Re: [MBZ] rebuilding a W123 front caliper
I will admit to having violated the manual's stricture against splitting the halves of the calipers now on more than one occasion without apparent adverse consequence. Makes inspection/cleaning a bit easier and reinstallation of the pucks a lot easier. Last time on my V'gon following a sudden almost catastrophic brake failure I only discovered a hairline crack in a caliper bore after I'd split the thing. Might otherwise have wasted time & $ trying to refurbish a piece of junk. I do like your idea about using a grease gun though, Jim. I do these things infrequently enough that I pretty much always have to reinvent the wheel & turn that little chore into a major donnybrook. The first puck's easy and iirc, if you make that one the one in the half that doesn't have the bleed valve and then split the halves it's pretty easy to seal the bore in the mating surface allowing you to push the other one out. -joe
Re: [MBZ] rebuilding a W123 front caliper..
What I do is rebuild the one side and then put piston back in. Use a C clamp to hold that piston in and do the same trick for the other side. I don't like to do it this way because it prevents a thorough cleaning and drying before reassembly. I use a big washer with a rubber sheet to seal the opposite bore, and the C clamp. -- Jim
Re: [MBZ] rebuilding a W123 front caliper..
What I do is rebuild the one side and then put piston back in. Use a C clamp to hold that piston in and do the same trick for the other side. Trampas -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Kevin J. Slater Sent: Saturday, August 26, 2006 5:36 PM To: LarryT Cc: Mercedes Discussion List Subject: Re: [MBZ] rebuilding a W123 front caliper.. Hey Larry, thanks for the warning. As it turns out I didn't have a fitting that would allow me to connect the air compressor to the caliper. So I took a finger of a disposable rubber mechanics glove and wound it around the tip of my air blaster nozzle. That allowed me to make a so-so seal against the place where the brake hose connects. A little air and one puck out. Now I had to figure out how to get the other one out with a gaping hole in my caliper. It looked like the bleeder fitting might be the ticket so I tried air in there and viola', the other puck was out. Now I just have to get it cleaned up and reassembled. Thanks for the tips Peter, Jim and Larry. I think I may be in business with just a rebuild. ...Kevin LarryT said: > Hi Kevin, > Yes, Haynes covers it. > > As far as using a air compressor - those saying it's dangerous are not > wrong! I used air to get the pistons from my 911 calipers - luckily I > kept > a piece of 2x4 in the caliper so the piston would hit the wood instead of > the metal caliper - but the surprising thing is the force exhibited when > the pistons come out!! Ka Blam!! > > Make sure you lubricate all parts with fresh brake fluid during assembly. > That keeps them flexible and helps them go into place. > > Good luck - > > Larry T (67 MGB, 74 911, 78 240D, 91 300D) > www.youroil.net for Oil Analysis and Weber Parts > Test Results http://members.rennlist.com/oil > PORSCHE POSTERS! youroil.net > Weber Carb Info http://members.rennlist.com/webercarbs > Porsche Road Test http://members.rennlist.com/roadtest/ > . > - Original Message - > From: "Kevin J. Slater" <[EMAIL PROTECTED]> > Cc: "Mercedes Discussion List" > Sent: Friday, August 25, 2006 2:05 PM > Subject: Re: [MBZ] rebuilding a W123 front caliper.. > > >> Jim and Sunil, >> >> thanks for the responses. Since I don't have experience doing this, I'm >> wondering if there is a procedure for it in the shop manuals (I'm >> doubting >> it since they expect the mechanics using those manuals are experienced) >> or >> maybe in the Haynes manual. I'm great a disassembly, but a procedure is >> always welcome to cover the things that experience teaches. >> >> ...Kevin >> >> Jim Cathey said: >>>> The '79 240D project car for my son has a leaking left front caliper. >>>> Bought a rebuild kit from Rusty. Any tips or pitfalls that I need to >>>> be >>>> aware of? This is my first time rebuilding a caliper so any tips >>>> appreciated. >>> >>> It's easy and fun! No real pitfalls, I use 600-grit wet-and-dry >>> sandpaper in a bucket of water to clean gunk and corrosion off of >>> the pucks and out of the bores. Work parallel to the sealing rings, >>> not perpendicularly. You don't want scratches (and there shouldn't >>> be any) in a direction that will encourage leaks. >>> >>>> make sure you have an air compressor to blow out the pistons. doing >>>> it any >>>> other way is hard. Also, fit the rubber boots to the pistons BEFORE >>>> you >>> >>> I've done this, but its scary and a little bit dangerous. Compressed >>> air really bangs the pucks out of there, you need wood to catch the >>> puck against. I've chipped a puck before doing this, and people have >>> been hurt too. >>> >>> Much better is to drive them out with the brake system, though that >>> takes >>> a bit of fiddling to get the second puck out. Or you can do as I did >>> recently and use a water-filled grease gun to do the job. Tres cool! >>> And totally safe. http://cathey.dogear.com/mb190d.html >>> >>> I still use the air compressor, but only to dry things off. >>> >>>> slide the pistons into the cylinders. Once the pistons are totally >>>> seated, >>>> it's really hard to fit the boots on. >>> >>> Just put 'em on before you fully seat the pucks. You don't have to put >>> them on before you start to insert them, unless you find that to be >>> easier for you. >>> >>> -- Jim >>> >>> >> >> >
Re: [MBZ] rebuilding a W123 front caliper..
