Brake Problem

[Atreyus]

I have a 97 4runner SR5 3.4L v6 and as I was driving home from school while it was raining here in Pasadena, CA. I had to break all of a sudden and noticed that my brakes made a loud thump sound and it was almost as if my brakes or front axle was shaking or if it were going to fall off or come loose. Is this part of the ABS braking system or is something bad happening? It only happens when I brake all of a sudden and it has happened rarely. Any info on this would be great thanks!

 

[raydouble]

Check for play in the front wheels/steering rack and make sure all your brake hardware is there and tight.

 

[SkidPalace]

Sounds like the normal operation of the ABS braking. Not to be condescending, but are you familiar with how it works? When the vehicle senses wheel slippage, the ABS system rapidly pulses the brake pressure in an attempt to keep the tire adhered to the road surface (if you want to know how/why, google static and kinetic friction). If you can do so safely, take your truck to an area of loose sand, dirt, grass, snow/ice or even wet pavement especially pavement right after a rain. Get moving at a decent clip and then jamb on the brakes hard and you will hear the system kick in. It sounds like a rubbery buzzing and you will feel your brake pedal pulsate.

 

[TheDurk]

I'm with SkidP here, sounds normal. Actually, the whole car jerks, not just the pedal, as the wheels start to lock up and release. I usually do just what Skid describes after brake work, just to be sure the ABS is still on-line. (I know there is a light, but I don't trust anybody whose first name is 'Idiot'.)

The ABS comes on unexpectedly sometimes on dirt or ice--still scares me for a split second until I remember what it is. In the rain, I avoid hard braking unless it's an emergency.

 

[Atreyus]

Yeah I did some extensive research on it but the way it responds even if its doing its just still scares me lol. I'm definitely going to avoid hard stops in rain...the weather in southern cal is insane yesterday its raining, today its sunny and the next few days its going to rain...