2002 SR5 - Brake Pedal Dead Zone

[JewFro]

Hi All,

I've had a nagging problem with my 2002 4Runner's braking system since not long after buying it in March. It currently has 184,000 miles.

When the truck is first driven or you've been cruising on the highway for a while without brake use there is always an odd dead zone in the initial pedal travel followed by an abrupt grab or the brakes. The dead zone always remains, the grabbiness does not.

I attributed it at first to needing front brakes since they had a significant vibration but after doing the Tundra upgrade with fresh calipers, rotors, pads, and lines, the issue only slightly improved.

Could it be the rear brakes causing this? I removed the drums yesterday and found the rear shoes to look almost new but the fronts were unevenly worn with 75% material remaining at the top slowly deteriorating to 25% material at the bottom of the shoe.

I'm guessing things aren't operating smoothly and its time for a rear brake refresh but wanted to get some forum input first. For what its worth I thought they were out of adjustment and started using the parking brake regularly a few months ago which works fine but didn't help the issue.

 

[Majindan]

If you have uneven wear that could mean the front brakes could've had a sticking caliper piston (if it was pulling to one side before the upgrade). I would just adjust the drums and parking brake to spec, and listen for the hydraulic brake pump to come off and on.

There is a way to test the brake pump to ensure it's holding the proper pressure via Google.

 

[JewFro]

If you have uneven wear that could mean the front brakes could've had a sticking caliper piston (if it was pulling to one side before the upgrade). I would just adjust the drums and parking brake to spec, and listen for the hydraulic brake pump to come off and on.

There is a way to test the brake pump to ensure it's holding the proper pressure via Google.

I'll look into the brake pump check but it definitely cycles. Shouldn't using the parking brake regularly take care of the adjustment? I've read conflicting schools of thought there with some saying let the auto adjuster do its job via handbrake use.

By uneven wear I meant the rear shoes are not worn evenly between the front and rear portions of the drum. The shoes towards the rear of the drum have almost no wear while the shoes towards the front of the drum are lightly worn at the top and significantly worn at the bottom.

 

[Majindan]

I'll look into the brake pump check but it definitely cycles. Shouldn't using the parking brake regularly take care of the adjustment? I've read conflicting schools of thought there with some saying let the auto adjuster do its job via handbrake use.

By uneven wear I meant the rear shoes are not worn evenly between the front and rear portions of the drum. The shoes towards the rear of the drum have almost no wear while the shoes towards the front of the drum are lightly worn at the top and significantly worn at the bottom.

You may just need to buy a drum rebuild kit w/springs etc. Parking brake is supposed to assist in adjusting the drums, but over time you'll still have to do it yourself manually.

 

[JewFro]

You may just need to buy a drum rebuild kit w/springs etc. Parking brake is supposed to assist in adjusting the drums, but over time you'll still have to do it yourself manually.

Thanks, at this point that is probably what I'm going to do. I've already got to order parts to do front brakes on my SO's 2012 Corolla and will add this to the parts pile.

 

[gamefreakgc]

Easiest way to adjust the rear brakes is to jack up the rear wheels, remove the rubber cap from the back of the dust shield and use a small flathead screwdriver to tighten the gear (you'll see the teeth). Do it one click at a time and periodically rotate the wheel. You should hear when the pad starts to contact the drum. When you do, back off 1 click and you're done. Repeat on the other side.

This involves no tools other than jacking up the wheel & a screwdriver.

 

[kevincva]

Check the rear wheel cylinder for a stuck piston.

 

[JewFro]

Check the rear wheel cylinder for a stuck piston.

How would you go about checking this with the drum off? I'm hesitant to suspect bad wheel cylinders unless both are sticking the same way causing the rear most shoe to have less wear than the front shoe.

 

[kevincva]

You would have to have the drum off, then try pushing the front shoe against the wheel cylinder and see if it pushes the rear shoe out. This is not definitive but something to look at.

 

[gamefreakgc]

How would you go about checking this with the drum off? I'm hesitant to suspect bad wheel cylinders unless both are sticking the same way causing the rear most shoe to have less wear than the front shoe.

It's common for the rear shoes to wear unevenly. Mine did the same thing until I changed the pads & adjusted the brakes.

 

[JewFro]

You would have to have the drum off, then try pushing the front shoe against the wheel cylinder and see if it pushes the rear shoe out. This is not definitive but something to look at.

Makes sense, should be able to push the cylinder just like a caliper piston. Somehow from age 16 to 30 I've never had a vehicle with drum brakes.

It's common for the rear shoes to wear unevenly. Mine did the same thing until I changed the pads & adjusted the brakes.

Odd but good to know. I assumed something must've been sticking to cause the uneven wear but with this and the other replies I'll try adjusting them first and taking a drive.

Just in case I picked up drums, shoes, and hardware from Napa when getting front rotors/pads for my girlfriend's 2012 Corolla. I'll just return anything that isn't needed.

 

[gamefreakgc]

Makes sense, should be able to push the cylinder just like a caliper piston. Somehow from age 16 to 30 I've never had a vehicle with drum brakes.



Odd but good to know. I assumed something must've been sticking to cause the uneven wear but with this and the other replies I'll try adjusting them first and taking a drive.

Just in case I picked up drums, shoes, and hardware from Napa when getting front rotors/pads for my girlfriend's 2012 Corolla. I'll just return anything that isn't needed.

If the drums are pricey but need to be replaced, you can have them turned at a machine shop (some NAPAs have machine shops, the one near me does). They take off a little material but create a smooth surface again. After 200k miles mine were very pitted. Made a difference. I think it's something like $20-$30 a drum to turn them.

 

[JewFro]

If the drums are pricey but need to be replaced, you can have them turned at a machine shop (some NAPAs have machine shops, the one near me does). They take off a little material but create a smooth surface again. After 200k miles mine were very pitted. Made a difference. I think it's something like $20-$30 a drum to turn them.

I'd heard of that but this Napa wasn't one of them but at $140 for drums, hardware, and shoes, the cost wasn't bad.

Everything was so crusty I went ahead and replaced everything and luckily it made a significant difference. It wasn't mentioned earlier but the truck still had a slight brake pulsation after the Tundra upgrade and part of me suspected the drums which turned out to be the culprit.

They still need slight adjustment as the e-brake handle is higher than it used to be. When the wheels were in the air I adjusted until the shoes dragged slightly and then backed the adjusters off 5-6 clicks. Doing this the e-brake felt perfect but when on the ground you have to pull too high IMO to hold the truck.

Either way, very happy with the braking performance now.