Hey Larry, thanks for the warning. As it turns out I didn't have a fitting that would allow me to connect the air compressor to the caliper. So I took a finger of a disposable rubber mechanics glove and wound it around the tip of my air blaster nozzle. That allowed me to make a so-so seal against the place where the brake hose connects. A little air and one puck out. Now I had to figure out how to get the other one out with a gaping hole in my caliper. It looked like the bleeder fitting might be the ticket so I tried air in there and viola', the other puck was out. Now I just have to get it cleaned up and reassembled. Thanks for the tips Peter, Jim and Larry. I think I may be in business with just a rebuild. ...Kevin LarryT said: > Hi Kevin, > Yes, Haynes covers it. > > As far as using a air compressor - those saying it's dangerous are not > wrong! I used air to get the pistons from my 911 calipers - luckily I > kept > a piece of 2x4 in the caliper so the piston would hit the wood instead of > the metal caliper - but the surprising thing is the force exhibited when > the pistons come out!! Ka Blam!! > > Make sure you lubricate all parts with fresh brake fluid during assembly. > That keeps them flexible and helps them go into place. > > Good luck - > > Larry T (67 MGB, 74 911, 78 240D, 91 300D) > www.youroil.net for Oil Analysis and Weber Parts > Test Results http://members.rennlist.com/oil > PORSCHE POSTERS! youroil.net > Weber Carb Info http://members.rennlist.com/webercarbs > Porsche Road Test http://members.rennlist.com/roadtest/ > . > - Original Message - > From: "Kevin J. Slater" <[EMAIL PROTECTED]> > Cc: "Mercedes Discussion List" > Sent: Friday, August 25, 2006 2:05 PM > Subject: Re: [MBZ] rebuilding a W123 front caliper.. > > >> Jim and Sunil, >> >> thanks for the responses. Since I don't have experience doing this, I'm >> wondering if there is a procedure for it in the shop manuals (I'm >> doubting >> it since they expect the mechanics using those manuals are experienced) >> or >> maybe in the Haynes manual. I'm great a disassembly, but a procedure is >> always welcome to cover the things that experience teaches. >> >> ...Kevin >> >> Jim Cathey said: >>>> The '79 240D project car for my son has a leaking left front caliper. >>>> Bought a rebuild kit from Rusty. Any tips or pitfalls that I need to >>>> be >>>> aware of? This is my first time rebuilding a caliper so any tips >>>> appreciated. >>> >>> It's easy and fun! No real pitfalls, I use 600-grit wet-and-dry >>> sandpaper in a bucket of water to clean gunk and corrosion off of >>> the pucks and out of the bores. Work parallel to the sealing rings, >>> not perpendicularly. You don't want scratches (and there shouldn't >>> be any) in a direction that will encourage leaks. >>> >>>> make sure you have an air compressor to blow out the pistons. doing >>>> it any >>>> other way is hard. Also, fit the rubber boots to the pistons BEFORE >>>> you >>> >>> I've done this, but its scary and a little bit dangerous. Compressed >>> air really bangs the pucks out of there, you need wood to catch the >>> puck against. I've chipped a puck before doing this, and people have >>> been hurt too. >>> >>> Much better is to drive them out with the brake system, though that >>> takes >>> a bit of fiddling to get the second puck out. Or you can do as I did >>> recently and use a water-filled grease gun to do the job. Tres cool! >>> And totally safe. http://cathey.dogear.com/mb190d.html >>> >>> I still use the air compressor, but only to dry things off. >>> >>>> slide the pistons into the cylinders. Once the pistons are totally >>>> seated, >>>> it's really hard to fit the boots on. >>> >>> Just put 'em on before you fully seat the pucks. You don't have to put >>> them on before you start to insert them, unless you find that to be >>> easier for you. >>> >>> -- Jim >>> >>> >> >> >> -- >> "Thank God for Microsoft" -- Linus Torvalds >> >> ___ >> http://www.okiebenz.com >> For new parts see official list sponsor: http://www.buymbparts.com/ >> For used parts email [EMAIL PROTECTED] >> >> To Unsubscribe or change delivery options go to: >> http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com >> >> >> -- >> No virus found in this incoming message. >> Checked by AVG Free Edition. >> Version: 7.1.405 / Virus Database: 268.11.6/427 - Release Date: >> 8/24/2006 >> > > -- "Thank God for Microsoft" -- Linus Torvalds
