Front brakes are mushy, what should I try?

[chuck c]

I just rebuilt all 3 calipers. The rear is working properly but the front is not. The lever is mushy and they have no power. I bled them pretty carefully but there could still be air trapped in the lines. They were completely drained while disconnected. Is it my master cylinder? What else can I try to be sure there's no air in the lines?

 

[Denver]

Hate to sing the praises of mity vac's yet again, :roll: but the damn thing's work great! :smilie_happy: Vac + pumping the master, will get all the air out, & bleeding the master from the bolt with the RUBBER line clamped shut is another trick to get trapped air out of the master, on the clutch as well as brake's. opcorn: Did you rebuild the master? :headscratch: Some dirt is sometimes trapped in the end of the bore, & need's scraped out, to get the brake's to work well. :yes:

 

[slabghost]

chuck c » Sun Jul 03, 2016 6:47 pm[/url]":1hermdld]
I just rebuilt all 3 calipers. The rear is working properly but the front is not. The lever is mushy and they have no power. I bled them pretty carefully but there could still be air trapped in the lines. They were completely drained while disconnected. Is it my master cylinder? What else can I try to be sure there's no air in the lines?

Try this first. remove most of the fluid from the master and remove the rear caliper. Use a C clamp to compress the piston in to force as much fluid and air possible back to the master. Remove the fluid from the reservoir and pour in new fluid. Now reinstall the caliper and pump the piston back out. Keeping the reservoir at the "full" level. You should now have full brake power.

 

[chuck c]

Did not touch the master yet.
slabghost's suggestion to force fluid and air back up to the master by compressing the caliper is simple. I'll try that first.

Next, I do have a vacuum pump. I've made a vac bottle and in the morning when the blue RTV I used to seal the hoses is set I'll give it a try. It's the same kind of rig as a Mityvac.

If neither of those work I'll make a rig to force fluid down from the top.

Q: I'm doing one side then the other. Is that allowing a bubble of air to move back and forth? Should I have both bleeders open at once?

 

[slabghost]

Try the procedure and see if the master functions as it should.

 

[chuck c]

GAH! I've tried everything! The vacuum pump did work nicely. I'm sure the master is just worn out. I will order a kit and rebuild it. No riding this weekend, much sadness. I'm running out of riding weather!

 

[slabghost]

Everything? Did you try the procedure I posted? With both calipers?

 

[chuck c]

slabghost » Mon Jul 04, 2016 1:05 pm[/url]":9pm3pycj]
Everything? Did you try the procedure I posted? With both calipers?

Yes. I'm sure there's no air in the system.

 

[slabghost]

okay no air. but the procedure forces the return of fluid to the master assuring that side of the path functions as it should. Even a new master needs primed.

 

[joedrum]

well it rather easy to check the master ..with fluid in master and line off put thumb over hole if it sucks on the thumb its working ..in fact this is the first place to bleed ..if master has air ..the rest is doomed to bleed ...you said in first post brakes are mushy ..that indicates the master is working some ....if return hole is pluged some ..as mine were ...the brakes ability to push the piston is no better than the amount of fluid that can return to master ...this causes resistance....and brake fall to the level of return flow ...the typical mushy feeling fron brakes give ...if you can pump up brakes and there mushy this is most likely the reason ...when the return hole is cleared as v posted ... brakes are easy to bleed as fluid moves now through entire system ...not by passing the return hole ....if one front brake is left on and the other taken off and pads ..a c clamp can be use to back bleed ..the caliper piston on single piston brakes pust the most volume of fluid over master by long ways ...use c clamp not tp pump piston to far out and to push fluid ..bottoming piston ...put all back together and then do other side ..no drip no error and thebest bleed out there as it bypasses nothing ...

my single piston front brakes on hooch bike are in tip top shape ...was quick and took yrs to think of as i hate brake fluid on me :cheeky:

 

[dan filipi]

If it will pump up and hold pressure, the seals are ok...or am I missing something?

 

[zman]

Cant say for sure but some have had luck taping or strapping down the lever overnight, also did you clean and lube the sliding bolts on the caliper?, It can give uneven pressure if they cant move properly.

