So my rotors have been warped for awhile, something that I noticed happening after driving on mountain roads here in AZ. Recently though, I noticed a vibration starting to happen at speeds above 35 mph while off the brakes, and it felt a bit like an unbalanced wheel. The vibration was not consistent though, it would come in hard then I'd slow down and it would go away for awhile. At first I thought maybe the rotors had finally warped enough that they are hitting the pads when passing through, so this weekend I installed to new rotors and pads.

I did not have trouble compressing the pistons in the calipers, but I did notice that the calipers on this vehicle do not separate on "slide pins" the way a car typically does. So beyond adding lubricant to the back face of the pads, I didn't lubricate anything. After reinstalling everything yesterday the truck felt fine, but today on the way to work the mystery vibration came back. When stopped at a light I pumped the brakes hard a few times and the vibrations went away for the rest of my drive.

It seems like a caliper might be sticking, but my question for you all is:

Is there a way to clean and lubricate these calipers, or is replacing the calipers the only solution if one is sticking? Thanks

I think you're just used to seeing the cheaper single-sided sliding caliper brakes used on many cars. The fixed caliper brakes are better. There's nothing outside and exposed to grit and rust that needs to slide back and forth to make the brakes work. Only the pistons, and they are protected behind rubber seals. That said, in rust-prone environments, moisture can get inside the seals, or the brake fluid can get too much water in it, and the pistons can get sticky in their bores. And there's not much to do other than replace the caliper with a new/rebuilt unit. Or if you're adventurous, rebuild it yourself. But it's generally not worth the effort.

If you were able to press the pistons back into the calipers without much resistance, they're not stuck. And lubricant isn't really needed on the back of the pads - there's no real movement or friction going on there.

Generally, a warped or unevenly textured surface (which is the more likely cause of braking shudder) rotor won't cause any issues when the brakes aren't engaged. And if they're bad enough to do that when not engaged, they'd be FAR WORSE when the pedal is down. I'd be looking for something else loose on the front suspension if you're feeling it through the steering wheel. Outer tie rod ends, control arm bushings, ball joints (especially the dreaded lower ball joints). Get under there and pry on things with a hefty pry bar (not a dinky little screwdriver). Maybe even (being REALLY careful, lol), have someone wiggle the steering wheel back and forth while you look for things wiggling around that sholdn't be wiggling.

So to provide a little more information, the inner/outer tie rods, lower ball joints, upper and lower ca bushings, CV axles, and suspension have all been replaced in the last 2 years/20,000 miles. I will check the lower ball joints though to rule that out.

I'm not feeling a shimmy in the steering wheel anymore now that the brake parts are new. Its more of an unbalanced wheel vibration, or similar to how it feels when braking on warped rotors, but it happens when not braking and not all the time. The strangest thing to me is how inconsistent it is. I can't make it happen, or predict when it will happen, but I noticed that pumping the brakes seemed to make it go away for the rest of my drive. I may try getting reman calipers from the part store before I ruin these brakes I just got.

As simple as this may sound, start with the easy stuff first.

1 - Bring your rig in for a tire rotation and a balance. If anything the guy may come to you and say "Hey did you know that you need...so and so?" Free diagnostics!

If it's a stuck piston, they're easy to replace and fairly economical.

I had a similar problem and determined it was a combination of rear axle seals leaking into my drums and my drums being out of round. It caused the whole vehicle to shake while driving most noticeably at highway speeds, and would vibrate worse when braking, then go away if I braked hard enough. Try pulling your parking brake while driving to see if it changes any. (Hold the button while pulling so it doesn't stay on.)

Well I just went for a drive on my lunch break and never encountered the vibration. Had the truck up to 50 mph and everything was smooth. I'll see what happens on my way home later.


Haha this isn't a bad idea. I'm actually due for a rotation soon anyway.

I will try gently pulling the e-brake next time I feel it, though its worth noting I have also replaced the rear axle seals, as they failed and leaked into the drums last year. I'm doubting they are bad already, and I haven't smelled any gear oil around the wheels like I did when that happened. But I should rule out the rear brakes.

A good way to check for a sicking caliber is temperature.

Take the truck out for a spin somewhere where you don't have to brake. Do a few miles then coast to a stop without using the brakes, or as little as you can.

Then get out and see if anything is hot. The fronts may be slightly warm, but they should be both the same and in no way hot. The rears will be stone cold if working properly.

Just a quick and dirty check but it'll tell you if you have anything dragging.

Well last night on the drive home I had no problems, and today on the drive into work I also encountered no problems. I'll update this thread if it happens again or if I solve it. I've had trouble finding information about vibrations like this.

I'll also check the brake temperatures to see if anything is hot. It is worth noting that for the past week or so I have been trying to get into the habit of parking with the ebrake engaged. I have a slanted driveway and felt maybe it was better for the parking gear if I didn't let the truck roll back. I have never left the brake on while driving, but I wonder if IT somehow got stuck or caused the drum brakes to drag, since that's the only thing I can think of that I'm doing differently.

Lift the caliper out of position and remove the pads. With the pistons extended but not out of it slot; spray liberally with brake cleaner and use a plastic bristle brush to thorough clean pistons. Push pistons back. Assemble, pump brakes, done.

So the vibration came back, and this time I narrowed it down to a brake drum. Also, until this time, I have stopped using the hand brake then parking in my driveway.

Yesterday I spent most of the day on an offroad trail, and used the hand brake to safely park the truck several times. When I got back to the highway and got up to speed, the vibration started again. This time, I distinctly noticed the smell of hot brakes, so I pulled into a gas station and splashed water on the drums. The right brake drum was not hot, but the left one steamed off like a hot frying pan.

I let it cool and drove it the rest of the way home. The smell went away, and the vibration never came back. I believe that somehow the use of the hand brake is causing this drum to get stuck.

Ck parking brake bell cranks for sticking?

^that, and maybe gummed up parking brake cable housings.
Have someone pull on the parking brake while your underneath the truck observing the bell cranks and parking brake cables.

Yes drums are overlooked a lot of times... Also lots of aftermarket rims can cause vibration issues as well as they are designed to fit a pile of different vehicles and sometimes will not balance correctly without spacers in there. I seen people have that happen. However, they spin balance perfectly. Really making people scratch their heads as to the cause of the vibration issue.

Sounds like your bell crank assembly is getting stuck. It happened to me when I first got my 4Runner. Dorman makes a bell crank kit for $30 on rockauto that comes with everything to replace both bellcranks. More Information for DORMAN 924753

You need to take 4runner in for a brake job at a good shop. Front Calipers should be replaced. Go to Amazon. You can use remanufactured. No one sells OEM calipers.

On my SR5 2005 V6 my front calipers (4 pistons / half were froze) were stuck. Rebuilding them at a shop is a waste of time. There are 4 pistons on each 2005 4runner front brake caliper.

Shop around for remanufactured calipers. Your rear calipers are likely OK.

What year 4runner is yours? 2nd Generation?