All brake parts are new but.......

[Guest]

Tried using search but couldn't find my specific issue. I have a brand new master for my front brakes w/new lines to a rebuilt caliper w/new pads. I have bled everything till I have fluid without bubbles coming out the bleeder on the caliper but the pistons won't pump up. I have tried pulling the brake lever to the grip then releasing the bleeder dozens of times to no avail. I have clamped the lever to the bars overnight also to no avail.

Could I have air trapped in the caliper? Do I need to take the caliper off & push the pistons back in?

Paul

 

[Steve]

Yep, you have trapped air, but not in the caliper. It's likely in the master cylinder. Remove the brake lever, crack the banjo bolt open. Use a large Phillips screwdriver or a drift pin to push the piston in as far as it will go. Close the banjo bolt, then release the piston. There is a little bubble that stays just above the outlet of the master cylinder. The piston does not normally move far enough to force it out, so you need to push it farther with the screwdriver.

.

 

[Guest]

But like I said, I have fluid pumping out the caliper bleeder when I compress the lever so I know there is fluid to the caliper.

 

[Steve]

You can get fluid all day by whatever bleeding method you want, including a Mity-Vac, you will not displace that bubble.
You have to remove the lever and push the piston farther than the lever will.

If nothing else, humor me. Try it, then tell me "it didn't work" so I'll stop suggesting it.

.

 

[Guest]

I'll be giving it a try later today & reporting back, thanks.

 

[cowboyup3371]

Nasty,
Honestly, I listened to him BEFORE doing my MC and NEVER had a problem with it afterwards except for the little problem of a non-drilled return hole. These guys know what they are talking about.

 

[Guest]

You can get fluid all day by whatever bleeding method you want, including a Mity-Vac, you will not displace that bubble.
You have to remove the lever and push the piston farther than the lever will.

If nothing else, humor me. Try it, then tell me "it didn't work" so I'll stop suggesting it.

.

Well, I removed the lever & used a screwdriver to push in that piston & I'm sorry to say it didn't make any difference although I did get 1 bubble to come out.
I ended up taking the caliper apart to make sure the pistons were moving freely (they were) then rebled the system & the lever finally firmed up. It's not perfect yet & I will re-bleed in day or so but it's much better.

 

[raistian77]

Older GM trucks were horrible for this same problem, it is always caused by air trapped in the M/C. I always start bleeding at the M/C then move on from there.

 

[Steve]

Well, I removed the lever & used a screwdriver to push in that piston ... then rebled the system & the lever finally firmed up.

Thank you.

.

 

[Guest]

Don't edit my post to suit your own needs. I tried what you suggested & it didn't work. The least you can do is be a man. It took a complete dis-assembly/re-assembly of the caliper before the brakes held.

 

[bonanzadave]

It took a complete dis-assembly/re-assembly of the caliper before the brakes held.

Glad ya got it figured out.

The least you can do is be a man.

Hey Mr. Nasty, if you want any future help with your Bike Steve is probably the last guy you want to make pi$$y comments to. If he was any where near you he might have even come over to help. That may not happen now.

Man up Steve !! Geesh...

 

[Steve]

If he was any where near you he might have even come over to help. That may not happen now.

No problem. I don't currently hold a passport, so I won't be crossing any major borders.

However, word from Mrs. Steve indicates we might be applying some time soon for a possible trip "down unda".

.

 

[Steve]

Don't edit my post to suit your own needs. I tried what you suggested & it didn't work. The least you can do is be a man. It took a complete dis-assembly/re-assembly of the caliper before the brakes held.

At least you started with bleeding the M/C as suggested. You said you did get a bubble out.
Subsequent re-bleeding (following caliper disassembly that might not have been necessary) got more of it out.

Close enough for me.

To help firm it up the rest of the way, ... what is the angle of the M/C on the handlebar? :-k

If you can tip it so the banjo bolt is a bit below level, the air bubble that might still be there will rise toward the piston and the bleeder hole. Push one of the pistons back in the caliper to force fluid back to the reservoir, it should take the air bubble with it. You can watch the fluid in the reservoir to verify.

.

