Differential bore calipers ??

[Wicked]

Concerning these 4 piston differential bore front calipers (brand is unimportant though these are PM).....  Manufacturers state that the smaller bores should be at the leading edge of the rotor. This is supposedly to allow for softer less aggressive braking with light lever use - just one of their claims to fame. Of course there would be a measurable difference because of the different diameters with identical psi's, but would you really notice it by seat of the pants or from a safety standpoint? Only reason for asking is cause I have a right side caliper that I'd like to use on the left....

[harley_cruiser]

Concerning these 4 piston differential bore front calipers (brand is unimportant though these are PM).....  Manufacturers state that the smaller bores should be at the leading edge of the rotor. This is supposedly to allow for softer less aggressive braking with light lever use - just one of their claims to fame. Of course there would be a measurable difference because of the different diameters with identical psi's, but would you really notice it by seat of the pants or from a safety standpoint? Only reason for asking is cause I have a right side caliper that I'd like to use on the left....

The leading edge of a brake pad wears the fastest, that is why the small puck is first. Stick your foot out of a moving car, your foot is pulled back and your toe gets all the pressure.
Your stock HD pad, if you look at it, is offset so that the leading edge does not get as much pressure, plus look at the shape and you can see how it does not have as much material.
Same for drum brakes, front shoe is smaller.

[Wicked]

Yup - all true....   from about yr 2000 and on. Before that HD design had no offset of pads verses pistons or shape of pads themselves to allow this. Still wondering if it's a large safety issue though?

[harley_cruiser]

Yup - all true....   from about yr 2000 and on. Before that HD design had no offset of pads verses pistons or shape of pads themselves to allow this. Still wondering if it's a large safety issue though?

Can't answer that, I would think the leading edge with the large puck would wear much faster, do not know if the uneven wear would cause the pucks to bind.
Would you have to flip them upside down, the bleeds be on the bottom the feed on top?
How about turning the forks left to right, just thinking out loud.

[FSG]

keep the smaller bore at the leading edge, L on the Left only, R on the Right only 

[harley_cruiser]

Wicked, what bike is it on? What size fork? Can you get a fork for the other side with a mount?

[Wicked]

Naw.....it's a custom build that was in an accident. Previous tech had the lone caliper mounted behind on the right with both sliders on backwards.  Removable caliper mounts so reversed the sliders to proper and mounted caliper at the front of the left side. I thought it should be mounted behind on the right but according to FSG this is the proper way with the large bore being the leading end.
[attach=0]
Man...this whole thing was cobbled! Starting with front tire backwards to tail lites not working and all in between...

[ThumperDeuce]

I've been running dual 6 piston differential bore PM calipers up front and 4 piston on the rear for about 10 years now.  Pads wear pretty evenly and the brakes apply well with a light touch.  I've been happy with them.

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[harley_cruiser]

Naw.....it's a custom build that was in an accident. Previous tech had the lone caliper mounted behind on the right with both sliders on backwards.  Removable caliper mounts so reversed the sliders to proper and mounted caliper at the front of the left side. I thought it should be mounted behind on the right but according to FSG this is the proper way with the large bore being the leading end.
[attach=0]
Man...this whole thing was cobbled! Starting with front tire backwards to tail lites not working and all in between...

Read what FSG says again.

[Wicked]

Did so - and:

keep the smaller bore at the leading edge, L on the Left only, R on the Right only 

this says the opposite in the last 2 sentances of the .img:

keep the smaller bore at the leading edge, L on the Left only, R on the Right only 

[mrmike]

Top of caliper is bottom, bottom of caliper is top, rotationally speaking that is,lol

Mike

[Hossamania]

Naw.....it's a custom build that was in an accident. Previous tech had the lone caliper mounted behind on the right with both sliders on backwards.  Removable caliper mounts so reversed the sliders to proper and mounted caliper at the front of the left side. I thought it should be mounted behind on the right but according to FSG this is the proper way with the large bore being the leading end.
[attach=0]
Man...this whole thing was cobbled! Starting with front tire backwards to tail lites not working and all in between...

