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Brake system failures an MJ commonality ? ? ?


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When i bought the truck it had all the brakes replaced pior to the sale/trade for it, but they still didn't work turned out the Reman master Cylinder was shot out of the box got it warrantied out now the breaks are acting and same way as they did before.

 

So i am guessing another M/C failed on me tonight . . . pump pump hold pressure slow fades way . . . with no leakage to be seen ! ! !

 

I'll trouble shoot further later on, I just limped the MJ home tonight and of course she's loaded heavy enough to sit level anywho i guess for now its back to driving the K2500 :wall: I miss the jeep already :fs1:

 

:hmm: So i got life time stuff so it'll be fixed with what it had for now, But is there Good brake stuff ? . . .its good stuff . . .better stuff ? :???:

 

Currently the whole brake system is O'reily's life time stuff . . . any good/better after market direct replace stuff ?

 

Mike

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Almost every time I use a reman MC it seems like I go through a few bad ones before I get a good one. If they miss one little burr when honing the cylinder, it will cause a defect.

 

Another thing you may want to check is the rear brakes. If the pads aren't adjusting correctly, or the wheel cylinders are bad, it can create the same symptoms.

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The WJ master and booster swap is so easy, with such a huge benefit, I'm surprised more people haven't done the swap. I think people put too much thought into getting the booster arm end ground down flat. I just took the WJ booster to a disc sander and sanded down the end until it looked like the pictures and had a similar gap to the old booster (I didn't measure), drilled out the hole with step drill, and it worked first try. I've never had any brake light issues, they come on right when the free play is out of the pedal, and turn off every time. Maybe I just got lucky :dunno: , as I had planned on measuring the spacing with a set of calipers, but I couldn't find them and got impatient. :rotf:

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:dunno: Sounds like a PITA to me :doh:

 

Measure this tweak that adjust this these parts work ok those parts work better but all of the parts can be modified to work . . . Sounds cobbled to me :shake:

 

I simply want to unbolt toss in trash and rebolt up bleed out drive, Yep i want it just that simply :banana: I guess i'll just continue on using the factory MJ brakes, i will just have to learn that its NOT really a truck as well as try to stop using it as such . . .

 

 

Mike

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i'll just continue on using the factory MJ brakes, i will just have to learn that its NOT really a truck as well as try to stop using it as such . . .

If it isn't a truck ... what is it? "Real" trucks don't have master cylinders? Or are you saying that Chinese aftermarket parts for "real" trucks never fail after 3 or 6 months?

 

Put things in perspective, Mate. AMC/Jeep did not make the part that went bad on you, so how does that in any way reflect of the design or quality of the vehicle? The master cylinders used in the early XJs and MJs were exactly the same as the master cylinders used in Fords of the same vintage. Including Ford trucks.

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If the truck was ran with in spec all would be fine, but its Basically a 1/4ton sized truck built like a 1/2ton truck and i am running it like a 3/4-1ton truck . . . So for me its more of a "car" with a bed so to speak . . .

 

Only thing i see the GC master/booster doing is burning up the pad's/shoes faster, Tho i am sure it'll stop better no doubt but now your putting WAY more pressure to the lines calipers and wheel cylinders the AMC/Jeep had ever intended . . .

 

Which will only cause them "cheap Chinese" parts known as "bendix brand" (I thought Bendix was OEM AMC/Jeep) to fail more often and wear much faster :thumbsup: while only stopping marginally better ;)

 

Truck's been grossing 6375LBs to 7125LBs ;) That 4 banger 4spd n 3.73s spins them 235's under said load just fine :banana:

 

It'll get up to and maintain 70mph with no issues tho i try to take route where i only gotta run it 45ish to be easier on the truck . . . Just saying mechanically it'll tow Full sized truck loads at highway speeds should the need arise . . .

 

Braking seem's to really only be this trucks down fall . . . i guess it is what it is, Unless i wanna make shift another Booster/Master into the system.

 

Not a big fan of Make shifting things like Brakes :eek:

 

Mike

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Under normal operation you will not be applying more pressure through your braking system. The brake pedal effort will be lessened so you won't press the pedal as hard for the same braking result. This will have NO effect on the lifespan of the pads.

 

The M/C might say bendix on it, but if it came out of an A1 Cardone box (Oreillys reman master cylinder) then it was rebuilt in mexico.

NOT OEM

 

I would warranty it out at OReillys and ask instead for the brakebest select new master cylinder, you will pay the difference, but it is FAR less likely to fail.

 

 

And you say you use it like a full sized truck, so in what way would it mean it's a car with a bed?

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Currently i have an AMC-V8 engine in the bed i have to brake very hard for marginal stopping . . . So to make it stop normal i would in fact be applying more pressure to the system on a daily basis . . .

 

I definitely do pleny of down shifting and this is before the M/C malfunction now i am really replying on the Engine/trans for stopping and slowing power . . .

 

Mike

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Currently i have an AMC-V8 engine in the bed i have to brake very hard for marginal stopping . . . So to make it stop normal i would in fact be applying more pressure to the system on a daily basis . . .

 

I definitely do pleny of down shifting and this is before the M/C malfunction now i am really replying on the Engine/trans for stopping and slowing power . . .

 

Mike

 

Something is definitely off then, with the weight of the V8 in the bed, it should still stop normally. I have had mine loaded down with firewood (locust logs, weighing more than a couple AMC V8s), and only took a little more than normal to stop it. That was also with 33s. Are you running cheap pads and shoes? Good ones will make a difference!

 

And again, are you sure the rear brakes are properly adjusted? This could explain ALL of your problems. Even if there are new parts, it doesn't mean the self adjusters are self adjusting.

