Brake Pedal / 356B Drums

[Ken Tuvman]

Hi Everyone,

I'm a new owner of a '61 356B Coupe - we installed new brake slave cylinders on all 4 wheels, new hoses, new brake lines, and new master cylinder.

My son is co-owner of the car and he works at an auto shop and is an ASE mechanic - here's my question:

We bled the brakes on a lift at shop and bled the air out of the lines- we haven't driven the car since doing this but unlike motorcycles with drum brakes (my reference point) when we push the pedal it doesn't stop at the top of the travel distance. We've held each wheel when applying the pedal and the brakes seem to work (they stop the wheel).

My son says the drums need to "seat themselves" that by driving it the centrifugal force will put them in the right place - he did use the star wheels so there is some resistance when turning the drums but again we haven't driven the car yet.

We haven't adjusted the E-brake yet.

I know there is some adjustment on the rod connected to the brake pedal that pushes the master cylinder but just wondering what your experience is.

Primary goal - be safe and doing things correctly.

Thank You,

Ken

[Martin Benade]

The rod must have a small amount of play- 1 or 2 mm. Pushing the pedal several times should centralize the shoes well enough, then see if they need a little more adjusting.

[Ken Tuvman]

Thanks for your reply Martin - I'm sort of concerned that even though the wheels are stopping, the pedal doesn't just stop like a car with disc brakes - I know drums are different but it just seems like when the shoes hit the drum the pedal shouldn't go down anymore - I guess we'll figure it out and take it slow when we do our test drive.

[Mike Wilson]

Have the drums been checked to see if they are up to spec, turned and the shoes arced?

Mike

[Peter Poulikakos]

Ken

he did use the star wheels so there is some resistance when turning the drums

If i recall the brakes shouls be let off approx 7 clicks of the star wheel.

[Ken Tuvman]

Hi Peter - thanks for your reply. Are you saying after the star wheels have been turned so there is resistance, we should then back off @ 7 clicks on each wheel?

I don't recall there being resistance on the front wheels and those our double shoes - shouldn't there be resistance on front wheels? Wondering if we missed something in the front - there's no air in the lines but I think brake pedal should not go down so far - it's going down about 2-3 inches or 5-8 cm

[Martin Benade]

Fronts also should have a little drag. Maybe the drums are worn too much. Air in system shouldn’t affect the star wheel adjustment.

[Peter Poulikakos]

Hi Ken
I dont have a manual handy. I do recall that once the wheels are locked from the adjustment of the stars they should then be backed off a number of clicks. I thought it was about 7.
Im sure if you do a search on the forum you will find the correct method.
If not I will take a picture if the manual and post it on the forum.

[Harlan Halsey]

You turn the first star wheel until the brake shoe locks the drum solid. Then back off 6 clicks. Spin the wheel. It should turn with no brake drag. If not try 8. Do this for all 8 adjusters. Check to see that you have at least half pedal. Now make five or six stops. Repeat the whole adjustment. The car should now brake well. You can now try for a higher brake pedal by reducing the back off. How many clicks back off you actually need depends on the roundness of your brake drums. You will soon get the idea of how Porsche drum brakes work. Even if the car is driven regularly the brakes may pull a little when cold. After a while, you don't notice it you just compensate automatically. Drum brakes will work even with slightly out of round drums and worn brake shoes, but they work best with all new shoes of the same type lining which have been arced to smooth round drums. Then they are good as new. BTW you don't have to have equal diameter drums. You can have them turned one at a time if need be. (I once heard of a shop turning a brand new drum to match a worn one. What a waste.)

[Bruce Smith]

Good advice Harley. I take issue with one thing though. If your car pulls at all, it should be corrected. Otherwise, an emergency stop could put you into a tree or oncoming traffic. Many deaths have happened this way.

[Vic Skirmants]

Ken; drum brakes usually have a more solid pedal than discs; caliper flex can cause that, or using silicone fluid.
If your pedal is still moving after full contact, then you still have air in the system.

[Ken Tuvman]

We resolved the brake issue today - thanks for your suggestions.

It turns out the star dials were not properly set - therefore brake shoes were not coming into contact with drums.

Now we have a nice feeling when we tap the brakes - we even have brake lights after connecting wires to the new master cylinder.

Thanks again!