‘62 Coupe brake issue.

[rustytractor]

I’ve always had a braking issue with my ‘62 Coupe. Starts out fine but after driving  a while you can feel the brakes starting to bind and you can feel the steering wheel start to shimmy when braking.

When coming off the brakes and creeping at very slow speeds (like when in a traffic jam)  the car sort of “lopes” and you feel it slightly holding and then releasing and the steering wheel rocks a bit (hard to explain this any better).

I rebuilt the wheel cylinders a few years back but was concerned one was sticking and holding on when the fluid was warm and finally got round to investigating yesterday starting at the front. The wheel cylinders looked fine with no leaks or weeps.

The brakes were cold so this doesn’t really answer the sticking when warm question BUT I did notice a glaringly obvious issue in that there were two leading shoes on one side of the car and two trailing shoes on the other. I’ve now rectified this and reassembled everything ready to test - it’s on the lift and I’m going to replace the gearbox sump gasket before going for a test drive.

Would the mismatched brake shoes cause the problem I’ve been having ?

I really bloody hope so 🤔🙏

[Roger Zimmermann]

Maybe. Have a look at the retracting springs. If one is weak, the brakes from that wheel are applied slightly which is making that drum hot.

[The Tassie Devil(le)]

Would the mismatched brake shoes cause the problem I’ve been having ?   

The shimmying that you are referring to sounds like the possibility of warped drums.

I don't think that the odd shoes would be a problem at the moment at low speeds, as unless the shoes have been radius ground, there would be no full-contact between the shoe and drum.

Bruce.

["Cadillac Kid" Greg Surfas 15364]

Russel.
From what you describe I would check that the drums are concentric.  As long as they are not yet oover spec you might just have them turned while they are off.  I believe you need to true the drums while they are mounted to the hubs.
Greg Surfas

[rustytractor]

If one or both of the drums were warped or distorted wouldn’t I feel it all of the time, at least to some degree? I know that heat makes things worse but surely I’d feel something all of the time and would see that the drum wasn’t running true when spinning it with the wheel off? (admittedly the brakes would be cold but nevertheless)

["Cadillac Kid" Greg Surfas 15364]

Russel,
It doesn't take much of a distortion to show up as pedal pulsations. It is the inside of the drum that needs to be true of course and IF it was turned non concentrically when the drum warms up and expands it would be noticable.
The point being, just check to bew sure the drums are "true"
Greg Surfas

[rustytractor]

Russel,
It doesn't take much of a distortion to show up as pedal pulsations. It is the inside of the drum that needs to be true of course and IF it was turned non concentrically when the drum warms up and expands it would be noticable.
The point being, just check to bew sure the drums are "true"
Greg Surfas

Fair point. After I've given it a test drive to see if the problem is the same/better/worse/gone I'll check everything else. One thing I wondered is whether the servo (brake booster) is faulty.

If I still have a problem I can either pull the one from either my still dead '64 CdV (if it's compatible) or from my '62 MM Hearse (again, if it's compatible) and see if that makes a difference first. Does anyone know if either of these will fit the '62 Coupe?

How about the pushrod from the booster to the master cylinder - are these adjustable and if so how do you check and adjust the length ?

["Cadillac Kid" Greg Surfas 15364]

Russel
Don’t over think this.
Greg Surfas

[rustytractor]

Russel
Don’t over think this.
Greg Surfas

It's not really over thinking - I have 8 days to get this fixed before I have to take the '62 along with the '41 and '53 Coupe on a 500 mile round trip to Liverpool for my step daughters wedding.

I'm so damned busy I have very little time before now and then to effect repairs so need to cover all the bases beforehand if possible. Don't forget that I'm in England and parts availability and delivery speed isn't anything like inside the US

Just trying to understand my "just in case" options.

[The Tassie Devil(le)]

Don't forget that it could be the back drums that are distorted.   With a single circuit brake system, any corner could be faulty.

When I had a pair of rear drums machined, the machinist wanted the rear wheel so he could attach it to the machine to hold the drum in alignment, as without the support, the drum was too flexible to machine properly.

This was on a '60, but never had this problem before with any drums I had machined.

Bruce.

[savemy67]

Hello Russell,

I would suspect that if you had two leading shoes on one side and two trailing shoes on the other, the car might pull to the side with the leading shoes due the greater area of the lining on that side - more friction/stopping surface.

