Wobbly AF caliper after new rotor and pads install - video

A6 All/ S6 All
#1

First im not a mechanic, Im an ee, but I do all my own work for the most part as we all know shops tend to not be reputable. I have about 5 years experience with audis to include some stage 3 builds so I like to feel I am mechanically inclined. This has me stumped!!! I have extensively researched the internet and can not find the answer. Has anyone EVER experienced this?

Video Link: https://youtu.be/zE8bA7InhjA

Worse on drivers side, however both calipers wobble. Carrier’s are tight (untouched during brake change). I drove the car 20 light miles, no changes. Yes the slide pins are tight and yes the calipers do not wobble when the brake pedal is pressed. Upon depression of pedal, slowly you can wobble the caliper back to being wobbly again.

I just disassembled the calipers and removed the bushings to inspect. They “appear” normal but can not compare till my new ones come in from the dealer. PN 4E0698647

#2

Stuck piston in caliper perhaps? not retracting all the way?

Maybe the caliper spring (the one in the front) is donezo

#3

Hey murphenur, thanks for the tips. The pistons are good to go as well the springs. I decided to investigate more so I removed the right wheel (previously able to move caliper with one finger through the wheel) and was able to violently shake the right caliper also = to the amount of the left shown in the video.

Getting sick of driving the c5 4.2, getting pissed, I put the old rotors and pads on, pressed the brakes, and calipers were stuck like glue. 0 movement. So I believe that there needs to be some break in before the caliper all presses nicely together with all the new shit. I have read some similar issues on some R32 or RS246 forum.

Put the new JHM rotors and Hawk pads on and went for a drive to buy beer. Pass 60 MPH and car starts to shake violently from the front right. I tap the brakes and vibration escalates 3x. Pulled off right rotor and was not happy with what I found. Now I am bald lol

#4

Watched the video…that is nuts.

Has to be a pin/bushing issue, no?

#5

Yes but when replaced with old rotor and pad I was not able to shake the caliper at all lol

#6

The bracket bolts to the hub with two large m14 or m16 bolts i believe no? That would be the only place for the bracket to be loose relative to the spindle.
i tighten those with blue loctite to 120 flt lbs. Has a serrated flange head too shouldnt come loose unless they were not torqued properly to begin with.

Just reread that when you put old rotor on its fine.
Maybe the bolts are hitting the back of the rotor and not allowing a good clamp between bracket and spindle?
Only 2 bolts, has to be something simple, peep back behind the rotor im sure you will find the answer quickly

#7

I never un-bolted the carrier bolts from the hub. They are tight as hell on there.

I think it is these causing the flex: https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/front-guide-bushing-set-priced-each/4e0698647/ as they are the ONLY rubber part on the caliper and I can visibly see axial play in that location when looking down through the caliper.

I have asked several service reps and they say they never replace these. I removed mine for inspection as well and they are fine IMO, guide pins are pretty tight, no tears, etc. I will still replace as they are only $40 for a set of (4)

https://i.imgur.com/GXg1uxe.jpg

https://i.imgur.com/B7IDoSE.png

“possibly” when new rotors/pads on there they may be a bit loose. I am also pulling and pushing several hundred lbs on those calipers to move them. My friend is not able to wiggle them as much… I have just never seen this before and am perplexed.

That is a good idea Greg5OH, thank you for the idea, but the guide pins when fully threaded come flush with the interior of the caliper. I have taken these apart 2x both sides now trying to diag and am tired of being a brake guy lol

Starting to not matter anyhow as I am going back to stock for now till I get the rotor troubles worked out. :-[

AudiLife

#8

a loose caliper with new pads and rotors makes even less sense. If it tightens up with the old pads then it leads me to wonder if the new rotors are thick enough?

I think something is wonky with the new rotors I hate to say. I see in the video that the rotor moves a bit too with the caliper.

I’d hedge that the rotor is not the right spec. take a pic of the old one side by side with the new one.

Just curious.

#9

So what did you find?

#10

I found that I am going to throw away those floating calipers and figure out a monoblock setup. C6 RS6 or Brembo GT. The GT kit is 380 MM so I can run a 19" LW wheel no problem. RS6 which is 390mm “may” be too big for most 19s

What I found, is that it is semi-normal, and once the pad is bedded that looseness / wobble will go away. I’m back on my stock rotors for now while I contemplate how to proceed :frowning:

#11

Brembo also make a 365mm kit too that fits. and a 400mm kit. just have to look up under the A6 chassis

#12

Problem solved 8)

As they say, when in doubt just throw $ at it

https://i.imgur.com/b9q1TGX.jpg

https://i.imgur.com/s7dSjjq.jpg

=

https://i.imgur.com/tOPLBLC.jpg

This is actually the right caliper, just some quick test fitment teaser. No more wobbly wobble.

Looking to test fit the stock s6 wheels later, fingers crossed I can run them as my winter set next year

#13

I want these rotors and the accompanying weight savings soooooo bad, but if I had the same issues…I’d seriously immediately give up on the car considering how fatigued I am from fixing all the other issues…

#14

Glad you got that taken care of.
What rotors did you end up going with with? How much did they set you back? looking at replacing my rotors soon.

#15

So did you need a new caliper…

#16

This took me a lot of time and risk as I see no one had done this retrofit yet. For starters C6 RS6 Master is the same as the C6S6. Calipers purchased from v8a6 (thank you v8a6!)… I am going to say that the “wobbly” caliper is not really an issue, but how these are designed, persay. Give yours a tug next time your doing a brake job and id imagine youll see the same. But I dont like it!

Calipers were $800 - C6 RS6 / C7 RS7 (similar to and same pad as Benz 63s, ZL1, Aston Martin, GT-R, CTS-V, etc)
Discs, bells, and hardware was $1240 shipped + $41 in Duties - AP Racing / Loba, 390x36

This was just a test fitment to confirm RS6 sizing is the same as the S6, still waiting on pads for the 63 AMG to come in today (soft hawk streets), and caliper fixings (spring, pins, etc), and new bracket bolts from the dealer to mount. Will most likely run the rubber lines for now until I source ss front lines. Maybe source ss lines from the rs7.

My stock calipers are fine, running them as we speak, they are just “old” 120K and needed the guide pin bushings replaced, seals are fine. I will be selling these on az in a few weeks for someone who wants a bbk upgrade to their c6 (non 3.0t) or their d3.

I am just not a fan of floating calipers and find it hard to “trust them” under abuse, I just want to make sure I have done all I can do to make sure I stop every time safely. Also the monoblock does have some curb appeal :wink: I wanted some weight savings over the stock discs as well being they are ~38 lbs!! lol

Before I install anything I plan to weigh stock vs this setup and report back. From calculations the 390 mm rotors are 29Kg (64LBS) VS stock S6 385s which are 76 lbs, so savings of 6 lbs per side. Still TBD…

“I’d seriously immediately give up on the car considering how fatigued I am from fixing all the other issues…”

  • LOL, how I felt about my boost leak machine stg3 allroad. Took me 2 years to get all the leaks to stop. I am already seeing leaks around my chain tensions on this 10 banger so I plan to replace those seals / o-rings soon, I believe my thermostat is bad to, so I think it is just beginning for me.

Again, we have audis for a reason