Technical 9" Ford rear end Drum Brake/Backing Plate Question for the HAMB the Brain Trust

I'm in the process of converting a Lincoln Versaille rear axle from disc to drum brakes for our '38. Some key details:

• The measurement from the outside of the axle flange to the outside of the axle housing bearing flange is a shade above 2.5" (2.515").
• I purchased the new loaded backing plates and drums from Quick Performance.
• The drums are 11" diameter and the shoes are 2.25" wide.
• The outside flange on the backing plate (that nestles into the drum recess) is 5/8".
• When laying face down on the bench, the backing plate nestles into the drum recess about 1/2"+ (see first photo).
• When mounted on the rear axle, the drum recess barely nestles into the backing plate flange an 1/8" or less. (see second photo).

So, my first question is, does this matter? I'm thinking the drum recess should nestle at least 1/2 way over the backing plate flange as a way to keep water and debris out of the brakes. Am I correct in this thinking? It's like the recess on the backing plate where it attaches to the axle bearing flange is too deep. I could cut out the center, remove 1/4" or so and then re-weld it or...are there backing plates with different offsets (if so, does anyone know a part number or listing by vehicle or part number that lists the amount of offset?)? Am I over-thinking this and this is not a problem? I contacted Quick Performance and asked them about it (they said they've never heard of or encountered this before), they asked me to send an email with photos (and I've not heard back from them since).

Thanks in advance for any input and feedback.

 

In normal hot rod use, it doesn't matter. For daily driver winter storm use, it might matter?

but the problem probably stems from using a disk brake rear...they had funky axles. A picture of the brake assembly mounted, with the axle in place, but not the drum, might show us something useful?

 

I'm not sure how exact that is going to be simply because different drum manufactures might have a tad more or less material in that flange. The main thing is that the shoes are making full contact with the drum and most of the time that contact surface area starts about 1/8 or so in from the edge. Then the metal part of the shoe doesn't rub the inside of the drum when the drum is on the way and the drum doesn't rub the backing plate.

 

Thanks Jim, here's a couple additional photos without the drum installed.

 

That looks like it should. I was thinking that the flanges on the axle housing were a bit cockeyed compared to standard drum brake flanges but that wheel cylinder looks to be straight up at 12 O'Clock where you want it.
As long as the shoes contact the drum where they should and nothing rubs life is good.

 

Here's a pic of the inside of the drum. There is a chamfer on the edge, but it's less than 1/8" deep, so the shoe should reside just at the edge, though fully within the drum.

On your second comment, yeah, I removed the cockeyed bearing housing flanges and installed new ones straight up.

 

For a little more history, I read this thread

QP doesn't seem to state the offset in their listing for the brakes, eh?

 

Thanks Jim...my memory (good, but short!) forgot about that thread.

When I spoke to the guys at Quick Performance last week, I specifically asked about backing plates with different amount of offset, they said they didn't offer any others.

 

sounds like you're either going to live with it how it is, or get some different axles made?

oh...also see if the drums are round...a friend just put some of those brakes on the new 9" in his 32, and he said he had to turn them a lot to get them to work

 

Yes, each specific backing plate offset has a matching brake drum width.

What are the part numbers on the backing plates you purchased?

https://www.vintage-mustang.com/threads/10x2-5-rear-brakes.1005482/

https://67fastbackproject.blogspot.com/2015/06/rear-drum-brake-rebuild.html

https://www.jalopyjournal.com/forum/threads/ford-10-inch-back-plates-with-small-bearings.1044138/

https://www.vintage-mustang.com/threads/rear-drum-size-and-id-help.1146888/

 

As long as the contact area is inside the chamfer life is good. It's usually between 1/8 and 1/4 in on most drums as that is where they leave the wear ridge in the drum. You seldom see any with shoes right up to the edge of the drum surface. For that part the space on the inside can differ a lot as there are some setups where there might be 2-1/4 or 1-1/2 shoes using the same drums and backing plates depending on the application. Ford is horrible with the "oh if it has this we used that" too.
I went out to take a shot of a drum surface but the one I could get off is too rusted. Looking at two F 150 nine inch rears I have they have different styles as one is like what you have and one has a raised piece and no flange to the outside of the backing plate.

 

Looks to me like an axle flange shaped shim, but with a smaller center hole to keep the bearing in place should get you where you want to be if you can't live with it as it is.

Chris

 

Thanks for looking. I just did a straight edge measurement from the axle flange to the inside of the shoe, and the same measurement on the drum. The inside edge of the shoe would ride on the drum chamfer...Damn!

I may, as Jim suggests order replacement axles...or, I might take a hard look at sectioning a 1/4" - 3/8" out of the backing plate recess.

 

Thanks ..there are no part numbers on the backing plates supplied by Q.P.

 

That might be some good thinking...I might need to look at that more closely. Thanks for your response.

 

I'd just put a shim behind the backing plate.

I remember seeing them back in the day. Don't remember who used to sell them...

...

 

To close the bracket, and thanks all for your input and suggestions. @lostone and @Happydaze, I looked real hard at your suggestion(s). I could have made 2 shims per side. The first shim being the same thickness as the backing plate as the axle bearing sticks out that far, and the second would be the balance of offset required with a smaller center hole to retain the bearing. Or, I could have done this with a single shim and a stepped bore. It would work, but now the t-bolts would be too short (they're barely long enough now to hold the backing plate and the heavy duty bearing retainer plate)...adding another 3/8" would have required making or buying new t-bolts.

@squirrel, Jim's solution of new axles is likely the "right way" to do it...but then there's the cost, lead time, shipping etc.. So, long story short (and because I'm frugal, impatient, stubborn and have tools)...I decided to cut and section the backing plates. I figure a couple days of my time and zero cost and it's done. So I first made a jig using some scrap, a chunk of 3/8" thick steel plate and an old bearing race that was the right diameter. The purpose is to hold the 2 pieces in the correct relationship to each other. I used the second backing plate as the guide.

After the 2 pieces were cut apart (with a zip wheel), I chucked the center section in the lathe to true up the cut.

I then clamped the outer portion into the mill and cut away the offending thickness.

I then inserted the 2 pieces in the jig, clamped it and tack welded it together. I'll do a test fit tomorrow before I finish welding the 2 pieces into one.


Again, Thanks all for sharing your thoughts, knowledge and ideas.

 

very slick!

 

Thanks.

 

Don't forget to stamp Part #anothercarguy 2.0 on those for the poor guy who ends up caretaking it in 80 years!
On that test fit, you could even dial indicate the edge after bolting it all together and spinning the drum.