Re: [MBZ] rebuilding a W123 front caliper..
Jim: Not to be picky, but the "o" in "o-ring" refers to the cross section -- if it isn't round, it's not an o-ring, it's a seal. The piston seal in a caliper doesn't act like one, either, it is square not to seal the fluid in, but to pull the piston back slightly when the pressure is relived (a quick way to check to see if you need a new on is to watch the pads while someone applies and releases the brakes -- if they don't move back that tiny bit, the seal isn't working correctly and needs to be replaced). An o-ring will allow free movement of the piston, as they were developed to do --the nice thing about them is that they rotate a tiny bit in both directions as the parts move, permitting lubrication to occur and wear to be at a minimum. One of the patents appropriated by the US government during WWII, to the great loss of the inventor. Even 600 grit paper in the bore below the seal can cause problems, either by leaving grit embedded in the bore, removing too much material, or raising burrs that actually reduce clearance. Stuck brakes are a PITA. Peter
Re: [MBZ] rebuilding a W123 front caliper..
DO NOT, EVER sand either bore or piston with ANYTHING. If it won't clean up with brake parts cleaner, you need to replace the caliper. I don't mean to imply that you're cutting metal with this stuff, it's just a gentle buffing to cut the gunk, which is aggressively tenacious in some cases. The only thing I use is 600 wet, a tiny chunk pushed around with my finger, and I clean it out pretty thoroughly afterwards. The piston is also chrome plated, and a smooth surface is required for the piston seal (it's NOT an o-ring!) to retract the piston. A rough Hence the 'O'. It's an O-ring with a square cross-section. surface will cause the piston to remain out, and it will also usually cause it to leak brake fluid. If it does, I'll know what to do. -- Jim
Re: [MBZ] rebuilding a W123 front caliper..
DO NOT, EVER sand either bore or piston with ANYTHING. If it won't clean up with brake parts cleaner, you need to replace the caliper. Sanding either bore or piston is going to cause them to be out of round and/or too large (or small), and the piston will surely bind and stick. The piston is also chrome plated, and a smooth surface is required for the piston seal (it's NOT an o-ring!) to retract the piston. A rough surface will cause the piston to remain out, and it will also usually cause it to leak brake fluid. Clean piston and bore with lint free cloth and brake parts cleaner. I've never seen anything that didn't come right off with brake parts spray and a rag. Corrosion of bore or piston below the piston seal requires replacement of caliper. Corrosion of the piston above the bore is OK, and you can CAREFULLY clean rust in the bore above the pistons seal with Scocbrite IF you then very completely flush out the caliper. Grit of any kind, sandpaper or Scotchbrite, will cause the piston to stick sooner or later. Peter On Aug 25, 2006, at 3:03 PM, Jim Cathey wrote: wondering if there is a procedure for it in the shop manuals (I'm doubting it since they expect the mechanics using those manuals are experienced) or maybe in the Haynes manual. I'm great a disassembly, but a procedure is always welcome to cover the things that experience teaches. My description _was_ the procedure! The hardest part of the job is getting the pucks out of there. That's why I liked the grease gun idea, it eliminates the scary 'hammer-of-extreme-pain' step with the air compressor that I used to use. Remove rubber sealing caps Remove pucks Remove 'O' rings Carefully wet-sand the bores and the pucks to shiny cleanness Clean and blow-dry entire caliper, passages and all Put in new O rings Put sealing cap on puck Lube bores and pucks with brake fluid and install Snap seals over bores -- Jim ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] rebuilding a W123 front caliper..
