stuck caliper or wrapped rotor?

[kacper]

Hi!

Sometimes I feel that my brake pedal is pulsing.
My front rotors and calipers are 2 years old with about 20 000 kilometers. The rear brakes I replaced about 8 months ago. how I can diagnose my calipers ?
Simply greasing the slide pins will help ?
if caliper piston I stuck
Can I see that without reassembling whole thing?
I'm gonna take a look at it in 3 days. Your input would be appreciate

 

[iBison]

My front driver froze up last year. I had the same pulsing and it would pull to the right on braking. I think it's coming back as I'm starting to have the same symptoms. I used a big discount code at advance and bought one with lifetime warranty. I kept my old rotors so the next time I can have them turned ahead of time and not replace them.

On these it's not the slides that freeze up, but the pistons. I'll let someone more technical explain checking them out.

 

[paraordnance]

there is no such a thing as wrapped rotors. Its a myth. Pulsation can be caused by either frozen caliper or by unevenly deposit of pad material on the rotors. Rotors don't wrap, its physically impossible based on circumstances.

 

[meonard]

Run-out and/or out of parallelism is your issue.

The two most common causes of brake pulsation are rotor run-out (WARPAGE) and/or thickness variation (Out of parallel). Your 4-runner has fixed caliper design which is much more sensitive to runnout and parallelism issues than most other cars that use floating caliper types.

As a result the specifications for runout on the 4-runner is .001". Cars with floating calipers are usually .003". This can be measured with with a dial indicator. You can pick one up at Harbor Freight pretty cheap ($20-$25).

As far as machining your rotors on a bench lathe (off the car) I do not recommend it. The reason is there are many variables introduced by the bench lathe. Such as the lathe adapters, the condition of the rotor mounting surface called the "Hat." Also a consideration is the hub surface. Any rust on the hub surface will hold the rotor away from the hub in that area causing run-out. Keep in mind this can also be an issue even when installing new rotors. You want to use a dremmel on the hub so it is as clean as possible before reinstalling the rotor.

I have done the research on this and can tell you that a bench cut rotor will have .003" - .006" of run-out after being reinstalled on the car. One caveat, in areas with low rust (the Southwest/Texas) there is not as much rust and you are more likely to get away with a bench cut. But I cannot overeremphasize the importance of measuring run-out after the rotor is re-installed to make sure it is within spec. Now if you do decide to do it this way, and your measured run-out is out of spec. you should try and phase match the rotor. What this is is simply rotating the rotor one position on the hub/studs then remeasuring with your dial indicator until you find the position with the lowest measurment.

The only proper way to machine a rotor on any car, but especially the 4-runner is to use an On-the-car brake lathe. This machine will cut the rotor exactly as it runs on the vehicle. It eliminates all the variables, and will eliminate runnout. A good OCL (on car lathe) will cut the rotor to less than .0005" run-out. I have used a bunch of them but think the Pro-Cut is the best. If you go to Pro-Cut.com they have a list of service centers that have this equipment. This is the machine approved by Toyota.

As far as other opinion on this thread about calipers causing the issue or pad residue, I flatly disagree. Everyone is entitled to thier opinion but that is patently false. If someone in one of my shops said that I would send them to the lube bay until they figured out what they were doing.

I hope this helps.

 

[gm350reratliff]

The two most common causes of brake pulsation are rotor run-out (WARPAGE) and/or thickness variation (Out of parallel). Your 4-runner has fixed caliper design which is much more sensitive to runnout and parallelism issues than most other cars that use floating caliper types.

As a result the specifications for runout on the 4-runner is .001". Cars with floating calipers are usually .003". This can be measured with with a dial indicator. You can pick one up at Harbor Freight pretty cheap ($20-$25).

As far as machining your rotors on a bench lathe (off the car) I do not recommend it. The reason is there are many variables introduced by the bench lathe. Such as the lathe adapters, the condition of the rotor mounting surface called the "Hat." Also a consideration is the hub surface. Any rust on the hub surface will hold the rotor away from the hub in that area causing run-out. Keep in mind this can also be an issue even when installing new rotors. You want to use a dremmel on the hub so it is as clean as possible before reinstalling the rotor.

