YJ braking upgrade will not bleed rears - JeepForum.com
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Unread 10-24-2013, 01:04 PM   #1
jeep_boy02
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1980 CJ7 
 
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YJ braking upgrade will not bleed rears

Installed a YJ MC, Booster, bracket in my 80 CJ7... it was out of '92 I believe, no plastic pieces like I've read about the '95 upgrades...

I have a hand held vacuum bleeder and the fronts seemed to bleed out just fine but I am getting dang near not a drip from the rears. Barely any from RR and absolutely nothing from LR.

manual from the vacuum bleeder said closest to MC then work back, which is opposite from what I've always done... I even tried to gravity bleed them today, did the quick push on pedal to "reset" PV and then broke open the RR... got some drippage but no flow. the LF was tried and even left the bleeder screw out for over an hr and it didn't seep enough to even make a wet spot to the bottom side of the axle(SOA).

Should I have them "power bled"? any advice?

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Unread 10-24-2013, 01:20 PM   #2
jdarg
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Just a thought...did you bench bleed the master before mounting it?

I know on some years of Jeeps you have to either unscrew the pressure sensor from the combo valve or pull out a switch on the combo valve in order to bleed properly sometimes.
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Unread 10-24-2013, 01:39 PM   #3
jeep_boy02
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I bled the master with it mounted in jeep before hooking up lines.

"Combo valve"... not sure, I've never messed with anything like that on a cj. Is it in the mc or the pv?
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Unread 10-24-2013, 02:36 PM   #4
MoneypitCJ5
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Try alternating front and rear. I bet it's the proportioning valve closing off that's causing a problem.
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Unread 10-24-2013, 02:50 PM   #5
jeep_boy02
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I do remember seeing some where a clip looking deal to slide in place on the pv for brake work... is that a tool for holding it open to bleed? Dont remember where I seen it tho, common parts store stock item?
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Unread 10-24-2013, 03:02 PM   #6
MoneypitCJ5
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Yeah you can get the tool or create your own. If you alternate bleeding front and rear each time it works just as well.
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Unread 11-01-2013, 02:32 PM   #7
jeep_boy02
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Found a tool, it wont fit in the cramped space...

could I tell if it was sticking by just looking at it?

the nipple is sticking out past the body and I can depress it easily and it springs back.

should I replace the wheel cylinders? read on a yota forum that was causing a similar problem.

does the valve need to be in or out for bleeding? Im assuming pressed in
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Unread 11-01-2013, 08:25 PM   #8
jrussblues
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The problem with the YJ conversion is that if you do not adjust the pushrod between the booster and master cylinder it will compress the master cylinder piston just enough so that it essentially provides no pressure to your rear brakes. You can pull of the master cylinder and adjust the pushrod sticking out of the booster until it does not compress the master cylinder when you bolt it up to the booster. I have fought this fight before. Also be prepared for a funky pedal feel.
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Unread 11-01-2013, 09:04 PM   #9
CrankyD
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Quote:
The problem with the YJ conversion is that if you do not adjust the pushrod between the booster and master cylinder it will compress the master cylinder piston just enough so that it essentially provides no pressure to your rear brakes. You can pull of the master cylinder and adjust the pushrod sticking out of the booster until it does not compress the master cylinder when you bolt it up to the booster. I have fought this fight before. Also be prepared for a funky pedal feel.
Agreed, there are threads on here about making an adjustable pushrod for the swap. Definitely pull both wheel cylinders and replace them if they are more than a few years old, This is probably the problem. Also check out my M/C swap thread.

http://www.jeepforum.com/forum/f8/fr...-guts-1213015/
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Unread 11-01-2013, 10:44 PM   #10
Spieg8
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Quote:
Originally Posted by CrankyD View Post
Agreed, there are threads on here about making an adjustable pushrod for the swap. Definitely pull both wheel cylinders and replace them if they are more than a few years old, This is probably the problem. Also check out my M/C swap thread.

http://www.jeepforum.com/forum/f8/fr...-guts-1213015/
I may be wrong, but I think the adjustable push rod is for the pedal side of the booster, not the MC side.
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Unread 11-01-2013, 11:14 PM   #11
jrussblues
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The adjustability is on the pushrod coming from the booster going in to the mc
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Unread 11-01-2013, 11:45 PM   #12
skizriz
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Quote:
Originally Posted by jrussblues View Post
The adjustability is on the pushrod coming from the booster going in to the mc
If you adjust this rod too far, the front brakes will not release after a few miles when they get hot. Found that out the hard way.

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Unread 11-02-2013, 12:34 AM   #13
jeep_boy02
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So I need to separate the mc to find this adjustment? ... I did the cut and thread and add a coupler to the pedal mount. Will go ahead and do the wheel cylinders too
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Unread 11-02-2013, 07:44 AM   #14
jrussblues
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Quote:
Originally Posted by jeep_boy02
So I need to separate the mc to find this adjustment? ... I did the cut and thread and add a coupler to the pedal mount. Will go ahead and do the wheel cylinders too
Pulled the mc from the booster and you will it
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Unread 11-02-2013, 06:46 PM   #15
Spieg8
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Quote:
Originally Posted by jrussblues View Post
The adjustability is on the pushrod coming from the booster going in to the mc
This made me curious so I did some research. I believe you are referring to something like this?


Not sure if this is a difference in model years or maybe factory vs. aftermarket, but my booster does not have an adjustable rod on the MC side. Mine just has a fixed length post... no way to extend or retract.
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