How to remove brake caliper
01-12-2014, 02:38 PM
#1
Audiworld Junior Member
Thread Starter
Join Date: Dec 2013
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
How to remove brake caliper
I've run "search" on this site, and manually slogged through 20 pages of posts; to avoid redundant threads; but can't find ANYONE with definitive instructions on how to remove the front brake calipers. My wife brought our 2001 A6 4.2 home with a blazing hot, sour-smelling driver's side front brake. I'm assuming that the caliper is siezed. With thousands of hours of garage experience I figured "no problem". After jacking up the car, removing the wheel, and next removing the black rubber dust caps I stopped, stumped. The caliper pins are round inside; no star; no hex; nothing. Most of what I find onLine says a 7mm hex; but no way. Really? How do these magical calipers come off,, please help ...
01-12-2014, 02:59 PM
#2
AudiWorld Super User
Join Date: Mar 2003
Posts: 6,001
Likes: 0
Received 0 Likes
on
0 Posts
Does the 4.2 have HP-2 calipers on it? I'm not sure.
In any event, most of the front C5 calipers were/are secured with bolts from the rear of the hub/knuckle/bearing carrier. On S6s, a very close cousin, they are 22mm, very hard to reach without a lift (put steering at lock in appropriate direction) and are very tight (140 lb-ft?)
Grant
In any event, most of the front C5 calipers were/are secured with bolts from the rear of the hub/knuckle/bearing carrier. On S6s, a very close cousin, they are 22mm, very hard to reach without a lift (put steering at lock in appropriate direction) and are very tight (140 lb-ft?)
Grant
01-12-2014, 03:01 PM
#3
Not sure which calipers you have - but it sounds like you may have the HP2 4 pad calipers. There are two 19 or 21 MM bolts that hold it onto the knuckle, it isn't setup like your normal caliper...my memory is a little fuzzy because it's been a long while since I did it.
01-12-2014, 03:28 PM
#4
AudiWorld Super User
Does the 4.2 have HP-2 calipers on it? I'm not sure.
In any event, most of the front C5 calipers were/are secured with bolts from the rear of the hub/knuckle/bearing carrier. On S6s, a very close cousin, they are 22mm, very hard to reach without a lift (put steering at lock in appropriate direction) and are very tight (140 lb-ft?)
Grant
In any event, most of the front C5 calipers were/are secured with bolts from the rear of the hub/knuckle/bearing carrier. On S6s, a very close cousin, they are 22mm, very hard to reach without a lift (put steering at lock in appropriate direction) and are very tight (140 lb-ft?)
Grant
01-12-2014, 04:11 PM
#5
Audiworld Junior Member
Thread Starter
Join Date: Dec 2013
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
The caliper has a "Lucas" emboss on the flange, and a 4-BD decal on it. It's probably been replaced, I'm guessing. 92k miles on the clock; and I just bought it a few months ago. To my "GM" eye, it is a 2-piston, 4-pad caliper. On the backside of the caliper is where I removed the dust covers to reveal the upper and lower "mystery" bolts, with no apparent hex or torx head on it. Seems to me these should be the bolts I need to remove to get the caliper off. Also, would it be odd, now that it is cooled off, that the caliper appears to be working fine? I'm an Audi fan, for life, for real, but my Chevy stuff never did this ... weird. 
01-12-2014, 04:37 PM
#6
AudiWorld Super User
My bentley admits the use of a Brembo 18 series brake caliper…if you have to drive pins out to replace brake pads rather than use a pair of pliers to compress the brake pad retainer springs (HP2), you have the brembo calipers. BTW…the Brembo calipers also have 8! pistons…non floating caliper with looks like hat rotors, i.e, two part rotors. If you don't have two part rotors you've more than likely got HP2 calipers.
The brembo calipers are held with two socket head cap screws…you'll have to clean them out to get the right hex head wrench in there.
The HP2 calipers are held in with two ribbed head bolts and a washer (makes no sense to me but that's what the bentley says!). Supposed to replace the ribbed head bolts if you remove them. They're hex head bolts…clean everything off to get to them. Probably 22mm like on the 02S6.
The brembo calipers are held with two socket head cap screws…you'll have to clean them out to get the right hex head wrench in there.
