Brake shoe Wear Question

[RoadsterRich]

Got to thinking about brakes too much and have a curiousity question...

With drum brakes, does the front or rear shoe on a single wheel typically wear faster? The brakes in question are a single cylinder system on the 1930 Chrysler. It has the hinge pins at the heel (bottom of the backing plate), and the single dual piston cylinder at the toe (top of the backing plate). Should the brake shoes wear evenly, or will one or the other wear faster if things are properly adjusted? Also will the brakes on the front wheels wear differently than the brakes on the rear wheels with regards to which shoe wears faster?

Thanks!

Rich

[56Roadmaster]

Hi Rich,

The forward shoe will (in your Lockheed system) wear somewhat faster do to what is called self-energizing. The forces in the brake drum tend to PULL the shoe in to the drum on the shoe that expanding in the direction of rotation (forward shoe) and PUSH the shoe away from the drum on the shoe that is expanding opposite to direction of rotation (rear shoe) That being said the Lockheed brakes were later modified to have a stepped wheel cylinder and/or a primary and secondary shoe. with the smaller piston and/or shorter brake lining being installed on the self-energizing side. Bendix did a really slick deal with their arrangement which caused both shoes to be self energizing, the basic idea still used in today's drum systems. Don't worry about trying to improve what you have though, as long as the cylinders are good and linings good and true, they will last 10's of 1,000's of miles.

....OH but are they a pain in the rump to adjust

[RoadsterRich]

Scott,

Thanks for the information. The wheel cylinders which I took off my car were later (mid 30's from the part numbers) Lockheed stepped cylinders. So obviously that had been replaced at some point. What prompted the question was that the pads towards the rear of the drums were significantly more worn on all 4 wheels. This was contrary to what I expected. I am thinking that the major adjustments might have been signficantly out. The front piston was frozen nearly fully extended on all 4 wheels, while the rear piston was only about 50% extended. And there was little or no contact on the front shoes. The front linings looked like they were brand new, however the rear linings were worn down nearly to the rivets.

As another question, where is a good place to get brake shoes relined? I had mine done at a truck service facility. I am marginally okay with the job they did. The linings they used were obviously premade for a different shoe as it has some extra rivet holes, on the other hand they do fit and are the proper thickness and width. They also ground the ends slightly on each end, is this normal too?

Thanks!

Rich

[Guest DeSoto Frank]

Rich,

Better shops will chamfer the ends of the lining...

I thought I'd let some other folks have a go at the lining wear question before I added my 2 cents worth...

Here's something to keep in the back or your mind: while Chrysler Corp had one of the first practical hydraulic brake systems (Lockheed), it was not necessarily the BEST that ever was...that said, the set-up they used from 1924 was reasonably effective (especially when compared to the 2-wheel mechanical set-up that was "standard" at the time! ), and reliable and got relatively few up-grades or re-designs until 1957 (some 33 years !)...besides changes in drum / lining diameter /width; stepped vs. straight bore wheel cyls; and the change to 2 single-piston front wheel cylinders (1946-on; biggest change during the Lockheed brake era), this system was "it" for Chrysler.

Here's the thing with the Lockeed brake "with two fixed anchors"...while the leading shoe (relative to direction of drum rotation: this would be the front shoe while driving forward and the rear shoe while backing-up) is "Self-energizing" (motion of drum tends to "pull" the shoe into tighter contact w/ drum), the shoes are NOT "Self-equalizing" (like the Bendix mechanical and later hydraulics, or the Huck brake on Chevrolets)...that means that each shoe is it's own separate little universe with the drum, and the wear on a given shoe is greatly dependent on how its adjusted , and how the car has been driven...

With every thing free, working, and properly adjusted (minor & Major adjusters), I would expect to find the greater wear on the front shoe, as this shoe does most of the work when braking (since most of our driving is done with the car going forward...), in regards to this LOCKHEED two-fixed anchor system...(Now. if your front pistons were stuck, then the front shoes weren't doing much braking; the rear shoes were doing all the work, and that's why they were worn more...and the car probably didn't stop too well either!)