Hi Kevin, Yes, Haynes covers it. As far as using a air compressor - those saying it's dangerous are not wrong! I used air to get the pistons from my 911 calipers - luckily I kept a piece of 2x4 in the caliper so the piston would hit the wood instead of the metal caliper - but the surprising thing is the force exhibited when the pistons come out!! Ka Blam!! Make sure you lubricate all parts with fresh brake fluid during assembly. That keeps them flexible and helps them go into place. Good luck - Larry T (67 MGB, 74 911, 78 240D, 91 300D) www.youroil.net for Oil Analysis and Weber Parts Test Results http://members.rennlist.com/oil PORSCHE POSTERS! youroil.net Weber Carb Info http://members.rennlist.com/webercarbs Porsche Road Test http://members.rennlist.com/roadtest/ . - Original Message - From: "Kevin J. Slater" <[EMAIL PROTECTED]> Cc: "Mercedes Discussion List" Sent: Friday, August 25, 2006 2:05 PM Subject: Re: [MBZ] rebuilding a W123 front caliper.. Jim and Sunil, thanks for the responses. Since I don't have experience doing this, I'm wondering if there is a procedure for it in the shop manuals (I'm doubting it since they expect the mechanics using those manuals are experienced) or maybe in the Haynes manual. I'm great a disassembly, but a procedure is always welcome to cover the things that experience teaches. ...Kevin Jim Cathey said: The '79 240D project car for my son has a leaking left front caliper. Bought a rebuild kit from Rusty. Any tips or pitfalls that I need to be aware of? This is my first time rebuilding a caliper so any tips appreciated. It's easy and fun! No real pitfalls, I use 600-grit wet-and-dry sandpaper in a bucket of water to clean gunk and corrosion off of the pucks and out of the bores. Work parallel to the sealing rings, not perpendicularly. You don't want scratches (and there shouldn't be any) in a direction that will encourage leaks. make sure you have an air compressor to blow out the pistons. doing it any other way is hard. Also, fit the rubber boots to the pistons BEFORE you I've done this, but its scary and a little bit dangerous. Compressed air really bangs the pucks out of there, you need wood to catch the puck against. I've chipped a puck before doing this, and people have been hurt too. Much better is to drive them out with the brake system, though that takes a bit of fiddling to get the second puck out. Or you can do as I did recently and use a water-filled grease gun to do the job. Tres cool! And totally safe. http://cathey.dogear.com/mb190d.html I still use the air compressor, but only to dry things off. slide the pistons into the cylinders. Once the pistons are totally seated, it's really hard to fit the boots on. Just put 'em on before you fully seat the pucks. You don't have to put them on before you start to insert them, unless you find that to be easier for you. -- Jim -- "Thank God for Microsoft" -- Linus Torvalds ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.405 / Virus Database: 268.11.6/427 - Release Date: 8/24/2006
Re: [MBZ] rebuilding a W123 front caliper..
wondering if there is a procedure for it in the shop manuals (I'm doubting it since they expect the mechanics using those manuals are experienced) or maybe in the Haynes manual. I'm great a disassembly, but a procedure is always welcome to cover the things that experience teaches. My description _was_ the procedure! The hardest part of the job is getting the pucks out of there. That's why I liked the grease gun idea, it eliminates the scary 'hammer-of-extreme-pain' step with the air compressor that I used to use. Remove rubber sealing caps Remove pucks Remove 'O' rings Carefully wet-sand the bores and the pucks to shiny cleanness Clean and blow-dry entire caliper, passages and all Put in new O rings Put sealing cap on puck Lube bores and pucks with brake fluid and install Snap seals over bores -- Jim
Re: [MBZ] rebuilding a W123 front caliper..
