Soft Pedal While Turning

[Alex01]

I've been trying to solve a brake issue for the last week or two and have been losing the battle. I'm looking for a bit of insight from you all since I'm about to admit defeat and take it to the shop.

Key issue: After turning hard right the brake pedal became soft and I would need to pump the brakes in order to stop the jeep. After speaking with the guru himself I was told it could likely be a bad wheel bearing or a bent axle which is causing the caliper piston to be knocked back.

What I have done so far.
1. Started with bleeding brakes
Outcome: No Change
2. A. Replaced wheel bearings and visually inspected axle/tube for obvious signs of damage - none
B. Swapped out my brake calipers with the OEM take-offs from @tomtaylz low millage LJR (looking back I shouldn't have added another variable) - Bleed the brakes
Outcome: Pedal became softer than before but could more or less stop the jeep.
3. Order New Master Cylinder - Install - Bleed the brakes
Outcome: Brake is firm while the jeep is off but once turned on it is spongy again.

I am confident the master was bleed correctly and I do not see any leaks in the system. I inspected the brake lines and nothing seems to be swelling when the brakes are applied.

I did notice yesterday when Tom was over helping bleed the brakes that the left side caliper would slide slightly on the caliper slides but the right side stayed ridged.

Any help or troubleshooting procedures would be appreciated.

 

[Goatman]

Have a friend spin the tire with you underneath with a flashlight to look for wobble. Can also be done with tire off, just make sure rotors are on tight with lug nuts.(Spacer to take up gap may be needed. Also, how old are the soft lines to the calipers? Could they be going bad? If they are that could cause a soft pedal too. With new master and new calipers it doesn't leave many other options. Did you bleed all 4 corners? New fluid throughout can't hurt either. Rear drums (I assume) set right? Might as well get it all up to snuff.

 

[Alex01]

Have a friend spin the tire with you underneath with a flashlight to look for wobble. Can also be done with tire off, just make sure rotors are on tight with lug nuts.(Spacer to take up gap may be needed. Also, how old are the soft lines to the calipers? Could they be going bad? If they are that could cause a soft pedal too. With new master and new calipers it doesn't leave many other options. Did you bleed all 4 corners? New fluid throughout can't hurt either. Rear drums (I assume) set right? Might as well get it all up to snuff.

Axles are from a rubicon so it has disks all the way around. The brake lines are SS RE extended lines that came with the 3.5" lift I originally installed. The plan today is to swap them out with YJ lines. I noticed yesterday the knuckle has a fairly deep groove in the where the brake pad sits so that will be swapped out also.

All 4 corners have been bleed each time something has been changed. I've ran about 100oz of fluid through the system at the point.

 

[Alex01]

My plan to test it out today was foiled. The upper ball joint tried to come out with ths knuckle and is now toast. Amazon says tomorrow so I'll attempt again once they arrive.

 

[Daryl]

Does your Jeep have ABS?

 

[Alex01]

Does your Jeep have ABS?

It does not.

 

[Daryl]

It does not.

Good, sometimes it’s a bitch to get the air out of the ABS valve. I would check to make sure the calipers slide freely in the caliper brackets. I would also remove the caliper bolts and boots, clean the grease off and reapply fresh caliper grease. Those can get real gummy and sticky over time.

 

[Alex01]

I may have jumped the gun on thinking the ball joint failed. The upper has vertical movement and not side to side which after further read I guess is normal.

 

[Daryl]

I may have jumped the gun on thinking the ball joint failed. The upper has vertical movement and not side to side which after further read I guess is normal.

Yup. Check out this picture. Upper on the left, lower on the right.

 

[Alex01]

Issue has been solved. The knucke damage must have been the cause. I think it's braking even better than before. It will lock up the front tires fairly quickly.

I read that these could be repaired by filling in the missing bit with a weld and grinding it flat. @Daryl @bobthetj03 @DrDmoney or anyone else on the rubicon trip want to fix this one and have a spare?

 

[Daryl]

Issue has been solved. The knucke damage must have been the cause. I think it's braking even better than before. It will lock up the front tires fairly quickly. View attachment 107935

I read that these could be repaired by filling in the missing bit with a weld and grinding it flat. @Daryl @bobthetj03 @DrDmoney or anyone else on the rubicon trip want to fix this one and have a spare?

Good job. I would just replace it. Unfortunately I don’t have a spare.

 

[DrDmoney]

Issue has been solved. The knucke damage must have been the cause. I think it's braking even better than before. It will lock up the front tires fairly quickly. View attachment 107935

I read that these could be repaired by filling in the missing bit with a weld and grinding it flat. @Daryl @bobthetj03 @DrDmoney or anyone else on the rubicon trip want to fix this one and have a spare?

Glad you figured it out, I think you would have to stick weld it with a high nickel rod to fix it. Thanks for the offer though.

 

[DrDmoney]

Is this the cause of the problem?

 

[Alex01]

Is this the cause of the problem?

Right here.

It should be flat like on the top to the left of the red mark .

 

[Alex01]

I think those marks where the cause to the problem of why I couldn't get the pedal to firm up. I believe I has having the lose of power issue because the caliper was contacting the new shock mount at full bump. I added a few washers to the stops to prevent that issue.

 

[DrDmoney]

Right here.
View attachment 107949
It should be flat like on the top to the left of the red mark .

Those are so perfect they look machined in. Did you check the other side to see if it was damaged too?

 

[Alex01]

Those are so perfect they look machined in. Did you check the other side to see if it was damaged too?

The other side was replaced a year or two ago and are flat.

Here is a photo from the spares off Tom's jeep (and my shoes). You can see the knuckle is already being worn down in the same area on the top half.

 

[DrDmoney]

So it has a good firm pedal and it’s not pulling in any direction? Did you also change out the brake lines?

 

[DrDmoney]

The other side was replaced a year or two ago and are flat.

Here is a photo from the spares off Tom's jeep (and my shoes). You can see the knuckle is already being worn down in the same area on the top half. View attachment 107951

So that’s damage from the brief time you had it on to replace your old one?

 

[Alex01]

So it has a good firm pedal and it’s not pulling in any direction? Did you also change out the brake lines?

Yes, the pedal is firm and it brakes straight. I did not swap over the lines at this point since I didn't want to add another variable. My thought was they worked previously so I wanted to at least get back to where I was a week ago before I started messing with the brakes. I could have saved lots of time/money/frustration if I just replaced the knuckle and added washers to start with.