Braking issues...help please

[ARK_SWAMP_RIDER]

I needed new pads/rotors on the front of my 4runner, and pads on the rear, so I decided to just do pads/rotors all around. I did the front pads/rotors last week and all was well. I got the rears done today, and now I'm having issues. I went with Napa Ultra Premium pads/rotors if that matters. When I apply the brakes, I get a bouncing feeling, coming from the rear. If I get on the brakes hard, you can hear the tires start squealing as they grab (doesn't bounce here). It also doesn't do it when going slow, say 25mph or less. I'm not getting any lights at all on the dash. Can you guys think of something that could cause this? I had no issues at all with the pistons in the calipers, they moved freely during the install. It feels as if they are engaging then disengaging repeatedly, but it also causes the rear to hop/bounce. I've checked fluid, it's right on the mark. I've tried pumping my brakes before taking off, still does the same thing. Any advice would be appreciated. Thanks!

 

[zerowkul98]

Sounds like air in the line maybe? Have the lines bled.

 

[12guns]

good call on bleeding the brakes. I didn't even think of that when thinking about this issue earier.

 

[Jed]

You shouldn't have to bleed the brake unless you replaced the caliper or disconnected the brake line for some reason. But if you do decide to bleed the brakes, make sure you have the ignition key on (but engine off) when you bleed the fronts. You'll hear the pump activate throughout the bleeding process.

My guess is that the rotors you got have some lateral runout and are causing the "bouncing" feeling that you're getting. And I also think there's a real good chance it's the rear rotors that are causing your problem. If the rotors are out of spec, I would bring them back and have them replaced. Don't cut new rotors....it's a waste of money and you'll end up with new rotors that are thinner than they were originally.

 

[riverwolf]

Another thought besides air in the lines, which is a good one. Did you happen to notice the DOT friction codes on the NAPA pads? The OEM pads are FF front, EE rear, or at least mine were. If the NAPA pads are different (say FF front and rear), you could throw off the brake bias between front/rear due to a more aggressive pad on the rear.

-Brent

 

[Ducman]

A few things

Hmm strange.

Did you clean the mating surface where the rotor hat meets the spindle? Is it possible there was some rust/crud between them causing the rotor to not sit perfectly flush?

I've never had an issue with Napa Ultra premium ROTORS. I've used them on every vehicle I've owned for the past 6 years with no issues. I do however always use OEM pads on all my vehicles so I can't comment on the napa pads.

I think you are going to have to pull a wheel off and have a look to see if anything looks out of place.

 

[ARK_SWAMP_RIDER]

Everything was perfectly fine for a week after I did the fronts. I did the rear today, and immediately after the issue was there, so no doubt in the rear brakes. I'm wondering if it's a bad rotor, but I don't have anything to gauge or test them. No lines were disconnected, and I only did pads/rotors (no issues with calipers). I'm just not use to good, solid brakes. When the tires grab and squeal, it's the fronts, just because they're grabbing so hard (much harder than before). I'm super happy with the fronts and their performance. Even with the bouncy rear, my 4runner still stops much better than before, even better than when I was on stock tires which is nice.

The mating surface was clean. The pads are ceramic fronts and semi-metallic rear which I believe is just like OEM, but I don't know the friction codes.

 

[CJ3Flyr]

You may have gotten a defective rotor which is pretty rare with the rotors you bought.

The other thing is the vehicle has a dynamic proportioning feature. The coefficient of friction may be messing with the electronic brains of the system.

How many miles do you have on the brakes? I'd wait for 150-200 and if it doesn't clear up take the rear rotors back to Napa. Most Napa's turn rotors on site so they can measure runout. I wouldn't let them turn it but let them use the machine for the diagnosis.

Good luck...
:cheers:

 

[ARK_SWAMP_RIDER]

So far, just about 30-40 miles at most on the rear brakes. I'm not too comfortable driving around like this, it's pretty bad. How (or can I) tell if the issue is from the dynamic proportioning feature? If this is more than likely an issue with the rotors, I may swing by the local Napa where I purchased them and see what the guy says (owned/run by the same guy, just a small town shop so hopefully he'll take care of me). Right now that seems like the best approach, unless there's something else that comes to mind.

