Brake advise
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Lead Driver
Joined: Oct 2016
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From: Houston/Sugar Land
Sad that you have to check this since a mechanic installed the brakes but while you have the drums off measure the length of brake material on the shoes.. believe it or not the leading shoe should have slightly less material than the trailing shoe, and if the mechanic somehow put both trailing shoes on one side that wheel will be very lockup prone.
The brake dust wiped off on the cylinder is on the passenger side. The driver side had almost none on it. They were replaced about 500 miles ago.
Lead Driver
Joined: Oct 2003
Posts: 8,476
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From: Madison, WI
Pic is too dark to see the extent of the friction surface on the leading shoe. You might be able to boost the brightness of the pic, or just re-shoot it and compensate for the uneven light pouring in from frame left. It does look, however, like the leading shoe has a smaller friction surface.
If the friction surface is the same length on all four shoes, then the set was mis-packaged; either you got all trailing shoes or all leading shoes.
If the friction surface is the same length on all four shoes, then the set was mis-packaged; either you got all trailing shoes or all leading shoes.
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Lead Driver
Joined: Oct 2016
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From: Houston/Sugar Land
Pic is too dark to see the extent of the friction surface on the leading shoe. You might be able to boost the brightness of the pic, or just re-shoot it and compensate for the uneven light pouring in from frame left. It does look, however, like the leading shoe has a smaller friction surface.
If the friction surface is the same length on all four shoes, then the set was mis-packaged; either you got all trailing shoes or all leading shoes.
If the friction surface is the same length on all four shoes, then the set was mis-packaged; either you got all trailing shoes or all leading shoes.
Wow that would be unusual but certainly a possibility. The pads are all the same length on mine. From the earlier post from Paul (which I appreciate) I couldn't tell if he was referring to pad thickness or pad length or both. So madpogue, you are saying the pad surface length of the leading and trailing shoe should not be the same? If so like I said mine are all the same length. Anyone have any conflicting info on these shoes before I visit Big O.
More Turbo
Joined: Oct 2016
Posts: 501
Likes: 7
From: Deep East Texas
I may be wrong but I think if you take the shoes off and place one on top of the other, you will see that one pad is longer than the other. I looked at the lengths of the pad when I replace my brake shoes.
More Turbo
Joined: Jun 2003
Posts: 687
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The linings are designed to be the same thickness, but different lengths. Depending on the design, the bigger lining goes to the rear, because of the "self-energizing" action of drum brakes under a braking condition. The shoes expand out, then the primary shoe (the front-small one) is wedged down into the drum because of drum rotation. This is the self energizing action. The secondary (the rear-larger one) shoe is wedged up into the drum because of drum rotation.
Since the primary show wedges down, the top of the shoe is of less importance to braking and therefore there is less pad at the top of the primary shoe. The secondary shoe wedges up, so the bottom of the pad is less important, except for when the parking brake is applied. This is why the secondary shoe has more material, it uses the whole pad under different conditions, where the primary one does not.
Since the primary show wedges down, the top of the shoe is of less importance to braking and therefore there is less pad at the top of the primary shoe. The secondary shoe wedges up, so the bottom of the pad is less important, except for when the parking brake is applied. This is why the secondary shoe has more material, it uses the whole pad under different conditions, where the primary one does not.
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Lead Driver
Joined: Oct 2016
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From: Houston/Sugar Land
After I read your post I measured the entire length of the shoes from metal end to end. All four are 15 1/2". I remeasured the pads from end to end. Shoes are the same length and the pads are the same length 10 1/8" . So if you had one pad longer than the other I must have a mixed up set especially since the pad thicknesses are different on mine. Sandy
When my friend got these he may have given O'riley the wrong year or they may have given him the wrong year. ?????
Post Fiend
Joined: Apr 2002
Posts: 19,311
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From: Waterloo, Iowa
just pulled the hubs and the trailing shoe pad thickness is bigger than the leading shoes on both sides. The actual pad length on all four shoes are the same. Approx 11 1/8". Any clue from the pic? Leading shoe is to the right. The brake dust wiped off on the cylinder is on the passenger side. The driver side had almost none on it. They were replaced about 500 miles ago.
When braking, the forward shoe tends to continue on in the direction of rotation (down); and away from the anchor pin, secured by a spring.
The primary shoe in turn, is directly connected to the trailing shoe through the adjuster link. This rotation forces the trailing shoe up, on the direction of rotation, but it's always tight against the anchor pin when moving or braking in the forward direction, so it has has nowhere else to go and wedges itself out, against the drum, providing greater braking action and stopping power than would otherwise be the case. This is the "servo" or bendix self-energizing design. When adjusted properly and serviceable it works pretty well. The springs and everything needs to have good quick return action when the pedal is let off. A bad hose, weak springs or gouged shoe pads will interfere
with this.
The trailing shoe is normally thicker, and was oftentimes a slightly different lining composition.
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Lead Driver
Joined: Oct 2016
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From: Houston/Sugar Land
The linings are designed to be the same thickness, but different lengths. Depending on the design, the bigger lining goes to the rear, because of the "self-energizing" action of drum brakes under a braking condition. The shoes expand out, then the primary shoe (the front-small one) is wedged down into the drum because of drum rotation. This is the self energizing action. The secondary (the rear-larger one) shoe is wedged up into the drum because of drum rotation.
