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  #1  
Old 01-22-2018, 04:26 PM
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Decided to reseal rear brake caliper, ran into an odd issue.

Instead of the usual "It's broke/I'm stuck, I need help!" threads, I decided I'll include my experiences and progress this time, to make it more interesting and maybe it will help someone out one day.

So, I've decided I'll reseal caliper myself. It's gotten so bad that when I parked the car, the next morning there was a puddle of brake fluid on the ground. The brakes don't work AT ALL(No I didn't put my foot to the floor, well I hope I didn't). The caliper was leaking, when I pumped the brakes, only the left piston moved, oddly enough, when I released the pressure by unscrewing the bleeder screw, I could very easily move either piston in or out with my thumbs, took absolutely no effort (made a fun play toy for a second ). In short, the right piston was not frozen. Also the dust boot on the right looked disfigured.

The pads and rotors have worn dead even, so I guess under normal operating pressure everything equalizes.The piston on the left was leaking on the get go, then when I pushed the left piston in, the right one moved out it also started to leak out from the dust boot. So both of them where leaking from their dust boots.

Correct me if I'm wrong, the only way they can leak from their dust boots is if the square cut sealing ring is leaking, which allows a little bit of fluid to slip past the piston and out the cylinder right?

The boot was bulged and inflated and you could feel fluid, is this normal?
Here's a video of the phenomenon.
https://youtu.be/OIBqmopgwNU

Onto the the pistons, they came out easily, so easily in fact I only used my hands, I saw immediately that they where corroded. At this point many would trash them, or sand them but I didn't think either route was necessary.



So I took out my phosphoric acid and wiped it down with a paint brush and scrubbed it off with a towel to my amazement they came out nearly rust free.

https://youtu.be/jpGi2SqSoSU
Final result
https://youtu.be/5PemK4w6f3c

Now onto the actual problem

The remainder of the dust boot is stuck on the outer edge of the cylinder bore, somehow it fussed itself on there and won't come off. How do I get this stuff off? Pain staking cleaning? Machine shop? Media blaster?
Weird has such a trivial thing can have such a huge impact on progress.
I've never heard of this kind of issue before.

Here's a video of it.
https://youtu.be/nVjJ7S_1aUo
Is that due to the fact that is simply have no choice but to split the calipers to replace the dust boot? Are they caught in between something I can't see?

Looking forward to everyone's opinions.



Attached Thumbnails
Decided to reseal rear brake caliper, ran into an odd issue.-39810342142_77e92cb63c_b.jpg  
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1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

Last edited by Father Of Giants; 01-22-2018 at 04:39 PM.
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Old 01-22-2018, 05:05 PM
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I rebuild a lot calipers, and here is what I do. First I remove them from the car and pop out the pins and pads. Next push in the cups as far as they can go and pry off the dust seals. Next spray them with brake clean and blow them with air. Then plug the hole for the inlet pipe, and pop them into the bead blast cabinet. This removes all paint and rust. Then blow air into them to get the cups out. Put a block of wood or rags between them. next split them in half, remove the seals and run a hone inside to clean them up. On the cups I use 0000 steel wool with oil to clean up any rust staining. As they are hard chromed. If there is any pitting they will leak, so they need to be replaced. Next is to clean them with brake cleaner again, and pop in the new seals, insert the cups with new dust seals, and bolt them back together. Then repaint them in the color of your choice. ( I go with black) and they are good to go for another 10-20 years.
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Old 01-22-2018, 05:06 PM
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I've never split the caliper doing a rebuild.
Splitting Brake Calipers?
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Old 01-22-2018, 05:36 PM
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Quote:
Originally Posted by vonsmog View Post
I rebuild a lot calipers, and here is what I do. First I remove them from the car and pop out the pins and pads. Next push in the cups as far as they can go and pry off the dust seals. Next spray them with brake clean and blow them with air. Then plug the hole for the inlet pipe, and pop them into the bead blast cabinet. This removes all paint and rust. Then blow air into them to get the cups out. Put a block of wood or rags between them. next split them in half, remove the seals and run a hone inside to clean them up. On the cups I use 0000 steel wool with oil to clean up any rust staining. As they are hard chromed. If there is any pitting they will leak, so they need to be replaced. Next is to clean them with brake cleaner again, and pop in the new seals, insert the cups with new dust seals, and bolt them back together. Then repaint them in the color of your choice. ( I go with black) and they are good to go for another 10-20 years.
I would prefer the least invasive method possible to solve the issue. I also don't have a vise to hold the caliper in order to split it. Luckily I live in the south so there's no rust whatsoever. Are there situation when splitting is a must?