Now, the Bendix & Huck set-ups had a deal going on where the bottom anchors were "floating"...(like that star-wheel adjuster gizmo between the bottom of the shoes on Bendix; Huck brakes had a pivoting link thingy on a spider)...this allowed some of the self-energizing force of the front shoe being "pulled into the drum" to be tranferred to the HEEL of the rear shoe (while the piston is also forcing the TOE of the rear shoe against the drum...), therefore providing some built-in equalization between the front and rear shoes....our MoPar Lockeed brakes don't adopt anything like this until 1957, when Chrysler introduces their "Center-plane" brakes, and then the "Total Contact" brakes - still Lockheed-based, with the two wheel cyls in each front drum, but now the shoes "float" in the drum - fixed anchors are gone)

Finally, in 1963, Chrysler Corp. went to Bendix "self-energizing / self-equalizing /self-adjusting" drum brakes (like everybody else)...

When Bendix came out with their version of the hydraulic service brake, around 1935 -'36, they had had 12 years to "study" the Chrysler/Lockeed brakes in action, and see how they might do things differently/ better (?)...remember too that this was still the age of the Almighty PATENT...

So, while the Chrysler-Lockheed brake system was pioneering, and had its thirty-year + "day in the sun", so did the Bendix-type hydraulic, just starting later...1936-1966 with relatively few design changes (aside from self-adjusters and other minor details); in fact, the Bendix design is still pretty much what you find inside of most modern drum brakes....

More than you ever wanted to know about brakes, I'll bet...

[Guest stude8]

I used an outfit in Antigo, WI for relining 1930 Studebaker shoes (Bendix 3 shoe system) I think they are called Antigo Auto Parts. Very fast turn around (Like 2 days) good workmanship with correct lining materials. UPS shipment was surprisingly quick. Try them first, everyone else was 50% or more higher in cost. Stude8

[RoadsterRich]

Thanks! I'll keep them in mind. I used a local company but they seemed a bit pricey, and I'm only moderately happy with the results. Not to mention it took them over two weeks to get the job done.

Rich

[Guest boettger]

Rich,

Does your Chrysler have steel brake drums as opposed to cast iron?

If so be sure to keep close track of wear.

I believe that the original linings for the steel brake drum system was a woven lining and not a hard composite lining.

Modern brake linig material is very tough on the steel drums. The drums will wear quite rapidly.

I'm looking for some replacement Drums for the DeSoto as I went with the modern composite linings. Now the Drums are quite worn!

[RoadsterRich]

Steve,

Now that is a very good question. I've always assumed they were cast iron, but never checked. For that matter I'm not totally sure how to check. I'll read up in the manuals and see if they discuss it. The linings that were in it were from the 50's or 60's and had been worn down to the rivets on the rear pads, while the front pads looked like they were brand new.

Is there an easy way to distinguish the steel from the cast iron? I know mine readily rust if moisture gets near them...

Rich

[Guest DeSoto Frank]

I think I'd better defer to Boettger, since his MoPar is closer in vintage than mine...

But, my De Soto has "composite" drums: the rims are cast, but the face is pressed steel. The steel face is somehow swaged to the cast iron rim...

If you look at a 1935 - ? MoToR's manual (possibly other manuals - they all seem to use Chrysler factory photos) where they show a picture illustrating checking the drum diameter with the Miller brake gauge, if you look closely at the drum itself, you'll see a series of rectangular "spots" around the inner, outer edge of the drum face - these are "keys" (like dovetails) where the drum and face are "locked" together...

This would idenify a cast iron drum...

I would think that all-steel drums are made in one piece...

I do know that cast iron and steel give off different spark patterns when held against a grinding wheel, but that's a pretty crude (and destructive) way to check it out...

[56Roadmaster]

Rich

I had good luck with Brake and equipment warehouse (800) 233-4053 They are at 455 Harrison St. Minneapolis, MN 55413-2408 ask to speak with Rob. They have done alot of work for Ed on his Chrysler brakes and I just had some done for a 51 Desoto, sleeve and reline, they do good work. website: info@brakeplace.com the prices are very reasonable.

For those stepped cylinders they should be availble at NAPA still, you have to match them up in the NAPA buyers guide. Another source is Northwestern Auto supply Inc. (616) 241-5611 or (800)704-1078 they are at 1101 S. Division Grand rapids, MI 49507

Happy Hunting.

PS FYI the method of attaching the new linings to the shoe: either rivets or boding is equally strong and durable.