Brake calipers sticking.

[kook911]

Ok guys kinda stumped at this point. My brake calipers are sticking on the front axle. I have replaced them with new ones from advanced auto thinking that was my problem. 

 

When the Jeep is cold or just starting up the brakes do not stick. The brakes stick after I have been running for a little bit. I can tell or at least I think that’s my problem because if I’m on a hill and set the Jeep in neutral the Jeep will not roll back. Also I can feel the Jeep slowing down on its own without me hitting the breaks. Last thing is I can smell the brakes burning. The fluid is clean. Any ideals on what else could be causing this? 

[gogmorgo]

Figure out which brakes are sticking. Should be easy enough, they'll be the ones where the wheels are warmer than the others. Drums can stick and drag if the hardware is old and crusty. Worn out wheel bearings can also cause misalignment of the pads and rotor in the front, less so in the rear, that would manifest as dragging brakes.

A plugged up brake line could cause dragging, either through some foreign contaminant in the system or internal wear... steel lines that have nasty old fluid sitting in them can rust out from the inside, rubber hoses can have flaps break loose and obstruct return flow.

 

Do you have any modifications to your brake system? Suspension lift, load-sensing prop valve deleted, etc?

[DirtyComanche]

Master cylinder would be my first guess given what you've done.  I'd give it a last hurrah at bleeding, and make sure the booster is disengaging, and then proceed to the master.

[Eagle]

Are the pads not retracting, or is the wear only on one pad on each side? Check the caliper mounts. I think I remember someone awhile back posting photos of where the calipers had worn a groove into the slider arm on the bracket, causing the calipers to hang up rather than float. I think he repaired it by welding up the groove and then re-shaping it with a file to the original configuration.

 

[DirtyComanche]

1 hour ago, Eagle said:

Are the pads not retracting, or is the wear only on one pad on each side? Check the caliper mounts. I think I remember someone awhile back posting photos of where the calipers had worn a groove into the slider arm on the bracket, causing the calipers to hang up rather than float. I think he repaired it by welding up the groove and then re-shaping it with a file to the original configuration.

 

 

Yeah, that's common, and I forgot about it happening.

[kook911]

22 hours ago, gogmorgo said:

Figure out which brakes are sticking. Should be easy enough, they'll be the ones where the wheels are warmer than the others. Drums can stick and drag if the hardware is old and crusty. Worn out wheel bearings can also cause misalignment of the pads and rotor in the front, less so in the rear, that would manifest as dragging brakes.

A plugged up brake line could cause dragging, either through some foreign contaminant in the system or internal wear... steel lines that have nasty old fluid sitting in them can rust out from the inside, rubber hoses can have flaps break loose and obstruct return flow.

 

Do you have any modifications to your brake system? Suspension lift, load-sensing prop valve deleted, etc?

 

Both sides are hot to the touch.  I could have a plugged up line but I don’t know how to check for that. The drum hardware is pretty much brand new as I just replaced it. No mods to the brake system. I do have a 3 inch lift and I need to delete the prop valve.

19 hours ago, DirtyComanche said:

Master cylinder would be my first guess given what you've done.  I'd give it a last hurrah at bleeding, and make sure the booster is disengaging, and then proceed to the master.

How do you make sure the booster is disengaging?

 

9 hours ago, Eagle said:

Are the pads not retracting, or is the wear only on one pad on each side? Check the caliper mounts. I think I remember someone awhile back posting photos of where the calipers had worn a groove into the slider arm on the bracket, causing the calipers to hang up rather than float. I think he repaired it by welding up the groove and then re-shaping it with a file to the original configuration.

 

I take a look at it tomorrow and see if that is the problem or not.  

[gogmorgo]

If it's both front wheels, there's a good chance it's the same thing causing the issue on both sides. Likely a master cylinder issue as Dirty suggested, but possibly not. 

Is there any free travel in the brake pedal, and does it return all the way on its own? It should have a tiny amount of movement before it engages, and it shouldn't lift up much if at all from where it returns to, I don't think. 

[kook911]

23 hours ago, gogmorgo said:

If it's both front wheels, there's a good chance it's the same thing causing the issue on both sides. Likely a master cylinder issue as Dirty suggested, but possibly not. 

Is there any free travel in the brake pedal, and does it return all the way on its own? It should have a tiny amount of movement before it engages, and it shouldn't lift up much if at all from where it returns to, I don't think. 

Brake pedal feels the same as my XJ. I can’t lift up on the pedal and it returns back to normal without any problems. 

[Dzimm]

I had the same issue with my truck after swapping to a dual diaphragm booster and master.  Turns out the rod in the booster was too long and I had to adjust it.  

 

If you haven't touched the booster and master this likely isn't the same problem but the symptoms being the same makes me think there is either a problem in your master/booster or the lines right at your master.

[kook911]

16 hours ago, Dzimm said:

I had the same issue with my truck after swapping to a dual diaphragm booster and master.  Turns out the rod in the booster was too long and I had to adjust it.  

 

If you haven't touched the booster and master this likely isn't the same problem but the symptoms being the same makes me think there is either a problem in your master/booster or the lines right at your master.

