S4 Brake Help pls.

[innov8]

I'm new here... I am an active member of the Pelican Parts forums but I need some help with my Audi. Thanks for any help you can offer.

I have an 01 S4 Avanti (B5) with 138k. This morning I started to replace my rear pads and rotors. Before I got very far, I realized I did not have all the parts needed... I didn't purchase new caliper mounting bolts as recommended in my "Haynes VW Passet & Audi A4" manual.

My questions:
- Is there a better manual available for S4's (B5)? I have a Bently manual for my old 911 but I haven't found one specific to the B5 S4.
- What it the service (thickness) on the front and rear rotors? It isn't listed in the Haynes Manual.
- While inspecting the rear brakes, I noticed that one of my Lucas calipers is missing the rubber dust shield and the other is torn. To replace these, do I need to rebuild the entire caliper?
- Do the rear pads need shims or is a spray-on "disk quiet" product OK?
- What is the best parts source for Audi's (price and quality of selection)? I purchased new pads and rotors from Pelican Parts but I didn't do much research on this.

I love my Audi...it rocks my 105 mile daily commute into NYC. I am looking forward to becoming an active member of your community. Thanks again for any help and advice you can offer.
Best, Patrick

[docurley]

Hope this helps

GENERAL TIPS FOR REAR

1.) When changing front or rear pads, make sure to open the master cylinder reservoir cap so as to not build excessive pressure in the M/C.

2.) Have an old turkey baster on hand to remove any excess fluid from the reservoir. (brake fluid spillage will take your paint off)

Tools:
- 13mm open end box wrench and socket
- 15mm open end box wrench
- 8mm Hex Key/Hex Socket
- Hammer
- 3/8 ratchet/breaker bar
- Brake Caliper tool - you can buy from Harbor Freight or rent a "brake cube" from Autozone. The one I show is the purchased one from HF.
- Adjustable wrench

1.) chock the front wheels, put car in gear, and take off the E-brake

2.) Jack up the back and remove the rear wheels

This is what you should be looking at now:



3.) Next, you remove the 2 bolts holding in the rear caliper. This is done by placing a 13mm socket or box wrench on the bolt, while holding the 15mm nut with a box wrench or adjustable wrench.



There is that top bolt, and then one on the bottom of the caliper

4.) The caliper should now pull off. The pads will probably stay on the rotor, and aren't fastened in any way (except possibly with a squeal-preventer compound, although my originals weren't). Pry the old pads out.

5.) Compress the caliper piston with the caliper tool.

You can see on the piston two small holes. If you look at the tool, there are two pins that fit in these holes. Basically the tool twists the piston while it pushes

In this picture, one hole is at the 12 o'clock position, and the other is at 6 o'clock



Here is the tool installed


pic courtesy of ModifiedA4

Twist the caliper tool until the piston is completely compressed.

6.) Now its time to remove the rotor. If you aren't doing this, skip down step 8

There are two 8mm hex bolts holding in the rear caliper carrier. These must be removed (bolts are greenish color). I sprayed them with PB Blaster and used my 3/8 breaker bar and 8mm Hex Socket. I had to hit the breaker bar with a hammer to break them loose



With the bolts removed, the caliper carrier comes off and the rotor just slides right off.

7.) Put the new rotor back on the hub, and install the two 8mm Hex bolts. Tighten to "good and tight" torque spec

8.) To install the rear pads, lay them in place on the rotor. They should stay there by themselves. Then try to place the caliper over the pads and rotor. This is easier than putting the pads into the caliper and installing the whole assembly.

9.) The rear pads have "spring" mechanisms on the back sides that fit between the caliper and the pads. Make sure that these are in the correct position (inside of the caliper) when you put the caliper on. It is easy to get the end of the spring poking out of the hole in the caliper, so watch out for this.

You can sort of see the springs in this picture. Make sure they are not sticking out of this slot in the caliper (slot in the very bottom of the pic):



10.) Reassemble the caliper. You can use a Blue loctite on the bolts to keep them from falling out if you want. You will need to use the double-pliers method again to tighten the caliper mounting bolts.

11.) Do other side

12.) Before starting car and driving: Pump the brake pedal several times until it firms up and feels relatively normal. Check brake fluid level. Pump pedal again after starting car just in case. The pumping seats your loose pads against the rotor. (If the pads are loose and you drive off, you may be surprised by a brake pedal that goes all the way to the floor.)

Follow manufacturers recommendations for bedding in the new pads.

Now you have new rear pads


Brake Bleed Procedure (W/O ESP):

A VAG-COM IS NEEDED FOR VEHICLES EQUIPPED WITH ESP

Per RKA's advice, do not bleed the brakes before doing your pads. Replace your pads and rotors first, then bleed brakes with calipers and pads fully attached to the vehicle.

Also, this write-up uses the "pumping the brake pedal" method. CAUTION: If you push down to far on the brake pedal while doing this, you can damage seals in your master cylinder. Some people put a 2x4 under the brake pedal to keep the pedal from going down to the floor.

Tools:
- 11mm box wrench
- 1/4"id clear vinyl tube
- some sort of plastic catch can - soda bottle/juice bottle
- a "helper" to pump your brakes
- 1.5 - 2L of Valvoline SynPower DOT4 Brake fluid


Basically, there is one procedure that you do on each caliper. Start at the furthest point from the master cylinder and work your way toward it.

