split calipers - seals - Warren?

[jpahemi]

Kobalt,
Just buy another set of calipers. In the 911 world, $150 really isn't a heck of a lot. Think of the time and aggrevation you're going through trying to get the right answers and right parts; is it worth it?
Regards,
j.p.

[KobaltBlau]

Thank you for your reply, Warren. I would greatly appreciate those measurements on the SS calipers if you can make the time.

Best Regards,

[KobaltBlau]

Some notes:

The person who sold me these calipers (who I have not named, but who does post on pelican) never installed them. he bought them exactly as he sold them to me. Thus, he would never have run into these problems. It is the person who last used the calipers on a car who is at fault.

Now I am just trying to find some proper seals, hopefully from ate 'SS' calipers from a mercedes as Warren mentioned. I would like to put these calipers back together, partly as a matter of principle. with a good cleanup, new seals, and new very high grade bolts, they should be better than an old set that has never been split.

I also need to get the pistons out to inspect the bores. This is awkward since I don't have the seals or the drive bit to put the calpers back together to use the compressed air method, which is the only method I know that works. I may have to buy some bolts and possibly some o-rings just to get the pistons out. probably with o-rings and a torx bit I could just snug em enough to get enough of a seal to blow them out, without buying new bolts quite yet.

Thanks, All.

[Dan Owens]

Kobalt,

You're now seeing why no one splits these open anymore. It's a pain in the A$$ more than being really difficult. Someone in the chain of purchases should have spoken up that they were already split open but hey that's another debate/thread.

If you have an old valve stem laying around you can trim the wheel end down in a cone shape to fit into the fluid port where your trying to find the seals for. Then go to the gas station and use the air pump to pump air into each of the split halves, The cone shaped end will fit right into the fluid port and blow the pistons out. Just watch your hands when they come out of the calipers. I blow them into a cardboard box with a folded towel on the bottom.

[Eugene at Pelican Parts]

Originally posted by KobaltBlau
I also need to get the pistons out to inspect the bores. This is awkward since I don't have the seals or the drive bit to put the calpers back together to use the compressed air method, which is the only method I know that works.

Going with a tip from 101 Projects, I repeatedly slammed the caliper halves down onto some wood... HARD. The tip worked but the effort was TREMENDOUS. If you decide to attempt this, be sure wear gloves or wrap a rag around the caliper to absorb some of the shock to prevent your hands from ripping apart. Wear ear plugs too - metal slapping on wood is LOUD.

[KobaltBlau]

Thanks, Eugene.

Originally posted by Dan Owens
Someone in the chain of purchases should have spoken up that they were already split open but hey that's another debate/thread.

Indeed.

Originally posted by Dan Owens
If you have an old valve stem laying around you can trim the wheel end down in a cone shape to fit into the fluid port where your trying to find the seals for. Then go to the gas station and use the air pump to pump air into each of the split halves, The cone shaped end will fit right into the fluid port and blow the pistons out. Just watch your hands when they come out of the calipers. I blow them into a cardboard box with a folded towel on the bottom.

But there seem to be two fluid passages from one side to the other side of the caliper (see my photos in this thread), and since there is one piston on each side I don't see how they would not connect. Any thoughts on this, Dan?

TIA

[vash]

can you pry them up with two big arse screwdrivers? one from each side?

[jpahemi]

Hello Andy,
Here's a link to a company that sells SS pistons:
http://www.fortunecity.com/silverstone/tread/1046/id23.htm

This company sleeves the bores with stainless and supplies the correct SS pistons; the one catch is the price: @ $200 per caliper.
http://www.stainlesssteelbrakes.com/

Rgards,
J.P.

[KobaltBlau]

Originally posted by vash
can you pry them up with two big arse screwdrivers? one from each side?

Tried something like that and it looked like it was going to get ugly fast.

Thanks for the links JP, I'll look into those if my pistons end up being damaged; I hope they won't.

[jpahemi]

Andy,
If you don't use the pistons, couldn't you drill the center, then tap the hole , then use a puller.
J.p.

[KobaltBlau]

yes, but until I pull the pistons out I don't know that they will need to be replaced. In fact, If I'm going to be replacing pistons I'd be tempted to buy a new pair of calipers or something.

[Dan Owens]

Andy,

Yes you're right about the two holes or ports, top and bottom. You can take a C clamp and a small square of plastic or rubber and clamp it over either hole. Then use the air on the other hole. Start with lower air pressue and slowly work your way up. I think most of the time they pop out with about 30 to 35 lb of pressure. You may want to squirt in some type of brake cleaner/solvent first, WD40 or plain brake fluid and let them set for a short while first, then drain them back out. From the looks of the calipers they've been sitting like that for a while. Cleaner/Solvent/Fluid will help loosen and lube the pistons and inside of the seal before you try to remove them. They should come out without too much trouble either way. Someone else may chime in here with a better idea but hey give it a go and keep us posted on your progress.