 

[CJ3Flyr]

So far, just about 30-40 miles at most on the rear brakes. I'm not too comfortable driving around like this, it's pretty bad. How (or can I) tell if the issue is from the dynamic proportioning feature? If this is more than likely an issue with the rotors, I may swing by the local Napa where I purchased them and see what the guy says (owned/run by the same guy, just a small town shop so hopefully he'll take care of me). Right now that seems like the best approach, unless there's something else that comes to mind.

The dynamic proportioning is a one in a million longshot IMHO, I was just throwing it out there...

It sounds like it's bad, let the Napa guy go for a spin.

 

[ARK_SWAMP_RIDER]

I'll check with him on that in the morning, and then see. I spoke with a local mechanic, he said just pump the brakes before taking off, but that's made no difference. I keep thinking they'll smooth out, but it's not gotten any better. I'll be driving another 20-30 miles between now and when I can get by the shop, so if nothing's better I may swing by and see what the owner says. I just want to make sure I know what I'm talking about before I walk in saying my parts are defective.

 

[Jed]

I'm telling you...it sounds exactly like excess lateral runout on the rear rotors. If you can get your hands on a simple dial indicator, you can check it yourself. I believe the spec is a maximum runout of 0.004".

A new set of rotors will probably solve your problem.

 

[ARK_SWAMP_RIDER]

After the drive home, I'm pretty set on rotors being the issue. It feels just as the fronts did when they needed replaced (jerking, except the front just caused the steering wheel to shake). I can't really tell if the brake pedal is pulsing, too much shaking going on. The shaking definitely gets more rapid as speed increases. I got out of town and hit 55-60 mph and it jerks like crazy, much faster than at lower speeds (which makes sense if it's a warped rotor). My question now is this: should I go talk to the Napa store first thing tomorrow morning, or wait until next week when I have a few more miles on them? Thank guys, I appreciate the quick response!

 

[Jed]

My question now is this: should I go talk to the Napa store first thing tomorrow morning, or wait until next week when I have a few more miles on them? Thank guys, I appreciate the quick response!

Go now. Take the rotors off, put them back into the boxes and ask for a new set. If they give you a hard time, just tell them that the rotors aren't true and you don't want them cut.

 

[Ducman]

Yep

Yeah, I'd go right away myself and get them exchanged.

You could also pickup a cheap dial indicator and check them yourslef, they are great tools to have.

I'm still shocked to hear that those rotors could be that "untrue" out of the box, but from what you have told us I have to agree that sounds like the most likely source of the problem.

Keep us posted.

 

[ARK_SWAMP_RIDER]

Finally checked it and figured it out. Verdict: warped rotor on the rear driver's side. I'll be going by Monday morning to swap it out. Thanks guys!

 

[Jed]

Nice. Don't worry, I'm not going to say "I told you so" more than once! LOL

 

[TechWrench]

Another possibility is that when installing the rotors, something got inbetween one of the rotors and the hub it mounts on. This will cause the rotor to not turn true, which will cause a pulse in the braking. I would remove the wheels, use two lug nuts to tighten the rotor to the hub and spin the rotors to see if there is any lateral runout observed. If any is noted, try removing the rotors, clean the inside mounting surfaces of both the rotors and the hub with a wire brush and mount them again, and check for runout again. If it is still there, then take the rotors back. Also check both calipers. If something, like one of the small clips that the pads ride on, is not seated right, and the pads can't move in the calipers properly, or the calipers are not able to slide on the rails properly the rear brakes may not be applying evenly and causing brake shake.

 

[ladywolf]

glad ya got it figured out.

 

[zerowkul98]

That same thing happened to me when i switched out my rotors n pads. My 1st ones were Raybestos, and one rear was warped. Switched it out. Went back to OEM rotors n pads though.