Rear Brake Lockup (356A)

[Jim Alton]

After six weeks of changing a starter bushing it's time to do a little chassis lubrication and brake maintenance on my 1958 356A.

One problem I've had as long as I've owned the car is that the rear brakes will lock up if I'm not very careful about applying the brakes suddenly.

The car still has the brake shoes that were in it when I got it. I have changed the front brake backing plates (it had homemade Carrera brakes) and made all the front wheel cylinders point in the correct direction. I also changed the soft lines a while back.

The rear brakes produce a lot of dust--the front brakes don't. Could different brake shoe compositions cause the rear brakes to grab or lock?

Somebody on this forum saw photos and said I have 356B backing plates. Is that possible, and if so could that do more than affect the parking brake.

[Dick Weiss]

Several questions are arising here, Jim; Not showing photos make it difficult to understand what you have.

1. Front Carrera backing plates? The plates have screened vents and a lotta holes? (A photo available?)
2. Rear B backing plates--do they have a double lip around the edges vs the single lip on the A plates?
3. Brake shoes being different from front 4 vs the rears? Were they arced to match the drums and all were adjusted properly?
4. The parking brake action would be the same w/either backing plate if installed properly.
5. The rear brakes locking w/a hard "stab" of the pedal, but not the fronts, and the front cyl's pointing toward the direction of rotation?

Looking forward to answers,
Dick

[Jim Alton]

Several questions are arising here, Jim; Not showing photos make it difficult to understand what you have.

1. Front Carrera backing plates? The plates have screened vents and a lotta holes? (A photo available?)
2. Rear B backing plates--do they have a double lip around the edges vs the single lip on the A plates?
3. Brake shoes being different from front 4 vs the rears? Were they arced to match the drums and all were adjusted properly?
4. The parking brake action would be the same w/either backing plate if installed properly.
5. The rear brakes locking w/a hard "stab" of the pedal, but not the fronts, and the front cyl's pointing toward the direction of rotation?

Looking forward to answers,
Dick

1. Here are some shots of the "Carrera" front brakes which I replaced in early 2012.

Home made Carrera brake

Home made Carrera brake

Home made Carrera brake

Home made Carrera brake

2. I haven't pulled the rear drums in a while--I'll get back to you. I should have photos but they're hiding.

3. I've never changed brake shoes so I don't know if they're different, except that the rear's produce lots of black dust and the fronts don't.

I haven't arced them but something over 20,000 miles (during my stewardship) should be enough to match radii.

5. Yep. A stab on the brake pedal locks the rears. Here's an after photo which should be just after putting on new backing plates.

Non-ventilated left front brake

I think I got it right. I spent a long time looking at the shop manual. I think the right front may have had a brake cylinder wrong.

[Martin Benade]

It looks correct to me. That was a pretty half-hearted attempt they made at Carrera brake cooling. The holes are so small the screen was not really needed.

[Vic Skirmants]

With the wheel cylinders pointing correctly, and new flexible lines, the only thing left is the brake shoe material. If the front compound is more of a racing type, and the rears are a street version, that could be it.

[Jim Alton]

I pulled the left side brake drums. The front and rear shoes are definitely a different construction:

Left Front: butt-joined shoe

Right Rear: fillet on shoe

It seems quite likely the friction material's also different.

Another problem (which post-dates the brake grabbing) is a transmission oil leak which is NOT from the oil seal.

[Dick Weiss]

Jim,

Your last photo shows the latest series of brake shoe(s) w/the corner reinforcement(s) and the tapered arc of the blade's "T"
vs the earlier shoe(s) w/its concentric arc to the shoe arc.

Dick

[Mike Smith]

How about swapping the Fronts to the Rear and the Rears to the Front?

You may have an arcing problem but it would be an interesting exercise

In addition, talk to the boys that Race Drum Brake Cars
There is no air around the Rear Brakes, they always run hot unless other mods are made

Photo is of a Porsche Ventilated Rear Plate - Note that the Mesh that Porsche used was too fine

[Al Zim]

