Technical Drum brake problem Wilson welding plates/speedway drum SOLVED!

Sometimes, you just gotta f#%¥ with the dick ya got.
NOT BLAMING THE WILSON BACKING PLATES. JUST STATING WHAT THE SETUP IS.
32 pickup came in my shop with an electrical issue. I noticed the brakes ,,, sucked. Wilson welding finned backing plates with Buick style finned drums. Built about 15 years ago. A rebuild of the braking system, a replacement drum from speedway (modified to fit) and a change to the pedal ratio and viola'. It stops! BUT..... now with the proper brake pedal ratio under HARD braking there is a grinding noise. Turn out the lower edge of the leading shoe on the drivers side where the speedway drum is catching on the inside of the drum. Ok,, can't hit the edge of the shoe if it ain't there! Whip out grinder and trim the edge of the shoe. All that did was move the point of contact up the shoe.
Pulling my hair out, trying to figure out where the problem is, I switched sides with the drums and now it does it on the passenger side, but on the trailing shoe!
Here's what I've looked at so far.
By all measurements I can do, the modified speedway drum is near identical to,the one that was on the truck.
Had new drum turned With the spindle attached) to clean up a small out of round condition.
Had shoes arc-ed and ground to see if they were true.(they pretty much were)
The hardware looks correct by pictures found here.

So, what would make this one drum pull one shoe to the outside under hard braking?
I'm stumped, so please don't assume "surely he already checked......."

 

Drum turned into a cone shape?

 

I should also mention the truck has what appears to be a speedway axle and uses modified ford hubs of unknown vintage.

 

I was wondering that very thing. That's why I had them turned.

 

I'm going to say its the fault of the drum since the grinding moved to the other side with the drum and the problem did not exist before the new drum was added.
If the contact is all the way around the drum, I see to possible faults:
1) The area where the drum attaches to the spindle has a deeper draw then the original drum. Picture that the braking surface is 1/8" closer to the backing plate then the original drum was.
2) The braking surface was not machined deep enough (or cut deep enough when it was turned).
I see two possible options:
1) See if there is enough material on the drum at the contact point to cut the corner a little deeper, there may not be enough material there to remove what would be needed to solve the problem.
2) Put a shim between the spindle and the drum, spacing the drum out from the spindle what ever distance you need.

If the contact point is not all the way around the drum, that would mean the drum at the spindle mounting point is probably not round or flat. The extra grinding of the contact area or shimming between the drum and spindle may make the drum serviceable for a short time or a long term.

 

Thank you for your thoughtful reply.
Art, my brake guy, Is old school and 73 years old. So I trust his work.
I believe the drum should be true because he took material off all the way across.
My apologies for not posting a pic of the hub arrangement. Shimming would make the problem worse.
Thanks again,

 

And yes sir, the contact point is all the way around .

 

The coloring of the brake shoe in in the pictures that show it looks suspect…is it only actually making contact with the drum at the very center?

 

Rather then shimming (yes it would make it worse in this case), you could get the top mating surface of the drum (between the drum and the spindle), cut. The hard part would be determining how much to cut off.
I think I would see if your friend can cut the inside corner of the drum safely first. If there is enough material there, it might be the easiest fix.

 

I thought about that as well, the problem could be the shoes, but when he moved the drum, the other side had the same issue, but on the other shoe. He didn't have a problem before, and it sounds like he may have used the same shoes.
The possibility does exist the hardware that holds the shoes to the backing plate are not functioning correctly, and its also possible the shoes are bent, but the drum is the new addition, I'd start there.

 

I will look closely. The wear pattern on the drum would indicate it is making good contact. However, the shoes on the drivers side( where this was moved from) were the only shoes I had arced.

 

When I did the brake job, I replaced the shoes, wheel cylinders. master cylinder and the one drum. The problem MAY have existed before to a point, as evidenced by similar marks on the drum I replaced. I also corrected the pedal ratio, allowing more pressure to go to the brakes then ever before.
So, I'm thinking possibly the increase in braking pressure made the problem ( if indeed there was one before) worse?
I took the new shoes from the offending side to Art my brake guy, and he arc-ed them. so they should be good.

 

I'd have to think that Gene pretty well nailed it. Somewhere between the outer surface of the drum and the inner edge of the drum there is a slight difference from the old drum.
A shim between the drum and hub won't work but a machinery shim between the wheel bearing cone and spindle or behind the inner wheel bearing hub might move it out just enough to clear without compromising anything. You are probably just looking at a few thousandths. Those can usually be found at and industrial bearing house.

 

Also worth noting, the shoes are 2 inch wide, the drum 2.5. The shoes touch at the very back of the drum. It appears to me the shoes are being"drug" almost a half inch over to make contact.
Taking material off the side of the shoe (not shown, drivers side) just resulted in moving the contact point upward.

 

Great minds think alike?
I had some thin shims and stacked 3 of them maybe .20? it seemed to help a little, but further shimming will start to move the shoe off the drum.
I also think Gene is right about their being a difference in the drum I cant find...
I did read that people are running speedway drums with Wilson welding plates though.

 

Machine 0.060" off of the face of the drums where they touch the hub.

Or, 0.060" off of the back side of the hubs.

 

All manufacturing processes have tolerances. You may have just ended up with the far-end of both, unfortunately.

