single or dual disc brakes?
Harley Brake IssuesDiscuss single or dual disc brakes? in the Harley Tech & Harley How-to forums; Anyone here spend the time and money to upgrade your ride from a single to dual front disc brakes?
What's involved and is it worth it?...
All I can tell you is that 2 of my sickles have single front and 1 has dual front..
I feel no diff in the braking of the 2 singles from the dual..
I know, that doesn't sound right but how it is with mine..
Some folk think the single slightly pulls to the side and I have experienced that on some applications and I would not tolerate it on my current sickles but it is not present so I don't need to think about it..
One way to assure there is no pull is going dual but if you don't have pull then it's a moot point..
I did get better front braking when I installed an 11.5" rotor replacing the 10".. I once read in Thuder Press that the OD doesn't make a diff and the diff feel is an illusion, well, I don't always agree with what I read especially if I get a diff result from actual doing it..
Often installing a smaller master cylinder will give a waaay better feel of control in your hand.. It takes a slightly longer stroke but with more pressure,, go tooo small though and you run out of juice..
Hey-- you just might have to try the duals to know for sure from you own experience..
__________________ "Fill your hands you son of a bitch"
Rooster Cogburn
Last edited by frisco-rigid; 03-29-2008 at 08:34 PM.
I can't accept a single disc causing a pull to one side unless your forks or axle is loose. But the value of a larger disc is more mass to increase friction - which helps slow you faster, and the increased size of the rotor allows it to release the built up heat quicker for less brake fade.
Or not....
__________________ Ride An Old Harley Like It Was Meant To Be Ridden
Actually it's the extra leverage from that extra inch and a half of rotor..
Since the caliper pads/discs/pucks are roughly all the same size they do not have any "increased mass" to use,,, as stated, it is the leverage..
Of course, if the pads are extra large, more surface area of the rotor will be used resulting in better braking.. Heck then you could use 6" rotors..!
It is the heat from the friction that slows the rotor so getting rid of the heat is not the goal or the result of a larger OD rotor..
I guess too much heat can built up but certainly not with sickle rotors unless you ride the brake or for some mal-adjustment the pads are contacting the rotor waaay more than just the little that is appropriate.. Happened to me long ago.. The rotor warped and looks like a dinner plate, still have it--- I'm going to make a stool seat out of it..
I personally have never experienced brake fade with Disc brakes,, drum yes..
__________________ "Fill your hands you son of a bitch"
Rooster Cogburn
Are you running dual piston or four piston calipers ? My old FXDX has dual disc single piston front and feels about the same as single disc dual piston. Could be I am getting slower ?
My antique has dual drum front and works good part time. The Blue Ridge mountains are no longer any place I will ride it.
Wow, dual front drums,, inefficiency squared..!! Oooh, just joshin...
The 93" shovel has a PM solid-mount dual-action 2-piston in rear..
It also has one solid-mount 2-piston dual-action Brembo?? or Grimecka?? in front..
The 120" has a GMA solid-mount 2-piston dual-action in rear..
It also has 2 solid-mount dual action 2-piston PM's in front..
The 80" has a stock OEM single action rear and stock OEM in front and they work as good or better than the others..
I am going to the old single-action 1-piston floating Banana in rear of the next sickle.. As with sooo many so-called super advances like Single-fire ign. or dual action brake calipers, I am going back to the old-style.. I have run those "advanced" things, not just tried them, and found that for me I felt absolutely no increase of "good" and sometimes an increase of the "bad"..
__________________ "Fill your hands you son of a bitch"
Rooster Cogburn
This thread got me thinking about the brakes on my FXR4. It has the later model dual piston calipers and floating discs. Anyway, the more I ride the bike (I bought it used around Thanksgiving '07) the more I'm not very impressed with those front brakes. I would have thought they'd be much stronger than the single front disc setups but that doesn't seem to be the case really. The stopping power is definitely not double that of a single disc according to my own seat of the pants.
So, as I was pondering this, I thought, "Well, if all you did was add another caliper and disc to the single disc wheel and didn't change the master cylinder you would be dividing the pressure put out by the master cylinder into two parts. To my way of thinking it would cut the pressure going to each caliper in half. The net gain in stopping power would then be zero. The discs would stay cooler which I guess could, but not necessarily, increase stopping power a bit but not by much. Of course it will help brake fade caused by heat build up but still...."
I'm just throwing this out there to see if there is some flaw to my logic that anybody can see hear cuz I'm not seeing any really great benefit to this dual disc setup and it adds weight to the front wheel.
single or dual disc brakes? 
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