The HP2 calipers are held in with two ribbed head bolts and a washer (makes no sense to me but that's what the bentley says!). Supposed to replace the ribbed head bolts if you remove them. They're hex head bolts…clean everything off to get to them. Probably 22mm like on the 02S6.
01-12-2014, 06:40 PM
#7
AudiWorld Super User
My bentley admits the use of a Brembo 18 series brake caliper…if you have to drive pins out to replace brake pads rather than use a pair of pliers to compress the brake pad retainer springs (HP2), you have the brembo calipers. BTW…the Brembo calipers also have 8! pistons…non floating caliper with looks like hat rotors, i.e, two part rotors. If you don't have two part rotors you've more than likely got HP2 calipers.
The brembo calipers are held with two socket head cap screws…you'll have to clean them out to get the right hex head wrench in there.
The HP2 calipers are held in with two ribbed head bolts and a washer (makes no sense to me but that's what the bentley says!). Supposed to replace the ribbed head bolts if you remove them. They're hex head bolts…clean everything off to get to them. Probably 22mm like on the 02S6.
The brembo calipers are held with two socket head cap screws…you'll have to clean them out to get the right hex head wrench in there.
The HP2 calipers are held in with two ribbed head bolts and a washer (makes no sense to me but that's what the bentley says!). Supposed to replace the ribbed head bolts if you remove them. They're hex head bolts…clean everything off to get to them. Probably 22mm like on the 02S6.
Trending Topics
01-13-2014, 10:18 AM
#8
AudiWorld Super User
Join Date: Mar 2003
Posts: 6,001
Likes: 0
Received 0 Likes
on
0 Posts
if they are HP-2s, and the consensus here is that they are, two 22 mm f-ing tight bolts on the BACK of the hub.
Stuff you are looking at is to dis-assemble the caliper and to lube the floating pins, whcih is also a good idea. Those are stars by the way.
IIRC, triple-squares
Nice calipers too. very light.
Grant
Stuff you are looking at is to dis-assemble the caliper and to lube the floating pins, whcih is also a good idea. Those are stars by the way.
IIRC, triple-squares
Nice calipers too. very light.
Grant
01-13-2014, 02:23 PM
#9
AudiWorld Member
My bentley admits the use of a Brembo 18 series brake caliper…if you have to drive pins out to replace brake pads rather than use a pair of pliers to compress the brake pad retainer springs (HP2), you have the brembo calipers. BTW…the Brembo calipers also have 8! pistons…non floating caliper with looks like hat rotors, i.e, two part rotors. If you don't have two part rotors you've more than likely got HP2 calipers.
The brembo calipers are held with two socket head cap screws…you'll have to clean them out to get the right hex head wrench in there.
The HP2 calipers are held in with two ribbed head bolts and a washer (makes no sense to me but that's what the bentley says!). Supposed to replace the ribbed head bolts if you remove them. They're hex head bolts…clean everything off to get to them. Probably 22mm like on the 02S6.
The brembo calipers are held with two socket head cap screws…you'll have to clean them out to get the right hex head wrench in there.
The HP2 calipers are held in with two ribbed head bolts and a washer (makes no sense to me but that's what the bentley says!). Supposed to replace the ribbed head bolts if you remove them. They're hex head bolts…clean everything off to get to them. Probably 22mm like on the 02S6.
01-22-2014, 05:40 AM
#10
Audiworld Junior Member
Thread Starter
Join Date: Dec 2013
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
Whew! Nothing like having to wait for a bank holiday to get some time off work and hit the garage with the Audi! The bolts were on the back; correct. They were dirty; correct. They were a hex, 21mm in size; and I had to move the hard brake line to get to the top bolt. A 24" breaker bar plus a little persuasion broke them loose, and I have the caliper off (!). The caliper guide pins are clean, shiny, greased, and the unit moves freely. The more time I spent with the caliper project, the more a 'burnt' smell permeated the garage. I think she's seized. I c-clamped each piston and gently turned on it, but neither retracted more than 1/8", if that. Then when I stepped on the brake pedal several times, neither piston moved out more than an 1/8" either; movement was hardly noticeable. That, plus the burnt smell, is leading me to believe that the caliper is shot. Pads were all in great shape; hardly worn; and very even all the way around. The rotor is clean and true as well. Bad caliper? Carfax says brakes were "rebuilt" at 78,000 miles; who knows what they did; `Dee' (for Au-DI) has 92,000 on her now.
