Rear Brake Bias and "Is It Ever Normal" Question...

eb2143

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Dec 26, 2005
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Rhode Island
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I am on the fence with whether or not to proactively replace an original left rear caliper and would love for someone to sway me one way or the other.

Background:
I recently replaced the rear pads and rotors. Both lower guide pins had frozen and it led to uneven pad wear and squealing noises on right hand sweeping turns and while backing up. On disassembly of left rear (LR), I did not see any definite glazing or obvious signs of a sticking caliper/overheating. The LR parking brake mechanism stuck occasionally in the winter but I believe this was mostly ice and worn out cables.

My question is about the left rear brake caliper with 260,000 miles (last original caliper left on the car): It is building brake dust on wheel at 2x the rate of right rear. After normal driving with light braking, the left rear wheel is warm and the other three wheels are ambient temperature. Again, no obvious signs of strongly dragging caliper such as the characteristic smell. My last tank was 54 mpg, so if the LR is sticking, it isn't often, nor is it clamping with much additional force.

My best guess: Most likely, the LR is doing a disproportionate share of braking under normal use, or b) it sticks intermittently. I know there is strong rear brake bias on these cars for light application, but should there be side-to-side variation? The right rear is a pretty new TRW caliper and it cleans the rotor surface well, so I do not have any reason to suspect it's somehow compromised.

So, should I proactively replace the 260,000 mile LR caliper to avoid premature wear on new pads and rotors?

PS: The LR does seem a bit beat up in that it was much more difficult to reset the piston than the RR (yes, I'm using the Metalnerd tool); also, the external rubber seal twisted WITH the piston, which it isn't supposed to do.
 
Last edited:

vanbcguy

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Feb 22, 2013
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'93 Passat - AHU mTDI with GTB1756VK
Just do it. Brakes are too important and it's obviously got you worried. The piece of mind alone is worth the cost of a caliper.
 

Corsair

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Aug 17, 2003
Location
Auburn, New York
TDI
2002 Jetta GLS TDI 5M
#2 x2. And... Some other VW's used "helper springs" on the rear calipers, to add more force in the "retract" direction on the E-brake lever. I don't think those springs came stock on your model (nor on my 2002), but they can be added easily. Their presence also firms up the "pull" on the e-brake handle a bit. I got mine from IDParts.
 

tongsli

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Joined
Jan 31, 2000
Location
Baltimore, MD
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2000 Jetta TDI, 2004, Jetta Wagon TDI PD
#2 x2. And... Some other VW's used "helper springs" on the rear calipers, to add more force in the "retract" direction on the E-brake lever. I don't think those springs came stock on your model (nor on my 2002), but they can be added easily. Their presence also firms up the "pull" on the e-brake handle a bit. I got mine from IDParts.
They came stock on the GLI and 256mm by 22mm rear brakes. I bet they should be on ALL vw rear calipers that have the holes for them, they just saved $12.00 on each car to take them off.

My humble opinion

Change the caliper. #2 X3
 

austi012

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May 16, 2014
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well
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2000 Beetle TDI
For god's sake don't cheap out on brakes. Replace it if there's any question whatsoever.
 

eb2143

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Dec 26, 2005
Location
Rhode Island
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Well I'm not worried about a safety issue to be honest, or worried at all. More of a "if it isn't broken (or is it?), don't fix it" question. Car is braking really well, but I've noticed the left rear is doing disproportionate share of braking. A caliper is so simple that it's hard for me to figure out a mechanism not related to fluid pressure/flow, given that there is no evidence for the parking brake sticking.

For s*its and giggles, I would love if a few members tried touching their hand to the LR and RR wheel after a short/medium length drive with light braking. Are they both warm? Neither warm?

I will probably start by going to the wrecker and picking up slides and carrier. I'll see what they want for a caliper and decide then. It's nice that MKIVs are fixtures of boneyards these days :)


Some other VW's used "helper springs" on the rear calipers, to add more force in the "retract" direction on the E-brake lever. I don't think those springs came stock on your model (nor on my 2002), but they can be added easily. Their presence also firms up the "pull" on the e-brake handle a bit. I got mine from IDParts.
I've had these installed for a couple of years.
 

JB05

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Oct 20, 2005
Location
Il.USA
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Golf,2005,anthracite blue
I bought a right rear reman caliper from O'reilly back in June and it came with new sliders and bolts as well as copper sealing washers for the brake line connection. My bleeder screw had seized and the piston was difficult to twist using the metalnerd tool. This replacement caliper was plug and play, and I installed SS speed bleeders in all four calipers. I would keep away from the bone yard for used brake parts.
 

MrBigTruck

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Aug 24, 2009
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Kansas, USA
TDI
2000 Beetle, 2000 GTI ALH swap, 2006 Jetta, 2006 Jetta, 2008 Mercedes GL320 CDI
The left rear drags on both of my 2000 Beetles. It always has and probably always will. I've replaced nearly every part in the brake system on one of the two: master cylinder, 3 different calipers, new rotors, short line over the axle, line going to the caliper from the body, guide pins, wheel bearings, stub axle, even the axle bushings themselves...I've run it with disconnected e-brake cables, bled the system including the system bleed with the VCDS and they still drag and wear out at least twice as fast as the right rear. It's always hot on the left rear and water sizzles if I spray it on there. I hate it but I've given up and just live with it now.
 

eb2143

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Joined
Dec 26, 2005
Location
Rhode Island
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The left rear drags on both of my 2000 Beetles. It always has and probably always will. I've replaced nearly every part in the brake system on one of the two: master cylinder, 3 different calipers, new rotors, short line over the axle, line going to the caliper from the body, guide pins, wheel bearings, stub axle, even the axle bushings themselves...I've run it with disconnected e-brake cables, bled the system including the system bleed with the VCDS and they still drag and wear out at least twice as fast as the right rear. It's always hot on the left rear and water sizzles if I spray it on there. I hate it but I've given up and just live with it now.
Very interesting!

I was going to ask if not doing the ABS flush with VCDS was a plausible cause of my observation on the left rear, but it doesn't look like it based on your troubleshooting. I have VCDS but always get too lazy to use it when I bleed the brakes. My understanding is that the proportioning "valve" on the MKIV is internal to the ABS unit?

A deteriorating flex hose can occasionally block fluid returning when you release the brake.

But not likely.
Thank you, I will take a look

I would keep away from the bone yard for used brake parts.
Probably good advice...from my perspective on this left rear thing, I'm not yet convinced there's a real problem worthy of dropping $100-$200 on it. I have heard guides and carriers should be replaced as sets though. I'm surprised your caliper came with guides.
 

eb2143

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Joined
Dec 26, 2005
Location
Rhode Island
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Update: Replacing the left rear caliper appears to have fixed this issue. No original calipers left now :eek:
 

JB05

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Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
Thanks for the update. It seems that our rear calipers take a beating from salt and what ever. The VCDS ABS bleeding procedure made a big difference in my braking. It was kind of fun actually.
 
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