Brake Centering Challenges

jbwthree

jbwthree

Member
Good morning and happy 4th all. I have a dilemma with my brakes that I can’t sort out. I am in the reassembly phase of a full brake rebuild and I’m having trouble getting the shoes centered. The drums and shoes were done by Randy Gross and I rebuilt the backing plates with new roller guides in the front and back. Everything checks out dimensionally near perfect on the backing plates. Upon assembly of the drivers front, I could see that the shoes were off center, biased upward by about .060”. I could get the drum on but it dragged even with the adjuster backed out. Passengers side centered and fit perfectly. Disassembled and rechecked the drivers side multiple times to no avail. I then moved to the drivers rear brake and had the same issue but worse, I can’t even fit the drum on. I then tried turning the head of the roller pins down about .020” to see if I could effect the centering. It seemed to help a little on the front but I’m still not close on the rear. I am at wits end - this is a simple assembly with very few degrees of freedom !

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On the front, the Flat Head Ted kit will make the shoes self centered. Other than that you could file or grind down the roller tracks (roller guides) or continue machining down the rollers. The instructions in the mechanics books call for bending down the roller tracks but I would think that filing or grinding would be easier. I have the Flat Head Ted kit.
 
I don't like new tracks because you could damage the backing plate taking the old ones off and/or you could damage it riveting on the new one. Not to mention how close the repro is to the original.

The model a guy I know and hang out with a lot has been around for a long time and welds up the originals amd mills them back down.

I would do what has been said about filing the tracks and/or going to flathead ted. Not my preference, but if you do go this route, make sure you use the whole kit and not just pieces.
 
Buy or make a brake centering tool. Then you can see where you are going with the brake shoes, not covering them in the drums.
 
To make a simple centering jig, I just make up a piece of PVC to fit snugly over the spindle, drill a hole straight thru it for a snug fit of the piece of heavy wire. Bend a 90 in the wire end. Spinning the 'thing' on the spindle and setting the wire to the shoes you can see what needs to be done.
 
nkaminar said:
Chris, Can the new tracks be bolted in with grade 5 or 8 hardware and lock washers?
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Don't know, I have never tried or seen it. The rivets are somewhat small and the bolt would have to barely stick out to not hit anything inside. You would still have the same problem with rivets so you are not really getting anywhere.
 
Thanks for the feedback guys. I have a centering tool from Brattons and that is how I can see how far the shoes are off. It seems to me like a lot of material to take off of the roller tracks. As I mentioned above, they are to spec with new parts and instead of grinding the tracks, I’ve turned down the pins in an attempt to adjust the center.


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Are your brake adjusting shaft pins new? I had a problem with the new pins. The shaft is supposed to be .490 in diameter. Mine were .494. This did not allow the shafts to fully seat in the brake adjusting housing, thus holding the top of the brake shoes slightly higher than they should have been. Measure the diameter of the shafts or remove the brake adjusting wedge cap and insure that the pins are seating fully. I had to grind mine to about .486 diameter before they fully seated, and brakes aligned.
 
ahirt said:
Are your brake adjusting shaft pins new? I had a problem with the new pins. The shaft is supposed to be .490 in diameter. Mine were .494. This did not allow the shafts to fully seat in the brake adjusting housing, thus holding the top of the brake shoes slightly higher than they should have been. Measure the diameter of the shafts or remove the brake adjusting wedge cap and insure that the pins are seating fully. I had to grind mine to about .486 diameter before they fully seated, and brakes aligned.
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They are new, I will check that measurement. Thanks !


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jbwthree said:
They are new, I will check that measurement. Thanks !
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The Brake Centering Gage is a measuring device, -not intended to be a correction device. It is to determine if there is excessive wear or out of specification components.

The likely issue you are having is the A-2017 Brake Shoe Centering Bracket is either out of specification, -or it is not properly located onto the Brake Housing Plate. When all of the parts are within factory specifications, you don't need a 'centering gage'. Ford's assembly line workers did not use a 'centering gage' when they assembled the brakes.

FWIW, Ford did not allow his Agency mechanics to install the Centering Brackets onto the Housing Plates, ...and on the Engineering Print they gave a maximum tolerance of around 2-thousandth of an inch in either direction out of specified location. Think about this for a second, two thousandth (0.002") of an inch is about half the size of what a typical human hair measures!! Unfortunately, if you do not have a fixture made to correctly locate these brackets when installing them, you are actually 'whizzing in the wind' hoping to have good brakes. Even the F/H Ted four-sided pins cannot hit this location with that kind of accuracy. This is why I have said over and over, when the stock braking system is rebuilt to factory specifications, you don't need any of these 'band-aids' to have good brakes.

.
 
BRENT in 10-uh-C said:
The Brake Centering Gage is a measuring device, -not intended to be a correction device. It is to determine if there is excessive wear or out of specification components.

The likely issue you are having is the A-2017 Brake Shoe Centering Bracket is either out of specification, -or it is not properly located onto the Brake Housing Plate. When all of the parts are within factory specifications, you don't need a 'centering gage'. Ford's assembly line workers did not use a 'centering gage' when they assembled the brakes.

FWIW, Ford did not allow his Agency mechanics to install the Centering Brackets onto the Housing Plates, ...and on the Engineering Print they gave a maximum tolerance of around 2-thousandth of an inch in either direction out of specified location. Think about this for a second, two thousandth (0.002") of an inch is about half the size of what a typical human hair measures!! Unfortunately, if you do not have a fixture made to correctly locate these brackets when installing them, you are actually 'whizzing in the wind' hoping to have good brakes. Even the F/H Ted four-sided pins cannot hit this location with that kind of accuracy. This is why I have said over and over, when the stock braking system is rebuilt to factory specifications, you don't need any of these 'band-aids' to have good brakes.

.
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what exactly are you recommending he do?
 
ericr said:
what exactly are you recommending he do?
Click to expand...

Something is not to spec or the brake shoes would be centered.

"Fixing" the problem by turning down the roller pins is just compensating for one problem while creating another, and should have indicated that something else was wrong.

Sometimes the problem may not be obvious, and often repro parts are to blame.

A good starting point as ahirt suggested would be the upper brake adjusting pins
 
nkaminar said:
Chris, Can the new tracks be bolted in with grade 5 or 8 hardware and lock washers?
Click to expand...

Nkaminar,
When the rivets are bucked into place, they fill the holes in the backing plate and track. This eliminates loose fit motion of one to the other. I would not trust the grade 5 or 8 hardware to prevent any motion of the track.
 
Send them back to Randy Gross and pay him to make it all work together properly.

Brakes take experience and special tooling to make them work right. These guys can do a full set up so that it is bolt together. It is much smarter and likely cheaper in the long run to pay the guy with the right tools to do the job right.

As Brent pointed out brakes are actually a precision job on the Model A. They really far from simple to get right.
 
I’m wondering whether you e put the adjusting pins in correctly there’s an offset to them so that if you have the pins reversed, your shoes sit cockeyed, the bottom of the shoes closer to the backing plate than the top (front), or front to back difference on the rear. Functionally this would make the shoes look high of center and dragging. I haven’t seen anything about the offset anywhere, so maybe it’s just my 29, but that’s my guess.
 
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