You can have a car that will not start..no problem! You can have a car without a windshield..Its a race car! You can have a car without seat belts..it an old car! When you have a car without brakes you are in TROUBLE! It is pointless to discuss the value of your car or the value of your life! Without excellent brakes both are worthless. Imagine how much fun it is to get stabbed in the chest with a thick steel steering rod. Start from scratch purchase new parts for everything from the backing plate to the cotter pin. Get you shop manual out and learn how to properly install the rear wheel seal and cap that holds the backing plate to the car. If you carefully measure your drums we (I do not know if anyone else does this) can arc the shoes. Do not use the VW rear axle seal kit for your car BAD NEWS! Your oil leak is probably the pin that holds the cast part of the outside of the axle to the axle tube. Remove the 3 bolts that hold the tube to the spring plate. Loosen the clamp that holds the small end of the axle boot to the axle. Make sure the boot is free. Use an aerosol carburetor cleaner to clean around the pin right side up and upside down. Then use wicking lock-tight on the up side of the pin and let it set overnight with some warmth present. Turn over and do the same thing on the other side. Follow the workshop manual for assembly. Most people do not know how to install the rear backing plates properly. You are always welcome to call us regarding parts prices and questions. 800.356.2964 al zim

[Jim Alton]

Is this the dowel pin?

Dowel pin? Left Tear 356A T2

It looks reasonably dry. Thanks for the suggestion--it's something I never would have concluded.

There's a little leakage around the axle now that the tension from the brake drum is off:

Left rear axle--one day after removing brake drum

I don't think it was leaking there before (it looked dry but no pictures). Also, the corresponding part of the brake drum's bone dry:

Left rear brake drum

Here's the inside of the brake after a cursory cleaning and time for a little oil to seep out through the axle.

Another view inside left rear brake

It doesn't look like the dowel pin's to blame but I'm mystified as to what is. When the car's on jackstands some oil leaks at the axle boots--particularly the left boot but that doesn't seem t be a problem with weight on wheels. The inside of the left rear tire and wheel showed the leaking was going on for a while.

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As an aside, the front brakes surprised me. I've put about 30,000 miles on this car plus whatever the previous owner put on these brakes. Parts of the front shoes have zero wear. There's an unworn strip on the outboard side that's about 25% of shoe width at the leading edge and maybe 10% or a little less at the trailing edge.

There is a place in Long Beach that arcs brakes: CH Topping & Co. It might be time to visit them.

[Vic Skirmants]

Sounds like the drums need a trim.

[Al Zim]

Your pictures are (as usual) worth a thousand words. Take your bearing cap off. Remove the spacer that seals against the oil seal. Then remove the washer and the o-ring. Two situations may exist. The first is that the washer is bent. You have probably purchased a VW part where the metal washers are thinner. This is not allowing a good seal against spacer. The second is that you have not shimmed the backing plate properly (SEE THE SHOP MANUAL) correct this and use the thicker shim. Zim's sells this as a kit. Finally torque the axle nut properly. Use of the Torque dude makes this a simple operation that can be done with a 3/8 inch torque wrench.
I am not in favor of cutting on the drum if it needs to be cut then you need it to be restored. Use the guy in Colorado, Martin Willis at The Machine Shop.
al zim

[Jim Alton]

Your pictures are (as usual) worth a thousand words. Take your bearing cap off. Remove the spacer that seals against the oil seal. Then remove the washer and the o-ring. Two situations may exist. The first is that the washer is bent. You have probably purchased a VW part where the metal washers are thinner. This is not allowing a good seal against spacer. The second is that you have not shimmed the backing plate properly (SEE THE SHOP MANUAL) correct this and use the thicker shim. Zim's sells this as a kit. Finally torque the axle nut properly. Use of the Torque dude makes this a simple operation that can be done with a 3/8 inch torque wrench.

I am not in favor of cutting on the drum if it needs to be cut then you need it to be restored. Use the guy in Colorado, Martin Willis at The Machine Shop.

al zim

Thanks. It just so happens that I usually use your Torque Dude for reinstalling rear brake drums.

I went through that shop manual section some years back after I had to take the transaxle to Larry Markham for a broken differential. Maybe practice will make perfect.

The uneven brake shoe wear is in the front left brake. Martin Willis at The Machine Shop did work on my rear drums when Larry noticed wear on the axle splines. The first step now will be measuring the drums.

[David Baugh]

From your description, I doubt that your oil leak has anything to do with the axle seal or o-ring. If it did, I would expect to see oil coming out of the slinger hole thru the brake drum, and/or around the axle nut. You didn't mention that, nor did I see evidence of it.

Dave

[Jim Alton]

From your description, I doubt that your oil leak has anything to do with the axle seal or o-ring. If it did, I would expect to see oil coming out of the slinger hole thru the brake drum, and/or around the axle nut. You didn't mention that, nor did I see evidence of it.

Dave

I think you're right. As you can see from the photo of the brake drum, it's bone dry at the axle.

I'm wondering if maybe I should unbolt the rear hub and reassemble with some sealant like orange LocTite.