uuuuuu Whats up with my brakes!

[Infidel Edition]

So my 300+ trip to drill became a 9 hour 450+ mile trip in the snow!
All was good to go until I had to turn around from a fatality on 58 and back track 40 miles to I5 south and take the scenic route.

Ice and Chain beat Interstate the entire way at 5 - 20 MPH!
I hit my brakes to slow down for a semi and it's like air in the line soft.
I pump a few times and their back. Weak, but back.
Eventually, after I pass a toyota with big a$$ tires stuck in the snow, I find a rest stop.

Fluid was fine.
Lines were fine (covered in snow, but fine)

mushy but semi functional.
No clue

[gary63]

when was the last time you flushed the hole brake fluid with new. You my have some water or air or just old brake fluid.

[4.3LXJ]

You need a new master cylinder. The plunger cups are going bad on you

[bigjim350]

Also make sure there isnt any fluid coming out of your brake drums. The rear wheel cylinders are prone to leaking too.

[cantab27]

Also make sure there isnt any fluid coming out of your brake drums. The rear wheel cylinders are prone to leaking too.

x2 has happened to me ....

[Infidel Edition]

when was the last time you flushed the hole brake fluid with new. You my have some water or air or just old brake fluid.

Over the summer, I did all 4 wheels ~ and flushed all the fluid through. As well, a month and a half ago, put the longer lines on front and back and bled them at that time...


Also make sure there isnt any fluid coming out of your brake drums. The rear wheel cylinders are prone to leaking too.

Don't think I'm leaking any fluid as it was completely full. Like no more could be added full.


You need a new master cylinder. The plunger cups are going bad on you

So master cylinder? Would the caps go from 'ok' to 'AAAAHhhhhh' on the same road trip? I mean litterally no noticiable issues to "did a brake line blow out?"

One of the guys in my unit was saying in the cold, the engine isn't producing enough vacuume for the brakes...
Does the brake booster run off vacuume?
...and if so, could it be that?

I know it's not the brightest thing, but I'm driving it home tomorrow over the same snowy passes and crap.
As long as I pump them, they build up enough to work.
+ being a stick, I can use the engine to control my speed a bit.

And finally, if it is the master cylinder and/or the booster, is there a better (upgrade) replacement?
Or just keep it XJ stock?

[Infidel Edition]

Also make sure there isnt any fluid coming out of your brake drums. The rear wheel cylinders are prone to leaking too.

When I did change the rear brakes, it was like pulling a jello mold off.
Just black gel.

So I replace cylinders and all of the hardware at the same time.

[bigjim350]

If the booster was bad it would be a harder pedal to push not softer. When a booster goes bad it's like having manual brakes, which eguals a very stiff pedal.

Sent from my SPH-L300 using Tapatalk 2

[4.3LXJ]

One of the guys in my unit was saying in the cold, the engine isn't producing enough vacuume for the brakes...
Does the brake booster run off vacuume?
...and if so, could it be that?

I know it's not the brightest thing, but I'm driving it home tomorrow over the same snowy passes and crap.
As long as I pump them, they build up enough to work.
+ being a stick, I can use the engine to control my speed a bit.

And finally, if it is the master cylinder and/or the booster, is there a better (upgrade) replacement?
Or just keep it XJ stock?

Engines produce about the same vacuum at any temp. And yes, the vacuum of the engine is used in that big can on the fire wall to help develop enough force to operate disc brakes easily. As long as you can pump the brakes up, you will be OK. You can upgrade to the dual diaphragm booster (the can) off a ZJ for increased braking. Takes a little fabbing on the plunger off the brake pedal though. But that master cylinder will need to be replaced

[gary63]

I would go with booster or master cyl. starting to go bad when my booster was going out the pedel would start off hard and bleed down alittle at atime.

[Infidel Edition]

Engines produce about the same vacuum at any temp. And yes, the vacuum of the engine is used in that big can on the fire wall to help develop enough force to operate disc brakes easily. As long as you can pump the brakes up, you will be OK. You can upgrade to the dual diaphragm booster (the can) off a ZJ for increased braking. Takes a little fabbing on the plunger off the brake pedal though. But that master cylinder will need to be replaced

how much of a mod is needed?
...if I'm going to be dealing with the brakes anyway ~ I would just as soon make it better.
- so replace both in 1 swoop

[4.3LXJ]

I have the booster, but haven't done it yet. But from what I have read, there is a little work on the rod that goes from the brake pedal to the booster that needs to be done. A friend of mine did it and he doesn't weld, so I am thinking it can be done with hand tools

[Infidel Edition]

I'm going to raid the pick'n pull and I'll pull the booster off an XJ
AND a ZJ and see what it looks like.

Cause if I break it there, it don't mater as much :rolleye0012:

I noticed on RockAuto, it lists the ZJ booster as the D clip?
Maybe the rod from the ZJ needs to attach to the XJ brake peddle as well...

Friday's mission = pick'n pull!

[xj4life2]

the booster off a 96 xj I believe, is a dual diaphragm booster and a larger internal diameter master cylinder I cant say if its a direct swap on a 89 or not I had to replace the entire Renix system on mine to do it but it still only took a day. But I agree with steve the master is gone

[Infidel Edition]

so I finally had some time to work on it...
and discovered the tire was flat.
so as I pull it off, the drum clanks...
the clip on the bottom that holds the spring and the cable was cracked and let go of both...

got a new one (for each side) and rebuilt the brakes ...
good as new!

pry would have figured it out sooner if the ebrake worked (have to lengthen it a few inches before I tighten it down for use...