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too much rear brakes !

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  #11  
Old 06-04-2017, 03:18 PM
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The dual front rotor has a 1/16 larger piston but I think it would be exactly opposite what you need. Think, when it comes to hydraulics, a small piston must be moved a large distance to get the large piston to move significantly. Get you an adjustable racing proportional valve and double flair it back where the pressure brake light switch is. Personally, do not consider travel more than exact pressure you apply. So a larger front piston may make motion shorter but the effort to push it harder. I think what is happing is as you apply brakes, the rear tire is unloading.
Good luck on trying to set it up. Might want to wear a full body armor Sports bike outfit.

https://www.summitracing.com/parts/s...chRRoCvh7w_wcB
 

Last edited by Jackie Paper; 06-04-2017 at 03:22 PM.
  #12  
Old 06-04-2017, 07:36 PM
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Originally Posted by TSheff
Bigger piston would lock even sooner. No reason for a properly operating system to lock-up without intentional pressure applied. Does your wheel turn with NO drag, when off the ground? Do you get a full pedal travel when bleeding?
If only 3mm of travel you might want to check the adjustment nut @ the MC, sound like it is too far in and MC piston doesn't have full travel.
i thought it was the other way around--> bigger piston=slower displacement given the same area

I like the part about adjustment nut, thanks !
 
  #13  
Old 06-04-2017, 07:39 PM
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Originally Posted by RIPSAW
I think what is happening is as you apply brakes, the rear tire is unloading.
Very good point ! Maybe TOO much front
 
  #14  
Old 06-04-2017, 08:06 PM
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Originally Posted by michla
thanks guys
this isn't a problem with "sticking" rear brake....the caliper pistons retract just fine and I flush the entire brake system with Drag Specialties DOT5 fluid every spring before riding. All and always good points though, thanks.

The entire braking system is fine, it's just the proportion of pedal travel as relating to the arc of the foot pedal. 3mm maybe is "soft" braking and suddenly beyond that it wants to "grab" hard. Not much margin at all there ! The master cylinder is just fine, all is good--it's the setup I'm looking to modify and was wondering if anyone found a larger piston master cylinder that would bolt up or? I'm not wanting to shorten the brake pedal (although that is always one solution to reducing the pedal pressure needed if you know what you're doing with welding reinforcements etc).

I might give Swifty's post for the Lyndall gold pads a try but don't stop there....I'm all ears (and eyes).
It still sounds like you have sticky pistons or a plunger. You apply a little pressure and the pads just touch, then you apply a little more pressure which overcomes the "stickiness"; and bam your brakes grab.
 
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Old 06-04-2017, 10:58 PM
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Originally Posted by michla
i thought it was the other way around--> bigger piston=slower displacement given the same area

I like the part about adjustment nut, thanks !
Larger piston MC moves more fluid per same length stroke that a smaller piston, that's why larger pistons are used for multi piston calipers or dual disc. Think small 2CC syringe vs lager 20CC syringe.
Still want to know if you get a full range pedal stroke when bleeding.
It's not a huge project to remove, tear down, clean, and rebuild if damage is found. Sounds like all your seal are good, so a thorough cleaning may be all that is needed. I've found MC's put together wrong, so if you problem has always been there, it's worth verifying.
 
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  #16  
Old 06-05-2017, 12:48 AM
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Originally Posted by bad tappets
It still sounds like you have sticky pistons or a plunger. You apply a little pressure and the pads just touch, then you apply a little more pressure which overcomes the "stickiness"; and bam your brakes grab.
good point !
 
  #17  
Old 06-06-2017, 02:57 PM
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Originally Posted by TSheff
If only 3mm of travel you might want to check the adjustment nut @ the MC, sound like it is too far in and MC piston doesn't have full travel.
Well, it's not that...checked linkage and there's no "adjusting nut/rod" on the softail, just a directly attached arm from the pedal pivot to the master-cylinder clevis.
 
  #18  
Old 06-06-2017, 04:59 PM
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Originally Posted by michla
Well, it's not that...checked linkage and there's no "adjusting nut/rod" on the softail, just a directly attached arm from the pedal pivot to the master-cylinder clevis.
Have you checked a Service manual to assure it is assembled correctly (rotor centered).
Other than that - as I said I would fully redo.
I've never had too much brake or grabbing, disproportionately.
Keep us posted on any findings, results, and solution.
 
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  #19  
Old 06-06-2017, 05:29 PM
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Has you or anyone else changed pedals ??? as to a longer one that would add leverage to master cyl for more pressure but not noticed by your foot !!!!

Example
I ride a Sportster it has a short pedal I put a lot of pressure to apply brakes , Then I get on my Tour Glide and if I'm not careful I lock up the rear wheel , the pedal is much longer on the Tour Glide and gives more leverage

What are you used to ???
 
  #20  
Old 06-06-2017, 09:17 PM
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Whatever you do, do NOT introduce air into the system.

Clean the caliper. Rebuild it if necessary.

I have been using Lyndall Z-plus pads on both the front and rear of Reaper for over a decade, and I highly recommend them. Much better performance than OEM, almost no dust, and quiet.

Cheers!
 
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