In turn, this could have caused more heat build-up in one drum, maybe causing the drum to become eccentric.  The "loping" sensation you describe is almost exactly the way I would describe the sensation of warped rotors on a car with disc brakes.

As Greg suggested, have the drums measured for any out of round condition, and have them turned.  A brake shop should be able to turn the drums with the hubs so they can make them concentric.  I would think the cost should be no more than ten pounds per drum.

I think it is less likely that the booster is faulty, than the drums need to be "trued".  It would be very unusual for a vacuum failure to cycle back to normal every few seconds as you applied the brakes.  If I recall correctly, '62 was the first year for a dual-circuit master cylinder.

Sort out the linings, check the springs as Roger suggested (if the shoes were installed incorrectly, maybe the springs were as well), road test.  If problem still exists, have drums turned.  Check the modified Cadillac forum for a pdf master parts catalog.  This may tell you if you can use your '64 drums if the '62's are not turnable.

Respectfully submitted,

Christopher Winter

[rustytractor]

 

Hello Russell,

I would suspect that if you had two leading shoes on one side and two trailing shoes on the other, the car might pull to the side with the leading shoes due the greater area of the lining on that side - more friction/stopping surface.

In turn, this could have caused more heat build-up in one drum, maybe causing the drum to become eccentric.  The "loping" sensation you describe is almost exactly the way I would describe the sensation of warped rotors on a car with disc brakes.

As Greg suggested, have the drums measured for any out of round condition, and have them turned.  A brake shop should be able to turn the drums with the hubs so they can make them concentric.  I would think the cost should be no more than ten pounds per drum.

I think it is less likely that the booster is faulty, than the drums need to be "trued".  It would be very unusual for a vacuum failure to cycle back to normal every few seconds as you applied the brakes.  If I recall correctly, '62 was the first year for a dual-circuit master cylinder.

Sort out the linings, check the springs as Roger suggested (if the shoes were installed incorrectly, maybe the springs were as well), road test.  If problem still exists, have drums turned.  Check the modified Cadillac forum for a pdf master parts catalog.  This may tell you if you can use your '64 drums if the '62's are not turnable.

Respectfully submitted,

Christopher Winter

Thanks Chris, this is what I suspected. I was working on the brakes until the wee hours last night - so far I’ve found and corrected the front end fault but also found the leading and trailing shoes were reversed on both sides of the rear plus the wheel cylinders were well past there best - I fitted new cylinders and reversed the shoes so at least I now know everything is where it should be.

I went for a quick drive around 1am and there’s a huge improvement to all round braking - I can lock the wheels up now which I couldn’t ever do before although there’s a pull to the right which will need attention next week. This doesn’t prove much with regards the sticking when hot issue as I’ll need to go for a longer drive to heat the system up to see if that’s still an issue.

Oddly the car started to intermittently lose power so I’ll have to resolve that before going for a long drive.

Oh the fun never ends 🤬

[rustytractor]

So:-

Rebuilt master cylinder
Stripped and reassembled front brakes with leading/trailing shoes correctly positioned (2 x trailing on one side, 2 x leading on the other on initial inspection)
Checked front brake hoses for degradation - both ok
Stripped and reassembled rear brakes with new wheel cylinders and leading/trailing shoes correctly positioned (backwards on initial inspection)

Just took the car out for an hours hard drive - absolutely beat the crap out of it and none of the original problems were apparent, no brake binding or pulling so I’m happy that the bulk of the problem is resolved. 

There was still a slight vibration under hard braking but that seemed to improve as the reversed shoes started to bed in.

Once I’d parked up I felt all of the wheels, only the passenger side rear felt noticeably hotter.

Any thoughts ?

[savemy67]

Hello Russell,

Much of the time, adjustment using the star-wheel adjusters is done by feel, sometimes by counting teeth, sometimes by feeler gauge.  Regardless of how careful one is, and which method is used, I think the best one can do is to come close to the ideal shoe adjustment.

At this point, if you are confident that the star-wheel adjusters are located and functioning properly, you may want to do several maneuvers with the car in reverse, and let the adjusters attempt to equalize the shoe travel at each wheel.

If you re-used the old shoes, even though you relocated them properly, there may be a slight difference in the braking surface of the shoes.  If you get the shoes arced, this may take care of this issue (if it is an issue).

Respectfully submitted,

Christopher Winter