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View Full Version : Brakes: We goofed, 1940 brake cylinder



BubbaBear
09-03-2012, 08:09 PM
We goofed. Several weeks ago we disassembled the 1940 Studebaker brake cylinders. The bodies went into Super Clean overnight and the next day were rinsed, dried, honed and coated with brake fluid and put aside for later rebuilding. Yesterday we got around to the rebuilding. I opened the container with the aluminum caps and remembered they had not been cleaned. Unfortunately I did not remember the reason I had set them aside. I had set them aside because they were not supposed to go into the Super Clean. But then I forgot the warning not to expose aluminum to Super Clean for long periods. We soaked them overnight. This morning they are covered in a white crystalline like powder. Any idea of how to remove this? Are they salvageable? Since the rubber parts do the actual sealing will pits or other imperfections on these cause a problem? How best to clean these now if they can be cleaned. And if not where to find replacements?

BobPalma
09-03-2012, 09:30 PM
We goofed. Several weeks ago we disassembled the 1940 Studebaker brake cylinders. The bodies went into Super Clean overnight and the next day were rinsed, dried, honed and coated with brake fluid and put aside for later rebuilding. Yesterday we got around to the rebuilding. I opened the container with the aluminum caps and remembered they had not been cleaned. Unfortunately I did not remember the reason I had set them aside. I had set them aside because they were not supposed to go into the Super Clean. But then I forgot the warning not to expose aluminum to Super Clean for long periods. We soaked them overnight. This morning they are covered in a white crystalline like powder. Any idea of how to remove this? Are they salvageable? Since the rubber parts do the actual sealing will pits or other imperfections on these cause a problem? How best to clean these now if they can be cleaned. And if not where to find replacements?

By "the aluminum caps," do you mean the actual pistons?

If so, buzz them off on a wire wheel brush and see how deep they are pitted. They might be OK.

But if there's any doubt, find some new ones. It just depends on the depth of the pits, if any. That can't be judged without a detailed photo. BP

BubbaBear
09-03-2012, 10:47 PM
I will clean them up and post a pic tomorrow. Since they do not make a seal and only transfer movement from the rubber to the shoe I hope they do not need to be perfect.

avantilover
09-04-2012, 03:08 AM
Perhaps brake parts should be perfect?

BubbaBear
09-08-2012, 01:05 PM
OK, I tried a buffing wheel on the Dremel. I can get them clean. But they are severely pitted in the places where they had serious corrosion before. Other areas clean nicely. So even tho it was a stupid mistake to put them in the Super Clean it may not have been the problem. Just cleaning them in any manner could have resulted in the corrosion. Does anyone have any idea if this will cause a problem? They are not part of the sealed hydraulic system. Or can anyone suggest or help us locate replacements.

K-Hawk
09-14-2012, 06:35 AM
perhaps some fine rouge or fine buffing paste will clean and not remove much metal. Pressure is behind the piston and the flat surface pushes the out to the drum. We just don't want the sides sticking while they travel in the bore, hone the bore nice.Silicon brake fluid might help too, keep down corrosion may lube better . Good Luck

BubbaBear
09-14-2012, 09:17 AM
I have going to be missing a number of fine buffing compounds but the metal is missing and it is going to be missing no matter what. It is on the sides and hey are buffing out smooth. I think that I would have had this problem even if I had not used the Super Clean. They were heavily corroded before. All of the metal loss is on the sides. none on the edges. It would seem to me that it would not cause a problem. I hopefully have another set coming.

mbstude
09-14-2012, 10:37 AM
No way I would ever use pitted wheel cylinders.

A good friend ended up sending the WC's in his '38 Commander to http://www.applehydraulics.com/ and had them sleeved. Not cheap, but they never have to be replaced again.

BubbaBear
09-14-2012, 10:51 AM
It's not the wheel cylinders. It's the pistons. And the pistons are not part of the sealed hydraulic system. They only take the movement of the rubber and transfer it to the brake shoe. They do not seal anything.

Frank DuVal
09-16-2012, 12:07 AM
I agree. If the pitted pistons slide well in the bore (DOT 5 silicone fluid works well here), you will have no problem with the pits.

Pits in the bore of the wheel cylinder are not acceptable in the area swept by the rubber seals. Pits in the bore right in the middle of the wheel cylinder where the bleeder and inlet port are are also acceptable to me. YMMV

This corrosion is found in DOT 3 systems after long periods. I have yet to find it in DOT 5 systems even after years of service.

Neal in NM
09-16-2012, 10:00 AM
You are correct about the pistons not doing the sealing. One problem about a reduced O.D. of the pistons is the (slim) possibility of them cocking in the bore. From the information you have posted, I don't see any problems. If you really feel strongly about having new I could machine some for you. Neal

RadioRoy
09-16-2012, 06:33 PM
Even tough there are pits in the pistons, there still should be enough of the original diameter left to keep them true in the cylinder bore. If there is so much corrosion that they do not stay straight in the bore, then they must be replaced.