Technical Page

This page will inform you of new TECH TALKS, Hands on Tech Seminars and information from Past Tech Talks and Articles.

Model A Brake Adjustment Procedure

Written by: Bill Rauscher

Inspired by: Jack Thomas

Every couple of months the Illinois Region M.A.R.C. has a technical seminar at the garage of Jack Thomas. Last month he had a seminar on adjusting the brakes on our Model A’s.

There are many books on how to adjust the brakes. There are also as many opinions of how the brakes should work as there are Model A’ers, but Jack is well known in our club to be extremely knowledgeable about Model A’s. As we watched him demonstrate the brake system and how the brakes “should” be adjusted, there were many questions and comments like “can you go over that again”, or “explain that theory one more time”. Most walked away confident they could adjust their own brakes.

With my new found knowledge I went out and built my own brake adjusting tool and tried his technique. At the end of this article, I will show you my results. The procedure is simple and can be done yourself (with the brake tool). You will find this procedure to be very easy to do and very effective when it comes to stopping your Model A safely. It worked so well for me that I asked Jack for his permission to pass along his technique to all our readers.

First the disclaimer! Your brakes MUST be in perfect working order for this adjustment to work correctly. This means that there can be no slop in any parts of your brakes. If your brakes are in need of repair in any way, any or all those repairs must be done first. Batteries not included…Your mileage may vary….Blah blah blah…! You get the idea, but don’t skip this step! Go back and put those “pills” in that you have been meaning to do!

Raise the car so all four tires are off the ground and set the car on jack stands. It is easiest to have all four tires off the ground but if you only have 2 jack stands, it is possible to adjust the brakes doing the front brakes first, then the rear brakes.

Pic 1

I made this brake adjusting tool from mostly extra plumbing parts I had laying around the house. It consists of some copper pipe, PVC “T”s cut in half and a few fittings and nuts. All of these parts can be purchased from any home improvement./hardware store for about $20.00. One of the nice things about this procedure is that you set the adjustment tool once, and it stays until you are finished.

Pic 2

Start by measuring the brake pedal up from the floor 2 inches and making a chalk mark or as shown in the picture wrapping a piece of masking tape around the shaft. When the pedal is depressed to this 2 inch point, our wheels will be locked.

Pic 3

Put one end of the brake adjusting tool on the brake and adjust the other end until it seats firmly onto the bottom of the steering wheel (the 6:00 position). Set the brake adjusting tool to depress and hold the pedal down to the 2 inch mark we made earlier.

 Pic 4

Rotate the steering wheel counter clockwise (make a left turn) about 90 degrees or until the brake pedal is fully released (approximately the 2:00 – 3:00 position). This will be the brake release position. When we need to apply the brakes again, we just turn the steering wheel clockwise back to the 6:00 position. Remember, all four wheels are off the ground so rotating the steering wheel takes no effort.

1. With all four tires raised off the ground remove the cotter pins and clevis pins on all four service brake rods and loosen the jam nuts. Pick a front wheel to start on. It doesn’t matter which one you do first as they will all be adjusted the same way.

2. Spin the tire you chose and adjust your brake adjustment wedge until the tire locks. Pull on the wheel to make sure it is locked. Now back off on the brake adjustment wedge until the wheel turns freely. You will not need to adjust the wedge again. All further adjustments will be done with the clevis.

3. Now, rotate the steering wheel ( brake adjusting tool ) clockwise back to the 6:00 position. ( Pic. 3) The brake pedal should now be pressed to the 2 inch position.

4. Sitting in front of the car, push back on the brake lever until the wheel is locked. Adjust the clevis in or out until the clevis pin slides in fully through the clevis and actuating arm.

5. Grab the wheel with both hands and try to rotate it. The front wheel should now be locked.

6. Now, go back and turn the steering wheel counter clockwise to the 2:00—3:00 position (Pic. 4) to release the brakes. If your front wheel spins freely you are done with this wheel. Repeat this same procedure on the other front wheel. The idea is to set the remaining 3 wheels to match the wheel you did first.

7. If , however you are still able to turn the front wheel with the brake pedal pressed to the 2 inch mark , even with a lot of drag, you have a little more adjusting to do.

8. Rotate the steering wheel to the 2:00—3:00 position ( Pic. 4). With the brakes released, remove the clevis pin, turn the clevis in (clockwise) 1/2 turn.

9. Reinsert the clevis pin and rotate the steering wheel clockwise putting the tool back to the 6:00 position. ( See how easy this tool works ) Try spinning the front wheel. If it is locked, you are done. Move to the next wheel. If you can still turn the front wheel, even a little bit, repeat steps 8 and 9 to adjust the clevis until the wheel is locked. You may only have to do this a few times. Release the brake pedal by turning the steering wheel as in Pic. 4. With the front wheels finished, it’s time to do the rear wheels. We will follow the same steps as the front wheels with one modification. Hold on, it’s not a big deal! Because the rear wheels are part of the drive train, there is already drag through-out the whole system, therefore it begs the question: How do you adjust the wedges of the rear brakes so you don’t have drag? Introducing the “3rd gear test”. ( OK, your right, I just made that up...it’s my article! )Here is how:

1. Remember to make sure the rear brake rods are disconnected from the service brake shaft and perform Step 2 mentioned above for adjusting the front wheels, but this time adjust the wedges on BOTH rear wheels.

2. With the brake tool in the released position ( Pic. 4 ), put the car in 3rd gear and start it. ( you DID leave the car on the jack stands didn’t you? ). Let the car run in 3rd gear with the rear tires spinning for about a minute then shut the car off. DO NOT APPLY THE BRAKES to stop the wheels. Let them coast to a stop then lightly touch the drums. Both should be cool or at worst slightly warm. If one or both are hot to the touch, you still have some drag. Back off one click on the adjusting wedge of the hot drum, let the drums cool a few minutes and retry the 3rd gear test until both drums stay cool while running.

