[s-cars] Caliper Guide Pin

[Dave Ellis]

I've had this exact problem on both my Audis.  There are two solutions 
that have worked for me.

In one case I replaced one rear S4 calliper carrier when in an effort to 
get the seized slide pin out it sheared right off inside the calliper. 
VM Autohaus in B.C. was able to ship me a complete carrier at a 
reasonable price.

In the other three cases I did the following:
   -removed the slide pins and boots from the carrier
   -cleaned and degreased everything
   -treated carriers and slide pins to a bath of 35%
    muriatic acid to remove the worst of the rust om
    the carrier and glide pins (ventilation required!).
   -wet sanded with fine grit sandpaper the glide pins
    to remove remaining rust and imperfections.
   -used a fine grinding bit and a dremel on the
    carriers to remove remaining rust and lumps,
    paying special attention to the boot mounting
    grooves and the pad contact areas (where the pads
    slide along the carrier as they wear).
   -cleaned carrier with TSP.
   -carefully sealed off the mating surfaces and
    slide pin holes on the carrier with rubber cement
    and tin foil cutouts.
   -used POR-15's Metal Ready to prep the carrier for
    painting.
   -used POR-20 and painted the carrier (two coats)
   -removed temporary tin foil cutouts and rubber
    cement (it just peals off).
   -reassembled.

This repair is a fair bit of work, but I've had no problems since. 
Basically I decided since I had the time then I'd save the money on new 
calliper carriers.  If I was to do it again now I'd probably just buy 
rebuilt to save time and paint them with POR-20 before installation.

I should also mention that I regrease the calliper slide pins once a 
year and at the same time clean and lubricate the parking brake cable 
mechanism on the calliper since it also tends to seize up if you're in 
an area where they throw sand and salt down during winter.

Good Luck!
-Dave



Evan Levine wrote:

> So last night after work I headed over to a friends house with some new
> rotors and pads for the back of the S4. The mission? Find the grinding
> noise. The result? Passenger side rear inner pad worn to the metal. The
> cause? The top caliper guide pin was so stuck that I couldn't move it with a
> hammer.
>  Are there any economical solutions to this problem without replacing the
> caliper? I've read that some people have sanded the pin and lubed it back
> up, is this really a safe and long term fix? Can you not just buy a guide
> pin?
>  Any input would be greatly suggested, for now I'm driving the car
> sporadically only but I'm sure eventually it's going to destroy the new
> rotor/pads as well.
>  EvanUrS4