Weird braking issue

[M1911]

I've had the following braking issue for a couple years, and have been unsuccessful in getting two different dealers to track it down.

When coming to a stop under light braking, the brakes feel grabby. That is, while I hold consistent pressure on the brake pedal, the amount of braking force increases and decreases rhythmically.

No, it isn't warped rotors -- I don't feel a shimmy in the pedal or the steering wheel and the mechanics say the rotors are within spec.

No, it isn't the transmission downshifting as I come to a stop -- I can reproduce the issue with the transmission in neutral.

It doesn't happen all the time. It seems to be worse after some stop-and-go driving. I don't think it is bad calipers, as the front calipers have been replaced.

When I bought my 4Runner new, I would often feel the brake pedal buzz for a couple seconds after a couple stops -- I believe that this was the electronic boost pump. I felt that for years. I realize now that I don't feel that any more. Could this be related?

Any ideas? Any suggestions on a top-notch Toyota mechanic near Boston?

 

[eskimochaos]

I've had the following braking issue for a couple years, and have been unsuccessful in getting two different dealers to track it down.

When coming to a stop under light braking, the brakes feel grabby. That is, while I hold consistent pressure on the brake pedal, the amount of braking force increases and decreases rhythmically.

No, it isn't warped rotors -- I don't feel a shimmy in the pedal or the steering wheel and the mechanics say the rotors are within spec.

No, it isn't the transmission downshifting as I come to a stop -- I can reproduce the issue with the transmission in neutral.

It doesn't happen all the time. It seems to be worse after some stop-and-go driving. I don't think it is bad calipers, as the front calipers have been replaced.

When I bought my 4Runner new, I would often feel the brake pedal buzz for a couple seconds after a couple stops -- I believe that this was the electronic boost pump. I felt that for years. I realize now that I don't feel that any more. Could this be related?

Any ideas? Any suggestions on a top-notch Toyota mechanic near Boston?

I've noticed it too its only with light-med pressure. If I apply more pressure its "fluid" if you understand what I mean.

The pedal doesnt pulse at all.


Im not going to lose sleep over it.

 

[PredBlue]

I've had the following braking issue for a couple years, and have been unsuccessful in getting two different dealers to track it down.

When coming to a stop under light braking, the brakes feel grabby. That is, while I hold consistent pressure on the brake pedal, the amount of braking force increases and decreases rhythmically.

No, it isn't warped rotors -- I don't feel a shimmy in the pedal or the steering wheel and the mechanics say the rotors are within spec.

No, it isn't the transmission downshifting as I come to a stop -- I can reproduce the issue with the transmission in neutral.

It doesn't happen all the time. It seems to be worse after some stop-and-go driving. I don't think it is bad calipers, as the front calipers have been replaced.

When I bought my 4Runner new, I would often feel the brake pedal buzz for a couple seconds after a couple stops -- I believe that this was the electronic boost pump. I felt that for years. I realize now that I don't feel that any more. Could this be related?

Any ideas? Any suggestions on a top-notch Toyota mechanic near Boston?

I can't say if it's "normal", but I've noticed a similar braking scenario on two 4th Gens (a 2003 and 2004) under light braking. Under heavier braking, this seems not to occur. Neither vehicle had any known mechanical issues with the brakes.

 

[M1911]

I can't say if it's "normal", but I've noticed a similar braking scenario on two 4th Gens (a 2003 and 2004) under light braking. Under heavier braking, this seems not to occur. Neither vehicle had any known mechanical issues with the brakes.

Odd. Any ideas what might be causing it?

 

[EDness]

funny...i experience the same problem a couple times recently. Stop and go traffic only.

 

[Jed]

Had the same exact issue. I replaced the rear rotors (and nothing else) and the problem was 100% gone.

You gave such a perfect description of the problem that I'd bet that you would solve your problem by replacing your rear rotors too. BTW, I also felt no shimmy or pulsation in the brake pedal or steering wheel whatsoever, so I didn't think it could be a rotor problem either.

 

[Jed]

BTW, I picked up a set of Raybestos rear rotors from a local auto parts store for $30/rotor.

 

[eskimochaos]

Had the same exact issue. I replaced the rear rotors (and nothing else) and the problem was 100% gone.

You gave such a perfect description of the problem that I'd bet that you would solve your problem by replacing your rear rotors too. BTW, I also felt no shimmy or pulsation in the brake pedal or steering wheel whatsoever, so I didn't think it could be a rotor problem either.

