Re: hydraulic rebuilds

[a6561TB@gnn.com]

Hi David, you are asking:

>Igor,
>You mention that you rebuild everything hydraulic...something I've not
>done. Are their any special tools or procedures required to rebuild a 
>caliper?

Yes. You need only one, but a very precise tool: 6" of a 2x4 ;)
On a serious note: you need a small wooden block to prevent the piston of 
going ballistic when you apply the shop air pressure to the empty brake hose 
hole in the caliper. Just put that block where the brake rotor would normaly 
be. Watch your fingers.

On a dual piston caliper you also need to hold one piston in with the 
C-clamp while working on the second one. Otherwise you'll be blowing both of 
them out, even if the first one is already done.
You also need a sharp pointed tool to extract the old O-ring(s).
There is a little trick on how to put the boot on the piston and then shove 
it in the cylinder bore without binding the boot. Just follow your Bentley.

Ah... you do need a special tool to screw the piston in the rear caliper.
I've dimentioned the piston and made one myself. I have no idea where people 
buy them. Zelinda Tools, may be?
 
Main rule of any hydrolic rebuild: keep everything sterile or even CLEANER!

>Are procedures/tools the same for master cylinder rebuilds?

It is a lot easier. You'll need the special  pliers for the locking rings. 
Craftsdude has them. Get the universal ones, switchable from the inner rings 
to the outer ones. A vise would help as a 3rd hand when you will be 
uncliping the locking ring on the butt of the master cylinder. Watch out for 
the piston rod, it will try to jump out on you. Watch your eyes.

Take a good look inside master cylinder. It's gonna be pretty messy if you 
dont replace your brake fluid often.
One more thing: bench bleed your master cylinder before intalling it back on 
the car!

Clutch slave is not rebuildable, i.e. theoreticaly it is (naturally, I 
opened it up out of curiousity), but Audi does not provide a kit for it.

>I think there may be some of this kind of work in my future!

Good! It is so easy to do, it's not even funny. You'll save tons of money 
and DEFINITELY get a good rebuilt part. Seven years ago I  briefly owned a 
Firechicken automatic that was breaking up on me every 2 days. When one day 
I lost brakes I decided not to rebuild the master cylinder myself (for the 
first time in my life) but to buy a rebuilt one from a vendor. I've gone 
through 2(!) bad rebuilt master cylinders in the row, got sick of it all and 
installed a new one @ the dealer price. Ouch!

Go to your local dealer and try to get a microfiche for your car. The dealer 
receives new updated fiches for all cars/model years almost every year. You 
should have no trouble getting an older one. In that fiche you'll find the 
available rebuild kits for your car with P/Ns. It makes the process of 
locating the parts so easy, just call around and shop. 

Recently I've rebuilt all of the hydrolic sys on my 200 in one shot: 
replaced the bomb and hoses and have rebuilt the pump and the rack. It took 
a lot of assorted parts. I went to my library and used their 50x 
viewer/printer to look up the necessary pages in the fiche. For ¢15/page 
I've printed them out complete w/exploded views and P/Ns.

And buy a box of disposable surgical gloves. Brake fluid is EXTREMELY 
agressive on the skin, you will be awash in it during the rebuild.

Good luck

 

Igor Kessel
the sweetheart: 200TQ, chipped and MOMO'd through out,
in Tornado "arrest-me-officer" Red;
the ex: 5000s, the EE's nightmare
Phila PA, USA
a6561TB@gnn.com