Odd sticking of driver rear brakes

[fastsoup]

Hello all,

I just picked up a 2006 A4 2.0T that had been sitting for about a year. The seller told me that the last time it was in the shop, they had recommended a caliper change to the driver rear. On my initial drive home I noticed drag on and heat from the driver rear. Today I dismantled both rear brakes and replaced pads/rotors and compressed both calipers back and put things back together. When I wired in the ebrake cable on the driver side and moved over to the passenger side to reassemble everything. Once the passenger side was done, I went to mount the tires and noticed the driver side wouldn't move...not an inch. The ebrake cable lever was completely seized! At this point, at least to me, it was evident that the driver rear caliper mechanism was toast. I purchased 2 rear calipers, re & re everything, performed a 2 man bleed (on just the rear calipers) starting with the driver rear, over to the passenger rear, and then back to the driver, and once more the passenger. I mounted the rims and went for a road test.*

Initals brake pedel feel was very soft and to the floor...but the car did stop. I proceeded to perform multiple 80-30kph soft braking to beed in the pads. I stopped the vehicle on a flat surface and left in neutral. Got out, took a look and the factory film on the rotors had been removed and there was slight smoke from the rear brakes. Continued on for a good 20 min drive to cool the brskes. The pedal did feel a little better as the drive continued so I am hoping that the soft cause is because of the new pads/rotors. I also tested the ebrake cable and although it did hold the car on in incline, the lever has to be pulled pretty high (almost topping out). Another thing that concerned me was when I got home, the driver rear rotor was significantly hotter than the passenger rotor??? And there was slightly more copper color on the driver rear rotor than there was on the passenger.

Could the ebrake cable be "dragging" on the driver rear more than the passenger?*

Could the 2 man method to bleed be not sufficient enough to release all the air in the system?*

​​Any insight or thoughts would be appreciated.*

F.*

​​​​​​​P.S - Long time BMW enthusiast...2nd Audi A4.*

[ImAudiHeree]

Well first things first you have air in your fronts thats why brake pedals soft they are a diagonal split system. So i would bleed out your fronts and then double check the rears to be safe.

[PNW Avant]

The manual technically calls for an ebrake adjustment after replacing the rear brakes. It’s a pretty rudimentary adjustment but does involve you setting the ebrake so that there is a tiny bit of “slack” when the ebrake is not pulled. Usually the issue with new brakes and pads is that the ebrake has TOO MUCH slack, given the new pad material.

It’s not really possible the left or right side is “dragging” more or less as there’s a mechanism in the console to make sure pull is even. However your cables could be damaged such that the cable is not moving correctly?


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[EvolutionArmory]

Should be pretty easy to diagnose, no? Leave the brake cable off. If the wheel doesn’t bind up anymore, replace the cable.

I thought these ebrake cables self adjusted after replacing them?

[fastsoup]

The manual technically calls for an ebrake adjustment after replacing the rear brakes. It’s a pretty rudimentary adjustment but does involve you setting the ebrake so that there is a tiny bit of “slack” when the ebrake is not pulled. Usually the issue with new brakes and pads is that the ebrake has TOO MUCH slack, given the new pad material.

It’s not really possible the left or right side is “dragging” more or less as there’s a mechanism in the console to make sure pull is even. However your cables could be damaged such that the cable is not moving correctly?


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I wasn't aware of the ebrake adjustment. I was thinking yesterday how I'd like to adjust it anyway to ensure a more "snug" feel when I engage the handle.

The cables seemed fine when performing the brake change. I guess I could get under the car and have my wife pull on the ebrake and see what the rear pads do.

[fastsoup]

Ahh...figured as much. I'll perform a full brake flush today and see how that does.

[fastsoup]

Should be pretty easy to diagnose, no? Leave the brake cable off. If the wheel doesn’t bind up anymore, replace the cable.

I thought these ebrake cables self adjusted after replacing them?

I was going to lift the rear end up this morning with vehicle in neutral and see how many "clicks" it takes for each side to grab. I have a feeling my driver side will have less clicks (possible tighter cable) hence the more heat off the rotor last night.

[PNW Avant]

Should be pretty easy to diagnose, no? Leave the brake cable off. If the wheel doesn’t bind up anymore, replace the cable.

I thought these ebrake cables self adjusted after replacing them?

I thought so too, but not the case. They adjust side to side, but doesn’t end up tightening itself for a short throw. Mine has been long throw since I did my brake change years ago. My dad just did the procedure after his rear brake job and the throw is very short. Haven’t got around to doing mine but looking forward to it.


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[IronAudi]

The manual technically calls for an ebrake adjustment after replacing the rear brakes. It’s a pretty rudimentary adjustment but does involve you setting the ebrake so that there is a tiny bit of “slack” when the ebrake is not pulled. Usually the issue with new brakes and pads is that the ebrake has TOO MUCH slack, given the new pad material.

It’s not really possible the left or right side is “dragging” more or less as there’s a mechanism in the console to make sure pull is even. However your cables could be damaged such that the cable is not moving correctly?


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Im replacing my drivers rear calipers due to this exact thing, the caliper was stuck on, every time i hit the brakes the brake wouldn't release so I went thru pads and a rotor in less than 6 months. I bought new everything to replace, I will be bleeding the system with new fluid since I have to replace the caliper. I hope I just had a bad set of rears from not changing my rear brakes till some of the caliper was rubbing previous to the last brake job. I 100% believe this is my fault. User error laziness etc.

[fastsoup]

The manual technically calls for an ebrake adjustment after replacing the rear brakes. It’s a pretty rudimentary adjustment but does involve you setting the ebrake so that there is a tiny bit of “slack” when the ebrake is not pulled. Usually the issue with new brakes and pads is that the ebrake has TOO MUCH slack, given the new pad material.