Did you rears appear to need replacing? I had my front brakes(pads and rotors) done at 37k and Im at 53k still on original rears.

 

[Jed]

Did you rears appear to need replacing? I had my front brakes(pads and rotors) done at 37k and Im at 53k still on original rears.

Pads or rotors? The pads probably had about 50% left of them (I only have 38K on my 4Runner) and the rotors appeared to be fine visually.

At first I wasn't sure why I was getting the "grabby" brake issue under light braking that M1911 described, but it was definitely caused by the rear rotors. If you have the same issue, I'd recommend investing in a set of rear rotors. It sounds like a strange issue, but I'm 99% sure a new set of rear rotors will fix the problem.

 

[Carl_G]

Such a good description of the problem.

I had the same problem a couple months ago. Replaced the rear pads; problem gone. Felt it a bit again today.

 

[M1911]

Interesting. I may have my mechanic take a look at the rear rotors next time around.

 

[Jed]

Interesting. I may have my mechanic take a look at the rear rotors next time around.

Do yourself a favor...don't bring it to your mechanic. Just go out and buy a set of rear rotors and install them yourself (it's very easy) and enjoy braking the way it was when your 4Runner was new. Trust me, you'll save yourself a bunch of money...

 

[M1911]

Do yourself a favor...don't bring it to your mechanic. Just go out and buy a set of rear rotors and install them yourself (it's very easy) and enjoy braking the way it was when your 4Runner was new. Trust me, you'll save yourself a bunch of money...

If I knew what I was doing, I might. I don't.

 

[Jed]

If I knew what I was doing, I might. I don't.

Okay, fair enough. But if you have the ability to jack up your 4Runner and remove the wheels, then you can definitely change out the rotors. It's just a matter of unbolting the calipers to get them out of the way, and then sliding off the old rotors and installing the new ones. Do you have a neighbor or buddy that could give you a hand? If not and you decide to bring it to someone, don't go to the dealer because they'll probably charge you much more than a local shop.

 

[Koz]

If you replace the rotors, replace the pads also (use OEM pads).

Koz

 

[Jed]

If you replace the rotors, replace the pads also (use OEM pads).

Koz

There's no reason to replace the pads unless they are worn out or close to being worn out. Why waste money for no reason?

 

[Uneek]

If you replace the rotors, replace the pads also (use OEM pads).

Koz

Koz is back!

There's no reason to replace the pads unless they are worn out or close to being worn out. Why waste money for no reason?

Well, IMO it would depend on the condition of the old rotors. If they were scored or grooved, then the pad contact surface with the new rotors wouldn't be 100% of that with new pads.

 

[Jed]

Koz is back!



Well, IMO it would depend on the condition of the old rotors. If they were scored or grooved, then the pad contact surface with the new rotors wouldn't be 100% of that with new pads.

Pads quickly conform to the surface of a rotor. So even if the old rotors were scored or grooved and therefore the pads were also scored or grooved, once you swap out the rotors, the pads will wear into the surface of the new rotors. And if someone was really concerned, he could simply use a piece of emery cloth to smooth out the pads.

The OP's complaint isn't something that would leave me to believe that there is any abnormal grooves in the rotors. It's more of a lateral runout problem, so replacing the rotors and using the same pads shouldn't pose any problem at all. That's exactly what I did on my own 4Runner and it's perfect.

 

[Koz]

Pads quickly conform to the surface of a rotor. So even if the old rotors were scored or grooved and therefore the pads were also scored or grooved, once you swap out the rotors, the pads will wear into the surface of the new rotors. And if someone was really concerned, he could simply use a piece of emery cloth to smooth out the pads.

The OP's complaint isn't something that would leave me to believe that there is any abnormal grooves in the rotors. It's more of a lateral runout problem, so replacing the rotors and using the same pads shouldn't pose any problem at all. That's exactly what I did on my own 4Runner and it's perfect.

You are absolutely correct with everything you said but, I've seen where pads looked great and they still caused damage to the new rotors. It is not worth the cost of the rotors and the wasted time. It’s like changing a timing belt and not changing the water pump. Also many people don't bother using a torque wrench on the lugs, VERY important. While you’re at it, change the brake lines to braided stainless. You would not believe the difference in brake feel.

Koz