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Rear brake lock up/grab before fronts drum brake setup

C

cclngthr

CEG'er
Joined
Sep 18, 2014
Messages
293
Location
Puyallup wa
Been troubleshooting a rear brake issue that the drum brakes, particularly right side grabs before the fronts, but only does it when the self adjusters, both the parking brake AND the adjusters at the wheels do their thing and overtighten things to the point where the rear brakes tend to drag. I replaced everything, wheel cylinders (were leaking when I replaced them), rear parking brake cables, right one was sticky, left one appeared fine, but replaced both for safety and ease of eliminating the issue. Also replaced brake hardware, springs and shoes.

I have readjusted the rear adjusters at the wheels and they tighten up soon after, a couple days of driving. It also tightens up too much if I use the ebrake, which I think the adjuster on that is pulling the cables on the rear too tightly. Reset everything, it operates normally until the adjusters overtighten things.

Replaced:
Rear parking brake cables
Wheel cylinders on both sides
Brake hardware kit
Brake shoes

Only thing I have not replaced is the adjusters at each wheel (ordered them from a yard, they are no longer available) or the parking brake handle assembly with the front cable.
 
The adjusters do not work like old school ones did. When all parts clean and working they run up 100% of the adjusting the first 1 or 2 times the brake pedal is pushed down and then quit until more wear shows up. The very fine notches in the spring loaded quadrant tend to fill with dirt though and that messes them up. I use like Xacto razor hobby knife to clean the grooves out and they cannot be worn either to slip teeth. The quadrant must be able to swing extremely easy too, the pin in hole. When you assemble, do it with the adjuster as loose as you can get it, you do NOT adjust them up to make shoes drag, It lets the drum go on easy. Then you simply push pedal down to take up space and set all parts, the brake adjusts at that time, if not the next one. No more reversing forever to get them set, in fact reversing now does nothing at all.

Your park brake could be sticking to not release brake on one side fully.

Are those shoes the one thick and one thin type? Putting them in backwards if so can mess you up. Thick one to the front.
 
amc49 said:
The adjusters do not work like old school ones did. When all parts clean and working they run up 100% of the adjusting the first 1 or 2 times the brake pedal is pushed down and then quit until more wear shows up. The very fine notches in the spring loaded quadrant tend to fill with dirt though and that messes them up. I use like Xacto razor hobby knife to clean the grooves out and they cannot be worn either to slip teeth. The quadrant must be able to swing extremely easy too, the pin in hole. When you assemble, do it with the adjuster as loose as you can get it, you do NOT adjust them up to make shoes drag, It lets the drum go on easy. Then you simply push pedal down to take up space and set all parts, the brake adjusts at that time, if not the next one. No more reversing forever to get them set, in fact reversing now does nothing at all.

Your park brake could be sticking to not release brake on one side fully.

Are those shoes the one thick and one thin type? Putting them in backwards if so can mess you up. Thick one to the front.
Click to expand...

The parking brake cables are new, all parts assembled correctly. The parking brake applies the brakes evenly (I used a cut drum to see what it is doing). The right side eventually overtightens after 2-3 days driving, causing the right side to drag the brake and heat up that side 80 degrees F hotter than the left side. Hitting the brake hard enough causes the right rear to lock up before the fronts and left rear.

When I pulled the parking brake cables off, temporarily, the right rear continued to overtighten, but slower than with the cables attached. When I look at the assembly in action, it appears the right side to skip teeth and not seat correctly against the notches. Left side is smooth and tighter against the base.
 
Are both the small quadrant springs pulling in exactly the same way while mirror imaged?, It's awful easy to get one backwards IIRC. The clearance on the shoe hook thinking needs to be the same. Been awhile since I looked at one but I have modded the hook clearance to tighten that airspace up and make both assemblies closer to the same. The idea being to correct some of the variance left to right. I used a paperclip straightened out as a gauge wire doing it. It ended up closer and forcing the two sides to be more even and closed up some space that the brake was self-adjusting over. The quadrants must be slick as the dickens at the pins so that they swing every single degree they are capable of doing, any sticking and one side gets off from the other. One side continuing to adjust says the brake assembly is not tight against itself all parts in the circle or some other deflection going on there, one that pulls up solid cannot keep adjusting. Skipping teeth is OK if it NEEDS to do it first couple of times but not over and over, the assembly at some point takes a 'set' once brake parts are all tight or something is wrong. If teeth stripped or rounded to not bite in and hold then could be an issue there, very easy to build up rust in the grooves as they are so small.