As I look at this picture, is this the left side, with the caliper out in front of the axle? If so, it seems it is backwards, as the larger bore is in the rear, which is the leading edge as the rotor rolls into the caliper.

[FSG]

Naw.....it's a custom build that was in an accident. Previous tech had the lone caliper mounted behind on the right with both sliders on backwards.  Removable caliper mounts so reversed the sliders to proper and mounted caliper at the front of the left side. I thought it should be mounted behind on the right but according to FSG this is the proper way with the large bore being the leading end.
[attach=0]
Man...this whole thing was cobbled! Starting with front tire backwards to tail lites not working and all in between...

As I look at this picture, is this the left side, with the caliper out in front of the axle? If so, it seems it is backwards, as the larger bore is in the rear, which is the leading edge as the rotor rolls into the caliper.

  if it is it is backwards 

Thumpers setup is a good correct example.   

[FSG]

Which is the front of the bike, A or B ?

[harley_cruiser]

Did so - and:

keep the smaller bore at the leading edge, L on the Left only, R on the Right only 

this says the opposite in the last 2 sentances of the .img:

keep the smaller bore at the leading edge, L on the Left only, R on the Right only 

"Smaller pistons up front,"
That is the leading edge.
"Larger Piston in the rear edge,"
That means trailing edge.

[Hossamania]

I think part of the confusion are the terms "front" and "rear"
The front of the caliper is the rear of the bike.
The rear of the caliper is the front of the bike.
Unless I'm confused. Again.

[harley_cruiser]

I think part of the confusion are the terms "front" and "rear"
The front of the caliper is the rear of the bike.
The rear of the caliper is the front of the bike.
Unless I'm confused. Again.

Well the front of the caliper is where the rotor enters it or spins toward it.
I think they are speaking the Queens tongue.

[Moparnut72]

With the way the picture was taken it is hard to see which way is the front. The forks are almost vertical in the picture.
kk

[Wicked]

Sorry guys....tween work I enjoy and medical crap I enjoy not so much - don't get here as much as I'd like.
FSG - "A" is the front of the bike.
Common sense and you both say the small pucks are to be to the leading edge to the rotor.
In the copied .img you posted tells me it's the other way, the way I read it anyhow...
Regardless.... I mounted it the way I showed to try. The front end has about 38deg of rake with about +6" tubes. It has a skinny 21" F tire and about 300mm R.  Got the front brake both warm and hot and there's no noticeable adverse effects under hard braking.... other than the obvious shortcomings of a bike of this design any anyhow....
We'll runner' this way for a bit.....

[harley_cruiser]

Sorry guys....tween work I enjoy and medical crap I enjoy not so much - don't get here as much as I'd like.
FSG - "A" is the front of the bike.
Common sense and you both say the small pucks are to be to the leading edge to the rotor.
In the copied .img you posted tells me it's the other way, the way I read it anyhow...
Regardless.... I mounted it the way I showed to try. The front end has about 38deg of rake with about +6" tubes. It has a skinny 21" F tire and about 300mm R.  Got the front brake both warm and hot and there's no noticeable adverse effects under hard braking.... other than the obvious shortcomings of a bike of this design any anyhow....
We'll runner' this way for a bit.....

Well that is definitely backwards, but I don't think it would affect brake pressure, I do feel it will affect wear. I think you will find the leading edge will wear out real fast. I would keep an eye on it and enjoy it, and let us know how it wears.

[harley_cruiser]

Looking at the photo, why not switch lowers left to right? And run it on the other side.

[Wicked]

Looking at the photo, why not switch lowers left to right? And run it on the other side.

Sure, I could do that. But then it would look like everyone else...... 

[harley_cruiser]

Looking at the photo, why not switch lowers left to right? And run it on the other side.

Sure, I could do that. But then it would look like everyone else......  u:wink:

And you wouldn't be able to find it in the parking lot lol.
Witch black fatboy is it?