Wrangler X 2006 TJ, rear brakes lock-up.

[Mark 47 willys]

I had this jeep for 2 years and the rear brakes started locking with hard braking.
No ABS system. Rear drums.
Manual said it was the combo (prop) valve. I had the Jeep dealer change it and flush the system (I supplied the valve new from Jeep). After driving it home all felt good, but after some time, I would lock the rears going down our dirt drive, or coming to a stop and pressing hard. At 50 MPH I can brake hard OK, slow to 30 - 40 MPH hit it hard and lock up the rears. It is not as bad as it was (Before changing the combo valve) but I do not think the rears should lock-up so? Manual said it could also be the master cylinder but not how to test it. I have adjusted the rear drums and all looks good.

 

[JPNinPA]

Is both sides locking?
Do you have a locker or locked axel?

Are the pads floating or are they moving with the caliper?
Do the rotors show signs of rust? I had a set on my new f150 (under warranty) that had a rust spot the size of a quarter and it caused the brakes to lock. It was only one seed of one rotor. The dealer said it was "soft metal"

 

[Mark 47 willys]

Rear drums, no locker (stock). When I first got the jeep it would lock one rear first, so I cleaned and adjusted all of the brakes. Both rears lock up evenly.
Is it just me???
With rear drums if braking hard can the rears lock up this easy? The jeep is very light in the rear.

 

[JPNinPA]

I had this jeep for 2 years and the rear brakes started locking with hard braking. No ABS system. Rear drums. Manual said it was the combo (prop) valve. I had the Jeep dealer change it and flush the system (I supplied the valve new from Jeep). After driving it home all felt good, but after some time, I would lock the rears going down our dirt drive, or coming to a stop and pressing hard. At 50 MPH I can brake hard OK, slow to 30 - 40 MPH hit it hard and lock up the rears. It is not as bad as it was (Before changing the combo valve) but I do not think the rears should lock-up so? Manual said it could also be the master cylinder but not how to test it. I have adjusted the rear drums and all looks good.

Ok rear drums! Sorry I missed that. Thought this was an 2006 tj. With disk brakes using a rotor with a drum parking brake. Didn't think 06 still used drums.

There are a few things. One is the pads are adjusted too tight. They should be backed off 3-4 clicks form causing drag on the drum. The result Is the fronts do 80 % of the work and the rear 20 %. Having said that the fronts may not be adjusted properly or have an issue. The second common item is all the points the shoe rides on. The dust plates have 3 points that the petal rides on. They wear into a groove. If the brake rides over the grove it may not move back over easily. There is also a point up top where they ride on a notched piece. This gets worn and rusty.


If it is disk brakes the pad could be loose and kicking out and dragging/sticking. On the caliper the Also on the caliper the gliders can stick. Again back brakes should only be 20% of total braking. Front brake issues can lead to rear brake issues.

 

[Mark 47 willys]

JPNinPA thank you: OK I will inspect all 4 brakes again next week. Can anyone that has a jeep like mine lock up the rear brakes when coming to a stop? I just do not think they should lock up like this, I may have the drums too tight but not rubbing?

 

[RestorationRides]

Here's a thought for you... Brake shoes (drum brakes only) are dragged along and sucked outward with the direction of the drum rotation as the brakes are applied (pivoting on their mounts), thereby adding a force multiple. I've seen it before, where the brake pads can be installed on the opposite 180 degrees side of the backing plate of the drum to which they belong so that it was drawing the pads up onto the drum surface with excessive force as the drum dragged past the shoe pads. This is because if you look at the pads the pad material does not cover the whole brake shoe but only part of it, so if you get those backwards, there's more pad material being sucked onto the drum surface on the highly leveraged end of the shoe then should be....

Hard to explain that one, I hope I made myself clear... Lol

GB

Sent from my Z970 using Tapatalk

 

[RestorationRides]

Oh, and one more thing. Make sure those are the correct shoes for that vehicle. Maybe somebody put the wrong ones in the box when manufactured or purchased the wrong ones when replacing worn shoes in the past...?

GB

Sent from my Z970 using Tapatalk

 

[69jeepcj]

If you look at your brake shoes, the braking material on one shoe is longer than the other. Don't remember which way they go, but one of them go's on facing the front of the jeep, if installed backwards it will affect your braking possibly causing your issue. I think the above posts are hinting to that