 

[raistian77]

Don't edit my post to suit your own needs. I tried what you suggested & it didn't work. The least you can do is be a man. It took a complete dis-assembly/re-assembly of the caliper before the brakes held.

Im sorry this is www.thegsresources.com
you must have meant to post at www.gsownersthatcanttakeafreakingjoke.com

 

[Guest]

At least you started with bleeding the M/C as suggested. You said you did get a bubble out.
Subsequent re-bleeding (following caliper disassembly that might not have been necessary) got more of it out.

Close enough for me.

To help firm it up the rest of the way, ... what is the angle of the M/C on the handlebar? :-k

If you can tip it so the banjo bolt is a bit below level, the air bubble that might still be there will rise toward the piston and the bleeder hole. Push one of the pistons back in the caliper to force fluid back to the reservoir, it should take the air bubble with it. You can watch the fluid in the reservoir to verify.

.

I tried to keep the master level when I did it. I can try to tip it so the bango angles down a bit to help with the final bleeding. I'll give it a try tomorrow. Thanks for the help.

Paul

 

[Steve]

You should not need any more opening of the system to do that. Either turn the handlebar so the M/C is angled properly or loosen it from the bar.
At the caliper, you might be able to pry the pads apart with out removing a caliper, but the worst you should have to do is remove one caliper from the fork leg, then pry the pads apart slightly. Same motion you would use to simply replace the pads.

With any luck, you will not have to open any bleeders or use any more fluid, the air will simply go into the reservoir. This is what some would call "reverse bleeding", where you force fluid into the system from the bottom. Only difference is that your system is already full, just need to move that last bubble.

.

 

[raistian77]

You should not need any more opening of the system to do that. Either turn the handlebar so the M/C is angled properly or loosen it from the bar.
At the caliper, you might be able to pry the pads apart with out removing a caliper, but the worst you should have to do is remove one caliper from the fork leg, then pry the pads apart slightly. Same motion you would use to simply replace the pads.

With any luck, you will not have to open any bleeders or use any more fluid, the air will simply go into the reservoir. This is what some would call "reverse bleeding", where you force fluid into the system from the bottom. Only difference is that your system is already full, just need to move that last bubble.

.

Hey Steve, just remember not to do this on a bike or vehicle that has ABS. reverse fluid flow can damage the solenoids.

 

[Steve]

Hey Steve, just remember not to do this on a bike or vehicle that has ABS. reverse fluid flow can damage the solenoids.

Thanks, good to know. :clap:

Does that mean that when it comes time to do the brake pads on my van that I need to open
the bleeders on the caliper to squeeze the pistons in to make room for the new pads? :-k

Sounds cumbersome, but it will probably be time to change the fluid, anyway.

.

 

[raistian77]

Thanks, good to know. :clap:

Does that mean that when it comes time to do the brake pads on my van that I need to open
the bleeders on the caliper to squeeze the pistons in to make room for the new pads? :-k

Sounds cumbersome, but it will probably be time to change the fluid, anyway.

.

Yes open the bleeders prior to pushing the pads back in.

Forcing Dirty Fluid Back into the ABS: [From Motor Service Magazine]

We believe the biggest brake bungle techs are making today is forcing caliper pistons back without clamping the hose and opening the bleeder. Since the line comes in near the bottom of the cylinder where the sediment is, this forces debris up into the ABS unit, and that will likely result in a comeback for a glowing anti-lock warning light. Just opening the bleeder as you may have done in the past isn't good enough anymore. You've got to choke off that hose. [Editor's note: you can buy inexpensive plastic pliers with rounded jaws designed to clamp rubber brake hoses without damage

they mention choking the hose
http://www.amazon.com/gp/product/B0017I47MQ

 

[Billy Ricks]

I never knew that about ABS pad replacement. I'll have to be more careful in the future. So far no bad results from doing it the old way. I guess I was lucky I was working on vehicles that had clean fluid. I haven't set any sensors off yet. I've replaced front pads twice on our 350Z within about 40,000 miles. It goes through pads in a hurry. Next time it needs pads I'll probably replace the rotors with Brembos.