Rear Brakes

[CPH]

Hint,

When you check your rear brakes for adjustment, do your self a favor. Spend a few bucks (very few!) and get a set of brake calipers. You can get them at almost any parts house. When you pull the drums, use the calipers to get the right spacing of your shoes from the drums. Clean the brakes and drums with brake clean or other brake cleaner, lube the adjusters with high temp brake grease, reinstall, do the backup and hit the brakes routine and your brakes will last a long time and you'll get good brake response. I am still with the original shoes at half new shoe thickness as measured by a set of calipers against a new pair of shoes I bought. I have 157,000 on my 97 and I tow my 27' fiver about once a month. Doing it the old way by course adjusting with the wheel on and turning it untill you think you feel drag and backing off, in my opinion, is too arbitrary due to the weight of the wheel tire combo on these trucks. One side could be missadjusted compared to the other due to the "human factor". Just my opinion.



Charlie

 

[GeoVeo]

CPH,



I agree with you about letting the self-adjusters to their work. It's been my experience that I can easily tighten my brakes but when I go to back them off, I have to reach in the hole with a second tool and push the adjusting arm out of the way or I'll be sawing away at the arm with the star. The service manual talks about pulling the star away from the arm when manual adjustment is necessary - say after a brake shoe/drum change. The self-adjusters are designed to allow a one-way rotation of the star - tighten only. Non-self-adjusting brakes allow the adjusting star to rotate easily in either direction.



I'm preparing for a long trip so I followed the self-adjusting procedure then took the truck out with and without the car hauler in tow to do some test panic stops. Stops straight as an arrow and I could hear the RWAL cycling. I think the self-adjusters are doing their thing.

 

[Eric_77]

The self adjusters on our trucks are the worst I have ever seen. I go through front pads like every 25k and rear pads have never been replaced. The rears I can feel get adjusted and work for a bout 5 miles then poof gone no rear brake again get adjusted work two three time then poof gone again. Brake guy said this is pretty normal for these trucks anyone else? The 92 I have just rear ABS and never feel the ABS kick in. the 96 has 4 wheel ABS and I feel the cycling but there is . 5-1 second delay after it releases before it cycles the scare factor there is unbelieveable.

 

[dieselburner]

You need to hit the brakes kinf of hard to get the adjusters to work. I do this after a trip right after towing my fifth wheel. I can hear the adjusters click. Once you get the hang of it and get a schedule, it's not that tough and the front brakes will stop wearing out so fast and the brake pull will go away.

 

[Eric_77]

Brakes never pull they just stop working in the rear and I am not going to stop in trafffic and backup to make them start working again. Besides I do lots of backing up to docks and such each day. The adjusters only seem to adjust when I am pulling trailer or have about 2k load in truck then just like they were done by hand 4-5 stops later nothing.

 

[dieselburner]

Well, Have fun wrenchin on it then...

 

[Joe G.]

The self adjusters have never worked right on my '95. Maybe on later models, but not on mine. I've tried all the back up and stop hard combinations I can think of and they just barely work if at all. So I have made it part of my oil change service routine to adjust the brakes when I rotate the tires. I slip the drums off and adjust the brakes with my fingers until the drum just slips on. This seems to work ok and the truck always stops straight.

 

[Fistfull]

Originally posted by Eric_77

Brakes never pull they just stop working in the rear and I am not going to stop in trafffic and backup to make them start working again. Besides I do lots of backing up to docks and such each day. The adjusters only seem to adjust when I am pulling trailer or have about 2k load in truck then just like they were done by hand 4-5 stops later nothing.

Curious as to what indications you are getting that the rear brakes are not working. Not sure about the actual percentages but the brakes as designed are heavily biased to the front (proportioning valve). The front brakes will do most of the stopping with minimal application (main reason they wear so fast). With the truck loaded more brake pressure has to be applied to bring the beast to a stop, more pressure = the rears finally start taking effect.



Taking a look at what happens to the rear brakes, when the brake pedal is pushed.



1. Hydraulic pressure generated from your master cylinder is transfered through the trucks hydraulic brake lines to the wheel cylinders.

2. The pistons in the wheel cylinders move away from each other due to the building hydraulic pressure between them.

3. The pistons push the tops of the brake shoes outward toward the brake drum.

4. The brake shoes contact the brake drum, at this point is where the brake pressure starts to climb and the proportioning valve starts to take effect (hopefully a similar story has been taking place on the front brakes).

5. The proportioning valve regulates the pressure front to rear per design as long as you keep your foot on the brake (Ever done a power brake burnout? <-- proportioning valve at work).



Both rear brakes recieve the same brake pressure, if one set of brake shoes is not adjusted out as far as the other, the pistons in that wheel cylinder will move farther before applying the same amount of force against the brake drum as the brake that is adjusted tighter. The farther the pistons in the wheel cylinders have to move the farther the brake pedal will move.