Like I said, the brake does not normally keep adjusting, it should do it pretty much all at the first couple times pedal pushed in and then stop. Car not moving at all and still should do it.
 
A real longshot......................thinking that one has the pressure limiting valves for the rear to let pressure not max out, if one was stuck then one side might be applying more pressure than the other. A problem though if ABS, the valves are part of the ABS unit then.
 
amc49 said:
A real longshot......................thinking that one has the pressure limiting valves for the rear to let pressure not max out, if one was stuck then one side might be applying more pressure than the other. A problem though if ABS, the valves are part of the ABS unit then.
Click to expand...

I was going to say the same thing.. Check to see if your car has proportioning valves on the hardlines on the rear where they meet the rubber brake line.. Chance's are one is gummed up/broken/stuck..

Im not a HUGE drum brake person. but after all u have replaced/fixed it really seems like that would be the problem.
 
amc49 said:
Are both the small quadrant springs pulling in exactly the same way while mirror imaged?, It's awful easy to get one backwards IIRC. The clearance on the shoe hook thinking needs to be the same. Been awhile since I looked at one but I have modded the hook clearance to tighten that airspace up and make both assemblies closer to the same. The idea being to correct some of the variance left to right. I used a paperclip straightened out as a gauge wire doing it. It ended up closer and forcing the two sides to be more even and closed up some space that the brake was self-adjusting over. The quadrants must be slick as the dickens at the pins so that they swing every single degree they are capable of doing, any sticking and one side gets off from the other. One side continuing to adjust says the brake assembly is not tight against itself all parts in the circle or some other deflection going on there, one that pulls up solid cannot keep adjusting. Skipping teeth is OK if it NEEDS to do it first couple of times but not over and over, the assembly at some point takes a 'set' once brake parts are all tight or something is wrong. If teeth stripped or rounded to not bite in and hold then could be an issue there, very easy to build up rust in the grooves as they are so small.

Like I said, the brake does not normally keep adjusting, it should do it pretty much all at the first couple times pedal pushed in and then stop. Car not moving at all and still should do it.
Click to expand...

That I will need to recheck. I did find a second set of adjusters and notice one of them has about 1/16 inch play in the space between the ratchet part and the bar itself, where the teeth can't mesh together and allow the ratchet part to slip from the brake shoe as it expands. I however notice (with a modified drum ring I made from a old drum) that when the brakes are applied, the adjuster ratchet gets pulled slightly and in doing that it rotates slightly, but when the parking brake is applied, and holds it for a period, the adjuster gets pulled, then slips back toward the stationary gear where the ratchet part rests. When I use the parking brake, the next time I drive it, it does not lock up until just before the fronts, meaning the wheel cylinder and hydraulics are ok. I did replace the wheel cylinders 2 years ago so they are good. I really can't see the adjuster well enough to see how it works while on the car especially the ratchet part and if there is space between the bar and ratchet part, which there shouldn't be any space at all; it should be snug enough to not get cocked at an angle, but just loose enough to slide.
 
I'm thinking that the adjuster on the car (I need to pull it back apart and recheck it) may have gotten loose on the shaft, where the ratchet slid away from the bar just enough to get hung up just enough to allow it to get pulled back and turned enough so it wouldn't retract and slide from the brake shoe as it needs to. I think it gets hung up on the shoe and is angled just enough to not slide against the bar and shoe.
 
It's sort of an oddball setup until you look at it close, I remember pulling the parts and spending a good 30 minutes studying how it would work the first time I took one apart. It was hard to tell which way the quadrant had to turn to be max brake off.

The teeth being as small as they are means everything has to be nice and perpendicular to let them bite, and any wear there and it doesn't work either.

Any proportioning valves on these if not in ABS unit could be at the master cylinder like the Focus ones are.
 
amc49 said:
It's sort of an oddball setup until you look at it close, I remember pulling the parts and spending a good 30 minutes studying how it would work the first time I took one apart. It was hard to tell which way the quadrant had to turn to be max brake off.

The teeth being as small as they are means everything has to be nice and perpendicular to let them bite, and any wear there and it doesn't work either.

Any proportioning valves on these if not in ABS unit could be at the master cylinder like the Focus ones are.
Click to expand...

The right rear locks up VERY easy, but the drivers side also locks up before the fronts, but after the right side.