This could be the problem. When I swapped in the 91 HO motor I used the 87 renix master and booster. I just removed the clip at the end of the rod and called it a day. Might be my problem. How do you adjust the rod?

[Dzimm]

1 hour ago, kook911 said:

This could be the problem. When I swapped in the 91 HO motor I used the 87 renix master and booster. I just removed the clip at the end of the rod and called it a day. Might be my problem. How do you adjust the rod?

What clip are you talking about?  Did you swap out the brake pedal assembly when swapping the AX-15?  Is the pedal sitting where it's supposed to be?  Did you add or remove any spacers between the booster and firewall?

 

To adjust the rod I'm talking about, leave the brake lines hooked up but unbolt the master from the booster and pull it out of the booster.  You will see a rod in there that you can adjust.  On the dual diaphragm ones it's a rod with an adjustment screw on the end and you have to hold the rod with needle nose and spin the adjuster in. 

 

Push the master back in to see if you feel it engage before the mounts bottom out against the booster, you will feel the master pushing fluid.  If you feel that, then it needs adjusted.  If not, it's fine.  That rod needs to just barely not touch the master.

 

You make small adjustments at a time and push the master back in to feel the engagement on the rod.  As soon as you no longer feel the engagement, you shouldn't have brake drag anymore but if you go too far you won't have good brakes. 

 

Here's a picture of what I used to adjust it.  Did 2 or 3 test drives/adjustments before I got it where I liked it without dragging.  Also a picture of the rod on a dual diaphragm, not positive what the Renix one will look like but it should be similar.

[kook911]

1 hour ago, Dzimm said:

What clip are you talking about?  Did you swap out the brake pedal assembly when swapping the AX-15?  Is the pedal sitting where it's supposed to be?  Did you add or remove any spacers between the booster and firewall?

 

To adjust the rod I'm talking about, leave the brake lines hooked up but unbolt the master from the booster and pull it out of the booster.  You will see a rod in there that you can adjust.  On the dual diaphragm ones it's a rod with an adjustment screw on the end and you have to hold the rod with needle nose and spin the adjuster in. 

 

Push the master back in to see if you feel it engage before the mounts bottom out against the booster, you will feel the master pushing fluid.  If you feel that, then it needs adjusted.  If not, it's fine.  That rod needs to just barely not touch the master.

 

You make small adjustments at a time and push the master back in to feel the engagement on the rod.  As soon as you no longer feel the engagement, you shouldn't have brake drag anymore but if you go too far you won't have good brakes. 

 

Here's a picture of what I used to adjust it.  Did 2 or 3 test drives/adjustments before I got it where I liked it without dragging.  Also a picture of the rod on a dual diaphragm, not positive what the Renix one will look like but it should be similar.

 

Yes I swapped the brake pedal out when I did the AX-15 swapped.  So now my brakes light work off the plunger and the other thing.  I can take pics if I need to clear it up.  Well I think it is where it is supposed to be.  There is a spacer between the booster and the firewall.

 

The thing is this is a new problem to me.  The jeep drove fine for years.

[Dzimm]

4 minutes ago, kook911 said:

 

Yes I swapped the brake pedal out when I did the AX-15 swapped.  So now my brakes light work off the plunger and the other thing.  I can take pics if I need to clear it up.  Well I think it is where it is supposed to be.  There is a spacer between the booster and the firewall.

 

The thing is this is a new problem to me.  The jeep drove fine for years.

Pictures would help. 

Sounds like your booster to pedal rod is too long for the pedal assembly so the pedal is actually keeping some pressure on the brakes.  In that case, since you already have the spacer between the booster and firewall, adjusting the inner rod would probably fix it.

[kook911]

First picture is the old setup I had. The brake switch was built into the lever. 

 

The second picture is what what I have current. 

[Dzimm]

Ah yes I see what you did.  I've only seen the swap the other way (new booster with old pedal) and with that you have to do some modification to get it to work.  

 

Did you have to push the booster to pedal rod to get the pedal hooked up? 

[Dzimm]

I happen to have an older booster with newer pedal laying around so I put them together and that resulted in the pedal not even close to hitting the brake switch which is adjusted all the way back and the booster spacer is installed.  I realize I don't have the firewall here but that's not 3/4" thick.  Without the spacer it would be pretty close.

Did you run into this at all?  I'm wondering if maybe your brake light switch is adjusted so far in it's not letting the pedal come out completely maybe?

[Dzimm]

Just curious if you got this figured out?  

[kook911]

53 minutes ago, Dzimm said:

Just curious if you got this figured out?  

 

I have not.  I had business that had to be taken care of.  

 

Somto to answer your question yes that is what I ran into.  I just pushed the brake light switch further in the get the lights to stay off. Maybe I need to fab something onto the brake pedal so the brake light switch isn’t pushed so far in?  

[Dzimm]

9 hours ago, kook911 said:

 

I have not.  I had business that had to be taken care of.  

 

Somto to answer your question yes that is what I ran into.  I just pushed the brake light switch further in the get the lights to stay off. Maybe I need to fab something onto the brake pedal so the brake light switch isn’t pushed so far in?  

You shouldn't have to Fab anything as adjusting the switch is fine, I just wanted to make sure you didn't push the booster rod in to get the hole to line up.  At this point I think adjusting the inner rod should solve it.