[KobaltBlau]

Update: there is good news and bad news. read the good news before you look at the pictures

Good news: one of my local hardware stores, the awesome mcguckin hardware in boulder, CO, had viton o-rings in stock. this material is brake fluid resistant and good to 400F (edit: standard viton is not brake fluid resistant, please read the rest of the thread for details). I bought 8, tempted to use them in the caliper rebuild for the split seals I have been talking about. I used these seals to do the compressed air method to pop the pistons out, snugging the cross-bolts with a torx bit, which worked fine, but I would not want to torque the ribe bolts fully with a torx. I was able to pop the pistons out quite easily with the DC compressor that comes with the car (watch those fingers!)

Bad news: Although my pistons were in nice shape (certainly reusable), my caliper bores looked like this _after_ several squirts of brake cleaner and scrubbing with mild steel wool. In fact, they didn't look too much different before and after this treatment, just a bit shinier:







note the dents around the lip of the bore are not from me, they are from someone else's prying apparently. The machined surfaces of the caliper and piston have no such mars.

Although I wasn't able to verify via search on the board that these bores are plated, mine appear to have been plated, then the plating was worn off in some areas. There is no pitting or corrosion, just what I perceive to be worn off plating; I could definitely be wrong. Note that the worn off looking area matches where the piston would usually be riding. What do you guys think of this surface?

If these are trashed, I would be tempted to use these spacers in my SC calipers, which I know are good. However, then I would have 2 sets of split calipers, which I'm not really looking forward to. 2 new carrera calipers are ~$400, I'm not overly keen on spending that but I'm not trusting used calipers at this point; these look tired, but maybe they are OK to reuse...?

TIA!

[jpahemi]

Hello Andy,
You could have the calipers sleeved in stainless and get the custom pistons of the same alloy (ss).
Regards,
J.P.

[Jim Smolka]

If I have read things correctly, you have SC brakes and now you have a set of front Carrera Calipers. I believe them main difference btwn the 2 types of front brake pads is the thickness of the spacers (thus Carreras have wider rotors). It should be possible to split your SC calipers and simply install the wider Carrera spacer and the associated seals.

FWIW, according to BA's book, Carrera rear M calipers wider than the SC rear calipers and Carreras have bigger pistons. Carreras have a proportioning valve to help prevent rear wheel lock up.

[KobaltBlau]

Originally posted by jpahemi
Hello Andy,
You could have the calipers sleeved in stainless and get the custom pistons of the same alloy (ss).
Regards,
J.P.

This costs as much as new calipers, No?

Jim Smolka, you are correct. I am retaining the SC rear calipers, which do not require a proprtioning valve. I could indeed use the nice condition spacers in the SC calpers, the question is whether I want to deal with splitting another set of calipers (still not having found the right seals, although my viton o-rings might work OK).

[KobaltBlau]

I want to clarify a bit since I was in a hurry when I wrote my previous post. Anyone have a source for sleeving the calipers in stainless? New calipers are $440 a set here at pelican, for reference.

edit: it seems that White Post Restorations can do this kind of work.

when you change the fronts from SC to Carrera calipers, all you are changing is the thickness of the rotor and the corresponding spacer in the carrera caliper. piston diameters stay the same as the SC brakes. hence you don't have to add a proportioning valve unless you change the rear calipers to Carrera as well, which isn't really necessary since they don't get heat overloaded, at least in my case.

Can anyone verify that these bores are supposed to be plated, and/or give an opinion on their appearance?

TIA!!

[Early_S_Man]

Andy,

0.422" OD = 10.72 mm
0.234" ID = 5.94 mm

If you can get some of those seals from a Mercedes dealer, I believe they will work on your 'A' calipers!

The original Ate finsh on the entire caliper was Cadmium plating, but it was for corrosion protection, not a hardened working surface! The pistons are hard chrome plated, and are the only critical item ... no pitting is allowable on the woirking surface of the piston! As long as the pistons can't 'rock' in the bore, finish is irrelevant!

[KobaltBlau]

Thanks, Warren! those do indeed sound like they would work. Have you ever attempted to source those seals?

Although I haven't cleaned my pistons up completely, they look very good. Don't you think the caliper bores look like they are missing plating? I see what you are saying about the rocking, pitting, and working surface, but I don't want to have any more flakes of plating choke up new my master cyl. or anything.

Thanks again!

[vash]

andy, i wish i took some pictures of my calipers when i rebuilt mine. (1975 car) they didnt look as bad, well....as widespread as yours but i did have that brown corrosion too. i scrubbed them as clean as i could and while they stayed the same color, they felt smooth. i put everything back together and tested VERY carefully. no leaks to date, and the car still stops great. everytime i take a tire off for whatever reason, i take a safety peek. hell, once you put everything back together, another rebuild kit is cheap. if you test safely, i think it is a good gamble.