McCaffrey

Rears lock up before fronts which can make it a bit frightening coming down lose hills where the rear wants to come around. With enough pressure both front and rear will lock. I just get more in the rear initially. Pretty sure everything is working correctly and all components are semi-new.

I'd like to get aftermarket pads/rotors in the front but 89 XJ so not an option. At some point I want to swap out with 1-piece knuckles and everything with later model to have this option. Any other ideas is appreciated.

Mods:
WJ brake booster and master.
C8.25 from an 93. Stock brakes.

Pelican

Rear locks first to keep it from coming around. Think about what would happen if the front locked first.

Jamie57

I was not going to comment on this but my concern for everyone's safety made me do it.


You do realize that in a disk brake/drum brake setup it is actually designed by the ENGINEERS to have the front disk do almost 60-75% of the braking don't you?


A vehicle where the rear wheel drums lock up first is a symptom of a malfunctioning system.
His braking is greatly compromised and could lead to a serious collision because the braking distance is now much, much greater than it should be.


This should be looked at by a braking expert before someone gets hurt.


To the OP, are your pads and rotors you currently have in good shape? Are the calipers stuck or seized? How old are the brake hoses? They have been known to collapse inside and reduce the volume of brake fluid to the caliper.


If the front is OK than the backs are either out of adjustment (too tight) or something else is making them come on too early.
A contaminated shoe or metal on metal are also likely culprits.


Either way your system is in need of attention NOW. Your WJ mod should not have made any difference except in making more pressure available to the system.

McCaffrey

I actually didn't even notice the problem until wheeling after a rain. Then I did some hard braking on the street and found the same issue. Yes, it's a big concern to me as well and I understand the danger. Hence my question. It's not my DD so it can sit until fixed.

Pads, rotors, shoes are all relatively new. Drums in good shape. Calipers are old though so I'll replace them per your suggestion. Hoses are less than 2 years and I'm very sure there is no air in the lines. But yeah calipers are cheap enough so I'll change those. Thanks.

PocketsEmpty

I'm going to guess that your adjustment is out of whack. Try turning it back some so that the shoes aren't pressing outward as much. Also be wary of your E-brake as this concerns it as well.

caronaxtr

Have you pulled your drums off the rears? You may have some crud in there. I had a similar issue with my TJ, ended up there was so much crud inside the drums that when I hit the brakes they would prematurely lock up.

Also, when you did the WJ mod, do you use the WJ proportioning valve? If I'm not mistaken, since the WJ had front & rear disk brakes that valve will put more pressure (psi) to the rears than the drums need.

Just a thought

McCaffrey

No. I used the stock prop valve. I'll check the rears for crud and over-tightness. Thanks.

cruiser54

Thank you for straightening that out!!
Saved me a bunch of *****ing and typing.

Rogue4x4

Proportioning valves can go bad too...may want to check it...check your adjustment as others have suggested

Jamie57

I learned in the first year I got my drivers licence (the hard way of course) that any idiot can go fast. It's the smart one's that can also STOP fast.
Every vehicle I have owned in the last 40 years has always had some kind of braking mod to help me stop faster.

salad

Sounds like what typically happens when drums get wet. I'd do a disc brake swap and be done with it.

Also the rear will always lock up more easily as there's very little weight back there. Not much can be done about that aside from loading up the junk.