Rear Brake Caliper Rebuild Emegernce brake snap ring

[Kevin C]

I went through the B7 rear calipers this weekend and wanted to pass on a tip on reinstalling the emergency brake mechanisms snap ring. One went together no problem. This is of course using the special 90° long reach snap ring pliers. The other caliper was a PITA. It would kind of go in but then snap back out. It turns out the mechanism was sitting a tiny bit high in the snap ring groove. The spring that I needed to compress to get it down in the bore is really beefy and there is not a lot of room to work. I tried using a drill press to push the spring down as I put the snap ring in, I got close but never got it in right.

Plan B. It took the part back out and noticed that the retaining tabs for the spring hat were a bit bent and the hat was getting pushed upwards. That would explain not being able to get the snap ring in.

The fix: I compressed the mechanism in a vice using a socket and peaned the tabs a little to tighten the assembly up (see red arrows). Five minutes of work and the snap ring was a cinch to get back in.

Tabs:
Ebrake.JPG

90° snap ring pliers: - Motion Pro 08-0279 Master Cylinder Snap Ring Plier
20190203_130901.jpg

Amazon Link: https://www.amazon.com/Motion-Pro-08.../dp/B000WJJ4U6

Quick tip: I slid the boot over the piston and installed them at the same time. Once the piston was in I hit the seal with compressed air and blew it up a bit. That moved it up the piston and made pushing the piston in the rest of the way a piece of cake.
20190203_133433.jpg

Glad that's done!

[All_Euro]

Thanks for posting this... I have some B7 brakes to refurb one of these days so this will come in handy

[Kevin C]

Thanks for posting this... I have some B7 brakes to refurb one of these days so this will come in handy

Quite a few people have how to's on the rear calipers and I know a few have struggled with the snap ring issue. As far as I can tell no one had a solution. I also put new seals in the front calipers and ran into a minor snag. The seal presses on and you need to press evenly on all sides to get it to seat. You can buy press tools but I looked around the house for an alternative solution.

This is what I came up with:

The lid from 365 Brand almond butter looks like a perfect fit.
20190203_222521.jpg

Previously I had spent ten minutes trying to get that seal on, it's a pain to get even enough pressure on it so that it doesn't pop off the lip on the opposite side of where you are trying to press. There is a steel ring molded into the base of the seal that takes a bit of force to seat. The jar lid seated it in less than ten seconds.
20190203_222738.jpg

[Spike00513]

Did you paint these?

I hear Ate and TRW seals are better than aftermarket such as Centric, FYI

Haven't tackled a full rear rebuild yet. Many of the DIY's I've seen were incomplete, leaving out the e-brake mechanism. Which I think the manual says to clean and coat in a lithium grease or something.

[Gin+]

This is the first I've ever heard of disassembling the ebrake mechanism, let alone tips and tricks. Amazing .

[Kevin C]

Did you paint these?

I hear Ate and TRW seals are better than aftermarket such as Centric, FYI

Haven't tackled a full rear rebuild yet. Many of the DIY's I've seen were incomplete, leaving out the e-brake mechanism. Which I think the manual says to clean and coat in a lithium grease or something.

I know you felt that your new brakes caused noticeable drop in fuel economy and questioned that it might be the seals you used; did it ever go any further than that? I used Centric on the back and Raybestos on the fronts. Next time I might go ATE. The seals I got looked OK, time will tell.

[ZERO FRAME GRAB]

Also you need to remember the position of the E-Brake arm, so you put it back on so there is the correct amount of tension on it.

[Kevin C]

Also you need to remember the position of the E-Brake arm, so you put it back on so there is the correct amount of tension on it.

From what I could tell the ebrakes internal spring sets the shaft to the retracted position. I put the arm on in the retracted position and tested that the piston moved when I moved the arm. It sounds like you have done on of these before, what was your experience ( did you have a problem or is there something that I'm overlooking?).?

[Spike00513]

I know you felt that your new brakes caused noticeable drop in fuel economy and questioned that it might be the seals you used; did it ever go any further than that? I used Centric on the back and Raybestos on the fronts. Next time I might go ATE. The seals I got looked OK, time will tell.

