Braking Rumble Jolt

S

Sharps

New member
When I come to a complete stop, the brakes on my 03 4x4 v8 4runner do like a slight rumble thing, It is almost like an ABS feeling but much less so I dont think it is that. I thought it could be a transmission issue or a 4wd thing. Has anyone had this, I have about 80k mi on it.
I searched the forums and it was only briefly mentioned in things I hate about... It did not have a full explanation and way to fix it. Any help is greatly appreciated.
 
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+1 for warped rotors.

Does it seem more obvious when the brakes are hot/been used some? Is it bad under light braking at higher speeds as well? As your rotors become more and more warped you will also feel it in your pedal as well as your wheel.

If this is the case you have two options.

1) If you have enough life left in your rotors you can resurface/machine them. This is when they shave the top layer off the rotors to make them flat/smooth again. After this is done once it seems that you are more likely to have your rotors warp again.

2) Replace your rotors.
 
It's not warped rotors at least for me. While braking at around 15 to 20 mph you feel a one time anti-lock buzz feeling in the pedal that lasts less than a second. It doesn't do it every time.
 
Ari Gold said:
It's not warped rotors at least for me. While braking at around 15 to 20 mph you feel a one time anti-lock buzz feeling in the pedal that lasts less than a second. It doesn't do it every time.
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have you measured the rotors to tell they're not warped? and is it a buzz or a rumble? because those are two very different feelings. generally a very slight rumble through the brake pedal is the early sign of a warped rear rotor. a buzz through the pedal is generally not brake related, but an issue with something in the engine bay. high frequency buzzes do not transmit well through the hydraulic brake fluid and brake lines.
 
SecretAgent said:
have you measured the rotors to tell they're not warped? and is it a buzz or a rumble? because those are two very different feelings. generally a very slight rumble through the brake pedal is the early sign of a warped rear rotor. a buzz through the pedal is generally not brake related, but an issue with something in the engine bay. high frequency buzzes do not transmit well through the hydraulic brake fluid and brake lines.
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I haven't measured them and they are not currently warped. It feels as though the ABS kicks on for one second or less while in the 15 to 20 mph range while braking.

A friend with a 2005 Tacoma had a similar experience though the sensation lasted a lot longer. He ended up having some type of ABS module replaced under warranty.
 
Oh and I've had plenty of warped rotors so I know what it feels like. Also this is the 35th car I've owned and I've never felt anything like this before.
 
Ari Gold said:
It's not warped rotors at least for me. While braking at around 15 to 20 mph you feel a one time anti-lock buzz feeling in the pedal that lasts less than a second. It doesn't do it every time.
Click to expand...
That sound like the electronic brake booster pump. It's on the other side of the firewall. It's normal.
 
M1911 said:
That sound like the electronic brake booster pump. It's on the other side of the firewall. It's normal.
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:iagree:

The system needs to build up pressure for the brake assist and ABS systems. What you need to check for is a leak of fluid or air. Check all lines and fluid level and any vacuum lines in the vicinity.
 
rook said:
:iagree:

The system needs to build up pressure for the brake assist and ABS systems. What you need to check for is a leak of fluid or air. Check all lines and fluid level and any vacuum lines in the vicinity.
Click to expand...

I will check this but it doesn't seem to fit the problem. If I'm going 60mph and press the brakes at say 300 feet from a stop light I don't get the sensation in the pedal until the last 75 feet.

Wouldn't there be enough pressure built up by then?
 
Ari Gold said:
I will check this but it doesn't seem to fit the problem. If I'm going 60mph and press the brakes at say 300 feet from a stop light I don't get the sensation in the pedal until the last 75 feet.

Wouldn't there be enough pressure built up by then?
Click to expand...

There is a very easy way to check if the buzz is from your brake booster pump: at a complete stop with the engine running in park or neutral, pump the brakes 4 or 5 times in a row, you will hear the buzz immediately after. You can do it again and again, it will happen every time you cycle like that.

I do think it's the booster pump that you're hearing. So it's normal if it's the case.
 
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