Noob life—rear brakes not working

Woe unto you that bought the first model year of a major remake, perhaps this section can help address any 2014 and later model Ural "imperfections". Here's a special section for folks with the latest rigs to discuss 2014 and later model-related topics such fuel injection, 3-wheel disc brakes, hydraulic steering dampers, spin-on oil filters and other anomalies that don't belong on true Russsian motorcycle ;-P We've gone from using big hammers and greasy wrenches to needing computers and Ouija boards in order to fix our rigs.
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Please keep this section specific to issues pertaining to 2014 and later models such as fuel injection, sidecar and rear disc brakes and so forth. Ask general or non-2014 and later specific questions in the main Hammerin' & Wrenchin' section.
HassoBoxhead
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Noob life—rear brakes not working

Post by HassoBoxhead » Sun Jan 27, 2019 2:02 pm

Yesterday I swapped the rear pusher for a new one and wanted to change the brake pads at the same time. When I put the new pads in place, the caliper wouldn’t fit so I tried to depressed the plunger using a “c” clamp. Didn’t move that much, so I opened what I’m assuming to be the bleeder pressure nut on the bottom right of the caliper, then tried to depress the plunger again...no joy. When I tried to depress the plunger, a bit of brake fluid came out of the nut at the bottom right. Having no luck, I put the old pads back in and tightened everything up.

Now I have no rear brakes, when I push the rear brake pedal, only the sidecar brakes apply. I went back and removed the rear wheel caliper and looked, when I push the rear brake pedal, the plunger doesn’t move.

What do I need to do? I’m at a loss and it’s likely something noobish, I know...any help would be most appreciated! Thanx!
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Re: Noob life—rear brakes not working

Post by harryball » Sun Jan 27, 2019 2:13 pm

I'd start by removing the rear caliper and properly bleeding them using a vacuum pump/tank. Then I'd install the new brake pads with the caliper and pump to get the brakes working.

Also note, you may have to adjust the parking brake out if it was dialed in to adjust for the worn brake pads.
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Re: Noob life—rear brakes not working

Post by Mr Wazzock » Sun Jan 27, 2019 2:14 pm

ARRRGHH! Image Image

I've not done it but rear cali is a pig to bleed, you have to have it off and turned so that the bleed nipple points up, I believe - someone will be along later to describe the procedure hopefully...

What Harry said, did you remove the parking brake lever, then unscrew the worm shaft fully out? If you didn't, that is why piston won't go back. If you did, then piston may be seized so needs more "Application", or a caliper piston retraction (pressing back) tool.

I would not disturb the rear brake hydraulics under any circumstances except to renew the fluid (EDIT: because it's such a PITA)

EDIT2: should not need to remove fluid to push piston(s) back, it should go back up to the reservoir. If looks like overflowing, then take the excess out of the reservoir. Do not open bleed nipple! HTH
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Re: Noob life—rear brakes not working

Post by windmill » Sun Jan 27, 2019 3:09 pm

Yup, you got air in the system, it needs to be bled.

When installing new pads, the parking brake cam needs to be fully backed off so the piston can retract.

Bleeding the rear caliper isn't that hard when done correctly......screwing up and getting air in it is a PITA to correct.
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Re: Noob life—rear brakes not working

Post by HassoBoxhead » Sun Jan 27, 2019 5:56 pm

Thanks all for the replies. Is there a step-by-step, noob-level link for bleeding the rear brakes?
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Re: Noob life—rear brakes not working

Post by Lmo » Sun Jan 27, 2019 6:52 pm

Thank God for my old drum brakes.. . . :?
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Re: Noob life—rear brakes not working

Post by HassoBoxhead » Sun Jan 27, 2019 9:38 pm

There must be instructions somewhere....
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Re: Noob life—rear brakes not working

Post by windmill » Sun Jan 27, 2019 10:10 pm

Lmo wrote:
Sun Jan 27, 2019 6:52 pm
Thank God for my old drum brakes.. . . :?
The discs are actually less hassle with less maintenance and adjusting once one has the basics figured out, and they work way better.
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Re: Noob life—rear brakes not working

Post by windmill » Sun Jan 27, 2019 10:18 pm

HassoBoxhead wrote:
Sun Jan 27, 2019 9:38 pm
There must be instructions somewhere....
Not aware of anything Ural specific. There's countless videos on how to bleed a motorcycles disc brake.

The only differences from any other disc brake is that one needs to remove the caliper so the nipple is facing up, and the parking brake cam needs to be fully backed off by removing the 5/8" nut and the cable arm, then turning the shaft all the way counterclockwise.
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Re: Noob life—rear brakes not working

Post by eastbloc » Mon Jan 28, 2019 7:42 am

I’ve had my rear brake caliper get stuck during pad changes and needed to use a press to get it to fully withdraw to get the new pads to fit. That’s with the caliper fully removed from the bike and disconnected from hydraulics.

