I replaced the rear shoes on my son's car- it has 180,000 miles. I bled the brakes, FL,FR,RR,RL in sequence. The brakes still feel somewhat spongy. They felt pretty much the same before replacing the rear shoes. He tells me that they don't stop very well. Front pads and rotors look good. Rear shoes adjusted properly and I even bled the brakes again about a week later. You can slam on the brakes and it will lock down the tires and skid straight, but the travel and spongy feeling has me uneasy. Am I missing something here? I did notice that bleeding the rear using a mighty vac hand pump didn't yield the kind of fluid flow the front brakes did. Maybe I am being too critical comparing to my Cadillac and F250's brakes. I thought about getting speed bleeders and trying them. Any advice? Thanks

 

In comparison to newer cars, older car brakes can feel a bit spongy. The main reason is that the rubber part of the brake lines start to deteriorate a little bit. When you press the brake pedal, instead of the fluid pushing the brake calipers, the brake fluid is also ballooning the brake lines a tiny bit. I got my biggest brake improvement by going to steel braided brake lines. The steel braids will restrict the brake lines from swelling when you press the brake pedal.

I have 275k miles on my 94 Accord, and the brake pedals are not spongy.

 

Thanks for the quick reply. Maybe spongy isn't the right word, just a lot of travel before the brakes grab.

 

Did you floor the pedal when bleeding?
Has it been a while since the brakes have been bled?

When bleeding brakes on an older car you only want to have the pedal travel its normal throw. Going past this normal area of travel may cause the seals to be damaged by traveling on a rough area of the bore.
Prefeable to use a vacuum bleeder, or at least place some blocks under the brake pedal to prevent an overthrow.

This is the same for wheel cylinders on drum brakes. If reusing the old cylinders, when the new shoes are installed they will push the pistons back into the bore into an area where the seals have not traveled/polished in a while. When this occurs the seals will not seal due to the rough surface, and may damage the seals. This is why it is always a good idea to replace wheel cylinders when replacing shoes. They are fairly cheap to replace.

Another factor is new/different brake fluid may swell the old seals, and new brake fluid is not compressible like old fluid, which will increase system pressure.

Verify that the rear wheel cylinders are not leaking or sucking in air.

How did you do the adjustment on the rear drums?
I usually do a groos adjustment with the adjusters til the drum can easily slide on but catches the shoes when trying to pull it off. Then fine adjustment by backing up and braking, this is how drums self adjust. If you have not backed the car up and braked a few times the adjusters may be out a bit, which would cause a long pedal but not spongy.

What condition are the hoses in? Any checking/cracking of the hose requires replacement. If the hose is covered in oil it should be replaced.

When I bleed the brakes on a FWD, usually a diagonally split system, I bleed in order of Driver Rear>Passenger Front / Passenger Rear>Driver Front. Those are the two halves of the system, it is not a 'front/rear' split.

 

its probably normal but you can adjust the pushrod

 

You should also lift up your interior carpet under the brake pedal to see if you have any leaks from your brake master cylinder. My brief recollection is that the master cylinder has 2 chambers, a primary and a backup chamber, and when the primary fails, you start using the backup, which you have have increased pedal travel before braking. I may be wrong on this.

My mechanic adjusted my rear brakes this weekend, and my brake engagement point is now higher. Not that it was low before, but my brakes now engage at a higher point.

 

Just to clarify this.

When cars began using dual piston master cylinders with split systems it was to prevent total loss of the brake circuit if a seal in the MC failed. Up until that point the only backup was through engine braking and the parking(emergency) brake.
With the split system if one circuit failed(MC seal, hose, hard line damage) there was still another fully operation hydraulic circuit.

FWD cars used a diagonally split system as loss of the front circuit would not allow for slowing down a car safely. Using the hand brake would not slow the car much and if too much pressure was applied the rears would lock and most likely induce a spin. Diagonally split system allows a much safer way to prevent total brake loss in FWD. I am not sure if diagonally split systems have migrated to newer RWD vehicles.

