denverbikeguy

For a while now, I've had your typical steering-wheel-shake brake rotor warp type feel when stopping. Lately it has been pretty bad, shaking the whole car when slowing. It has also developed a strong pull to the left when slowing, and panic stopping was actually quite dangerous as the front would dip *hard* and the thing would try to turn suddenly. Not good.

Today after reading some posts on here, I decided to adjust the rear brakes and see what happened. Well, it cleared up the left pull (this much I was expecting), however I didn't hold out much hope for the rest since it had been stopping with mostly front bias for a while. Strangely enough, the shake is gone! I can hit the brakes at any speed, any level, and she'll slow down faster, straight, and smooth as silk.

Any ideas on what was really going on here? Cause warped rotors would still be warped, I would think.

M&S4X4RUNNER

Hi! What did you adjust? the park brake cable or the rear shoe adjustment in the drum?
Mine's does the same thing but no pulling to the right or left tho'.

Thanks! Mike

X-FH

jacksonpt

Yes... warped rotors would still be warped, and Toyota rotors do have a tendancy to warp quickly (at least on 3rd gen 4Runners they do). Assuming they were warped to begin with, you should still have some vibration. The pulling to the left makes me think that perhaps a caliper is seized.

My only guess would be that perhaps you "over adjusted" your rear brakes so they are now doing the bulk of your braking??? I'm no expert on this though, so wait and see what others have to say.

denverbikeguy

Well, I also did the "braking going in reverse thing" after I got done. There was a big difference between when I did it previously, and now. The first time, it was weak as hell, however after a couple quick stops in reverse I could lock up the tires going backwards easily. Parking brake is much more effective, etc.

I don't think it was siezed just because with the tire jacked up, it spun quite freely. I adjusted them to where it'd spin around once with the tire in the air, on both sides, based on something I read on here. I dunno if it's overadjusted, based on the fact that it feels like other 4runners I've driven that stop like new. Plus I did the reverse-brake adjust method after lining everything up good and it behaved like I'd expect it to this time.

M&S - I adjusted the shoe, not the parking brake.

jacksonpt

I was talking about a front disc caliper. Often times, when a caliper seizes, it seizes in the "on" position, applying constant friction to the disc. When this happens, the rotor/pads quickly heat up, causing a loss in braking power. Under heavy braking, the vehicle will have a tendancy to pull to the side opposite the seized caliper.

M&S4X4RUNNER

Hey jacksonpt.. this is coming from the rear of my truck. now isn't there a proportioning valve or something backthere?

& thanks denver!

X-FH

jacksonpt

What is coming from the rear... the vibration/shaking?

denverbikeguy

After some more careful driving (in varied conditions), I can tell you that there is still a very slight shake from warpage there. However I think my rear brakes were so far out of adjustment that even going in reverse didn't cure it until I "got it close" manually, and it was putting insane braking force on the front end. Now I don't get nearly as much front dive as before. The shake is there but so minor that I missed it before... I may go with some slotted Brembos or something before next summer (when I have to tow a large trailer all over the place).

It was certainly an interesting learning experience, seeing how the parts affect the system as a whole...

M&S4X4RUNNER

Ummmm...shaking..
A few months ago, i replaced the rear brake linings, brake cylinders, brand new drums, adj. to factory specs (w/slight wheel drag), & both rear wheel bearings & seals.
Everything was fine until recently w/this "warp kinda feel" occuring at the rear of the truck when brakes are applied to a rolling stop.
You see, I don't abuse my truck, there's no hills where i live & drive, i have a 4" suspension lift on my truck & i have the brake proportioning "bracket-extension" installed, & the parking brake is right where it should be when you pull it.
So.......I went down to the Toyota expert's & talked to a few mechanics that i knew. one of them is a factory trained toyota mechanic & they could'nt find anything wrong.
So here i am...................................am i missing something????

X-FH

drifto808

my friend and i adjusted my brakes a while back and he is a mechanic at toyota. what he said is that the brakes self-adjust after everytime you lift your parking brake lever. see the thing is that my parking break cable was broken at first and the brakes were way out of adjustment. but from what i heard is that the front rotors do warp fast. my 2cents.

k-bomb

To prevent rotor warp, keep your rear brakes adjusted properly, so that the front brakes are not being overworked. As far as a warp coming from the rear drums, that is a rare situation. Likely causes of that would be leaving the parking brake on accidently while driving, or a bum set of drums. Like rotors, the drums can be machined back to round at any automotive machine shop for around 20 bucks for the set. This will cure the brake pulsation.

M&S4X4RUNNER

Hey thanks for your input guys!
I beleive i just fixed the problem! i remember back while 4 wheeling to my "ulua spot" (fishing grounds) that i reversed into a log on the side of the road... cause' i remember a clunk... we'll i did look under the truck & everything seems to be in place.
This was 2 weeks ago. I just bent down to look & i saw the rod that connects from the axle & the proportioning valve was bent beyond it's original location. so... i bent it back...
:pat: ...lol.........no more of them damn earthquakes!!
man i feel so stupid!

Lesson learned!

X-FH