Since the primary show wedges down, the top of the shoe is of less importance to braking and therefore there is less pad at the top of the primary shoe. The secondary shoe wedges up, so the bottom of the pad is less important, except for when the parking brake is applied. This is why the secondary shoe has more material, it uses the whole pad under different conditions, where the primary one does not.
Since the primary show wedges down, the top of the shoe is of less importance to braking and therefore there is less pad at the top of the primary shoe. The secondary shoe wedges up, so the bottom of the pad is less important, except for when the parking brake is applied. This is why the secondary shoe has more material, it uses the whole pad under different conditions, where the primary one does not.
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
Well I was gonna blather on about my F250 HDs and such, but duhhhh, RTFM! Here it is, right from the specs section of the 1995 FSM, for F150/Bronco:
Lining Thickness, primary (forward) - .224
Lining Thickness, secondary (aft) - .299
Lining Length, primary - 10.46
Lining Length, secondary - 10.62
So the trailing (secondary) shoe is both slightly longer and thicker than the leading. You might want to measure the lining length again, there might be that slight difference.
Now the weird part is, look at the pics of some of the sets available for the F150s on RockAuto. Some show a BIG difference in the lining length, one (Monroe) shows the linings "offset" differently between leading and trailing. Fah, who knows, there may have been some aftermarket/engineering changes over the years. Any idea what brand shoes these are?
Lining Thickness, primary (forward) - .224
Lining Thickness, secondary (aft) - .299
Lining Length, primary - 10.46
Lining Length, secondary - 10.62
So the trailing (secondary) shoe is both slightly longer and thicker than the leading. You might want to measure the lining length again, there might be that slight difference.
Now the weird part is, look at the pics of some of the sets available for the F150s on RockAuto. Some show a BIG difference in the lining length, one (Monroe) shows the linings "offset" differently between leading and trailing. Fah, who knows, there may have been some aftermarket/engineering changes over the years. Any idea what brand shoes these are?
Thread Starter
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Lead Driver
Joined: Oct 2016
Posts: 6,185
Likes: 633
From: Houston/Sugar Land
Well I was gonna blather on about my F250 HDs and such, but duhhhh, RTFM! Here it is, right from the specs section of the 1995 FSM, for F150/Bronco:
Lining Thickness, primary (forward) - .224
Lining Thickness, secondary (aft) - .299
Lining Length, primary - 10.46
Lining Length, secondary - 10.62
So the trailing (secondary) shoe is both slightly longer and thicker than the leading. You might want to measure the lining length again, there might be that slight difference.
Now the weird part is, look at the pics of some of the sets available for the F150s on RockAuto. Some show a BIG difference in the lining length, one (Monroe) shows the linings "offset" differently between leading and trailing. Fah, who knows, there may have been some aftermarket/engineering changes over the years. Any idea what brand shoes these are?
Lining Thickness, primary (forward) - .224
Lining Thickness, secondary (aft) - .299
Lining Length, primary - 10.46
Lining Length, secondary - 10.62
So the trailing (secondary) shoe is both slightly longer and thicker than the leading. You might want to measure the lining length again, there might be that slight difference.
Now the weird part is, look at the pics of some of the sets available for the F150s on RockAuto. Some show a BIG difference in the lining length, one (Monroe) shows the linings "offset" differently between leading and trailing. Fah, who knows, there may have been some aftermarket/engineering changes over the years. Any idea what brand shoes these are?
Thread Starter
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Lead Driver
Joined: Oct 2016
Posts: 6,185
Likes: 633
From: Houston/Sugar Land
The linings are designed to be the same thickness, but different lengths. Depending on the design, the bigger lining goes to the rear, because of the "self-energizing" action of drum brakes under a braking condition. The shoes expand out, then the primary shoe (the front-small one) is wedged down into the drum because of drum rotation. This is the self energizing action. The secondary (the rear-larger one) shoe is wedged up into the drum because of drum rotation.
Since the primary show wedges down, the top of the shoe is of less importance to braking and therefore there is less pad at the top of the primary shoe. The secondary shoe wedges up, so the bottom of the pad is less important, except for when the parking brake is applied. This is why the secondary shoe has more material, it uses the whole pad under different conditions, where the primary one does not.
Since the primary show wedges down, the top of the shoe is of less importance to braking and therefore there is less pad at the top of the primary shoe. The secondary shoe wedges up, so the bottom of the pad is less important, except for when the parking brake is applied. This is why the secondary shoe has more material, it uses the whole pad under different conditions, where the primary one does not.
If this is the case, the leading shoe would be on the right side in this picture. Is this correct?
More Turbo
Joined: Oct 2016
Posts: 501
Likes: 7
From: Deep East Texas
Would a picture of my brakes help you out? I took a lot of pics before and after I replaced them. Mine worked good before and after I replaced them. Except I left the parking brake on and drove about 10 miles.
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Lead Driver
Joined: Oct 2016
Posts: 6,185
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From: Houston/Sugar Land
A picture of your shoes installed where the linings show on either top or bottom would be great. If you can have a picture of the liners on top or bottom see if my picture is correct.
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