Replacing brake drum; not enough clearance past new shoes


#1

Hi everyone,

I’m almost done replacing my rear brake shoes and wheel cylinders (one cylinder was leaking), and it went without a hitch until I tried to get the drums back on the car. The drum gets hung up on the shoes and will not slide back on.

The car is a 1996 Mercury Mystique, 2.0L, 75000 miles.

The drum looks to be in good shape, and doesn’t have a lip at the edge like I’ve heard old drums getting.

The brake assembly has a goofy auto-adjustment bar, which appears to be fairly common in Fords. I turned it down as far as it will go, and both of the shoes are now resting on the wheel cylinder pistons, as well as their anchors at the bottom. I tried opening the bleeder valve and compressing the pistons more, but it seems that they are already in as far as they’ll go. The parking brake lever is fully depressed, and it does not appear that the parking brake is affecting the shoes (if the brake were on, then there would be a gap between the shoes and the wheel cylinder piston, right?)

I considered getting the drum turned to take off a millimeter or so, or sanding down the friction surface of the shoes, but this seems like it could be a bad idea.

Is there anything I’ve overlooked? If not, what would you guys recommend?

Thanks in advance,

Sam

edit: here are some images of the new installation. Anyone see anything wrong? http://imgur.com/a/vy7Ye


#2

Don’t turn the drums, something about the assembly of the parts is wrong, or the emergency brake is on. These drums came off this car?


#3

Yep, they came off fine. The emergency brake isn’t on, but that doesn’t mean it’s not stuck somewhere I guess.


#4

Did you check the old shoes to the new shoes to make sure the shoes are identical?


#5

They sure look identical, except for the pad thickness. All the holes are in the same places, and the little dimples along the edges of the liner match up.


#6

Looking at your pictures, I thought the pads looked too thick. Most disc/drum sets had very thin pads on the shoes. Those shoes look like they were made for an all drum brake system.


#7

This is where doing one side at a time could have helped. I am wondering if one of the parts is not in proper position and keeping the shoes apart (? check the bottom).


#8

It looks like you have two primary shoes on one side and two secondary shoes on the other. I think I’m looking at the two primaries. The primary has the shorter, thicker lining and goes toward the front of the car. Also, the rearward one looks to be up-side down. Seen it done before. Yours may not be the type of brakes that I’m used to so measure those linings and if the right side and left side are different, take apart and reassemble.


#9

If the parking brake cable has been adjusted in the past to compensate for the worn shoes you will have to back off the adjustment on the cable. Sometimes this is not so obvious when trying to force a drum on.


#10

The leading and trailing shoes are different thicknesses, but with the way these are set up, it’s impossible to get them mixed up. The trailing shoe lining has a bracket for the parking brake cable, and has a lever behind it for the parking brake to move the shoe, so it can only go on the trailing side. It also has a particular way it fits into the adjuster, and the other shoe doesn’t have a hole for the spring that returns the parking brake. These are the shoes I got, you can see that lever on the trailing shoe: http://www.rockauto.com/en/moreinfo.php?pk=297878&cc=1203286&jsn=38 I’m sure they’re on the correct side, but thanks for the ideas!

@galant I did do one at a time, but when the first drum didn’t fit on, I didn’t notice any differences between the sides, so I did the other side to make check if it was something funny about that particular drum, etc. But then I just had the same problem on both sides… so probably wasn’t the best call not to do the whole job on one side first.

@keith The new shoes are about twice as thick as the old ones! Especially the leading shoe looks extremely thick to me, but granted I haven’t seen many brake shoes before. I noticed that RockAuto has two different Motorcraft shoes available for my car, so it could be I bought the wrong one? The options are 8" and 9"; I bought the 8" which seem to match the old shoes, but still a possibility.

I gave up tonight and just put the old shoes back on; they still have plenty of friction material on them, and the main point of the job was to replace the leaking wheel cylinder which was a success. But hopefully soon I’ll take another shot at it. @Nevada_545, I’ll definitely check and see if I can’t lengthen the cable.