I routinely see people encounter the same condition between here and the various Ural Facebook groups.

I suck at setting up drum brakes and generally prefer discs, but must concede that the rear drums on my 650 work about equally well (both will lock up the wheel), the brake shoes last way longer and the system has fewer things to go wrong.
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Re: Noob life—rear brakes not working

Post by hotflash44 » Mon Jan 28, 2019 9:36 am

like mentioned above, remove the parking brake arm and the rubber cover from the rear caliper, then turn the adjuster counter clockwise CCW all the way.reason is if you have been adjusting the parking brake it needs to be adjusted back to allow the piston room to move back for new thicker pads. :cheers:
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Re: Noob life—rear brakes not working

Post by windmill » Mon Jan 28, 2019 11:14 am

eastbloc wrote:
Mon Jan 28, 2019 7:42 am
I routinely see people encounter the same condition between here and the various Ural Facebook groups.
The same calipers and masters are used on countless motorcycles, so is it being on a Ural that somehow causes issues, or maybe the issues are because of the user. Lack of knowledge, or maintenance appropriate for conditions can cause easily avoided issues.

I've noticed on Ural related forums some folks struggle with change. Some even seem to focus on issues they don't even have, and jump at every chance to repeat them or give advice.
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Re: Noob life—rear brakes not working

Post by eastbloc » Mon Jan 28, 2019 12:22 pm

I think I read somewhere that the caliper for the rear brake is in fact not used on countless motorcycles, but was designed for a Polaris three-wheeler. Few motorcycles need a parking brake.

I've also read some folks question the rotational position of the caliper as implemented on the Ural, but I'm no expert in hydraulic installation best practices.

I did find that the stock routing of the hydraulic line for the rear brake comes too close to the exhaust and heats up the brake fluid, leading to expansion related issues prematurely relative to the age of the fluid itself. I have to change my rear brake fluid every year to avoid this while the front and sidecar brakes do not suffer from this problem.
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Re: Noob life—rear brakes not working

Post by harryball » Mon Jan 28, 2019 12:29 pm

Having an M70/Retro that has had rear brake issues from day 1 (brake hose was chewed up due to bad routing by not me) and not being able to get the right parts from Ural, I have done it all with the rear brake caliper. I have bled brakes on the rear about a dozen times in the past 6 months. So, I use a "top end oil replacement pump" that sucks oil.

1) remove caliper to a) make it LOWER than the master cylinder and b) point the bleed port up.
2) fill up the brake reservoir with brake fluid.
3) put a 1/4" hose onto the nipple connected it to my oil vac and pump it up as much as possible.
4) crack open the bleed port and let it suck at least 1/2 the fluid through from the reservoir then close the port
5) Fill up the reservoir, pump up the pump and repeat 4
6) Repeat 5
7) Remove the pump, reinstall everything, top off brake fluid to the right level and pump the brakes.
8) adjust your parking brake

Like I said, I have done this at least a dozen times in the past 6 months, did my wife's brakes using this method too. Works well and every time.

Caveats:
The larger the pump the better it works, plenty of air volume sustains enough vac not to run out while moving fluid. If you use a smaller pump, just move less fluid each time and run it more often. The goal is for it to aggressively SUCK the fluid through purging air.
Using a compressed air venturi oil pump works well too.
Leave some used oil in your pump before introducing brake fluid and flush after the brake fluid with a bit of used oil too. i.e. brake fluid can be tough on the pump seals, The used oil dilutes

Hope that helps someone.
Last edited by harryball on Mon Jan 28, 2019 12:39 pm, edited 1 time in total.
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Re: Noob life—rear brakes not working

Post by harryball » Mon Jan 28, 2019 12:37 pm

Oh, AND...
Yes, back off your parking brake adjustment and then if you find you can't push the piston back in with 2 strong thumbs or light pressure from a C clamp, check that your brake peddle is not maintaining pressure on the brake master cylinder. I found that the "adjustment" on the brake peddle was causing the master cylinder to ALWAYS be under slight pressure. When the master cylinder is partially compressed, even slightly, the fluid will not flow back from the caliper when you press the brake cylinder back it. You are just pressurizing the fluid. Properly adjusted there should be NO pressure on the master cylinder from the brake peddle when not being pressed. I leave just ever so slightly of a tiny bit of play before the peddle engages the master cylinder.

Balancing the sidecar brake should always be done exclusively on the sidecar master cylinder. So your brake peddle to bike master cylinder might be as little as 1/2mm and should STAY that way. Adjusting how much gap before the plunger engages the sidecar master cylinder controls the balance.

Hope that makes sense.
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