The car does NOT have ABS. It is a LX version with the minimal equipment. Power windows, locks and AC. That's it.
 
It WILL have rear pressure at least limiting, you cannot run rear drums with front discs without some type of it. Pressure limiting stops exactly what you are complaining about, or too touchy rears locking too easy. Rears SHOULD lock first but way later, you should be deep into fronts before it happens and fronts about to lock too. Rears lock first due to all weight transferring to the front.

Diagonal braking system, the two rears are not connected hydraulically, so they will not likely lock exactly at the same time, but should be close.
 
amc49 said:
It WILL have rear pressure at least limiting, you cannot run rear drums with front discs without some type of it. Pressure limiting stops exactly what you are complaining about, or too touchy rears locking too easy. Rears SHOULD lock first but way later, you should be deep into fronts before it happens and fronts about to lock too. Rears lock first due to all weight transferring to the front.

Diagonal braking system, the two rears are not connected hydraulically, so they will not likely lock exactly at the same time, but should be close.
Click to expand...

My fronts don't lock at all, until I'm fully on the brake (standing on the brake). By that time, the rears stop the car, or I'm sideways. Since I have studs on the front now, I
'm hearing when they are about to lock up, and they are still rolling easy when the rears lock up and the tires are skidding.

I however notice the longer I'm driving, the backs get much tighter, and lock up even easier. Driving 40 miles in stop and go traffic, the rears are almost at the point of being tight enough to slow the car with the gas off, and the slightest touch of the brake sends the car sideways to the right.
 
The rear parking brake cables were replaced with the right being sticky. That problem is solved, but the overactive rear brake sensitivity is not solved. Tech said the right side overadjusts, but I'm thinking that it is a combination of factors where multiple issues are going on. If it is over adjusting, there has to be something causing it, and using the regular brake tightens everything, not the ebrake.I can drive 25 miles and the rears automatically tighten up tight enough to sieze them up while the fronts free wheel.
 
How are your rear wheel bearings? I haven't owned or wrenched a rear drum brake car in decades, but I have an ancient memory of one of my 1970's Fords having a brake adjustment issue because of a rear wheel bearing that was either bad or didn't have the correct preload.

I also recall that this problem can occur if one piston in the wheel cylinder assembly is frozen, but since you replaced wheel cylinders, this is unlikely.
 
gmorrell said:
How are your rear wheel bearings? I haven't owned or wrenched a rear drum brake car in decades, but I have an ancient memory of one of my 1970's Fords having a brake adjustment issue because of a rear wheel bearing that was either bad or didn't have the correct preload.

I also recall that this problem can occur if one piston in the wheel cylinder assembly is frozen, but since you replaced wheel cylinders, this is unlikely.
Click to expand...

The preload on wheel bearings should be fine, but that is going to be verified since when I now drive, right side clicks, .louder when braking, but also grinds too. Had the shop I work with replace the rear cables, once things tightened, noticed the clicking, until yesterday it started grinding.

When I got the car 2 years ago, rear brakes were leaking on both sides (unusual) and right rear shoe set was metal to metal in places. Fixed that by replacing everything in the back except cables and hardware, over the 2 years I have driven it, it wore the right side excessively, and the ebrake froze when I used it. I fixed the ebrake issue, but the right corner bias is still there.

If I have to I'll rebuild the system my way, where I build it so the rear brakes never lock up (very dangerous if they do; ass end slides out from under you) and the front bias is not diagonal, front to rear only with an adjustable proportioning valve where the front to rear bias is where it should be, 75% to the fronts, 25% rear, with no diagonal plumbing. Dealer confirms there always is one side that has more grab than the other, and it is diagonal. Likely will reconfigure the diagonal to front-rear with a limiting proportioning valve where I can reduce the 50/50 to what I expect it to be, minimum 60/40 to 70/30. This also should be done with rear discs as well. You never should have the rear lock up preferably at all, especially at partial braking, which mine is doing.

Only thing I can come up with, IF it is hydraulic related, is the master cylinder is designed for a ABS unit, where brake pressure is even front to rear, where on non abs units, the bias is more toward the fronts. I have noticed since I got the car, I've had to repair systems that were repaired incorrectly where wrong parts were installed for incorrect application. It wouldn't surprise me if the proportioning valving and brake valves are not right. Already had to repair incorrect welds on the subframe and rebuild front end due to shortcuts I discovered over time.
 
http://www.ebay.com/itm/05-2005-FORD...lXI95V&vxp=mtr

You don't have those parts on the bottom half of the M/C picced there do you? Those are the limiters screwed into the lower side of M/C. The M/C will be the same on both chambers as the braking is diagonal, any bias has to be external. On a Focus but the M/C almost the same.