Do the calipers in this order..

Passenger Rear
Driver Rear
Passenger Front
Driver Front

1.) Open master cylinder reservoir and a bottle of new fluid. Make sure the reservoir is full.

Here is the Master Cylinder:



2.) Pull off wheel and the brake bleed cover

3.) Pour enough brake fluid (new or old doesn't matter) into the soda bottle.

4.) Put the tube in the bottle make sure the end is below the fluid level.

5.) Put the other end of the tube over the bleed barb on the caliper

In this picture I used an adapter from a brake bleed pump kit. But the 1/4 tube will stay right on the bleeder valve.





6.) Keep box wrench on the bleeder valve at all times.

7.) Have "helper" pump brakes a few times until it gets hard to pump.

8.) Unscrew the barb (with hose on it) until fluid starts to flow. Probably 1/4 of a turn. Have helper keep pumping brake pedal. So that fluid flows.

9.) Tighten barb immediately after a few pumps and check fluid level in reservoir.

10.) Add new fluid to max line.

11) Repeat steps 7,8,9,10 until fluid color/consistency changes coming out of caliper.

Make sure that air pockets in the plastic tube don't get sucked back into the caliper.

12) Tighten up the bleeder screw, replace the cap, and put the wheel back on.

If the pedal goes to the floor with little/no effort after the procedure you got air in the system. redo the brake bleed. (or if you have an idea where you messed up, redo that caliper and the calipers after that one and you may be ok). If the pedal is still squishy, you could have a damaged seal in the master cylinder.

Hopefully everything went well and you can now keep up good maintenance on your brake system.

[innov8]

I did check out this under the DIYs... unfortunately, I am working on my rear brakes at the moment but the fronts will be next I am sure and the post will be well worn before I am through.

Any info on the rear Lucas Calipers for a B5 S4? Specifically, the rubber dust boots on the caliper? That's what I really need.

Thanks. Patrick

[docurley]

Oooops fixed now, it's for the A4 but it should be no different for the S4 just bigger calipers.

[innov8]

This is perfect! Just what I needed...you saved my another trip to the parts store...I didn't realize that I needed one of those 'fitted' caliber spreaders to seat the piston. I noticed the dust boot in your pictures is intact...mine is missing and torn... How do I replace them...or can I replace them without the cost of rebuilding or replacing the calipers? Is it even possible? Thanks again. I love this forum! Patrick

[docurley]

Originally Posted by innov8

This is perfect! Just what I needed...you saved my another trip to the parts store...I didn't realize that I needed one of those 'fitted' caliber spreaders to seat the piston. I noticed the dust boot in your pictures is intact...mine is missing and torn... How do I replace them...or can I replace them without the cost of rebuilding or replacing the calipers? Is it even possible? Thanks again. I love this forum! Patrick

I have to say I have never changed the gaitor but I would say it should be a straight forward job to do without rebuilding the caliper but don't quote me on that.

[innov8]

OK. I spoke with the parts counter of my local Audi dealer. They stated that they have never ordered caliper mounting bolts unless they were damaged or the caliper was seized. My "Haynes VW Passet & Audi A4" manual states "new caliper mounting bolts are required" when ever they are removed.

I also looked for a Bentley Manual to compare and cross reference but the S4 manual is only available as a download that will not run on my Mac OS. I am at a loss for information. Has any one changed their pads and rotors without replacing the "caliper mounting bolts" with new stock? Any side effects?

I really need to replace the pads as I had thought this would take an afternoon (foolishly) and have felt the pads go to the point that the windows rattle from the squeaking brakes.

As always, thank you for your support and knowledge. Patrick

PS. They don't sell the rubber boots for the cylinder inside the caliper so I assume this is not a service part.

[docurley]

I have never change mine and I have never had any issues and I have never heard of anyone else replacing them.

[innov8]

that's all I needed to hear. I'm thinking I might tackle this tonight. Thanks for ALL your help! I will post a project-wrap when I am finished.
Best, Patrick

[innov8]

OK. I got as far as removing the caliper and mounted the special tool to rotate the cylinder back into the caliper. I tried with all my strength to move the cylinder back (with the cap off the master cylinder and plently of space for brake fluid to raise). I even tried a wrench on the tool for more leverage...it never budged. As I mentioned above, the root boot around the caliper cylinder is totally gone from one caliper and partially torn off the one I was working on... at one place, the rubber boot is part seated and part out where the cylinder meets the caliper. Could this be the problem? Could my caliper be frozen or seized? The pads on this side of the car are much more worn the the other side (I am only working on the back brakes at the moment)... could this lend to the idea of a seized caliper.

are there any threads on replacing a caliper...? Do I do this one at a time or should i replace both at the same time (remember, both have damged boots). How much more complicated is it to replace the calper when the emergancy brake is integrated like on my Lucas calipers?

I know I have allot of questions but I am stubborn about getting this done myself... now that I started the project, taking to the local mechanic to fix seems like a lost battle!

Anyway, thanks again for all of your help thus far. I hope that you can help me with this current hurdle.

Best to all, Patrick