3. Rotate the steering wheel so the brake tool is at the 6:00 position (brake pedal pressed)( Pic. 3).

4. Pull on the brake rod of one wheel until the wheel is locked and turn the clevis until you can insert the clevis pin through the brake cross shaft and brake rod. Similar to step 4 above.

5. Grab the wheel with both hands and try to rotate it. The wheel should now be locked.

6. Turn the steering wheel counter clockwise to the 2:00—3:00 position (Pic. 4) to release the brakes. If your wheel spins freely you are done with this wheel. Repeat this same procedure on the other wheel.

Perform steps 7 and 8 above if the rear wheels did not lock in step 5.

The Big Test

After all the adjustments are made, install cotter pins in all the clevis pins. I bent only one side of each cotter pin enough to keep the pin from sliding out for now. Lower the car from the jack stands and lets hit the road.

Take the car up to about 35 MPH and press on the brake pedal...hard. All 4 tires should lock up. The car should stop straight. Get out and look at your skid marks. There should be a mark from all 4 wheels. If the car pulls to one side or only some of the wheels lock, go back and re-adjust the wheels. The following pictures will show what I mean.

For example. Here is a picture of my first brake adjustment test. It is a little hard to see so I used the arrows to help visualize, but you can see the right wheels locked up and there is one long skid. The left side shows one short skid indicating that the left rear wheel was not locking up as the other 3 were. Back to the garage and up on the jacks I readjusted the back wheels using only steps 7 and 8. Fortunately, you don’t have to go through the whole thing.

After readjusting, you can see that there are 2 long skid marks. I got really brave and this time increased my speed, took my hands off the wheel before pressing the brake pedal. It stopped straight as an arrow! I don’t think I have to mention to be careful and watch out for kids. They love Model A’s! When you are satisfied, return to the garage and correctly insert the cotter pins and tighten the jam nuts on all the brake rods. Double check to make sure everything is secure.

Let’s go for a ride!

Thank you Jack for all your insights.


Wood Graining Seminar
Jack Thomas’ Garage
Sat. February 9th 2008

            The purpose of this technical seminar was to teach those interested on how to create a wood grain appearance on various parts of the Model A, most obviously the dash.  This is more of a customization of your vehicle, but the Deluxe models did come from the factory with wood grained pieces.  The supplies needed to complete this project total in the neighborhood of $25.  The low cost of items, plus the ease with which the projected can be complete make this an ideal project for anyone to perform.  This list of supplies is as follows:

  1. Red Oxide Primer (in a spray can)
  2. Stain Pigment
  3. Mineral Spirits
  4. Container/Surface to mix pigment and spirits
  5. Tack Cloth
  6. Clear Coat (in a spray can)
  7. Polishing Compound (several varieties available, DuPont 606 used here)
  8. Cheap bristle brushes
  9. Gloves
  10. Saran Wrap

An important note, you can change the appearance of the final product by selecting different colors for the primer, which serves as a base coat, and the stain pigment.
            The first step is to make sure the part you are painting has been sandblasted.  At this stage you can use a standard primer if you would like, but it is not necessary.  Now the basecoat of red oxide primer should be applied.  Make sure you let this coat dry completely before moving on to the next step, preparing the stain pigment.
            To prepare the stain pigment it must be thinned out using the mineral spirits.  When mixing, your goal is to achieve a liquid consistency.  The amount of mineral spirits used determines the amount of time you have to work with the pigment before it starts to dry.  Take time to create the right consistency.  At this point you are ready to apply the pigment over the top of the base coat.  This is where you must decide if you want a straight grain finish or a burl finish.  We will describe the strain grain first and the burl second.
            To apply a straight grain to the part you need to use one of the bristle brushes.  A good hint is to cut down the bristles in order to stiffen them; this makes it easier to apply the pigment.  Once you have the desired consistency for the pigment start applying it with the brush.  There is no special technique to apply it, just keep working the pigment until you have the desired look.  Dragging the brush across the material in a straight line creates a straight grain.  It is necessary to watch for build up in corners.  It is highly recommended to do the entire piece all at the same time, this will ensure a consistent look for the part.  Now we will describe how to give your part a burl appearance. Instead of using a brush, you need to go and find the saran wrap hidden somewhere in the pantry.  You need to take a normal size piece and crumple it up in your hand.  To apply, dip the saran wrap in the correctly thinned pigment and then tap and twist in one motion the saran wrap on the part being wood grained.  You will develop your own style for this once you become comfortable applying the pigment.  Repeat the tapping twisting over the entire part.
            Since the mineral spirits increase the work time for the pigment, if you are unsatisfied with what you have created, you can simply wipe time pigment off of the part and start over.  This feature of the thinned out pigment ensures you always end up with a look you enjoy.  Once you have applied pigment to the entire piece and are content to leave the look of it as it is, you need to let it dry for 2-3 days to make sure it is fully dry before moving on to add the clear coat.
            After the pigment has dried, use a tack cloth to remove any dust that may have settled on the part. Now you can begin applying the clear coats.  You will want to apply 5 to 6 coats of clear.  Allow for drying between coats.  This number of coats is necessary to ensure that when the polishing compound is applied it will only smooth out the clear coat and not the pigment.  Once all the coats of clear have dried, follow up with the polishing compound.  Follow the directions for use on the polishing compound container.  The polishing compound is the last step of this process and helps to create a flat, smooth finish to the part.  Now you can reinstall the part on the car and admire you craftsmanship!     

          


           
               

 

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