 

[dan filipi]

Mushy feel can also be an expanding rubber hose. Mine got more firm with new lines.

 

[joedrum]

dan theres no doutb that that cloged return hole or impeded return flow will level out brakes to that flow only ....after yrs of thinking my brakes just sucked ..blaming hoses and bad design among other things also ...the dang return hole tho never clog completely was the problem all along ....the hooch bike feels like it can throw you over the bars now ....with all the spring mods i did ..the front brakes have no problem collasping the forks down ...like bang at any speed love the set up....to me this is another missed deal oldwings hidden a long time ...an expose here ..as it stands hooch has best brakes ive had on any wing ive own

 

[slabghost]

This discussion has taken longer to be posted than the procedure and results. Your bike your decision.

 

[dan filipi]

joedrum » 39 minutes ago[/url]":2spokfbg]
dan theres no doutb that that cloged return hole or impeded return flow will level out brakes to that flow only ....after yrs of thinking my brakes just sucked ..blaming hoses and bad design among other things also ...the dang return hole tho never clog completely was the problem all along ....the hooch bike feels like it can throw you over the bars now ....with all the spring mods i did ..the front brakes have no problem collasping the forks down ...like bang at any speed love the set up....to me this is another missed deal oldwings hidden a long time ...an expose here ..as it stands hooch has best brakes ive had on any wing ive own

I understand Joe but the system needs to be gone over as a whole. Nothing wrong with anyone adding their own experiences and adding their own opinion. After all we are talking about the brakes, the most important part on the bike.

 

[mcgovern61]

Air gets trapped in the top of the cylinders right at the bleeding screws.

The procedure I use that has worked every single time is simple and it does not matter if you pulled the hoses and started with an empty master, it always works for me.

1. Take both calipers off and push the pistons all the way back in. Clamp them there.
2. Fill the master, leave the lid off.
3. Gently pull the brake lever to get fluid into the piston in the master. (You should see fluid movement and might see air bubbles).
4. Pull brake handle all the way back to the grip and hold while cracking the right side bleed screw. (You are not trying to get a hard handle yet, just push fluid and air through).
5. Top the master as needed DO NOT LET THE MASTER GO BELOW HALF!
6. Keep bleeding the right side caliper until it is fluid only. Leave clamped and repeat for left side.
7. When both sides are showing fluid only, put right side back on caliper upper bolt leaving it tilted up so that the bleeder screw is at the top. Pull the handle but do not go all the way to the grip, just push the pistons slowing back into place (still on right side only).
8. Now, bleed the right side like normal building pressure and getting air out.
9. Once handle is firm, leave the right side caliper like that and perform the same procedure on the left side per steps 5 through 8.
10. Once bled and handle is firm, but calipers back on both bolts and ride!

:yes: :moped:

 

[joedrum]

ok ..im not discounting methods at all ...in a simple form ..the return hole is the smaleest hole in entire system ..so by common sense it is the first thing that can cause trouble ..id say it the main reason for swelled hoses ....and after repeated bleeding on all methods ..brakes up front were never great brakes ...lever out on master ...using caliper to bach bleed is the only way to target return hole ...the smallest hole in the system ...point being there huge benifitsdoing this is what i found ...no where on internet is there another process that targets return hole ...to me the biggest reason to soft brakes on the wings ive owned

though i agree many times it is just air ..and methods memtion are all good

 

[chuck c]

dan filipi » Mon Jul 04, 2016 2:18 pm[/url]":18gqvhj5]
If it will pump up and hold pressure, the seals are ok...or am I missing something?

It won't pump up. There's almost no pressure at the pistons. I will check the return hole.

 

[Denver]

It's possible there's crud inside the master bore, at the end. :roll: Displacing fluid, keeping pressure from building up enough to grab onto the rotor's. :yes: Have taken them apart, cleaned all passages, reassembled them with surprising result's, till the rebuild kit arrived. :whistling: Sometimes traded or sold the bike, without that kit at all. :hihihi:Rebuild that master, & ride :good: