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  #1  
Old June 9th, 2019, 15:22
ARB-XJ ARB-XJ is offline
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More soft brake issues

Just got done my one ton swap, D60/S10.5, all new hard and soft lines and calibers. Bleed the brakes together, pressure and gravity, not seeing any air bubbles at all. With the jeep off the pedal is rock solid after bleeding, but as soon as i turn it on the pedal goes right to the floor. Now i did try to move it, and at idle(all i was willing to try) it will stop the jeep no problem, but the pedal is still a complete sponge the goes to the floor.

Not sure where to go next? Keep bleeding? More air trapped? Jeep MC cant push enough for the superduty calibers?
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  #2  
Old June 9th, 2019, 16:39
Dragonlich1961 Dragonlich1961 is offline
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Re: More soft brake issues

im leading towords flow isues. look up the bore size of you current master and the bore size of the superduty the axles came from and compare
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  #3  
Old June 10th, 2019, 08:19
sandfreestyle sandfreestyle is offline
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Re: More soft brake issues

I just did a 60/14 with dual piston calipers on all corners and have similar problem. The stock MC can't push enough fluid for the dual pistons. The WJ booster and MC swap works but similar feel, Durango MC w/ WJ booster is much better, Ram MC w/ WJ booster is the biggest you can really go. The Durango and Ram MC bolt up with a modified bolt for a pushrod. Make sure to remove the seal in the prop valve if you had drums before the axle swap.

MC size comparison:
WJ - 1" bore
99-04 Durango - 1.125" bore
98-01 Ram Van (all) - 1.25" bore (shorter stroke)
98-01 Ram 1500/2500/3500 - 1.25" bore
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  #4  
Old June 10th, 2019, 12:46
cwyman6 cwyman6 is offline
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Re: More soft brake issues

Bigger the mc bore the harder the pedal which equals less travel. Time for a bigger master
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  #5  
Old June 10th, 2019, 12:48
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lazyxj lazyxj is offline
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Re: More soft brake issues

Quote:
Originally Posted by sandfreestyle View Post
I just did a 60/14 with dual piston calipers on all corners and have similar problem. The stock MC can't push enough fluid for the dual pistons. The WJ booster and MC swap works but similar feel, Durango MC w/ WJ booster is much better, Ram MC w/ WJ booster is the biggest you can really go. The Durango and Ram MC bolt up with a modified bolt for a pushrod. Make sure to remove the seal in the prop valve if you had drums before the axle swap.

MC size comparison:
WJ - 1" bore
99-04 Durango - 1.125" bore
98-01 Ram Van (all) - 1.25" bore (shorter stroke)
98-01 Ram 1500/2500/3500 - 1.25" bore
1998 Durango has a 1.065" bore.
It's what I'm running with ZJ rear discs and Vanco 48-mm dual piston front brakes. With a MC any larger, the boost is too low and the brakes cannot be locked up.
The master cylinder must be matched to the brake's caliper sizes.
Google "sizing master cylinder' for several sites that deal with this.
https://www.flickr.com/photos/lwade/...7616348032595/
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  #6  
Old June 10th, 2019, 14:13
ARB-XJ ARB-XJ is offline
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Re: More soft brake issues

Guess its time to get a ram MC..never ends..

Did drive the jeep around the block for the first time in 6 months, stopped fine, pedal just feels like its not doing anything.
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  #7  
Old June 10th, 2019, 17:17
RCP Phx RCP Phx is offline
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Re: More soft brake issues

I'm running a 2000 Durango, it's 1-1/8" and a direct fit for the +97 mc.
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  #8  
Old June 11th, 2019, 16:55
banderso banderso is offline
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More soft brake issues

I'd suggest not doing the ram master cylinder unless you've figured out how to fit a larger booster. I'm using the ram master with a dual diaphragm booster. Front brakes are Ford d60 dual piston, rears are e350 d60 disc. My pedal is high and hard. I love the feel. It gives the illusion of good brakes. But the truth is, with that giant master and relatively small booster, I'm not building enough pressure. PSI at the callipers is too low for effective braking. I have a Durango master to install. It's a trade-off between travel and pressure. I'd suggest one of the Durango parts will be the best option for you too.

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  #9  
Old June 18th, 2019, 14:43
ARB-XJ ARB-XJ is offline
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Re: More soft brake issues

Well i installed the ram 2500 master cylinder, bled everything again, inculding bench bleeding the MC....same....exact...issues...I dont get it. The pedal is rock solid with the jeep off. The moment you turn it on it can be pushed right to the floor. Again it will stop the jeep, it can even hold the jeep with hitting the gas, but the pedal is nothing but a sponge.

Am i just not bleeding them enough? Air trapped somewhere? I gravity bled them all twice, i guess i will power bleed them when the wife gets home...
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  #10  
Old June 18th, 2019, 14:49
sandfreestyle sandfreestyle is offline
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Re: More soft brake issues

You removed the seal/o-ring in the proportioning valve correct?
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  #11  
Old June 18th, 2019, 15:09
RCP Phx RCP Phx is offline
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Re: More soft brake issues

Pics of your set-up(front and rear) might bring clues.
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  #12  
Old June 18th, 2019, 17:14
ARB-XJ ARB-XJ is offline
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Re: More soft brake issues

Quote:
Originally Posted by sandfreestyle View Post
You removed the seal/o-ring in the proportioning valve correct?
Yes

Pics of the MC?
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Old June 18th, 2019, 17:54
RCP Phx RCP Phx is offline
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Re: More soft brake issues

No, showing your caliper orientation and bleeder screws.
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  #14  
Old June 19th, 2019, 14:09
ARB-XJ ARB-XJ is offline
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Re: More soft brake issues

they are all on the correct side, bleeder screws at the top.
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  #15  
Old June 19th, 2019, 16:47
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techno1154 techno1154 is offline
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Re: More soft brake issues

Quote:
Originally Posted by ARB-XJ View Post
they are all on the correct side, bleeder screws at the top.
If you were to use two strokes on the pedal, does it get higher? Thinking the fluid is somehow getting back into the MC from the calipers,...but on the XJ I do not see how that could happen,...the MC is a lot higher than the calipers.

The high pedal when the engine is not running is caused by the booster same as any other vehicle fitted with a vacuum brake booster. Your problem is beyond that. Difficult to trouble shoot online.

Is the rod from the booster to the MC the correct length? (I am grasping at straws here).
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