4runner shakes badly when braking at highway speeds

Hello, my 2002 4runner shakes really badly when at high speeds while braking. I have replaced my front rotors and pads. Previous owner had wheel alignment done in 2019 and it drives straight. My lower control arm and ball joint bushing are all good. And I also took off my front bush bar thinking that was the problem. Nothing has worked. I’m thinking it might be my rear drum brakes or it needs a brake fluid flush. I’m not sure what I should do. Need help!

 

Do you have ABS? Could it be the ABS pulsing the brakes?

Alternatively, if you have air in one of the brake lines, it applies that brake at a lower pressure than the others. Pulsations. You could try bleeding all 4 brakes, AND the LPSV, to see if one has some air in it. Remember to keep the MC full as you bleed the fluid out. Air in the lines is easy to see as it comes out. The brake fluid should be completely bled out of all 4, AND the LPSV, no less than every 3 years. It absorbs water from the air over time which changes the fluid's characteristics. Again, as you bleed down the fluid, make sure you replace it, with NEW, into the MC so it doesn't suck any air into the system.

Good luck!
Pat☺

 

I chased a shaking issue with my '99. Would shake the whole vehicle when braking from highway speeds or when braking down hills. Tried everything in the front end with no improvement.

Turned out it was the rear brakes. Don't remember if it had drum or discs, but got a complete rear brake job done and it was fixed 100%.

 

Thank you. I will look into the ABS and I’ll most likely drain the brake fluid soon and if that doesn’t work I’ll change the rear brakes.

 

If the rear diff breather gets clogged up, it can make diff oil leak from the rear axle seals into the rear brakes, which I believe should be drum brakes. Unless they were replaced with discs by the PO.

If they got oiled, especially if just one did, that could easily be your problem. The diff breather is easy to remove, so you can check to see if it is clogged up. AND clean it out. Be careful about trying to work on drum brakes yourself. They aren't as easy as they at first appear. IMHO, it's better to take the truck to a reputable shop, and let them replace the shoes. Same with the rear axle seals. As I understand it, it takes a special tool to replace the rear axle seals. I used to have an 87 4Runner I replaced the drum brake shoes on, and I vowed to never do THAT again. It took me about 4 hours to do, WITH the proper tools! Never again will I do brake shoes!

Good luck!
Pat☺

 

Hey pat. Ya I’m a HD mechanic on buses and I’ve done drums and shoes on a bus but never on a 4runner or any car for that matter so I’m not sure how different it is but I’ll definitely take the back tires off and inspect it. And as far as the dif leak would I be able to see oil on the shoes? Thank you for the information really appreciate it. Got my 4runner about 2 months ago now!

 

My 2001 did this for a while years ago. Replaced rotors twice with aftermarket. Problem went away with new OEM rotors.