Quote:
Originally Posted by sgnimj96 View Post
I've never split the caliper doing a rebuild.
Splitting Brake Calipers?
So this means the square cut seals, dust boot and piston can be installed without splitting correct?
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1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.
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Old 01-22-2018, 08:11 PM
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Quote:
Originally Posted by Father Of Giants View Post

So this means the square cut seals, dust boot and piston can be installed without splitting correct?
Absolutely. Plus heat shields, where applicable.
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Old 01-22-2018, 09:56 PM
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Originally Posted by tangofox007 View Post
Absolutely. Plus heat shields, where applicable.
Where are the heat shields. On the back of the pads?
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1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.
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  #7  
Old 01-23-2018, 10:30 AM
A guy who likes to Benz
 
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Quote:
Originally Posted by Father Of Giants View Post
Where are the heat shields. On the back of the pads?
Heat shields are installed on the piston just below the piston face which comes in contact with the pad. On the pistons I've rebuilt they help retain the boot on the piston and shield it from debris/heat.
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Old 01-23-2018, 10:57 AM
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Quote:
Originally Posted by Father Of Giants View Post

Now onto the actual problem

The remainder of the dust boot is stuck on the outer edge of the cylinder bore, somehow it fussed itself on there and won't come off. How do I get this stuff off? Pain staking cleaning? Machine shop? Media blaster?
Weird has such a trivial thing can have such a huge impact on progress.
I've never heard of this kind of issue before.




it is due the too intense heat...I had one (front) like that
I used thin screwdriver and fine steel-wool to pry/send the sucker off...

it is the inner side of the cyl.bore you have to be careful of...

cheers
ChO

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Old 01-23-2018, 01:18 PM
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Quote:
Originally Posted by cho View Post
it is due the too intense heat...I had one (front) like that
I used thin screwdriver and fine steel-wool to pry/send the sucker off...

it is the inner side of the cyl.bore you have to be careful of...

cheers
ChO

.
Thanks a lot! I'll get down to it.
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1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.
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  #10  
Old 01-27-2018, 07:02 PM
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Well, ran into a TON more green horn related issues. Assembing stuff wrong, or forgetting parts.
Brakes work good as new!

Need to buy somemore seal kits.
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1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.
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  #11  
Old 01-28-2018, 08:15 AM
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Quote:
Originally Posted by sgnimj96 View Post
I've never split the caliper doing a rebuild.
Splitting Brake Calipers?
Of course you can split them. Nothing complicated about it. You can rebuild an entire engine but you cant split a 4 bolt machined surface with a couple O rings?

The FSM never anticipated service 35 years after the fact with the comment not to split them. With the random quality of remans out there, for sure i split them every time. You arent fully rebuilding your caliper if your leave decades old O rings in place.
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Old 01-28-2018, 09:41 PM
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I am not sure on your year and model but fot the W123s the Centeric Seal Kits come with the internal O-rings you would need if you split the calipers. Don't know if it is still there but Centeric used top have a website.
I don't know if these sites are still active or not: http://www.centricparts.com/products/calipers
By vehicle
https://centricparts.centriccatalog.com/EcatMain.aspx?id=ANR&uid=ANR&sid=0

Once you have the part number for the kit you can go shopping on the internet.

As far as not having a Vice goes often you can mount the caliper back on the car and loosen the bolts that hold the calipers together. The same when you torqe them.

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