Separating a stuck brake piston and rebuilding the cylinders

[ZeroNilNada]

You are right, they are sleeved in brass. Talking with the gentleman at Sierra he stated that brass will adhere (for lack of a better term) to the cast iron much better than stainless. I've seen stainless sleeves that have actually been pressed out of the bore from the fluid pressure. He claimed that the brass won't do that.
More info here:
http://brakecylinder.com/BrakeFAQ.htm#stainless" onclick="window.open(this.href);return false;
http://brakecylinder.com/images/slipsleeve.jpg" onclick="window.open(this.href);return false;
As stated on the FAQ page, brake cylinders see very little wear. The amount of movement is relatively small and it's rubber bearing on brass. Not a lot of friction there.
I can't exactly remember what I paid but the price list on the Sierra website states that the Dunlop calipers go for about $60 apiece. Four plus shipping and tax will get you around to $300.

[ZeroNilNada]

One more thing I forgot, Sierra repaired a bent pin for me. All four calipers came back looking like new.

[Linda]

Well I got the Stuck cylinders separated. Then after some light cleaning they were sent off to Karp's Power Brake http://www.karpspb.com/ for some stainless steel sleeves. They came back in less than 1 week. Cost is $60 each, you may be able to get a volume discount. Ron Karp was very nice and answered my questions including why he prefers stainless to brass. He explained it but rather than try to repeat the tech speak he is going to write up a blurb to post here. He said sleeves coming out of the bore was not a problem for them. They use the Hal Ray system.
Also he is happy to answer questions directly of course.
Anyway, here's some photos:
http://ljordan704.shutterfly.com/pictures/90" onclick="window.open(this.href);return false;
Pins were straightened also.

Linda

[Linda]

I forgot to ask how to separate stuck brake pads from the pistons. 2 of them are really stuck. The pads are nearly new so I'd like to keep them. I tried the hammer, no luck.
Any ideas?

Linda

[notoptoy]

Linda:
Is the picture of the 4 calipers post restoration? The pins still look bent to me in that shot - hope it's just the camera angle and light.
I am surprised that the pads are so stuck, are they just stuck on the piston, and not in the caliper?
Only method a can think of is to secure the pad in a vise and whack the piston (are the pistons being kept and re-used, if so, DON'T do this)
Otherwise secure the piston in a vise, careful not to mar it, and whack the pad. If this does not work, refer to my signature.

[Linda]

Tom,
The pins are straight. They were straightened as necessary by the rebuilder. I was also told by another rebuilder that they don't have to be perfect...whether that is true or not, don't know. Also the pins can move a bit.
The pads are stuck on the pistons, guess because they have been on there awhile.
One technique is to put the flat side of the piston on the edge of a piece of wood in a vise, then tap the pad loose. It worked for the other 2, but not the stuck ones.

Linda

[tjp]

How is it that the pins get bent? Does this happen when removing the piston or when replacing the piston? I have two sets of brakes, one that just came off the car and the other that was on a part car (I think). I am thinking of rebuilding them and then selling them to finance more of my restoration. Is it cost effective to do this?

Thanks
Tim

[greydog]

OK, if the pad's that stuck, it's probably because of the corrosion of dissimilar metals (aluminum piston and steel backing plate on the pad). First thing I'd try is heat/cold. I'd put the pad/piston in the freezer overnight to see if that helps loosen it. They'll expand at different rates and the aluminum piston should warm up quicker than the pad will. Maybe it'sll be enough (I doubt it tho).
If that doesn't do it, I'd but a pison sized hole in a 2 x 4, support the pad on edge on a piece of metal and whack the 2 x4 with a bfh after I apply penetrant to the joint between the pison and the pad.

Good luck.
Dan

[spl310]

Well, lets see. Carl Jaeger sells new piston packs for $92 each, or stainless sleeved ones for $100 each. The seal kit is about $42. Dean is about the same price. Dann at Rallye is similarly priced for the new parts as well. So, if you have 4 resleeved and then put a new kit in them you are at about $285 plus shipping - lets say $300 for a round figure. Then when you sell them, you will have a hard time getting the prices that the vendors get. So at BEST, you profit margin is going to be $60 for a set of 4.

[Linda]

Hi Tim,
The cylinder pin can get bent when you try to remove the piston from the cylinder. Especially if you pry one side up too far. Someone suggested using a bearing puller, don't know, don't have one. Best technique for not bending the pin I found was to put the cylinder into a vise on one end only then using 2 large screwdrivers horizontally hooked under the piston attempt to nudge out evenly...top, bottom, top, bottom etc, and PB Blaster too. But if not too bent they can be fixed by rebuilder. The pins are not fixed anyway, they have some movement.
You only need to fix/sleeve the cylinder if the piston is OK. Seems like the piston is quite sturdy and would be hard to damage it.
But yes you do need the rubber rebuild kit which consists of the rubber ring (seen in the photo) and the dust cover rubber. Available from the vendors , maybe other sources too, possibly Jaguar etc. MKII Dunlop brakes as noted in the Tech WIKI.
I would think some people might want to buy a rebuilt unit, but others like to buy NOS. To each his or her own, right? Anyway cost again was 60 per cylinder and Karp's does not assemble, you do with the kit.
Update 2018: Karp's will now assemble for you for additional cost.
Linda

[GeoffM]

The seal kit is still available from Nissan.
The best way to remove the pistons is to use air. Wrap the piston assembly in an old shop rag or t-shirt so that the spray (and the piston) doesn't go flying everywhere...and it will. Plug one hole, a standard 3/8"(?) bolt will thread right in and use a rubber tipped shop air gun in the other hole to launch the sucker. Be careful.
When you are doing this, you hold the piston assembly wrapped in a rag while blowing air into the chamber but be careful...if you are pushing down on the piston too tightly, the piston will still pop out but you will push it back down cockeyed onto the pin and bend it.

If you are uncomfortable with compressed air, take them to a shop to do it.

[Linda]

The best way to remove the pistons is to use air.

Agreed. BTDTDW. Next option as posted.

Linda

PS Thanks to all who have been kind enough to offer advice and help.
Never can say that enough!

[GeoffM]

The best way to remove the pistons is to use air.

Agreed. BTDTDW. Next option as posted.

Ahh... Just noticed that in the OP

[Linda]

Got the stuck pads off the pistons. After a minor snag, the pistons with rebuild rubber kit, lubed with red grease, went together with the cylinders. Assembly lube can be used also. Everything painted with hi temp paint and then calipers reassembled with brake tubes correct after some research. One cylinder has an outer flare and an inner flare ("outie" and "innie") That one goes on the outside of caliper, with outer flare on the bottom. On the inside cylinder it is two inner flares ("innie"). The bleeder goes at the top, and the crossover tube goes in the bottom and crosses over to the other cylinder at the top. Then the tube coming from the brass junction box, which is also an outer flare, goes to the bottom of the outer cylinder, which is an outer flare.
Thought it might help to spell it out for other novices, could not find a write up.
Very happy with the brakes and Karp's Power Brake service.

Linda

[Jujuman]

I see the bent pin on linda's caliper. How do you remove and replace it. Does it screw off/on