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Mechanical brakes 31 nash


31nash880
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Hi everyone,

Have enjoyed learning from everyones posts . Many subjects and alot of smart people.

Finally got engine to run again after head rebuild. Still running gm carb but sounds so much better. 

Now to get it going down that road. Had to replace brake cables earlier. Brakes work now but would like to know how to properly adjust them. 

Any info is much appreciated. 

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Although you may find an original or reproduction manual with all the technical details, I have found that most such manuals will provide a guide to make your brakes safely operate, but only get you close to adjusting your brakes to function correctly. 

 

First, get all four brakes close to working together by jacking up each wheel and spinning each tire and make adjustments until the brake shoes barley drag.  Take a helper with you and drive to a gravel or dirt road.  Have your helper watch as you get up to 20-30 MPH and stand on the brakes.  Your helper can then determine which wheels lock up and which wheels need adjustment.  Repeat as needed until all four wheels stop the same.  

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Sounds easy but have many places that can be adjusted . Which is first since i replaced cables?

 

Had brakes after cables replaced but pedal was low. Adjusted at bar that runs across car. Helped alot with brakes but now brake light switch has issues. Had to insert a spacer to work temporarily. 

Edited by 31nash880
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Basically, as Mark said, start with the wheels and get them as close to centered (if that has been changed). Then adjust them as even as possible with no drag, be sure to stand on the pedal once before final check. Then work back from there to the pedal. getting things as even as possible.  They can't possibly be as challenging as a 27 Buick!

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  • 2 weeks later...

I did a complete brake adjustment on my 1931 Buick by the 1931 Specifications and Adjustments BOOK and unlike what has been said here it starts from the pedal.  The car has to be on jack stands or hoisted so all wheels are off the ground and can be turned.

 

1.  Disconnect link rods at rear brake backing plates and front brake cross car bell cranks.

2, Adjust each brake until you can't turn wheel by hand then back off the adjuster nuts 12 flats

3. Remove the brake rod clevis pin at the brake pedal and adjust brake pedal toe board clearance (set screw on pedal stalk under floorboard) to 1/4-1/2". 

4.  Disconnect the hand brake connecting rod by removing the clevis pin at the hand brake lever.  Now make sure cross shaft bell crank rests on chassis stop pin.

5 With hand brake handle and service brake pedal in their fully released positions adjust brake pedal link rod and link rod so clevis pin holes line up and clevis pin can be reinstalled to eliminate all slack without lifting cross shaft off stop pin.  This eliminates all slack in the service brake to cross shaft and hand brake to cross shaft rods.  Verify when this adjustment is done both brake pedal and hand brake lever are fully released and the cross-shaft bell crank is still at rest on the stop pin.

6. Adjust each front and rear wheel servo rod length to align clevis pin holes at backing plate levers in rear and cross car bell cranks for fronts and reinstall the clevis pins.  

7. Adjust each brake adjuster nut in 6 flats.  

8. Apply just enough brake to get brakes to drag and check to see that each wheel's drag is about the same.

9. Road test.  Brake application must not cause car to pull.  If it does adjust brake adjusters at wheels to correct.

 

Before you start adjusting your brakes take the time to remove front and rear brake drums and inspect the shoes to make sure they are not coated with grease and check for minimum required lining thickness. If they are coated with grease but linings are still thick enough to be serviceable you might get by with thoroughly cleaning the grease off linings and other parts and replacing leaking grease seals to prevent recurrence. 

Brakes 053.jpg

 

How about the drums- are they scored, coated with grease?  If you want your car to stop correctly these items have to be addressed before attempting to adjust the brakes 

Brakes 058.jpg

 

Taking the drums off is a good opportunity to clean wheel bearings, inspect the grease seals.  This is what I found in my front wheels on both sides.  Shoes and drums were clean and in good shape.  Wheel bearings were pitted and replaced.  Felt seals were good and re-used.

