Would seriously appreciate any thoughts on this:
My 2001 4runner violently shakes/shudders/wobbles when I apply the brakes, regardless of how fast or slow I’m driving.
It feels like the rotors are badly warped, but the rotors are good, brakes also. They were replaced about a year ago.
The car stops just fine - but the way it shudders is terrifying. The whole car shakes.
The brakes were bled a few weeks ago, and I was told the rear drivers side had “way too much air in the line.” Bleeding the brakes only slightly lessoned the shuddering.
The brakes were bled 2 more times, as air was again in the lines. No doubt they need to be bled again, but what’s the point until I resolve the issue?
The problem began a couple months ago, and has become gradually worse. I am getting different answers from different “experts”
I can’t afford to put money into a misdiagnosed repair so I’m hoping to find some direction here.
The wheel bearings, etc (front end) were replaced about two years ago.
I am not burning through brake fluid, only needed to add some after brakes were bled.
When car is cold it seems to be worse. A tad less d- d- d -d when braking after car has been driven and has warmed up.
There should not be any air getting into the brake lines, unless there is a bad line allowing air to be introduce it.
Sometimes a small rotted line can allow air to be introduced when you let your foot off the brake.
Somewhere there is a leak!!!
As for the shudder, it could still be the rotors if one got overheated.
At times a flexible brake line can act as a check valve and keep a caliper from retracting…then that causes the rotor to warp.
I would send this car to a good alignment shop. The alignment tech will find your problem with the shuddering.
Your mechanic is missing the problem, because even warped rotors should not Make the entire car shake that bad. I think you have suspension problems and brake problems.
It;s not safe for you, other drivers, your passengers, and even pedestrians. Get it checked out!!!
The reason I ask…is because my 05 4runner (and all of that generation) had brake shuddering problems due to one of the 4 pistons on the brake caliper sticking that caused uneven braking. This is a known issue with this generation 4runner. I thought 2001 didn’t have this issue…but maybe it did.
I had to replace the front calipers every 50k miles. After my second set I went to NAPA and bought a their calipers with a lifetime warranty. I used that warranty at least 4 times while I owned it.
Can you tell if the shudder is coming from the rear or front?
I’m struggling to picture how air can get into the system without fluid leaking from the same place (unless the reservoir went empty).
Here’s my guess having had many Toyotas and a Highlander that eats brakes. Your caliper froze. It then warped the rotor or this happened on multiple corners. Replacement a year ago? In my experience with old Toyota’s that means due for brakes. Hope it is a simple fix and I’m mistaken. Let us know.
Good idea above. One other, you may have an ABS problem. When the brakes were bled did they follow the ABS bleed procedure too? If I had that problem myself, I’d probably just replace the two front calipers, pads, and rotors with new ones. Replace the brake fluid with fresh, new rubber brake hoses, and a proper system bleed. There’s a good chance that will fix it, although you may never know the exact cause.
From what I see brake-bleeding on this vehicle requires the use of the Toyota scan tool ( Techstream). That tool is used to turn the ABS selenoids on and off during the process, to make sure the ABS unit is air-free. If that wasn’t done, as part of the next work, have the bleeding done again following Toyota’s procedure.
This doesn’t sound like a master cylinder problem to me.