 

I have considered that too. Posted here to make damn sure their isn't something I've over looked or didn't know before doing any more machine work. Just "looking before i leap".... for once.... lol

 

Story of my life.... lol

 

Show the inside of the drum where the shoes ride. The one on shot you have looks like the drums are cut poorly, I've seen rough cut drums make the shoes move a little (kind of like skinny bias tires catching a groove in the road). IF that's the case, just take a light slow cut to clean them up, while it's spinning hit the inside with 80 grit sandpaper. Just go straight in and out of the drum for a couple of passes, shoot with some brake cleaner and wipe with a clean towel. Now you have a nice cross hatch finish.

I've also seen rough cut drums/rotors sound like bad bearings when applied.


This looks like chatter marks to me, all the way around and that might make them walk.

 

OK< You lost me on this line:
"It appears to me the shoes are being "drug" almost a half inch over to make contact."

When the brake lining makes contact with the drum, are the shoes still supported by the backing plate? The shoes being drug over a 1/2 inch just doesn't make sense to me.
Pictures of the shoes on the backing plates maybe?

And since I'm showing my misunderstanding, is it possible to turn the outer edge off the spindle and mount the drum on the outside of the spindle? That would effectively move the drum away from the backing plate and the shoes.

 

Thank you. I'll try that.
It is noteworthy that it had the same problem with the factory finish on the drum, as well as the newly turned drum.
I'm also wondering if I need better shoes. These are the Oreilleys store brand Brake best.

 

I theorize the shoes are moving on the retaining springs. If you pull the drum of any set of brakes, you can pull the shoes out from the backing plate with relatively little effort.
This odd hub on outside arrangement is,, according to pictures, how they make the Buick drums work in this application..no room to put the hubs on the inside..

 

You are saying spindle when I think you mean hub. Very confusing.

 

Have you set both drums on the bench and inspected them to see if there is a difference in the area where the shoe is rubbing?
That area can be cut for clearance from all appearances but if you can see how it looks on the other drum you might know how much and how to cut it. That lip is built into the Speedway drums though but may not have been trimmed back enough.

Other than that measure and compare. Is the metal part of the shoes you just put on the exact width of the old shoes? Where was the wear pattern on the old drums? To my way of thinking you should have space between where the shoe rides and the inner edge of the drum something between 1/8 and 1/4 inch. I've rarely seen any drums where the lining rode on the drum surface closer to the edge than about 1/8 inch. That's From doing a lot of drum brake brake jobs every week in the 70's

 

The ridge near the front side of the speedway drum you show is not present in the one I bought.
I was would have been just above my rub line.
The back edge of the iron drum liner as shown in your pic, I had it machined off for backplate clearance, and took it down further with a flap wheel.
On The Wilson welding backplates, they are flat and the back side of the shoes touch them, the drum liner ring barely clears, so the shoes can't really be all that far up into the drums.
I have tried to compare the drums, the one I replaced is pretty beat up, wore out and out of round to boot. The rubmarks aren't near as bad, but this thing never had good braking till I changed the pedal ratio. I suspect by making the brakes better, it MAY have made an old issue much worse.
But I could be wrong....
The replacement shoes match up to the old with the exception of the material placement on the leading shoe.
I didn't study the wear marks before I had the other one turned. I didn't know this was going to be an issue. I'll post pics of the old drum (or wants left of it) when I get back

 

I'm going to assume when you said you "swapped sides with the drums" what you actually did was "swap sides with the drums and hubs". If that's the case the problem is with the relationship between the hub and drum.

The first thing I'd do is check the distance between the rear hub flange and the flange on the drum. In other words, straightedge on the drum flange, ruler down to the bearing flange where the bearing seal goes. Do both drum/hubs and compare measurements.

Next, I'd get out the modeling clay placing chunks of clay on the edge of the shoe, then put on the drum/hub to see exactly how much space you actually have between the brake shoe and the area in the drum where the shoe rubbed.

I'll be the first to say it; when you mentioned the replacement drum came from "Speedway" the warning light in my head lit up.

 

Is it rubbing along the whole edge of the metal part of the shoe or just on one area? Right now I don't assume that anyone's quality control is perfect but as those are probably production shoes that fit a number of applications they could be off a bit on the metal part. Maybe even the part that usually rides against the pad on the backing plate being bent out a bit when they were stamped in the shoe. Shoe being the metal part, lining being the friction part.

My one more thing deal is getting out of hand but did you by chance change the inner bearing and race in that hub and do they match the old inner bearing and race exactly? This whole deal is about thousandths of an inch that are probably around .020 if that.

 

Yes, I did mean the hub/drum as an assembly.

I did measure from back of hub to the back of the drum , using and actual straight edge, and not a random piece of bar stock. They are the same.

Modeling clay is a good idea. I actually keep Play-doh in my shop!
Agreed on the speedway drum. It was the only place I could find one.

 

The shoe is just rubbing on a tiny point. When the hub/drum was on the drivers side, ot rubbed a bit on the bottom tip of the leading shoe. I trimmed it away and it moved the rub point up the shoe. Clearanced it some more, and it moved the point up shoe.
Moved drum/hub to the passenger side, and it rubbed the trailing shoe.

Yes, I did change the back race, but I can't remember which hub. I knocked the old race out and took it to the parts store. I'll knock them both out and see if the match.

It's not getting out of hand. I need all the help I can get.