Brakes 061.jpg

 

Use the right wheel bearing grease designed for drum brakes.  Read what it says on this Valvoline grease can below "General Multi-Purpose Grease".  Disc brake grease won't properly support ball bearings used in older drum brakes.

Brakes 063.jpg

 

After reinstalling drums, you can begin adjusting the brakes.  Buick used fully mechanical brakes until the mid or late 1930's so my 1931 Buick used for the example here is all mechanical.

 

Step 1:  Start by disconnecting all of the brakes from the pedal system.  Front brake rods on 1931 Buicks should be disconnected right at the cross-shaft bell crank by removing the clevis pins. 

Brakes 025.jpg

 

Rear brakes are disconnected are disconnected at the backing plate bell-cranks by removing the clevis pins.

Brakes 026.jpg

 

Step 2:  The next step for Buick is to adjust the shoes until they are in hard enough contact with the drums to prevent you from

turning the wheels, then backing the adjuster nuts off 12 flats.  This is repeated at each wheel.

Brakes 049.jpg

 

Step 3:  Next remove the clevis pin from the brake rod at the brake pedal, then adjust the set screw at the base of the pedal stalk to give 1/4-1/2" clearance between pedal stalk and the bottom surface of the toe board.

Brakes 004.jpg

 

Brakes 005.jpg

 

Step 4:  Then remove the clevis pin from the hand brake handle to brake rod connection.

Brakes 007.jpg

 

Step 4 continued:  With both brake pedal and hand brake rods disconnected the brake cross shaft bell crank must rest on the stop pin as pictured below.

 

Step 5:  Now with the brake pedal and hand brake lever in fully released position adjust the brake pedal rod to line up the clevis pin holes and reinstall the clevis pin.  Then line up the hand brake clevis pin holes and reinstall the clevis pin.  Again, check to make sure brake pedal and hand brake lever are in their fully released position and verify the brake cross shaft remains at rest on the stop pin shown in the picture below.

Brakes 048B.jpg

 

Now the 4 brake rods can be reassembled. 

 

Step 6:  Start with the rear brakes making sure the brake is fully released with the backing plate lever resting on the stop

pin shown in the picture below.  Adjust the clevis so clevis pin holes line up and reinstall the clevis pins on each rear brake.

Brakes 074.jpg

 

Step 6 continued:  Moving to the front brakes make sure they are fully released by pushing the flex cable and brake actuating

rod forward into the slide housing as far as they will go.  Note that the brake flex cable wires must move freely in the cable

jacket or it will be impossible to assure full release and front brakes may stick on in use.  Assuming cables work freely and

front brakes are fully released adjust front brake clevis to align clevis pin holes at the brake cross shaft bell cranks and

reinstall clevis pins.

Brakes 049.jpg

 

Step 7:  Adjust each brake shoe adjusting nut, seen it 2 pictures immediately above, in or tighter 6 flats.

 

Step 8:  With the car raised so all 4 wheels off the ground apply just enough brake to get wheels to nearly lock up but not quite.

In the case of my car the hand brake operates all 4 brakes and makes a convenient way to apply the brakes as above and hole

them.  Fine tune the brake shoe adjustment by getting each wheel to drag equally.

 

Step 9:  Test the car on the road.  When the brakes are correctly adjusted the brakes should not drag, there should be some brake pedal travel without resulting in a low pedal condition and the car should not pull left or right when stopping.  If the car does pull brakes on the opposite side of the car from direction of pull may be too loose or brakes on the side of the pull.  Pedal travel should be considered when deciding to loosen or tighten brakes on one side of the car.

be too tight.

Edited by Str8-8-Dave (see edit history)
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Steeldraulic brakes are very good brakes and the info is easy to get on adjustment..as you see. There are a few special /plier wrench tools for early to late versions but you can fudge it.  If you reline and adjust them from rods to cables to drums,it will be 20 or 30 thousand miles before you think they need attention again.

 

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