I own a 1990 4Runner which has terrible braking power. The brakes pedal is very soft and almost touches the firewall when applied hard.
I've bled the brakes in the past trying to fix this problem to no avail.
On inspection of the rotors, I found the insides of both rotors have a 3/4" inch thick ring of rust. The brake pad doesn't seem to touch this portion of the rotors. Funny thing, it is on both rotors, on the inside surface closest to the axle. Can this be the soft brake problem?
I have a set of Brembo rotors ready to pop in, but I want to be sure it's just a rotor problem, not something else. I have a 2001 4Runner that stops on a dime. My 1990 really takes a long time to stop.

Help! Anyone know what's up with the rotor rust? And the soft brakes?

I'm ready to give up on my trusty '90...

Thanks
Frank

 

sounds like just the normal area of the rotors that the pads dont touch...

my truck did the same thing, i lived with it for a while, but the last time i rebuilt the front end, i put new calipers on it for the heck of it. it ended up given me a lot better pedal feel and braking. dont know why unless the old calipers were binding, or not all of the pistons were working... calipers ran me about 20 a piece, so not that much. cant guarantee it will fix the problem, but it might. Hope all works out!

 

thinkin bout it, could be a weak master cylinder too... but im still leanin towards calipers. let us know what you find out.

 

Interesting. When I had my '90, the brakes were incredibly sensitive and responsive. Even after over 200,000 miles with all OEM work (only replaced them once), they were great. I wish the brakes on my '00 were near as responsive.

 

Yeah, the brakes in my 90 are great too, even with the big tires.

Surferfrank - assuming you are indeed seeing that the swept area on the insides of the rotors is not being 'swept' and has badly rusted, then the probable cause is rusty caliper pistons. (Hard to believe 3/4 thick rust, I suspect you mean 3/4" area of thick rust... If you are seeing that only a portion of the swept area is being swept and 3/4" of what should be swept is not, then I would say first are the pads just worn out completely? and second rusty pistons. Also check the slide pins to see if they rusted badly too.

I wouldn't expect it to be a master cyl problem - you didn't describe pedal going to floor at stoplights or the rears locking up but the fronts don't or any master cyl type manifestations.

Since you have new calipers ready to go in, shrug and put em on.
(edit woops, I see you said rotors. By all means fix those calipers first!

 

frozen pistons in the calpers sending most of the force to the rear and the rear shoes are out of adjustment makeing for long through soft peddle dispite no air in the sytem.

least thats my guess.

 

I agree. This is common on the Ford vans at work. (not necessarily frozen pistons but out of adjustment rear drums

 

Caliper is stuck, could be the piston in the caliper or it could be a collapsed or bent brake line holding pressure there.

 

Frozen caliper and mis-adjusted rear brakes together will really raise havoc on you.

One way to prevent this....
Flush your brake fluid annually.

 

Just had to replace a caliper on my '93 - 3 frozen pistons. Stops much better now!