Not yet, still driving on them, ~22 horrible MPG's

[A4SoftWalker]

This is what I came up with:

The lid from 365 Brand almond butter looks like a perfect fit.
20190203_222521.jpg

... There is a steel ring molded into the base of the seal that takes a bit of force to seat. The jar lid seated it in less than ten seconds.
20190203_222738.jpg

Kevin would you mind throwing up the diameter measurement for your 365 Almond Butter jar cover for some of us that might have something else laying around?

THANKS a lot for sharing your experience in this area.

[Kevin C]

Kevin would you mind throwing up the diameter measurement for your 365 Almond Butter jar cover for some of us that might have something else laying around?

THANKS a lot for sharing your experience in this area.

The ID is about 70.3mm and the OD is 72 mm. A tiny bit larger would be better but this was close enough.

[A4SoftWalker]

The ID is about 70.3mm and the OD is 72 mm. A tiny bit larger would be better but this was close enough.

Perfect. Thanks Kevin.

[ZERO FRAME GRAB]

I bought a bunch of calipers from the junkyard an took them apart to powdercoat them. I haven't put them back together yet but, the E-brake arm sit on "teeth" so it looks like it needs to go back on in the exact position that you took it off from or the cable wont go back into the arm.

[Spike00513]

Kevin would you mind throwing up the diameter measurement for your 365 Almond Butter jar cover for some of us that might have something else laying around?

THANKS a lot for sharing your experience in this area.

Lol
I don't think I have anything else laying around
time to buy one for up to $10 at Whole Foods and quickly eat it with a spoon or put it on wheat bread
why do I feel about wasting only $10

Idk if there's anything better
because having a metal part custom-made would be costly
A plastic lid (as shown) could dry out and crack but only after many years.

[A4SoftWalker]

Lol
I don't think I have anything else laying around
time to buy one for up to $10 at Whole Foods and quickly eat it with a spoon or put it on wheat bread
why do I feel about wasting only $10

Idk if there's anything better
because having a metal part custom-made would be costly
A plastic lid (as shown) could dry out and crack but only after many years.

Nice excuse to mow through some butter.

I'm a pack rat when it comes to wrenching. I have lots of old plastic jars laying around to store things in as well as a TON of other nick-nacks. Just might have something to fit the purpose.
$10 is kinda high for that size jar but cheap for tools. I would scoop it out into a Tupperware container and have at it... lol

[Spike00513]

Nice excuse to mow through some butter.

I'm a pack rat when it comes to wrenching. I have lots of old plastic jars laying around to store things in as well as a TON of other nick-nacks. Just might have something to fit the purpose.
$10 is kinda high for that size jar but cheap for tools. I would scoop it out into a Tupperware container and have at it... lol

Bam
Blue lid
$2.50

[Natejo91]

When I did the brembo 18z front and B7 S4 rear brake teardown and rebuild for powder coating, these stupid snap sings were driving me crazy.
I think i bought 3 different pairs of pliers before i found some that worked. I wish I had this post 1 year ago lol
Good post for those doing it in the future though

[Spike00513]

trader joe's peanut butter looks like it might have the same top as well
I wouldn't be surprised if a lot of grocery stores do, and if they get it from the same supplier or something

[oaybar007]

I've been curious about the rear caliper rebuild process, if taking the ebrake mechanism apart is entirely necessary as well. All I've seen is people removing the ebrake mechanism and most times even the components have looked just fine. They just lube them up and put them back together.

I have a set of S4 fronts and rears already taken apart and have rebuild parts on the shelf for yet to install. I'm just getting to tear down the rears now and curious what the consensus is on the mechanism... can I leave it in tact? The parts literally look shiny and nothing that strikes me there.

Here are the fronts refinished. Well, this was a few weeks ago and they are now completely cured. Still on the shelf though. Still have to hit rears, then refinish the S4 splash shields front and rear, order new pads, rotors and all that fun stuff. etc. etc. etc.!