I have done the research on this and can tell you that a bench cut rotor will have .003" - .006" of run-out after being reinstalled on the car. One caveat, in areas with low rust (the Southwest/Texas) there is not as much rust and you are more likely to get away with a bench cut. But I cannot overeremphasize the importance of measuring run-out after the rotor is re-installed to make sure it is within spec. Now if you do decide to do it this way, and your measured run-out is out of spec. you should try and phase match the rotor. What this is is simply rotating the rotor one position on the hub/studs then remeasuring with your dial indicator until you find the position with the lowest measurment.

The only proper way to machine a rotor on any car, but especially the 4-runner is to use an On-the-car brake lathe. This machine will cut the rotor exactly as it runs on the vehicle. It eliminates all the variables, and will eliminate runnout. A good OCL (on car lathe) will cut the rotor to less than .0005" run-out. I have used a bunch of them but think the Pro-Cut is the best. If you go to Pro-Cut.com they have a list of service centers that have this equipment. This is the machine approved by Toyota.

As far as other opinion on this thread about calipers causing the issue or pad residue, I flatly disagree. Everyone is entitled to thier opinion but that is patently false. If someone in one of my shops said that I would send them to the lube bay until they figured out what they were doing.

I hope this helps.

I agree^^

Can the Pro-cut machine slotted and dimpled rotors?

I bought slotted and dimpled rotors last year from a company that advertised that their rotors don't warp. Well a year later, they are warped. Checked the calipers and no sticking pistons. Hard to find places that will turn the slotted rotors. I Would like to have the rotors turned on the vehicle but it's hard to find a shop I actually trust.

 

[ghs215]

I would think that it is a "warped rotor". Replace the rotors and you will also know if you have a stuck caliper when you try to retract them.

Unless you do some serious offroading, I would just get the 'mid' grade normal rotor. Cheap rotors 'warp' in about 2 years from experience. I bought the Bosch rotors and love them.

Good luck

 

[kacper]

Thanks guys!

I'll check all brake calipers tomorrow morning.
I have got some slide pins grease from canadian tire and I'll put it on all slide pins tomorrow.

I'm wondering If I take off the brake pads from the caliper and than press the brake pedal would I be able to Se the pistons without fluid leaking?

I have no idea how to diagnose them as I'm hobby mechanic

 

[ghs215]

Once you pop the caliper off and take the pads off, inspect the 4 pistons. They should be dry and somewhat clean looking. Look for fresh oil, if you do, then replace caliper. If there is some dry gunk, carefully wipe it off. Look of tears or anything not looking right. Next step is to 'carefully' use a pair of channel lock pliers and press each one of the pistons in slowly. Not too far! just enough to see that they move smoothly...they will move slow...if they move ok, then no problems...its your rotor. if you replace the rotor, replace the brake pads (rule of thumb no matter how much pad is left)

That's my 2 cents, hope it helps

 

[Sungod]

there is no such a thing as wrapped rotors. Its a myth. Pulsation can be caused by either frozen caliper or by unevenly deposit of pad material on the rotors. Rotors don't wrap, its physically impossible based on circumstances.

????? Have you ever actually worked on brakes? You are right. Metal never distorts when it gets hot.

[MENTION=84120]nevada[/MENTION] need a good laugh?

 

[nevada]

????? Have you ever actually worked on brakes? You are right. Metal never distorts when it gets hot.

[MENTION=84120]nevada[/MENTION] need a good laugh?

yes, I saw this post, and I almost responded to it. but I was busy, ironically enough, I was doing a brake job, and resurfacing some rotors.


I will say that normally, the problem(pulsation) is not a warped rotor, but in fact uneven friction material build up. but rotors do warp.

in either case, the solution is to replace, or resurface the rotor.

 

[paraordnance]

????? Have you ever actually worked on brakes? You are right. Metal never distorts when it gets hot.

[MENTION=84120]nevada[/MENTION] need a good laugh?

Yes I have worked on brakes many times in my life. Metal on 4runner rotors do not get hot enough to warp. It is uneven brake pad material diposited on rotors surface that cause pulsation. If you google "warped rotors" you will very soon discover what actually happening.

 

[TORCH]

So if I just replaced all my calipers front and rear and front rotors and did not use new pads and am having pulse with braking again then what should I do? Replace the pads or is it too late?

 

[paraordnance]

So if I just replaced all my calipers front and rear and front rotors and did not use new pads and am having pulse with braking again then what should I do? Replace the pads or is it too late?

Consensus is to replace them all at once, rotors & pads. You can turn rotors and replace pads. When you change them, make sure you follow correct pads bedding procedure to avoid this in a future.