Can I bleed just the rear brakes?

[coheed]

As the title states I'm wondering if I can just bleed my rear brakes without having to do the entire complicated procedure from the FSM. 

 

Reason I ask is I just recently bled all of my brakes when I had to replace my rubber lines, then I disconnected just the rear during my axle swap. Hoping to avoid doing all of them again.

 

Edit: I should have mentioned that I do still have the rear prop valve installed, and don't want the extra hassle of removing it at the moment.

[Pete M]

the only way to bleed the emergency line running to the rear is via the factory procedure.  BUT, since it's not normally opened during the work you did, you might be able to get away with regular bleeding of the main rear line.

[coheed]

8 minutes ago, Pete M said:

the only way to bleed the emergency line running to the rear is via the factory procedure.  BUT, since it's not normally opened during the work you did, you might be able to get away with regular bleeding of the main rear line.

I disconnected at the wheel cylinders if that makes a difference. And clamped the rear rubber line while doing all the work so I would lose as little as possible.

 

Is there a way to check if the emergency line has air in it aside from tripping it or doing the factory procedure? 

[JeepSchmidt O'Guinness]

I see where you're coming from because that's what the front distrobution block is supposed to do, keep pressure on the front lines when the rears lose it. But I think the return line from the rear proportioning valve will have gotten air into the system, which is why we have that unique bleeding procedure.

If you had pinched the rubber line between the return T junction and standard (driver/passenger) T junction before the axle swap,then it's possible the system didn't get air into the return line. 

.... But even then its better to do lil'more work and be safe than to take the easy way and regret it later.

 

P.S. pinching said rubber line is more of a last ditch option trail repair because of potential damage to the hose. But when you don't have the required fluid / just need to get back to civilization aka supplies it can work in a pinch ;P

 

 

Hour late and a dollar short

Edited July 3, 2023 by JeepSchmidt O'Guinness
I miss qwerty

[JeepSchmidt O'Guinness]

It just hit me, is that emergency line for if the front lines fail so the rear gets full pressure from the front block?

 

Coheed, sorry for misinfo' and quasi thread jack.

Edited July 3, 2023 by JeepSchmidt O'Guinness

[Pete M]

the emergency line is like Schrödinger's cat in the box.  no way to know what's inside without cracking it open. 

 

at this point you can either:

 

-do the whole thing and know it's right

 

or

 

-just bleed the rears and then drive and see what happens.  maybe it'll be fine. 

[coheed]

56 minutes ago, JeepSchmidt O'Guinness said:

It just hit me, is that emergency line for if the front lines fail so the rear gets full pressure from the front block?

 

Coheed, sorry for misinfo' and quasi thread jack.

No need man. It's something inquiring minds want to know.

50 minutes ago, Pete M said:

the emergency line is like Schrödinger's cat in the box.  no way to know what's inside without cracking it open. 

 

at this point you can either:

 

-do the whole thing and know it's right

 

or

 

-just bleed the rears and then drive and see what happens.  maybe it'll be fine. 

I have an old crappy rear valve I could try and slice open on the band saw at work  I noticed a lot of debate about the emergency line in my googling and we might be able to figure something out that way? Or would we need to cut the front block open?

[gogmorgo]

We’ve got good cutaway shots of the front valve already. 
 

Pinching off a line to stop it from dripping out while the system is open may not be entirely kosher, but people do it all the time. I wouldn't be too concerned about that unless you were particularly agressive with it.

I’d also say it’s probably fine just to bleed out the rears again. But it’s always better to do the whole system, get rid of any junk in the lines, and get the newest brake fluid possible into it. It also helps to keep the bleeders from seizing. I would only ever bleed part of the system if I wasn’t going to be able to get some of the bleeders open easily. If they’ve never been opened sometimes they’ll fight you. But if you do crack a front bleeder to bleed the bypass, you definitely need to go back and bleed the front again.