Front Brake Operating Pin Issue

BillCNC

BillCNC

Well-known member
Hey All,

For the last two days, I have torn my brake system completely apart trying to find a scraping issue when I hit the brakes. Also, my brake pedal wouldn't return fully and I'd have to manually lift it with my foot.

I found that my floaters on the drivers front needed to be loosened a little and that fixed that. But the real puzzler as the scraping issue. It turned out to be the drivers side operating pin. It was scraping something on the top causing a burr that the pin would scraped then hang up on. My only remedy until I figure the cause was to file the burr down and flip it end over end and reinstall.

What would cause an operating pins side to be scraped? :confused:

Regards
Bill
 

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Is the pin rubbing on the inside of the Spindle bolt? Is the front brake shaft (A-2076/7) arm on the end actually pushing straight down, ...or is it rotated too far where it is pushing it downward at an angle causing it to rub against the bore of the Spindle Bolt??
 
It could be several issues.
1. Backing plate not tight or front backing plate bolt holes enlarged not centered correctly causing the pin to not be straight in the spindle bolt inside bore rubbing on the ID of spindle bolt.

2. Spindle bolt a replacement with too small an inside bore causing same as above.

Many times backing plates are loose and when the brakes applies the backing plate rotated slightly and the brakes will apply but not release well because of item 1 above. Make sure all is well and tight. You will probably have to disassemble to see what’s up. Brent’s comment above is spot on as well. Sometimes the wedges are loose or worn or holes worn causing said issues.
Sometimes you can grind a bit off the shank of the pin if it’s over spec but I don’t like doing that. I’d rather grab a good original pin. Braze up end and shape if need be.

Larry Shepard
 
Its a new pin. Is it possible the pin was made too thick? Any way to check the dimensions against an original?
 
All good points, thank you guy's.

Does anyone have an original that they could measure or know of a ford original drawing that I could compare to. Calipers in hand...

Regards
Bill
 
BillCNC said:
All good points, thank you guy's.

Does anyone have an original that they could measure or know of a ford original drawing that I could compare to. Calipers in hand...

Regards
Bill
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The only measurement that you will need is to verify the overall length is correct. They must be exactly 7.2500" long from tip-to-tip. With regard to the diameter of the pin, if the oversized tip will go thru the bore of the Spindle Bolt, then there should be enough clearance. The issue I believe is, the pin is not staying in the center of the Spindle Bolt bore during the braking operation which is causing the edge of the pin's shank to gald. To me, this is a result of allowing the 90° arm on the end of the Brake Shaft (A-2076/77) to over-rotate which is pushing the Brake Operating Pin up against the bore of the Spindle Bolt, ...and that is causing the rub mark on the pin.
 
BRENT in 10-uh-C said:
The issue I believe is, the pin is not staying in the center of the Spindle Bolt bore during the braking operation which is causing the edge of the pin's shank to gald. To me, this is a result of allowing the 90° arm on the end of the Brake Shaft (A-2076/77) to over-rotate which is pushing the Brake Operating Pin up against the bore of the Spindle Bolt, ...and that is causing the rub mark on the pin.
Click to expand...


Excellent point Brent.
 
Great Post Brent

The recess in the actuating arms look good. They are not new but the operating pins and operating wedge's are. The king pins were installed 4 years ago and now have about 3,000 miles on them. My front brake actuating arms are not 15° forward, but 14°. I don't think that 1° would make a difference, could it?

Anyone know the diameter of the operating pins?

Regards
Bill
 
BillCNC said:
Great Post Brent

The recess in the actuating arms look good. They are not new but the operating pins and operating wedge's are. The king pins were installed 4 years ago and now have about 3,000 miles on them. My front brake actuating arms are not 15° forward, but 14°. I don't think that 1° would make a difference, could it?

Anyone know the diameter of the operating pins?

Regards
Bill
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Bill, I do not have the print in front of me but I can look it up come the first of the week if you like, however, the diameter of the pin just does not matter since the 'oversized' area on each end does pass thru the bore of the Spindle Bolt.

Additionally, the 15° forward location (-or 14° in your case) means nothing. This is nothing more than some restorer in modern times establishing an arbitrary number to illustrate their point when describing the desired static position. What DOES matter is the Front Brake Lever should be near-exactly vertical when the brake pedal is fully depressed. This is because that arm has the maximum amount of leverage to push that pin downward against the Brake Operating Wedge. It also does not matter what the static position of the Brake Lever is (-14° forward, or 15° forward, -or whatever #) if the arm goes past straight vertical when the brake is fully depressed. It that brake arm does travel past vertical, then it has the ability to push the pin over against the bore of the spindle.

It is also worth asking if you have verified the brake shoes are centered on the housing plates, -and the tracks, their location, the heads of the pins and the rollers are all within factory specifications. If any of those including tracks are worn or located incorrectly, it has the potential to cause the pin to travel much further distance to energize the shoes which ultimately will cause the Brake Shaft arm on over-rotate.
 
the static position of the Brake Levers should be 15 degrees at rest when adjusted properly because that is the point of maximum force at the levers. Routine brake adjustments should be done by resetting the levers to 15 degrees in order to compensate for wear of the shoes and maintain maximum leverage when stepping on the pedal. Same goes when replacing shoes. Works for me, so just sayin.
 
5lugnuts said:
the static position of the Brake Levers should be 15 degrees at rest when adjusted properly because that is the point of maximum force at the levers. Routine brake adjustments should be done by resetting the levers to 15 degrees in order to compensate for wear of the shoes and maintain maximum leverage when stepping on the pedal. Same goes when replacing shoes. Works for me, so just sayin.
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So please show me in Ford literature where this 15° number came from.

And, while you are at it, please explain why you feel that number is 15°, ...and not 12½°, -or 18°.
 
BRENT in 10-uh-C said:
It is also worth asking if you have verified the brake shoes are centered on the housing plates, -and the tracks, their location, the heads of the pins and the rollers are all within factory specifications. If any of those including tracks are worn or located incorrectly, it has the potential to cause the pin to travel much further distance to energize the shoes which ultimately will cause the Brake Shaft arm on over-rotate.
Click to expand...

Thanks Brent, It's todays project.

The tracks should be good as I reworked them 3000 miles ago. I added weld and dresses them up to spec.

Regards
Bill
 
Bill, what did you use as a template when you welding up the roller guides? I did mine and tried to use the flat that wasn’t worn and basically made a straight line off that. Hope you figure your problem out and give us details. Good luck!!
 
History said:
Bill, what did you use as a template when you welding up the roller guides? I did mine and tried to use the flat that wasn’t worn and basically made a straight line off that. Hope you figure your problem out and give us details. Good luck!!
Click to expand...

Yes, there is only a five-thousandth (-0.005") of an inch variance allowed with the location of the Centering Bracket (tracks) surface to play with. That number is less than the thickness of 3 human hairs combined, so if it is off then so will the brake shoes and the braking ability. I would first check with a centering tool to verify that the shoes are centered exactly and report back.

.
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Attachments

I sanded the metal and applied dykem machinist ink to the area, then I made some metal squares that were 1.312" (fronts) & 1." (rears) and rest them against the pins and used a scribe. I welded the tracks then ground them to spec. I used the gauges as I went along.

Regards
Bill
 
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