It’s not really possible the left or right side is “dragging” more or less as there’s a mechanism in the console to make sure pull is even. However your cables could be damaged such that the cable is not moving correctly?


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So I just jacked up the rear end and both wheels move fine. I did notice that the ebrake spring mechanism on the passenger side flips right back when I release the tension where as the caliper on the driver side eases back and needs another little mm push to be right up against the stop.

Could it be that I got a bad caliper or am I totally reading into this now?

[PNW Avant]

So I just jacked up the rear end and both wheels move fine. I did notice that the ebrake spring mechanism on the passenger side flips right back when I release the tension where as the caliper on the driver side eases back and needs another little mm push to be right up against the stop.

Could it be that I got a bad caliper or am I totally reading into this now?

I don’t know, can’t comment on that as I’ve never experienced a bad caliper. Just informed on the adjustment.

If you want to drive to Seattle you can have my old b7 a4 rear brake calipers (Seems you are in Vancouver). Been sitting in a box since I installed s4 rears.


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[fastsoup]

I don’t know, can’t comment on that as I’ve never experienced a bad caliper. Just informed on the adjustment.

If you want to drive to Seattle you can have my old b7 a4 rear brake calipers (Seems you are in Vancouver). Been sitting in a box since I installed s4 rears.


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I appreciate the offer...but I'd probably warrant these if they are bad.

[Theiceman]

typically what causes rear calipers to drag is the seized e brake mechanism internal to the rear caliper. the idea is the e brake pushes in the caliper and of course it moves back out as you let of the ebrake . if it is seized of course it does not back off an you have your dragging caliper .
Up until about 2000 the rear calipers were ratcheting. this allowed for self adjustment of the brake. Those of you who serviced those cars probably remember pulling on the ebrake to ratchet in the piston until it self adjusted. when winding the caliper back in you had to take the little arm off the back of the caliper to wind the piston back in . This was a real pain in the ass. and these things seized constantly.
My b7 i noticed did not work the same way so it must be manually adjusted now as mentioned.

Another reason for squishy soft pedal on rebuilt calipers is the seal assembly and this is very common. the rubber seal in the caliper itself is fighting the piston and will take some time to settle. when you let off the brakes the rubber seal is actually pulling the piston back into caliper to where it wants to be. that means more pedal travel to put it back. this will take a couple of days to go away. so when you have done your full bleed on all 4 wheels working from the furthermost wheel to the closest from the reservoir , give it a couple of day and see what happens . if you are getting what i am speaking of it will eventually harden up.

[fastsoup]

typically what causes rear calipers to drag is the seized e brake mechanism internal to the rear caliper. the idea is the e brake pushes in the caliper and of course it moves back out as you let of the ebrake . if it is seized of course it does not back off an you have your dragging caliper .
Up until about 2000 the rear calipers were ratcheting. this allowed for self adjustment of the brake. Those of you who serviced those cars probably remember pulling on the ebrake to ratchet in the piston until it self adjusted. when winding the caliper back in you had to take the little arm off the back of the caliper to wind the piston back in . This was a real pain in the ass. and these things seized constantly.
My b7 i noticed did not work the same way so it must be manually adjusted now as mentioned.

Another reason for squishy soft pedal on rebuilt calipers is the seal assembly and this is very common. the rubber seal in the caliper itself is fighting the piston and will take some time to settle. when you let off the brakes the rubber seal is actually pulling the piston back into caliper to where it wants to be. that means more pedal travel to put it back. this will take a couple of days to go away. so when you have done your full bleed on all 4 wheels working from the furthermost wheel to the closest from the reservoir , give it a couple of day and see what happens . if you are getting what i am speaking of it will eventually harden up.

I don't think my cables are shot. When I pull on the ebrake handle, both sides come down and engage the brakes; neither wheel will turn. When I release the handle, I see the mechanism disengage to release the brakes. What I don't like is the driver side needs a slight nudge to be fully release whereas the passenger doesn't require that nudge. The driver wheel spins freely without that nudge but I wonder if that small nudge is what caused the hotter rotor last night.


Does anyone have clear instructions on how to retighten the hand brake? I've search and no clear instructions anywhere.

[fastsoup]

Just crawled back under and the driver rear caliper is leaking. I wonder if it's a faulty unit which caused it to bind on my road test last night. I've got a new one coming...will post results later.

[fastsoup]

The manual technically calls for an ebrake adjustment after replacing the rear brakes. It’s a pretty rudimentary adjustment but does involve you setting the ebrake so that there is a tiny bit of “slack” when the ebrake is not pulled. Usually the issue with new brakes and pads is that the ebrake has TOO MUCH slack, given the new pad material.

It’s not really possible the left or right side is “dragging” more or less as there’s a mechanism in the console to make sure pull is even. However your cables could be damaged such that the cable is not moving correctly?


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Any chance you have a link to show how to tighten up the ebrake? Everything I am searching is coming up with B6 models.

[PNW Avant]

I will snap some photos of the bentley manual later.

[fastsoup]

I will snap some photos of the bentley manual later.

Appreciate that...want to button this thing up.

[fastsoup]

So I got the replacment caliper...hooked it all up...and it's leaking again!!!

Looks like from the brake line fitting. What are the chances that I've got 2 bad calipers? I went copper washer/banjo bolt/cooper washer and tightened.

What gives?

[PNW Avant]

So I got the replacment caliper...hooked it all up...and it's leaking again!!!

Looks like from the brake line fitting. What are the chances that I've got 2 bad calipers? I went copper washer/banjo bolt/cooper washer and tightened.

What gives?

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