Rear wheel lock-up, Does a '55 Special need proportioning valve.

[TexasJohn55]

55 Special Power Brakes. Has new wheel cylinders, hoses and MC rebuild. Drums look like new or turned, shoes have good lining and look to be seated so I degreased and sanded them. Has very good braking, too good on the rear, tends to lock up rears under hard braking below 40 mph, especially right rear but both will leave black marks. I have adjusted anchor pins and readjusted shoes, no effect. It seems to be improving the more I drive it, which isn't much, but it favors the rear brakes. Is it the nature of the beast?

[bhambulldog]

55 Special Power Brakes. Has new wheel cylinders, hoses and MC rebuild. Drums look like new or turned, shoes have good lining and look to be seated so I degreased and sanded them. Has very good braking, too good on the rear, tends to lock up rears under hard braking below 40 mph, especially right rear but both will leave black marks. I have adjusted anchor pins and readjusted shoes, no effect. It seems to be improving the more I drive it, which isn't much, but it favors the rear brakes. Is it the nature of the beast?

It should continue to improve as you drive it more. The shoes are conforming to the shape of the drum. Find your self a nice big empty parking lot and do some hard stops (on the verge of lock up , but try to not let them lock).

You should see more improvement with each application of the brakes.

[buick5563]

Short answer is no, John.

I am assuming you installed a new spring kit as well. Yes?

I would adjust them again, since they are seating. Seems like either the fronts are too loose, or the backs are too tight.

[Bhigdog]

Are you sure the primary and secondary shoes are in the right places? If the bigger lining shoe is to the rear, braking will be too aggressive.....................Bob

[TexasJohn55]

Are you sure the primary and secondary shoes are in the right places? If the bigger lining shoe is to the rear, braking will be too aggressive.....................Bob

That's funny Bob, there's my problem! I have the same problem, it is counter-intuitive and I always have to recheck my book. Why is the primary shoe the shorter one and the secondary shoe the longer one? I rechecked shoe location when I revisited the issue and they are correct, but I did not think to measure the diameter and width of shoes. My manual says that the 40 series only uses 1 3/4" shoes on the rear and 2 1/4" shoes on the front whereas all others use 2 1/4 on the rear also. The 70 series uses 2 1/2 front and 2 1/4 rear. Mike, I have never had issues with springs in the past, they looked good so I re-used them.

[old-tank]

John

Bleed the brakes again, check the shoes for any trace of contamination with either brake fluid or grease/oil, check that the front and back linings are matched (same brand and/or friction material) and of course do what others have suggested and drive it carefully until the brakes seat (consider adding weight to the trunk).

Locking rears do not alway mean it is a rear brake problem...could be that the fronts are not doing enough.

Willie

[buick5563]

Locking rears do not alway mean it is a rear brake problem...could be that the fronts are not doing enough.

Willie

Good advice. That was kinda what I was implying by saying to readjust em all.

John,

I haven't always changed to new springs either. I thought it was possible that the new springs were somehow the wrong size.

[TexasJohn55]

I was waiting for someone to chastise me about "degreasing" my shoes, got a PM on that. Yeah I know, I'm just cheap and I HAVE MORE TIME THAN MONEY. If they don't straighten up after some more driving and braking I will replace the linings but I didn't want to have to go through the procedure of arcing them to the drums and waiting for the new ones to seat in with the same symptoms or poor braking. I don't get to drive it that much, I need a new set of tires. I did find it interesting about the different shoe widths on different models, I need to recheck that.. I did notice that the shoes are color coded but did not make note of what colors at each wheel to see if they match up. I do have a small boat load of new linings of various sizes and part numbers but they must be riveted to the shoes. It might be easier to just buy some at O'Reilly. Thanks, John

[60FlatTop]

I have done a lot of work on well maintained original cars, low mileage ones where normally consumable parts last for decades.

Although brakes feel hard, the shoes need to be pliable enough to smoothly conform to and grip the drums during a stop. I think there is a chemical "outgassing" or aging process that causes brake linings to become less flexible over long periods of time.

I had one very low mileage car come in that would barely stop. the 40 year old shoes looked new. You would have sworn I was taking the owner's "blankie" away when I replaced those shoes. That's all we did and the car stopped just fine after. If you don't know how old consumable parts are just remember "When in doubt, change them out."

Bernie

[old-tank]

Bernie

That is an interesting theory. Maybe that is what is wrong with parts store replacements which may have been made a long time ago. http://forums.aaca.org/f162/brakes-ii-227946.html Maybe my issues with Raybestos shoes was due to just old linings (shelf age). Did you try to resurrect those old linings by sanding the glaze?

John

If you do get new linings, have it done at a brake/clutch rebuilder...don't even consider Raybestos unless you carry an anchor. I personally would have a clutch/brake rebuilder rivet your linings to the shoes.

Willie

[TexasJohn55]

Willie, My stock of brake linings are NOS Delco and Buick. I have a foot operated hydraulic riveter, I guess I need to restore/rebuild it for use. I am of the opinion that my NOS linings may be better than today's because they may still have asbestos in them. As for aging, I'm not sure that is an issue unless they have been contaminated with fluid or grease. The issue with today's brake shoes vary from one manufacturer and line to another. My son had some that were ineffective and some faded badly. He finally determined which brand and line to use. I think he likes Raybestos Red, but I will have to ask him if that was shoes or disc pads. John

Edited June 13, 2013 by TexasJohn55 (see edit history)

[60FlatTop]

My old cars all have brake lining from Rochester Clutch & Brake. I take the shoes and drums in for them to fit individually. Here's a set I had done for the '53 Jaguar: They are non-asbestos, bonded, and ground to fit. They sell three levels of stopping power; nice feel, sporty stoppers, and nose stand.

I see ads for NOS brake shoes from time to time. I'd probably throw them out. Because of my age and attitude its not really a discussion thing. Its more, just humor me.

Bernie