Since the world moved to pretty much all semi-metallic brakes I have come to expect a whole lot more wheel cylinder leaks than before, the brake worn material is what does it, the same as how the discs and drums wear far more than they used too. Steel to steel in essence there at all times now. The wear material is a whole lot rougher on wheel cylinder seals.

I've had Contour rear drum clicking when the drum gets out of round, the wobble then makes the shoe/backing plate rub points click as the shoe cycles back and forth. That extended out could make some of the adjusting too much.
 
amc49 said:
It WILL have rear pressure at least limiting, you cannot run rear drums with front discs without some type of it. Pressure limiting stops exactly what you are complaining about, or too touchy rears locking too easy. Rears SHOULD lock first but way later, you should be deep into fronts before it happens and fronts about to lock too. Rears lock first due to all weight transferring to the front.

Diagonal braking system, the two rears are not connected hydraulically, so they will not likely lock exactly at the same time, but should be close.
Click to expand...

Here is an initial test:

1. Right rear brake pressure: 1100 PSI
2. Left rear brake pressure 1000.PSI
3. Left front brake pressure 1150 PSI
4. Right front brake pressure 1350 PSI.

Normally, front discs should have 1500 PSI of pressure at each wheel and rears need to be limited to no more than 550 PSI. Tests confirm pressure rises, but does not go to 0 fast enough. Upon release of brake, the rears should go to 0 and fronts need to have 2-3 psi left in them immediately. It takes 8 hours for the rears to go down to 100 psi when the brake is used for 30 minutes to one hour. Right side is slower to retract, causing the brake adjuster to overadjust. Spring on the adjuster is too weak plus the ratchet part does not seat against the bar. it is loose.
 
amc49 said:
http://www.ebay.com/itm/05-2005-FORD...lXI95V&vxp=mtr

You don't have those parts on the bottom half of the M/C picced there do you? Those are the limiters screwed into the lower side of M/C. The M/C will be the same on both chambers as the braking is diagonal, any bias has to be external. On a Focus but the M/C almost the same.

Since the world moved to pretty much all semi-metallic brakes I have come to expect a whole lot more wheel cylinder leaks than before, the brake worn material is what does it, the same as how the discs and drums wear far more than they used too. Steel to steel in essence there at all times now. The wear material is a whole lot rougher on wheel cylinder seals.

I've had Contour rear drum clicking when the drum gets out of round, the wobble then makes the shoe/backing plate rub points click as the shoe cycles back and forth. That extended out could make some of the adjusting too much.
Click to expand...

No, the M/C on the contour isn't like that. The clicking I hear "might" be the springs hitting the rotating hub. Since the shop I used installed the rear brakes when they did the rear parking brake cables, I'm letting them deal with it since the police red tagged the car. When a police officer red tags a car for defective brakes, the car is out of service until the car is repaired and the state DOT/State Patrol does a full inspection on the brake system including a performance test by going 15, 30 and 60 mph where it has to stop within a specific distance with zero drift or movement toward the side.

http://www.ebay.com/itm/1998-FORD-C...ash=item33c2d82b8b:g:sUoAAOSwKOJYJmUe&vxp=mtr

This is a non abs M/C from a contour. no limiters are on it since the unit can be used with rear disc and drum brakes. The limiters are on the proportioning valve. The rear drum brakes should have no more than 600PSI of pressure at the wheel cylinder. The rear disc should have 900-1000 psi of pressure at the rear caliper.
 
'It takes 8 hours for the rears to go down to 100 psi when the brake is used for 30 minutes to one hour.'

Well, that certainly ain't right.
 
amc49 said:
'It takes 8 hours for the rears to go down to 100 psi when the brake is used for 30 minutes to one hour.'

Well, that certainly ain't right.
Click to expand...

Nope. I think the PCRV (pressure conscious reducing valve is hung up in the rear. I was reading where they often hang up, and either provide too much pressure (hangs up at rest) or blocks the fluid from returning to the master cylinder if it sticks where it is pressurized. I think both of mine are hung up where the valve is under pressure with the spring in the valve compressed.
 
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