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Brake issues

S

Sniper82

Lifer
When driving on the wet road the front tires slide alot when braking like the backs ain't catching. Have rotors in front and drums in the back. I recently put new shoes on the back but did not change or turn the drums.

Could the drums need replaced? The parking brake works fine. Also lines are bled.
 
By sliding you mean you're skidding right? If so, I would check the tires to see how much tread is left and if they're properly inflated.
 
Most cars have a 60/40 percent braking power (front/rear). Are all the tires in good shape?
If you replaced the rear shoes, did you adjust them properly after installing them? There should be a very slight drag as you spin the drum.

If all that is OK, the only other thing that could be wrong is that the proportioning valve isn't working properly. That helps split the braking power up evenly......

Bob
 
Originally posted by: cardiac
Most cars have a 60/40 percent braking power (front/rear). Are all the tires in good shape?
If you replaced the rear shoes, did you adjust them properly after installing them? There should be a very slight drag as you spin the drum.

If all that is OK, the only other thing that could be wrong is that the proportioning valve isn't working properly. That helps split the braking power up evenly......

Bob
Click to expand...

It's interesting that even with the rear brakes receiving 60-80% of the hydraulic pressure compared to 100% for the fronts, the front brakes still provide something like 75% of the stopping power, rear brakes largely just tag along.

Also, the front brakes should lock before the rear brakes do. Locking the rear brakes is much, much worse than locking the front brakes because if the rear brakes lock it can cause a spin.

It sounds to me like his brakes are fine but he has crappy tires or isn't properly adjusting his driving style for wet weather.

ZV
 
As mentioned before, make sure the rear drums are adjusted properly, and check your tires for wear and inflation.

Also how old are your tires and are they all-season?
 
I just put brand new tires on the front because I thought that was the problem. The ones I took off was wore quite a bit. The backs are fine. If I ease on the brake its ok but if I ever needed to stop all of a sudden I would be scr*wed. The brakes are real touchy though maybe I just need to keep my foot out of it.

I adjusted the rear brakes fine when I put new shoes on. Not sure if the tires I put on are all season since I don't know anything about tires.
 
All season tires will have a tread pattern designed to shed water (usually a couple center lines with grooves angled out towards the sides). If you didn't specifically get "summer" or performance tires, then you most likely have all-season.

What kind of car do you drive?
 
Sounds about normal for a disc/drum car. My Celica was the same way.

You could try doing a couple of quick stops in reverse (get up some speed in a parking lot) to make sure the self-adjustment on the rears has taken up all the slack it needs to.
 
Originally posted by: Sniper82
Yeah thats how the pattern looks. Its a 96 Geo Prizm.
Click to expand...

So, lightweight car, almost certainly cheap (although new) tires, and in the rain under hard braking, the front wheels lock first.

You have a 100% normal car. In those little FWD cars, the rear wheels do little more than keep the trunk obediently behind the front end of the car. Under heavy braking, there's almost no load at all on the rear of the car, so the brakes are biased heavily towards the front to ensure that the rear wheels don't lock and cause a loss of control.

ZV
 
Originally posted by: Sniper82
When driving on the wet road the front tires slide alot when braking like the backs ain't catching. Have rotors in front and drums in the back. I recently put new shoes on the back but did not change or turn the drums.

Could the drums need replaced? The parking brake works fine. Also lines are bled.
Click to expand...
I don't agree with some of the advice you are getting here. Your point, if I understand correctly, is that the car is behaving differently when braking than it did prior to your replacing the rear shoes.

Assuming I understand correctly, your problem is in the rear brakes as you already know. You've replaced the shoes and your rear brakes are now not doing their share of the work of stopping the car.

My guess would be that the lining material on the rear shoes in slightly wider that than what came off the car. When braking, the linings are contacting the drums only on their edges, the majority of the linings are not contacting the drums. Hence the reduced stopping power. You then need more pedal effort which translates to more braking being done by the fronts. Your system is out of balance. More of your braking is being done by the fronts than there should be.

The fix would be to turn the drums or replace them if necessary. You could wait it out until the new shoes conform to the drums. But you are not happy with the braking as is, so I think it would be better for you to turn or replace the drums.

Stopping is reverse to adjust the rears is great advice. It's the last step for me when replacing rear shoes. But if I'm right, it won't be the cure. Remove the drums. A quick look should tell the tale.
 
Originally posted by: boomerang
I don't agree with some of the advice you are getting here. Your point, if I understand correctly, is that the car is behaving differently when braking than it did prior to your replacing the rear shoes.
Click to expand...

I am curious about that as well. However, it is quite true that rear brakes do very little braking, especially in a FWD car such as a Prizm(Corolla). Because the cars are front heavy to begin with and then weight transfer just exaggerates that. Also, as ZV said, any car company's lawyer is going to prefer that the front brakes lock up before the rears, because oversteer is much more dangerous, especially in a FWD car.

Did you test this abnormality on different roads? It could have been the surface of the road you were on. When you replaced the shoes, did you get a new auto-adjuster, or lube the old one?
 
I'll take the drum off in a day or two to inspect the shoes and drums. I was just thinking I might need new drums. I didn't buy a new auto adjuster or lube the old one. I just cleaned everything and put new shoes on. Once finished I had my nephew apply the brakes, while the car was jacked up I tried to turn the wheel and they wouldn't budge to make sure they was working.
 
Originally posted by: Sniper82
I'll take the drum off in a day or two to inspect the shoes and drums. I was just thinking I might need new drums. I didn't buy a new auto adjuster or lube the old one. I just cleaned everything and put new shoes on. Once finished I had my nephew apply the brakes, while the car was jacked up I tried to turn the wheel and they wouldn't budge to make sure they was working.
Click to expand...

So you are saying that things have changed since changing the brakes?

While your test of the rear brakes while jacked up is good to make sure they are at least getting fluid pressure, it is not a very good way to gauge if they are working correctly, because of the immense difference in force needed to stop a free spinning wheel, and a wheel that is supporting ~600 lbs of car.
 
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