2008, 05:31 PM

Any suggestions on how much free play should be in your brakes. When I spin the rear tire there is a slight drag the tire doesn't go all the way around. At one point the drag goes away. It sounds like maybe the rotor is warped from the heat?

Also the front brakes squeal when they are applied? Will better pads elimiate this problem

shovelmike · #2 07-23-2008, 07:09 PM

Good evening, Flathead. The freeplay in the brakes is very minimal, in fact there is no pad retraction mechanism....just what little lateral runout that exists pushes the pads back .001" or so. The result is a brake system which is inherently self adjusting, instant brake response when pressure is applied. The trade off is a small amount of drag which you are feeling when you rotate the wheel. It is not unusual to find a certain spot which drags a little more.
If you have enough disc runout to be problematic you will notice pulsing in the brake pedal or lever and a grab-release-grab action when coming to a stop.
Squealing is a common problem..often aggravated by road dirt as well as the various pad compounds being used in an effort to find a suitable replacement for asbestos which they are no longer allowed to use.

frisco-rigid · #3 07-24-2008, 01:42 AM

Shovel is sooo right-on he said it twice, yeah baby..

I have always strived for as little drag as possible and sometimes it's more than other times with the same set-up on diff days.. I don't know why..

To be absolutely sure you have done all that can be done you must be totally sure the bleeding is Perfect, the rotor is NOT warped, the wheel is perfectly aligned and the pedal has at least Minimal free-play..

Even a teensy amount of air in the lines can prevent total release.. Bleed with patience..

I have gotten brand new rotors with UN-acceptable run-out and like Mike said it pulsates..

I have used the rubber type of Backing Pads to prevent squealing and they work fine..

flathead512 · #4 07-24-2008, 07:37 PM

Have you heard anything good about the Lyndall Brake pads?

milindh · #5 07-24-2008, 11:36 PM

I'm using Lyndall pads on my FXR4. They claim to offer better braking power but it was hard to tell the difference from the old well seated HD pads and the new Lyndalls but as they have seated in I really do think they are a little stronger. The best things about the Lyndalls is that they don't squeal and don't leave the back pad dust. Good customer service too. Also Lyndall claims their pads don't wear the discs as much as the sintered metallics of the HD's since the Lyndalls don't have any metal in them. With the high cost of floating discs like on my FXR4 that can only be a good thing.

hotrodsporty · #6 07-25-2008, 08:14 PM

that seems anti productive to me, if they do not wear the disc as much, then do you still get as short as stopping distance?, after all the basic principle of brakes is friction, the less friction the less effictive....right...or am I thinking of this in the wrong frame of mind?

shovelmike · #7 07-25-2008, 08:23 PM

It is indeed friction that is involved in braking, and dissipation of the heat produced. I haven't seen any difference in braking effectiveness between metallic and non- metallic pads...supposedly the theory is that there could be less heat induced brake fade with metallic pads under extreme conditions.

frisco-rigid · #8 07-25-2008, 10:09 PM

The pads are not supposed to wear the disc/rotor, the pads are supposed to wear away on the rotor.. The rotor wears away eventually but it's the friction that stops you and the friction is the pads job..
The rotor material does make a diff though.. I get better braking outa Ductile Iron and Mild Steel rotors.. Worst outa Stainless Steel..

The high friction pads are like V-rated tires, they stick more creating more friction but leave some of their little bodies behind as sacrifice so you can keep living your Bourgeoisie lifestyle.. (don't ask, I just couldn't help myself)

If I remember right the High friction pads are the HH pads.. My fav..

milindh · #9 07-25-2008, 11:11 PM

I'm not really sure what the function of the metal particles in sintered pads is but they have been around since at least the mid sixties. They worked pretty good especially when encountering high heat as in racing apps. Modern racers have gone beyond the sintered stuff however. Some of the formula cars actually run carbon fiber discs. I'm not sure what they run for pads but I'm sure it's not metal sintered. Lyndall claims higher friction and less disc wear than with HD pads. I think it is totally possible. Technology marches on.

What I've read about the Lyndall pads (and remember this is just what I read!) is that the pad material they use was being used in some high end car racing application and, at the request of some bike racers, Lyndall was able to get some of the wonder material and apply it to some bike backing plates. The results were really nice and they got rave reviews from everyone that used them. So Lyndall started producing and marketting them. I like 'em. Don't know what the magic material is but I do like them for the reasons I stated. I'll let y'all know my final opinion in another 10,000 miles.

Frisco, I don't doubt for a minute that you get better stopping power from the softer steel rotors than from stainless steel. SS has chrome in it and it is a slick metal. SS isn't particularly hard either, at least on the RC scale, but it's harder than ductile or mild steel and has high wear resistance. I'd bet the stainless rotors last longer. Not completely sure about that but that's what I think. I believe the main reason they sell 'em is cause they're pretty.

HarleyCruiser · #10 07-26-2008, 04:46 PM

Yea, with warped rotors you will get a pulsating, also the warped rotor will push the pads and caliper pistons farther away and you will have more free play in the pedal/lever.
Also, stock HD’s come with HH pads so do not go with anything less.