# Right rotor hotter than the left? Need help diagnosing...



## phatvw (Aug 29, 2001)

So I put new brake pads on: Ferodo DS2500 in front, Hawk HPS in rear.
My right-front brake rotor gets hotter than the left after driving. I don't think its the caliper guide pins seizing, because I just replaced them with the Tyrolsport caliper bushing kit and lubed them up with super heavy duty moly grease and everything.
Could the caliper piston itself seize in the extended position? How can I test this? It retracted fine with the brake reset tool and extended fine on pushing the brake pedal. The right rotor was very very hard to rotate by hand compared to left one.


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## phatvw (Aug 29, 2001)

*Re: Right rotor hotter than the left? Need help diagnosing... (phatvw)*

After reading some articles on google, I think it is likely that the caliper piston is sticking.
One site suggested putting old pads in there, and alternating pushing the piston all the way in, and then pressing the brake pedal so they go all the way out. Repeating that 5-10 times should restore function. If not, I need to replace the caliper.
I will try this, but are there any other sugestions? Is there any way I can lubricate the piston without using a pressure grease gun?


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## machschnellGTI (Mar 17, 2004)

*Re: Right rotor hotter than the left? Need help diagnosing... (phatvw)*

Try this...when the brakes get hot, jack the front of the car up. You said one of the wheels was hard to turn. Crack the bleeder valve on that caliper and see if the wheel gets easier to turn. If so, go get them hot again and crack the line at the TOP of the rubber hose. I'm willing to bet it doesn't change anything and the wheel will still be harder to turn. If this is the case, the hose is holding pressure in the caliper and the hoses need to be replaced. Try that and let me know how it turns out. When you first installed the pads, was there enough room in there or was it a tight fit...like the pads were a little on the thick side?


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## phatvw (Aug 29, 2001)

*Re: Right rotor hotter than the left? Need help diagnosing... (machschnellGTI)*


_Quote, originally posted by *machschnellGTI* »_Try this...when the brakes get hot, jack the front of the car up. You said one of the wheels was hard to turn. Crack the bleeder valve on that caliper and see if the wheel gets easier to turn. If so, go get them hot again and crack the line at the TOP of the rubber hose. I'm willing to bet it doesn't change anything and the wheel will still be harder to turn. If this is the case, the hose is holding pressure in the caliper and the hoses need to be replaced. Try that and let me know how it turns out. When you first installed the pads, was there enough room in there or was it a tight fit...like the pads were a little on the thick side?

The pads fit in there fine so I know they're the right size. I am planning to do a full brake fluid flush/bleeding this week, so I'll check the pressures as you suggest when I do that. How would the hoses hold pressure like that? Clogged with crud perhaps? If so, would a fluid flush fix it?
The lines are less than 3 years old and the fluid is about 1 year old. I will replace the lines with stainless steel soon, but I just want to get everything working before my track day.


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## machschnellGTI (Mar 17, 2004)

*Re: Right rotor hotter than the left? Need help diagnosing... (phatvw)*

The lines expand over time...which makes the hole through the middle smaller. they get to a point where the hole is completely closed. When you step on the pedal and 500+ psi is introduced to the system, the fluid can force its way through the line, when the pedal is released, line pressure drops until the line closes back up. This occurs at different pressures depending on the condition of the line. if the system is holding 10 pounds in the caliper it will maintain pad pressure against the rotor.


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## MikekiM (Aug 21, 2001)

Make sure you don't have air in the lines.
Air in one line won't compress the piston as well, and cause the opposite side to get a bit hotter.


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## Galactic02 (Mar 28, 2002)

*Re: (MikekiM)*

You say you packed it with tons of moly grease... I would clean it all out. More grease doesn't mean better. I think that is your problem to much will actually impead movement of the guides, only a small amount is needed to coat the pin.


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## phatvw (Aug 29, 2001)

*Re: (Galactic02)*


_Quote, originally posted by *Galactic02* »_You say you packed it with tons of moly grease... I would clean it all out. More grease doesn't mean better. I think that is your problem to much will actually impead movement of the guides, only a small amount is needed to coat the pin.

Well I didn't "pack" it. Just used enough to make sure the pins could slide back and forth by hand and cleaned away the excess. The stuff says its designed for caliper pins and other hi-temp applications on the package. I'll re-check them, but I think its more likely to do with the hydraulic system.


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## phatvw (Aug 29, 2001)

*Re: (Galactic02)*


_Quote, originally posted by *Galactic02* »_You say you packed it with tons of moly grease... I would clean it all out. More grease doesn't mean better. I think that is your problem to much will actually impead movement of the guides, only a small amount is needed to coat the pin.

Well you certainly get a








It was those damn caliper pins afterall. I believe I seriously overtorqued them on the right side and they seized up pretty good. I replaced the pins with the extras I had from my TT brake upgrade and cleaned up some of the grease. The brakes are smooth as butter now and the rotors are the same temperature. And stopping power is good.
BTW I bled the brake lines and all the fluid was clear without bubbles so I didn't bother flushing.
Thanks for all the tips!


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