Jim and Sunil, thanks for the responses. Since I don't have experience doing this, I'm wondering if there is a procedure for it in the shop manuals (I'm doubting it since they expect the mechanics using those manuals are experienced) or maybe in the Haynes manual. I'm great a disassembly, but a procedure is always welcome to cover the things that experience teaches. ...Kevin Jim Cathey said: >> The '79 240D project car for my son has a leaking left front caliper. >> Bought a rebuild kit from Rusty. Any tips or pitfalls that I need to be >> aware of? This is my first time rebuilding a caliper so any tips >> appreciated. > > It's easy and fun! No real pitfalls, I use 600-grit wet-and-dry > sandpaper in a bucket of water to clean gunk and corrosion off of > the pucks and out of the bores. Work parallel to the sealing rings, > not perpendicularly. You don't want scratches (and there shouldn't > be any) in a direction that will encourage leaks. > >> make sure you have an air compressor to blow out the pistons. doing >> it any >> other way is hard. Also, fit the rubber boots to the pistons BEFORE >> you > > I've done this, but its scary and a little bit dangerous. Compressed > air really bangs the pucks out of there, you need wood to catch the > puck against. I've chipped a puck before doing this, and people have > been hurt too. > > Much better is to drive them out with the brake system, though that > takes > a bit of fiddling to get the second puck out. Or you can do as I did > recently and use a water-filled grease gun to do the job. Tres cool! > And totally safe. http://cathey.dogear.com/mb190d.html > > I still use the air compressor, but only to dry things off. > >> slide the pistons into the cylinders. Once the pistons are totally >> seated, >> it's really hard to fit the boots on. > > Just put 'em on before you fully seat the pucks. You don't have to put > them on before you start to insert them, unless you find that to be > easier for you. > > -- Jim > > -- "Thank God for Microsoft" -- Linus Torvalds
Re: [MBZ] rebuilding a W123 front caliper..
The '79 240D project car for my son has a leaking left front caliper. Bought a rebuild kit from Rusty. Any tips or pitfalls that I need to be aware of? This is my first time rebuilding a caliper so any tips appreciated. It's easy and fun! No real pitfalls, I use 600-grit wet-and-dry sandpaper in a bucket of water to clean gunk and corrosion off of the pucks and out of the bores. Work parallel to the sealing rings, not perpendicularly. You don't want scratches (and there shouldn't be any) in a direction that will encourage leaks. make sure you have an air compressor to blow out the pistons. doing it any other way is hard. Also, fit the rubber boots to the pistons BEFORE you I've done this, but its scary and a little bit dangerous. Compressed air really bangs the pucks out of there, you need wood to catch the puck against. I've chipped a puck before doing this, and people have been hurt too. Much better is to drive them out with the brake system, though that takes a bit of fiddling to get the second puck out. Or you can do as I did recently and use a water-filled grease gun to do the job. Tres cool! And totally safe. http://cathey.dogear.com/mb190d.html I still use the air compressor, but only to dry things off. slide the pistons into the cylinders. Once the pistons are totally seated, it's really hard to fit the boots on. Just put 'em on before you fully seat the pucks. You don't have to put them on before you start to insert them, unless you find that to be easier for you. -- Jim
Re: [MBZ] rebuilding a W123 front caliper..
make sure you have an air compressor to blow out the pistons. doing it any other way is hard. Also, fit the rubber boots to the pistons BEFORE you slide the pistons into the cylinders. Once the pistons are totally seated, it's really hard to fit the boots on. On 8/22/06, Kevin J. Slater <[EMAIL PROTECTED]> wrote: The '79 240D project car for my son has a leaking left front caliper. Bought a rebuild kit from Rusty. Any tips or pitfalls that I need to be aware of? This is my first time rebuilding a caliper so any tips appreciated. ...Kevin 87 300TD 285k mi 79 240D 161k mi -- "Thank God for Microsoft" -- Linus Torvalds ___ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com -- Sunil Hari 1992 300D 2.5T - 286Kmi. [EMAIL PROTECTED] 513-205-7474
[MBZ] rebuilding a W123 front caliper..
The '79 240D project car for my son has a leaking left front caliper. Bought a rebuild kit from Rusty. Any tips or pitfalls that I need to be aware of? This is my first time rebuilding a caliper so any tips appreciated. ...Kevin 87 300TD 285k mi 79 240D 161k mi -- "Thank God for Microsoft" -- Linus Torvalds
