Having front brake issues

[mbogosia]

I recently bought a 1999 XJ. I noticed the front brakes were not very strong and they also make a scraping type noise when applied. I wouldn't call it grinding though. So, I replaced the front pads and rotors and sure enough they had some slight grooves on the backs of the rotors.

Now, it feels like my new pads and rotors are doing the same thing. They stop okay. Still kinda weak. The pedal feels firm so I don't think they need to be bled. Or could they need to be bled even though the pedal feels firm? If not, could my calipers be bad? Autozone has remanufactured ones really cheap.

Or, lastly do the xj brakes just kinda suck and I need to get used to it?

Thanks

 

[Windsors03Cobra]

I have an 88 POS and I believe the front brakes are just small for the truck, on mine it looks like amc/renault just sourced some chevy celebrity fwd pos brakes for it.
Weak sauce brake power in front, could be I have junk pads too but they are like 60% left and dont shake, shimmy or grind, they just suck.

Not to jack the thread but I have too have a front brake issue.
No fluid/pressure to the front right caliper, I'm thinking bad/delaminating brake hose that has choked off flow to the caliper. I plan to pull that hose off the line tommarow and hope to have fluid where the line meets the hose. Front brakes were working fine till I went and fixed the busted rear brake line and bled the brakes.

 

[WB9YZU]

I recently bought a 1999 XJ. I noticed the front brakes were not very strong and they also make a scraping type noise when applied. I wouldn't call it grinding though. So, I replaced the front pads and rotors and sure enough they had some slight grooves on the backs of the rotors.

Now, it feels like my new pads and rotors are doing the same thing. They stop okay. Still kinda weak. The pedal feels firm so I don't think they need to be bled. Or could they need to be bled even though the pedal feels firm? If not, could my calipers be bad? Autozone has remanufactured ones really cheap.

Or, lastly do the xj brakes just kinda suck and I need to get used to it?

Thanks

A common problem with Mopar knuckles is that the brake pad edges dig into the caliper brackets and make notches. This will make the caliper not function correctly. If you have that problem, and it's easy enough to spot with the caliper off, you can either replace the knuckle, or build up the area with a welder and grind it back down to spec.

An assembly problem on the late model calipers is not loading the outer pad correctly. The two "pins", or bumps on the backing need to fit in the two holes in the caliper. If you load it wrong, the pad will wear unevenly and may even squeal a bit.

Lastly, the caliper rides on two pins the bolts go though. You should be able to easily move those pins in and out.

I hope that gives you some ideas.

Loss of brake performance/lousy bakes:
It's a system. Both fronts and backs need to work right.
Brakes on the D35 axles were nothing to write home to mom about (10" IIRC) as they were skinny. The ones on the C8.25 are better (9", but fatter). A suprising amount of braking is done by the rears, so if they are out of adjustment, the effectiveness of your brake system is reduced.

 

[mbogosia]

Okay, I just greased the caliper pins and I still have the problem. I am beginning to think my rears are not helping and that might be the cause. Anyone know a write up on replacing the rear drum pads?

 

[WB9YZU]

Okay, I just greased the caliper pins and I still have the problem. I am beginning to think my rears are not helping and that might be the cause. Anyone know a write up on replacing the rear drum pads?

Not to sound like an azzhat, but...
You should get a service manual, like a Haynes, or a Factory Service manual. That is what those manuals are, one big "writeup".

Put it on stands, and take the rear wheels off. Now pull the drums. Take a look at the shoes. The Minimum standard I use is: If the liner is glued to the shoes, there should be atleast a good 1/8" left. If riveted on, the rivet heads should be atleast 1/16" below the liner. Above that good, below that, replace.

Keep in mind that your rear brakes may just be out of adjustment, but inspecting your rear shoes is a good idea anyway.

 

[mbogosia]

Good advice on the manual. I just hate thumbing through a book with bad pictures. I always feel like write up's on the internet have good information. I might jsut buy a downloadable manual tonight though.

If my rear brakes were failing wouldn't they make noise though? A grinding, squealing, etc... I hate to do it, but I might jsut buy new calipers and try that route. They are only $18 or so at the parts store.

 

[WB9YZU]

Good advice on the manual. I just hate thumbing through a book with bad pictures. I always feel like write up's on the internet have good information. I might jsut buy a downloadable manual tonight though.

If my rear brakes were failing wouldn't they make noise though? A grinding, squealing, etc... I hate to do it, but I might jsut buy new calipers and try that route. They are only $18 or so at the parts store.

Rears have been known to make cool noises too,

While you are up front, take a look at the hubs. They shold turn smoothy with no grinding feeling and no slop.

 

[mbogosia]

Will do. I appreciate your help. I will be back tomorrow and let you know how it is going.

 

[Matthew Currie]

Weak brakes and a firm pedal? Have you checked that you're getting enough boost?

1. Sit in vehicle, punch brakes a few times with engine off until pedal is completely firm. Now, holding pedal down firmly, start engine. Does pedal sink noticeably? If not, booster may be bad, or vacuum line to it.

2. Set handbrake or put tranny in park, let engine idle for a few seconds after the last brake application, and then shut off. Come back in a few hours, and push brake pedal. Do you still feel boost for the first couple of applications, before it firms up? If not, booster or valve in vacuum line is leaking.

You should also open up the rear brakes and check that they're all together properly, and then manually adjust them. The automatic adjusters can fail from various causes, including rusted cables and seized adjuster barrels. If they go far enough off, you'll have poor braking, though I'd expect that to be accompanied by a lower pedal.

And double-check on Zuki ron's suggestion about the damaged caliper slides. I'd expect it to pull to one side if a pad is hanging up, but it's possible that it's the same on both sides.

 

[mbogosia]

1. Okay, the brake did sink so I think my booster is okay..

I'm also going to pull the drums off and inspect the rear brakes this morning. When I pull my emergency brake it has to be all the way for it to actually hold. If I pull it 1/2 way and leave it I can drive around like it isn't even engaged.

 

[mbogosia]

UPDATE:

I checked the rear drums. The pads looked fine and I even adjusted them out a bit.

I then rebled the whole brake system. The brakes stop great now. I did one stop and everything in my jeep flew forward. LOL

But, I still have a weird noise. I am beginning to think it is my driveshaft or a axle bearing or something. You can hear it faintly even when not braking. Although it is much more pronounced when I brake. Sounds similar to a grinding brake pad but it is much less pronounced and I don't feel anything on my brake pedal. And it stops on a dime.