For more info and some visuals on how brake systems work > http://auto.howstuffworks.com/auto-p...ter-brake1.htm

Primary and secondary circuits in MCs tend to be hydraulically linked, note the two MC animations.

 

When my son was pumping the brakes I am sure he let them go to the floor. I didn't think of changing the rear wheel cylinders or brake lines, I may try that next and see if we get any better response. Although I did not see any leaking brake fluid from them. I am starting to think that it may be in the rear wheel cylinders or hoses just by the fact that they did not seem to flow no where near as much fluid as the fronts. The rear drums are tight, I adjusted just till the drums wont go on, backed off a bit then checked again the following week. If the wheel cylinders are bad will they leak?

 

Not always, as they may not leak fluid, but allow air to leak in to the system.
As for the lack of flow to the rear, drums in general and rear drums in a Disc/Drum system will have lower pressure than the discs. A lower flow will be seen compared to the piddling front discs.

 

I think I will replace the wheel cylinders and rear hoses just to be safe. The one thing I did notice when I replaced the rear shoes was that the top half of the shoes was hardly worn while the bottom of the shoes were almost worn out.

 

sounds like the wheel cylinders are bad ... swap and rebleed

 

That is most likely from a worn/non-lubricated backing plate.
There will be 6 raised flat surfaces that the shoe rests against on the backing plate. Shoes ride on these to expand out/retract in. When shoes are replaced the backing plate needs to be inspected and lubed. If the pads where the shoes ride on are worn they will have grooves that will catch the edge of the shoe(s) and prevent them from properly expanding out to the drum.
On a Leading/Trailing type of drum(typically found on FWD cars) the lower anchor point of the shoes is a wedge shape that allows the shoes to slide down and out to maintain proper take-up along with the auto star adjuster.

If the upper pads are worn to a point that the shoe catches, the upper shoe portion will not make contact with the drum, but the lower half of the shoes will still get pushed out through a pivot action as the shoe catches on the worn packing plate and the bottom pushes out.

Check the backing plate for wear, if it is light grooves you can usually file them down and regrease should fix the problem. If the grooves are deep the backing plates will either need to be replaced, or a machine shop will need to weld up some material and then machine the pads down flat.

A bent backing plate can bind up the shoe and cause it to not properly function.

Check the backing plate for excessive wear.
Clean and relube all the areas where the shoes ride on the backing plate, including upper and lower anchor points.
Verify wheel cylinders are not leaking.
Verify the self adjuster screw jacks are clean, lubed, and not worn.

 

The best thing to buy is the white and purple bottle of Permatex brake lubricant. It's about $20 or so but it's fairly big and will last a while. It has a higher temperature threshold than anti-seize.

The rule of thumb is to put some lube on anything in the brake shoe area that moves with the exception of course of where the shoes and drums contact. Just put some as you put the brakes together.

Make sure when you replace the wheel cylinders that you don't allow them to spread out or inward excessively as you put the shoes on. It's very easy for those seals to go bad if they do go out or in too much.

 

I worked on this car again today. Heard air while bleeding both the front and rear drivers side disk and drum brakes. Bled all the way around and still feel spongy. All 4 wheels seem to stop good while on the lift and while driving but I just can't figure out why there is so much travel in the brake pedal. How do you check the master cylinder?

 

you can adjust the push rod down by the pedal after loosening the lock nut

 

Accord brakes have always been solid,and that model year is no exception. Regardless of mileage,that brake pedal should be firm. If you are absolutely certain that that you have bled the system properly,then you likely have a master cylinder with a primary cup seal leak. This leak is internal and is known as "bypassing" you will not notice any loss of brake fluid as a result.



Easiest way to check is by clamping the rubber brake lines at all four wheels. The pedal should be rock solid and not go down. If it does,the MC is bypassing.....