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Posted By Discussion Topic: brake shoe position -- page: 1 2     fordmerc 07-08-2010 @ 9:45 AM reply profile send p.m. New Member Posts: 180 Joined: Oct 2009 my '39 brake shoes (R front only) are positioned asymmetrically: the forward shoe is so far forward that the drum binds; the trailing shoe is far from the drum; if I push/pull the rear shoe back, the front will follow, because the cylinder pistons seem to move well, but when I release the rear shoe, both again move forward. What did I do wrong? (new linings, "new" wheel cylinder) All other wheels OK after same restoration. supereal 07-08-2010 @ 10:10 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Did you correctly mount the wheel cylinders so the large end faces forward? The long lining goes toward the front, the short one to the rear. The anchor pins at the bottom of the backing plates are also eccentric adjusters. They are marked to show the high point of the eccentric. To properly adjust them, loosen the lock nut and turn the studs until the dots face each other. While applying about 30 pounds pressure to the brake pedal, turn the studs, left one clockwise, and right one counter clockwise, until the linings contact the drum. Release the pedal and adjust the brakes by the cams on the upper part of the plates until no rubbing can be felt. fordmerc 07-08-2010 @ 12:54 PM reply profile send p.m. New Member Posts: 180 Joined: Oct 2009 Cylinder is in correct position. All eccentric cams in proper position. I have removed the shoes and reinstalled them. The wheel barely turns without any pressure on the brake pedal. The instructions as you provided were followed for all other wheels with success. I did open the bleeder valve just enough to let a couple of drops of fluid out, with no change in status. I considered a defect in the wheel cylinder, but I cannot conceive of one since the two cylinder ends move in tandem when I manually push them from either end when the shoes are removed or, as when I move the assembled shoes back and forth. I'm missing something, but I don't know what! This message was edited by fordmerc on 7-8-10 @ 12:55 PM Johns46coupe 07-08-2010 @ 2:24 PM reply profile send p.m. Member Posts: 68 Joined: Apr 2010 This is a real shot in the dark but is it possible the spring in the wheel cylinder is installed backward or is hung on a burr or something? John fordmerc 07-08-2010 @ 5:19 PM reply profile send p.m. New Member Posts: 180 Joined: Oct 2009 The answer is: of course, any of those things could have happened. Interestingly enough, when I ordered all 4 wheel cylinders, the right front (problem) was not supplied and I had to go back to get the correct cylinder. If there is no easier answer, I will tear into the cylinder (but I don't really want to do that since a can of worms is worse than one!) Johns46coupe 07-08-2010 @ 6:51 PM reply profile send p.m. Member Posts: 68 Joined: Apr 2010 Sorry to be a PITA but disassembling and reassembling a wheel cylinder is a fairly easy job especially new and clean. Since you've looked at everything else it seems like the place to go. Here is a link with a picture. You don't even have to remove it from the car. http://www.vanpeltsales.com/FH_web/FH_images/FH_brakes-pics/Flathead_Brakes_wheelcylinder_1939to46.jpg John 39 Ken 07-09-2010 @ 3:59 AM reply profile send p.m. Member Posts: 380 Joined: Oct 2009 "when I ordered all 4 wheel cylinders, the right front (problem) was not supplied and I had to go back to get the correct cylinder". This could be the problem. There are two types of wheel cylinders sold today. Cheap made in China or wherever, and more expensive, USA made. To be sure, the USA made are far superior to the off-shore units. My bet is you have gotten at least one if not all of the off-shore units. A friend got one that actually jammed in the actuated position. Check it out as Johns46 said. If you have the cheaper units, do yourself a favor and replace them with USA units before more problems occur. JMO. Ken TomO 07-09-2010 @ 7:38 AM reply profile send p.m. Senior Posts: 7253 Joined: Oct 2009 Fordmerc, is the rear shoe under the clip or is the clip missing? Tom supereal 07-09-2010 @ 9:48 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 When brakes fail to fully release, and the pistons in the wheel cylinders are not stuck in the bore, It is likely that the master cylinder is at fault. When an old brake system is opened for repair, and is bled to remove entrapped air, often the residue in the master cylinder reservoir is stirred up, and the relief orifice is fully or partially blocked. A sure sign is that more than one, or all, wheel cylinders are affected. There is also a "residual" valve in the master which maintains some pressure when the brake pedal is released. This may also be trapping system pressure. fordmerc 07-10-2010 @ 4:22 AM reply profile send p.m. New Member Posts: 180 Joined: Oct 2009 The rear shoe is under the clip and appears appropriately placed The master cylinder is a "new" repro unit (mine was too far gone to use). I can remove the shoes and easily move the cylinder pistons in tandem. With the shoes in place, if I pull back on the rear shoe, the forward shoe will move back, but when I release the rear shoe, all returns to a resting position where the forward shoe is too far forward. Seems weird! I can't see any reason why a cylinder would choose a resting position that is asymmetric, so the problem must be elsewhere. Is there a difference in the shoes other than the lining? I am 99 44/100% certain that the front and rear shoes are where they were when I took them off for relining, but...

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