When I redo it, do you guys think it’s worth going to a Ford dealership parts desk to guarantee I get the right part (and at least eliminate that potential problem, if I did get the wrong thickness shoes), or is my luck as good there as at RockAuto? I reckon they can look up the VIN and get the exact part. Also, would replacing the drums at the same time help my chances at all?

Thanks everyone for the help!

At least the upside of this is that I can now do this whole job in about an hour, after disassembling and reassembling everything three times today.


#11

Guessing here & I’m sure some of our pros will correct me if I’m guessing wrong but I’m wondering if the 8 & 9 " is referring to the lining length & maybe the 9 " would be some thinner since they’re longer .


#12

No . . . 8" and 9" is the inside diameter of the drum


#13

Seeing as how the leading and trailing shoe theory is a viable one; what about the park brake levers being assembled to the wrong shoes?

Many brake shoes I’ve seen had the short lining as the front and the long one as the rear.

If they came assembled with the lever maybe there’s a possibility the reman facility botched it.
Most of the reman service people are not that sharp mechanically. They’re assembly line stick it together and roll it out right or wrong techs.

I’ve run into a number of various type of reman issues over the years whether it’s reusing worn out parts, leaving things out, or whatever.
In one case a reman 350 Chevy was missing the oil rings; on all 8 cylinders.

A reman facility in Tulsa some years ago shipped out 75 reman VW engines. Seventy one of them came back shortly with reman faults and I was one of the 71 victims.


#14

I thought reman brake shoes were no longer allowed?


#15

@keith

remanned . . . I believe it’s called relined . . . brake shoes are perfectly legal, and very common

What is NOT legal AFAIK is to use a rearcing machine . . . is that perhaps what you were thinking of?


#16

I’ve replaced brake drums many times, 60’s Galaxies, 70’s Ford trucks, VW Rabbits, & my 90’s Corolla, and never run into this problem. I did one time have to loosen the bleeding screw to get enough clearance, but it sounds like you’ve done that. It is indeed perplexing. hmmm … well here’s some ideas anyway…

  • do an experiment, see if the drum will go on ok with the parking brake completely disconnected. If so, that isolates the problem to something w/ the parking brake.

  • try if one side will go on, but the other won’t. If so, you may have some parts switched side to side.

  • I’ve had problems with Ford adjustment gadgets before binding up before due to wear and rust. Buy replacement parts and try it with new adjusting gadgets installed.

  • take those shoes to the place you bought them, and ask them to bring out a set just like those, same part number. Bring along your calipers shoes and measure to see if you just happened to get an extra thick set. Likewise, ask them to bring out a set from a different manufacturer and measure those. You might have just got unlucky and got an extra thick set.

  • Don’t machine the drums to solve this.


#17

That system looks similar to my 2006 Ford Focus. I replaced mine on Focus last year. So, I’ve seen and done only one in my life. I took a non-mechanic’s auto repair class about 30 years ago, so I know how they should look theoretically but I have only worked on one set. Now, that’s out of the way, here is my opinion.

I am thinking there should be some kind of shoe adjusting mechanism in the last picture you posted. Do you see the empty space immediately right and below the end of wheel cylinder? I think that space should be adjusted to make the shoe move closer to the wheel cylinder. In the second to the last photograph, I see a black circular thingy under the wheel cylinder and a little to the right of center. That may be the adjusting wheel of some sort. That’s where the adjustment mechanism for my Focus was.

The new shoes are thicker than the old shoes, so unless the new shoes are adjusted inward, they should not fit. The adjustment mechanism may be rusted or difficult to rotate, but there should be one.


#18

8 and 9" are the nominal inside drum diameters.


#19

If you look at the pic of the botton half of the assembly you will see that you have the right shoe over the rectangular retainer at the bottom but the left shoe is over the retainer at the top and under it at the bottom. This is keeping the left hand shoe from seating all the way.


#20
Many brake shoes I've seen had the short lining as the front and the long one as the rear.

I believe this only applies to the old Bendix design where the front shoe provided “servo” action to the rear shoe which did most of the braking.

When I redo it, do you guys think it's worth going to a Ford dealership parts desk to guarantee I get the right part (and at least eliminate that potential problem...

Absolutely. It looks to me like the left shoe in your pics is taller than the right one.