 

I will add that I now run rear discs, and it stops even better. The stock brakes aren't bad, but there is almost always room for improvement. I also have a 96 booster and MC in my garage just waiting on me to install it.

 

Only thing i see the GC master/booster doing is burning up the pad's/shoes faster, Tho i am sure it'll stop better no doubt but now your putting WAY more pressure to the lines calipers and wheel cylinders the AMC/Jeep had ever intended

 

How are you applying more pressure than they ever intended when THEY are the ones that switched to these boosters?

Your not really applying a lot more pressure than you can with the original parts anyway, it's just much easier to press the pedal, making for a much more comfortable and responsive feel.

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If all the W/C's Booster/master is going to do is make the pedal easier to push for my own comfort then its not what i want . . .

 

As for the components So when Jeep went tot he new booster/master combo they continued to run the same calipers and wheel cylinders as the old system did they ? . . .

 

Apparently i got more trouble shooting to do i guess, it'll have to survive for now cause i have to try and find $4,000 in 45 days or i'll be living in the MJ . . . Homeless in T-minus 45days . . . I need that K2500 to sell but no one seems to be interested, all trying to get everything for nothing :fs1:

 

 

Mike

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As for the components So when Jeep went tot he new booster/master combo they continued to run the same calipers and wheel cylinders as the old system did they ? . . .

 

Mike

 

Yes... they did. The rear wheel cylinders never changed, same part number for ALL year XJ and MJ, 84-01! The front calipers did go through a change in 1990, but that was before the dual diaphragm booster was installed in 96.

 

There are NO worries with this swap whatsoever! I did it on my old 90 XJ with nothing but positive results. It's also a very common swap and has been done many times. No one has ever complained after doing it.

 

At the same time, I agree it will not be a fix to your current problem, and is only considered an upgrade, not a fix.

 

I still say take a look at the rear adjustments! If the pads aren't tight enough, they will require excessive travel to engage, thus the cylinder needs more fluid than the MC pushes, resulting in a soft pedal. These can be manually adjusted with a flat screwdriver through the slot on the backing plate (below the axle tube, it should have rubber grommet in it). A service manual should be able to describe this procedure in better detail than I, but post up if you need help.

 

And I wish you the best of luck with your financial situation.... and they say the recession is over :shake: :mad:

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Yea I'm sure for the big company's the economic out look is much brighter.

But for poor folks like me the story is not quiet the same.

 

I'm not exactly driving a 22 year old truck for fun or as a hobby, for me obsolete relics are a way of life.

Glad this one was an AMC/Jeep.

 

Mike

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the WJ booster is capable of much more pressure than the old single booster, but that doesn't mean you'll be using that extra pressure all the time. your brake pads won't notice any difference day to day.

 

but when you do need that extra oomph to yank on the reins, whoa momma, it's there. :D

 

but I would exhaust all other possibilities first. likely won't make a lick of difference if something else is broken.

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:fs1: This little chunk of rolling scrap Iron is really pissing me off :wall: I pump the brake a few time and get nice firm pedal and smash down hard on the brake they won't lock up, but i can get them pour smoke like an SOB :headpop:

 

So they seem to be function just simple don't have enough power to stop the rolling weight :ack:

 

 

Mike

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From my experience, on the old MJ master cylinder and booster, I couldn't lock the wheels no matter what unless I was in a panic situation. When you are in a panic stop (ie: suddenly slamming the pedal from the top to the floor) The the pressure going to the wheels will be greater because of several reasons, one is that the rear prop valve will reduce pressure to the rear wheels to make them lock up later and create more system pressure at the front wheels because the rear wheel pressure is limited. Also, when you first slam the pedal down, you have more braking force as there is more vacuum pressure readily available to go towards helping you increase the braking force at the pedal. The same is true in my 91 accord as well. If you want brakes that will lock up the wheels at any time if you mash the pedal down, you need to upgrade boosters, thats really one of the only ways to do this. General rule of thumb, if you have a firm pedal, there isn't air in the system, and none should get in if you don't have pedal fade indicating a leak or bad part.

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:cheers: that is just how i tested them cranked it up to 75mph then slammed down as hard as i could on the breaks, the smell was horrendous :ack: The pedal didn't star to fade till shortly after the smoke n stench of hot brakes started pouring into the cab of the truck :dunno:

 

Nothing locked up, way way more smke came out the front then the rear but the rear did some smoldering :yes:

 

I hope i didn't abuse my truck to find out nothing, hopefully this info is helpful to you guys in some way, and YES i did check the rear brakes seem to be right par but tightened them 2 more "clicks" if you will . . .

 

If just stab the brake it'll do as above now it town i pump them 1 . . 2 then hit the pedal and get a firmer pedal but it really stop any better still labored and sluggish . . .

 

 

Mike

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I have the same problem, I can't lock up the brakes....not even on dirt, but I have extra rotating mass with the 35s. Also, I have 90' S10 calipers and pads, but I don't think they're the problem. The booster and MC are stock 89 MJ. Yesterday I picked up a WJ booster and MC, just need some hard lines from the MC to the distribution block and I'm in the money. I got em from a yard for 80 bucks and they pulled it for me...another yard wanted 150 for the two if I pulled it.

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:fs1: I broke my phone, oh and might be losing my internet . . . But i'll hit up a few yards this weekend stacked full of XJ's N wj's see if i can't scare up one of these neat MC/Boosters and get this swap done up . . . jamminz.gif

 

 

In case i don't see ya for a while MJ's for life :waving:

Mike

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:fs1: my rear brake are not working :wall:

They are adjusted perfectly, spin the rear wheels stand on the brake tires keep spinning :headpop:

 

So the front's have been doing all the stopping for a while . . .

Mike

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