Improved rear breaks

[saddlesore]

I have a 99 standard with 167,000 miles,  A couple of weeks ago I lost the rear breaks, completely.   I saw no loss of fluid and I bled the brakes.  After 18 years and even when new I finally have rear brakes.   I've bled the breaks several times over the years and only had minimal breaking.  After reading about the weak brakes i assumed it was normal and accepted it. 
The BIG difference came from using a vacuum pump for the first time.
I put clear tubing toward the end to watch for air bubbles.  I had fine bubbles coming through and finished using the old method.   Test ran and I had breaks for the first time since new.  Using a vacuum pump sucks...in a good way.
I feel stupid for going this long without proper brakes.   
Sorry for the long post.

[Bighead]

FWIW You need more fromt than rear Brakes....

[Tfrank59]

Well I'm curious why in your mind at least you and ended up losing your rear brakes completely a couple of weeks ago was that just because of air in the system you think? My rear brakes pretty much suck also and I've sort of accepted it over the years myself even though last year I put in a new rotor and I've gone through like five different types of pads trying to find the most effective match up by the way I'm using an EBC rotor now not OEM and Kevlar pads seem to work best strangely enough. But now you got me wondering if I need to flush the fluid and really bleed the crap out of it. Thanks for posting

[saddlesore]

I didn't find any leaks and  it's been a couple of weeks with no loss of breaking power.
The only difference was that I used a vacuum pump.  And yes, I ran a lot of brake fluid through the system.   
Somewhere in the tech file I read about cleaning and lubricating the brake pedal pivot point.  I did that with little difference.
Maybe other riders will bleed their brakes instead accepting the perceived  norm.

And yes, I use the front brakes most which just let me accept the lack of rear brake power.   

[Carl]

I started using a MityVac to bleed my brakes on my track car.  I always had better luck with it over the regular method.  There are several spots air can get trapped, so I would also tap the fittings, etc.  I also noticed that I used more fluid with the MityVac.  Could be that pulling, rather than pushing the fluid helps clear the lines.  IDK.

[WintrSol]

I suspect it was the very shallow angle between the master cylinder and slave cylinder that kept the air trapped in high spots along the brake line. I think the vacuum pump caused the fluid to move faster through the line, pulling more of the trapped air with it. Makes me wonder if elevating one end of the bike would help, like make the front higher, to get the air to move to the mc, or rear to get it out the slave. I also wonder how much tilt it would take. Hmmm ...

Or, the OP was trying to do the job single-handed, which is quite the contortionist operation. Opening and closing the bleeder while pressure is maintained on the pedal is quite a stretch!

[Gabriel]

"Brakes"
I quit "pump" bleeding decades ago, we had to many master cylinder failures afterwards.
Pushing the master cyl. further into the bore where it has never been can destroy the cup because of the crud build-up.
I have a pneumatic bleeder for cars, a Mity-vac and one I bought from Harbor freight that works as good as any of the mity-vacs I have bought through the years.

[Gryphon Rider]

One thing commonly ignored that can make a huge difference in rear braking is disassembling, thoroughly cleaning, then lubing while reassembling the brake pedal and its pivot.  If it's been years since it's last been done, you might be surprised how powerful the rear brakes can be, certainly enough to lock the wheel with firm pressure.

[bill-jr]

One thing commonly ignored that can make a huge difference in rear braking is disassembling, thoroughly cleaning, then lubing while reassembling the brake pedal and its pivot.  If it's been years since it's last been done, you might be surprised how powerful the rear brakes can be, certainly enough to lock the wheel with firm pressure.

This and prob new seals and or bushings really make a difference  .( Rebuild )
Sure gave me more stopping power. . .


photo upload

[saddlesore]

You're right, I check the seals whenever I change the rear tire.  I have seals and pistons in my parts box.    Sometimes the pistons are stuck and need to be freed.   

[John Schmidt]

And.....after rebuilding the caliper, install a SS brake line. The 20 yr. old rubber hose will cause you to lose as much as 50% of braking power depending on how much it expands when you press the pedal.

[Tfrank59]

Or at least to replace with OEM rubber lines

[Paladin528]

I just rebuilt both front calipers.  Flushed the master Cylinder and lines with 99% isopropyl Alcohol and refilled with good DOT 4 Fluid and Vacuum bled the heck out of them.  Brakes are now AWESOME.

[Cracker Jack]

And.....after rebuilding the caliper, install a SS brake line. The 20 yr. old rubber hose will cause you to lose as much as 50% of braking power depending on how much it expands when you press the pedal.

I totally disagree with the statement that you will lose 50% of braking power with soft brake lines. In fact, I say that you will not lose any braking power as long as the master cylinder does not bottom out.


Braking power is purely a function of lever force as determined by relative master/caliper cylinder sizes. Any mechanical friction from lever/pistons will "absorb" some of the lever force and will not be improved with new hoses of any kind.

What lines with stainless braiding will do is create a firmer lever with less "give" but will not improve braking. I personally like a lever with some cushion rather than one that feels  like a brick. I find that it is easier to modulate the braking force.

[John Schmidt]

And.....after rebuilding the caliper, install a SS brake line. The 20 yr. old rubber hose will cause you to lose as much as 50% of braking power depending on how much it expands when you press the pedal.

I totally disagree with the statement that you will lose 50% of braking power with soft brake lines. In fact, I say that you will not lose any braking power as long as the master cylinder does not bottom out.


Braking power is purely a function of lever force as determined by relative master/caliper cylinder sizes. Any mechanical friction from lever/pistons will "absorb" some of the lever force and will not be improved with new hoses of any kind.

What lines with stainless braiding will do is create a firmer lever with less "give" but will not improve braking. I personally like a lever with some cushion rather than one that feels  like a brick. I fine that it is easier to modulate the braking force.

Yup, I totally, absolutely,  indubitably agree with everything you said. MM-hm....yessiree! 

[saddlesore]

Now you've done it,   I'm torn because I replaced my lines with stainless steel a few years back.

[John Schmidt]

Now you've done it,   I'm torn because I replaced my lines with stainless steel a few years back.

I assume your comment is also tongue-in-cheek. Since you have them installed, you're already aware that SS lines are very effective and myself, having used them for decades, I find them as easy to "modulate" the braking force as the OEM rubber items. It's all in what you get used to using. As for loss of braking power with old and flexible hoses, that issue has been proven more times than I can remember so I pay little attention to the contrary. Just put on a new set of SS lines and compare the feel to the old flexible rubber ones and you experience greater braking action with less deflection of the pedal or handle. And the feel is solid, not squishy(technical term).