The only other variable is the profile of the brake shoe (worn in the middle or on the ends) to the size of the brake drum. If the shoes are not adjusted to fit the drum, (DANA designed the auto adjuster system to keep a set clearance between the shoes and the drum) or the drum is excessively worn, then not as much surface contact area is maintained between the shoes and the drum and less braking effect is available from the rear brakes.



Note: This is normal braking not RWAL



Sorry for rambling, got carried away, will try to not let it happen again.

 

[samb]

Rear brake adjust

When I adjust my brakes I tighten them up untill they lock up then back off 3 or 4 click. Just make sure both wheels are backed off the same. When you adjust them until they lock you set the brake shoes to the position they are at when working normal. Therefore you get better adjustment. If you don't lock them up then you realy don't know where they are.



Sam B.

 

[Eric_77]

How do I tell they are working?

Well after hauling a load or pulling a trailer; then the brakes are "touchy" just like after they have been adjusted. I don't adjust them my self Midas is just down the road and they do it for free for me. So I do not know the method they use.



How do I know they are not working anymore?

well after they have been freshly "adjusted" the e-brake goes about half way down later it goes almost to the floor. Braking is decreased more pressure most be applied, pedal goes further, etc.



P. S. I use the e-brake every time I park the truck old manual transmission habit

 

[Fistfull]

Take a look at the pic (my truck), "A" is pointing to a rod that is attached at the top to the backing plate (doesn't move) and the other end is attached to the lever assembly "B" which is attached to the rear brake shoe. Each and EVERYTIME the brakes are applied Rod "A" causes lever "B" to pivot and push on the star wheel adjuster "C".



IF the there is enough movement in the brake shoe BEFORE the shoe contacts the drum the star wheel adjuster will rotate slightly to increase the distance between the lower ends of the brake shoes, ie adjusts your brakes out.



IF the brake shoe does not move far enough before making contact with the drum the star wheel adjuster will NOT rotate, the spring built into lever "B" will absorb the movement to keep from bending anything when lever "B" contacts star wheel "C"



Note in the pic, the shiny spot on the star wheel caused by the lever time after time contacting the same tooth on the wheel. As slow as these brakes wear, it can be some time before the adjuster rotates to the next tooth.



You should never have to adjust the brakes, all you should have to do is drive the truck and the brakes adjust them selves. I have never adjusted my brakes, they work well and are consistant.



If Midas has to keep adjusting your brakes, there is something broken in this system or some other part of your brake system, take your truck to a different shop and see if you don't get better results, maybe someone else can find your problem.

 

[BC]

Elkaholic,



I'll be adjusting my rears this week.



My question: I was testing my brakes last week. I was doing 35 down a long straight road. I pushed the emergency brake to the floor and let off throttle. It took 3500 about 400 feet to come to a stop.



I have been in other cars and trucks and have done the same thing and came to a much quicker stop.



Because it takes 400 to stop (and it's really a costing stop) does this mean my rears aren't working? Out of adjustment? Something else I need to check?



Thanks for any info.



Bill Cook

 

[Eric_77]

Well I can tell you for a fact if the rears could not be locked up with the e-brake then they are not working. The ABS does not work on the e-brake system. Even my almost non-existent rear brakes I can lock up.

 

[BC]

Thanks, Eric, that's what I thought. I'm replacing the pads, flushing the fluid and going with DOT 4, and adjusting the rears. Can't wait to have some rear brakes again.



Bill Cook

 

[grtescpa]

Originally posted by CPH

Hint,

When you check your rear brakes for adjustment, do your self a favor. Spend a few bucks (very few!) and get a set of brake calipers. You can get them at almost any parts house. When you pull the drums, use the calipers to get the right spacing of your shoes from the drums. Clean the brakes and drums with brake clean or other brake cleaner, lube the adjusters with high temp brake grease, reinstall, do the backup and hit the brakes routine and your brakes will last a long time and you'll get good brake response. I am still with the original shoes at half new shoe thickness as measured by a set of calipers against a new pair of shoes I bought. I have 157,000 on my 97 and I tow my 27' fiver about once a month. Doing it the old way by course adjusting with the wheel on and turning it untill you think you feel drag and backing off, in my opinion, is too arbitrary due to the weight of the wheel tire combo on these trucks. One side could be missadjusted compared to the other due to the "human factor". Just my opinion.



Charlie

Why are my rear brakes wearing more on the secondary shoes than the primarys? My dealer say's nothing is wrong but I have never seen this befor. Should be wearing even.

 

[sam peterson]

grtescpa==the secondary shoes do most of the stopping. the primary shoe is thinner & shorter and energizes the secondary shoe by way of wheel rotation. {called self-energising system} that is the reason the secondary shoes are so much thicker & longer. ---Sam

 

[grtescpa]

Originally posted by sam peterson

grtescpa==the secondary shoes do most of the stopping. the primary shoe is thinner & shorter and energizes the secondary shoe by way of wheel rotation. {called self-energising system} that is the reason the secondary shoes are so much thicker & longer. ---Sam

Thanks Sam. What you said makes perfect sense. I just never had a vehicle befor that was this heavy and that explains why I see so much difference in the shoes.