This-


To This-

[jeridb83]

Hey guys I'm brand new here. Have a B7 S4 I'm going through and the calipers have been torn down (e-brake) mechanism removed too. I bought the rebuild kits after I stripped the calipers down, and had them sandblasted and powdercoated. My current issue too is the internal snap ring on the rear calipers that hold the e-brake mechanism. Unfortunately when I I disassembled them both snap rings broke and I disposed of them. My rebuild kits came with new ones but they are your standard internal snap ring design not the identical design as the originals. I called the Audi dealer, ECS tuning etc and no luck. Doesn't seem like anyone makes these. My issue is that the new snap ring seems to be just too large to fit. By too large I mean the body of the ring seems too thick in width and wont allow the ring to clear the metal shaft of the e-brake mechanism and into the snap ring groove on the caliper. Any advice? Thanks!!!!

[Kevin C]

Try test fitting just the snap ring into the body to verify fit. If that works see just how far off you are. I cant help with a thickness measurement but I do know for sure the factory parts on mine seemed too thick until I shortened the assembly up a bit by bending the tangs on the spring cage.

Take away, even putting the factory parts back in is a problem because the spring cage tangs deform a little over time and keep the snap ring from seating. You may or may not have snap rings that are too thick but for sure the factory parts need this fix.

Try compressing the cage and tightening up the tabs, it may be enough to allow the snap ring to seat.



Snap rings various OD's and thickness choices: https://www.mcmaster.com/snap-rings/...type~internal/

[kivan]

Kevin,
just wanted to thank you for an awesome tip. I was having trouble getting the snap ring back on on one caliper and your tip with compressing the emergency brake assembly and tightening the tabs helped me finally finish the work. It would have been even easier should I had the proper 90 degrees bent long nose snap ring pliers.
Thanks.

[Kevin C]

Kevin,
just wanted to thank you for an awesome tip. I was having trouble getting the snap ring back on on one caliper and your tip with compressing the emergency brake assembly and tightening the tabs helped me finally finish the work. It would have been even easier should I had the proper 90 degrees bent long nose snap ring pliers.
Thanks.

Thanks for the feedback and I'm glad it worked out for you. I was happy to figure this one out and the peanut butter cap reviews were pretty funny. I wonder what Spike has been up to?

[hightime80]

Bugging the crap out pf people on the Taco forum probably😂

[Kevin C]

A quick update on caliper rebuilding. I picked up a set of S4 rear calipers as an upgrade to the A4 B7 calipers.

1: The green Permatex brake lube says it can be used on caliper pistons, this is not good advice (Permatex 85188 Ultra Disc Brake Caliper Lube), The caliper piston on the caliper I put together last week end was stuck solid after 7 days, never using that stuff again. It might be OK for the slider pins but not for the pistons.

In the past I have used brake assembly lube like this one https://www.airosol.com/product/assembly-lube/ Probably still a good choice.

2: The E brake seal is lubed with grease from the factory (inside the piston and on the shaft). It appears to be a silicone based grease. I used Sil-Glyde brake lube. It works great. I also used it on the piston boot and piston. It's almost too slippery. It's a good thing to have some type of lube on the boot side of the piston. It helps to seal the boot and prevents corrosion on the caliper housing where the boot sits. I bought a tub of it on Amazon. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

3: I came up with another way to install the snap ring for the parking brake. A pad spreader and a socket helps to push the mechanism in while seating the snap ring. It's still awkward but it works.
20210717_155956.jpg
4: Some of the rebuild kits don't have the right sized O rings for the parking brake shaft. They must be sourcing from similar vendors because most kits were wrong. The Centric kits were right but one bag was not fully sealed and was missing parts. Piston seals also varied kit to kit. My advice is to inspect and compare, Bendix kits were wrong.

The main reason I do my own calipers is that if I have a good set of pistons and castings why send them in and end up with a beat up set that gets new seals. Where the piston boots seal gets beat up if the calipers see salt in winter. Mine were super clean, at least they were after I glass beaded the castings. My current prep is glass bead, deburr, self etching primer and then caliper paint. Powder coating is an option. So far what I have been doing has held up very well. And yes primer works just fine on calipers.