Shaking while braking.

Hello again all! So I've had this problem forever in a few different Jeeps, but I have a 1989 Jeep Cherokee Laredo, I had this problem with shaking whenever braking at anything higher than 25-30mph, figured warped rotors. Replaced rotors and pads, solved the problem, a week later, slowly made its way back. Replaced back brakes. Did nothing. Replaced rotors and pads again awhile later, this time did calipers too. Solved the problem. Again, a week later crept back up. Figured it was time to do this anyway, replaced ball joints, wheel bearings, axle shaft u joints. Tie rod, tie rod ends, adjusting sleeve... Whole new front end except track bar which had zero play, and steering stabilizer which should be changed. Got an alignment. Did leaf springs on both sides in back. Again, new rotors and pads(and pins in calipers.) solved the issue! Until a week later... Same stupid thing... Does anyone have any idea why the heck this happens to all of my Jeeps?

 

Wow. Same issue with numerous Jeeps. My guess. It's not the Jeeps. Just kidding.

Just a guess. And I hope some one with more experience and knowledge will help. But my guess. If you replace pads and rotors. You need to slowly break them in. If you don't. You create high and low spots on the rotors. And as they heat up with use. It makes the problem worse which. But again. Just a guess.

Anyone else??

 

Don't take this the wrong way but: new rotor(s) per axle, quality brake pads all around, no frozen calipers or pistons right?, not overtightening the lug nuts right?, proper pad/rotor break-in? Not picking on little rocks around the mall are ya lol?

 

Oh okay, how should I properly break in my rotors?

 

Hahaha. Can't tell ya the issues that little rock caused me. Lollll.

BTW. What this member....ahh....aggrex said. Brakes are very fickle. One little issue, stuck parts, or even a bubble. Can cause issues. Just take your time with brakes. The lack there of......can kill ya. Just a thought.

 

I noticed in the master cylinder there was a considerable amount of gunk mixed together with the fluid, could that be part of it?

 

Whether or not that gunk is related to your braking issues that brake system needs to be flushed out. Check the lines for corrosion, fill with fresh brake fluid and bleed the entire system.

 

I have found with late model Jeeps that the front brakes are very touchy. New rotors are a good thing, You say you replaced the calipers, for the record they are rarely the problem. Make sure all moving parts on the calipers and anchors are lubed with Sil-glide or something that is the equivalent. Also use the same lube for the back of the pads (helps with noise). With today's not ceramic pads brake in on temperamental vehicles is a must. I would stay on paved roads for a couple weeks if you can take that lol. For sure torque the front wheels by hand....no impact. This may be redundant but really should help son.

Jack

 

Not sure what's causing it but I would stop throwing rotors at it

 

Copied from: https://brakeperformance.com/bedding-in-rotors.php

Bedding In Brake Rotors

Anytime you install new brake rotors, brake pads, or both, it's advantageous to bed in your new brakes. Bedding in your brakes is just an industry term to explain breaking in your new brakes. Bedding in your brakes helps transfer an even layer of brake pad material onto the brake rotor which assists in smoother brake operation and improved braking power.

Having a uniform layer of pad material on the brake rotor is essential to minimizing brake squeal and vibration. For this procedure, you will need a good stretch of road and no traffic.

Use common sense and take precaution as BrakePerformance does not take responsibility for erratic driving, accidents, or damages done.

Note: When using Brake Performance Zinc-Coated rotors, as soon as you start braking, the friction from the pads will strip the zinc from the pad surface, turning it Silver and leaving the holes, slots, and the rest of the rotor zinc coated in the color you selected.

• Perform 3-4 medium stops from 45mph. Slightly more aggressive than normal braking. You don't need to come to a complete stop for each pass. This brings the brake rotors up to temperature so they are not exposed to sudden thermal shock.
• Make 10-20 aggressive stops from 45mph down to 5mph. For this set of semi-stops, you want to be firm and aggressive, but not to the point where ABS activates and the wheels lock up. It's important to note that you don't come to a complete stop but rather a semi-stop (~15mph). Accelerate back up to 60mph as soon as you slowed down to your semi-stop.
• The brake pads and brake rotors are extremely hot at this point and sitting on one point will imprint the pad material onto the surface unevenly. This can cause vibration and uneven braking.
• You may notice that your brakes will start fading, and sometimes smoke, after the 6th or 7th pass. This fade will stabilize and will gradually recess once your brakes have cooled down to normal operating temperatures. Drive carefully as your brakes may feel softer for the next few minutes.
• Try not to come to a complete stop and find a stretch of road where you can coast for 5-10 minutes, preferably without using your brakes.

After the break-in procedure, there may be a light blue tint on your brake rotors as well as a gray film deposit. The blue tint shows that your rotor has reached the appropriate temperature during the bedding process, and the gray film is some of the pad transfer material.

Some cars and trucks require two cycles of the bedding in procedure. This may be the case if you are using old brake rotors with new brake pads, or new brake rotors with old pads. This may also be the case if you don't think you fully heated up the brakes in the initial bedding procedure. In any case, it's required that you wait at least 10-15 minutes between each cycle as you don't want them to overlap.

 

I am going to tell a short funny story about my father in law rest his soul. He could remember when disc brakes came out . Well to shorten this story for several brake jobs he put the coating ( that comes with almost all disc pads now ) on the friction side of the disc pads! I remember him telling me one time that coating ##### don't work worth a damn . Once the brakes seat in it stops working and they squeal again. I had to bite my tongue to keep from laughing. I instructed him how to use it after that and he never had another problem with it. He also asked me to never bring it up again lol.....that didn't happen ....sorry Lloyd