Bleeding brakes

Old-tool-guy

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Region
USA
Ride1Up Cafe Cruiser. Rear brake is very soft, it gets hard if i pump the lever 4-5 times, reminds me of my old cars with air in the brake lines. I bought a service kit from amazon and have tried several times to bleed the brakes, but it’s not working. Need help.

I watched a couple of videos, here’s what i’m doing: i attach a full syringe to the bleed screw on the brake mechanism, remove the screw from the hand lever, push the oil up into a catch cup.

Is the problem the zoom parts? Should i consider replacing them with a better brand?
 

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it looks like really short hose that may make it harder. plus you want the little clamp that slides over the hose that clamps it on the barb on the caliper. the hose may be in that bag but you really want the hose clamp to keep the hose on the slipper. they pop off so easily. see that oval part that slips over the hose and onto the barb. a clear cup is better so you can see when clean fluid comes out.
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im just guessing here, but its possible using that kit has introduced air bubbles into the line. Me being me, i'd try using gravity to force any bubbles up to the lever, which means you'd have to get the front of the bike up in the air etc. If/when that happens to my bike, Ill probably reroute the hose externally so I could at least try to bench bleed it more easily. Wondering if you ever got it working?
 
I bled my rear brake from the top at the brake lever.
I elevated the front of my ebike then removed the rear caliper and laid it on the ground so the brake line would slope upwards allowing any bubbles to rise up to the brake lever reservoir.

I left the brake line connected to the caliper and oriented the caliper to let the bubbles rise up the brake line.
Mineral oil for brakes is really thin and a bubble can get stuck in a high spot along the brake line.
 
I get brake fluid flush once a year at 2500 - 3000 miles, Which ever comes first. Done at local dealer service.
It's not worth my time to do it.
My brake fluid two Emtbs renewed in mid January 2024 cost $130.
 
^ did it work well PC?

Once the funnel full of oil is screwed in, you just keep hitting the brake lever to agitate the bubbles.
That makes them rise to the top and into the funnel .

Let it sit overnight and all the smashed bubbles will rise to the top and into the fluid filled funnel.
 
I get brake fluid flush once a year at 2500 - 3000 miles, Which ever comes first. Done at local dealer service.

Flushing the fluid is different than bleeding bubbles.
I rarely need to use my brakes.

I'm still going to flush my lines from the top down when it comes time to flush my fluid.
Just keep the reservoir full and push the fluid through?

Either way, I'm going to do it myself.
I'll save hundreds of dollars and know how my e-bike works.
 
I didn't realized you used a kit PC, i was simply thinking of tilting the bike/line upwards and tapping on the hose starting at the caliper all the way up to the reservoir. if the mineral oil is thin, I wouldn't think its to difficult. ? also on these systems does pad wear effect sponginess?
 
I didn't realized you used a kit PC, i was simply thinking of tilting the bike/line upwards and tapping on the hose starting at the caliper all the way up to the reservoir. if the mineral oil is thin, I wouldn't think its to difficult. ? also on these systems does pad wear effect sponginess?
no but the levers will move in more as the pas wear. yo can deal wit that by taking the pads out and squeezing the leaves a bit til late pistons stay out a tiny bit.
 
I didn't realized you used a kit PC,

Yeah, I bought the kit, but I broke the damn funnel at the threads where it screws in.
I managed to bleed them without the funnel.
I used a dropper to fill the reservoir.

i was simply thinking of tilting the bike/line upwards and tapping on the hose starting at the caliper all the way up to the reservoir. if the mineral oil is thin, I wouldn't think its to difficult. ?

Yes, yes, and yes...
That's what you do.
Make sure that when you start at the caliper, you tip it and flick it so the bubbles rise.
Not just the brake line, but where the brake line attaches to the caliper.
Tip the caliper upwards towards the brake line.

Make sure that there are no arches to catch a bubble,..

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also on these systems does pad wear effect sponginess?

I wonder about that.
My car has a hole in the brake fluid reservoir lid to let air in when the fluid drops due to pad wear.

My ebike brakes are sealed.

If I squeeze the brakes on my e-bike, the pads squeeze the rotor, but do they fully retract due to suction created while pulling the brake lever?

On my car the pads move closer and closer to the rotors as they wear but the hole on the reservoir cap allows air into the reservoir to replace the oil.


On my e-bike, there is no air input to the reservoir, so the pads might be sucked back out to original position so that the brake lever may have to be pulled further and further with every brake application?
I dunno?

Maybe it's time for new brake pads when your brake lever hits the handlebars?
 
no but the levers will move in more as the pas wear. yo can deal wit that by taking the pads out and squeezing the leaves a bit til late pistons stay out a tiny bit.
seems to me, you wouldn't need to remove the pads for that to happen. doesn't the piston self adjust?
 
seems to me, you wouldn't need to remove the pads for that to happen. doesn't the piston self adjust?
some but the lever slowly creeps inward. not much it just takes a longer pull. I wanted the Shimano xtr levers that have a knob to adjust that.
 
Next time do as PC suggest.
Top off the fluid at the lever.
Search youtube for "brake lever bleed"
Tap the lines to dislodge any stubborn bubbles during the process
Only use the syringe for a fluid change or replacement of lines
I wouldn't suggest squeezing levers with pads removed as you could possibly overextend them... Just do a top off of fluid.
 
on my brakes (lmt'd) there is a little screw that can adjust the lever "reach" a tad

Yeah mine are adjustable too.
I adjust them to where I can squeeze the lever with one or two fingers but still have clearance for the fingers on the grips without hitting them with the lever.
 
I wouldn't suggest squeezing levers with pads removed as you could possibly overextend them... Just do a top off of fluid.
I have found by accident that it's not a problem but that could be just on my Shimano setup. but if you take it easy you can move the pistons out a bit. they actually don't want to stay out at all. Now if you take the pads out then peddle the bike to change gears before taking the wheel off then squeeze the lever fully ya that can do it. Plus if the pistons need cleaned yo need to do that anyway. just not a fully hard squeeze.
 
,.. but if you take it easy you can move the pistons out a bit. they actually don't want to stay out at all.

That's what I found. The pistons don't stay out.
I wonder if you remove the reservoir filler screw then push the pistons out, they might stay out?

The reservoir might not create a vacuum then when fluid is pushed down the brake line?
 
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