Tips – Chassis

 

Chassis

Brakes Description & Adjustment
Brake Adjustment
Rear Brake Cam Shaft Alert
Handbrake Rattle
Tyre Mounting
Tyre Changing
Newly Painted Wheels
Old Wheels
Wheel Cleaning
Wheel Nuts
King Pins
King Pin Bushes
Front-End Shimmy
Front-end Excessive Play
Rear Axle Thread Repair
Shock Absorber Servicing
Speedometer Repairs

 

Brakes Description & Adjustment

The following article is taken from a Brake Re-liner’s Manual put out for international correspondence schools, published in 1933.  This publication was purchased by my father, Norm Jeffree who was doing his apprenticeship at the time.  The book mentions 127 different makes of cars and trucks.  Several with hydraulic brakes and some with booster assistance.  I will mention a few to show the variety of vehicles covered—Acorn truck, Duesenberg, Gardner, Jewett, Page etc, etc.

EARLY FORD MODEL A

Early Ford Model A cars are equipped with four internal brakes, which can be operated by either the foot pedal or the hand brake.

Service Adjustments

With car on jacks release hand lever to full release position.  Tighten nut 1, Fig.4, for front and 2 for rear, until brake drags, then back off until wheel is just free, being sure to back off the same amount for each wheel.  If linkage has not been disturbed, the rear brakes should just begin to hold when pedal is down one inch.  With one and one half inch pedal depression the front brakes should begin to hold and rear almost lock.  Two inch depression should lock rear and hold hard on front but not lock.  If suitable adjustment cannot be obtained by wheel adjustment at 1 and 2, Fig 4, check the linkage.

Major Adjustment

All lever joints should be properly lubricated and wheel bearings tight.  Disconnect rods 3, 4, 5,and 6 at the equalizer shaft.  Levers 7 and 8 should be against stops 9 and the shafts at each side should be in the center of brackets 10.  Unless the shafts 11 are bent, the levers 12 should be vertical.  With levers 12 vertical and levers 7 and 8 against stops 9, adjust rods 3, 4, 5, and 6, just taking up free travel of the brake levers 13 and 14.  Adjust brakes as for minor adjustment.  This article has been copied direct from the Manual.

If you fit a floater motor to your Model A, you SHOULD replace shafts 11 with a one piece shaft.  This is another story, as the original one piece doesn’t have a hand brake attachment!

 LATER FORD MODEL A

Ford cars produced after the summer of 1928 are equipped with six internal brakes, one on each front wheel and two on each rear.  The service brake operates on all four wheels, while the hand brake operates independently of the service brake on the rear wheels only.  About the time of adding the separate hand brake, a new type of cross shaft was introduced which, however, is interchangeable with the two-piece shafts used on the earlier cars.  The pull rods were also changed, the earlier adjustable rods being replaced by rods which are non-adjustable.  The linkage layout is now as shown in Fig 5.  The construction and adjustment of the service brakes remains the same as on the earlier models mentioned in the previous newsletter.

Major adjustment

Make sure that all levers and joints are properly lubricated.  With the car on jacks, disconnect front and rear pull rods 2 and 3, Fig 5 at the wheel ends.  Disconnect pedal rod 4.  If the car is equipped with a multi disc clutch, adjust the length of rod 4 so that when the end of rod touches the cross member of frame, the brake pedal will clear underside of floor board by 1/2 to 3/4 inches.  Then connect rod 4.  If the car has a plate clutch, pull the brake pedal against its stop and adjust rod 4 until there is 1/16th inch clearance between rear end of rod and rear flange of the cross member.  Adjust brakes at wheels as for Early Ford Model A mentioned in January Newsletter.  Adjust pull rods 2 and 3 so that when all free movement is removed the rods can be hooked up without disturbing the position of the levers.

The above information was written when Model A’s were current everyday vehicles.  We as restorers have probably scrounged baking plates, shoes and rods etc, which may or may not be in top condition.  From my experience the pin holes (A-2027) in old shoes let them hang outwards and bind on the inside of the drums, which make it impossible to get a proper adjustment.  The backing plate Roller tracks (A2011-A) are scalloped and you don’t get a proper outward push.  If you have mixed and matched the Brake adjusting shafts (A-2042) your shoes wont sit in a perfect circle!  All of the 1933 information still wont get you the proper stopping we need in today’s traffic unless all of the above has been worked on, and brought back to original standard.

Alan Jeffree, MARC WA Newsletter Feb/March 2014
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Brake Adjustment

There are numerous articles available in our club library and videos detailing brake adjustment techniques.  Also, the use of front brake floaters and other accessories to improve the stopping or slowing power of the Model A are well documented and available from parts suppliers.  It is essential that all brake components are in good condition.  Also that:

  • The brake cross shaft is in the vertical position
  • The front actuating arms are positioned some 15 degrees forward with all free play removed
  • Adjustments are made with the brakes cold

The initial adjustment method recommended by Ford specified 60% braking on the rear wheels and 40% on the front wheels.  With the use of various accessories, it is now generally accepted that adjustment can be made with 60% on the front wheels and 40% on the rear wheels.  Why not aim for 50% front and back?

A brake pedal adjusting board is beneficial to make an effective and accurate adjustment (refer to the sketch below).  This device is made to suit your Model A.  After jacking-up the vehicle, turn the brake adjusters on all 4 wheels until the brakes just start to drag and then back off one or two notches.  Always spin the wheels in the direction of forward motion.

Position the pedal adjusting board between the front seat and pedal reference line.  Then depress the pedal to the first notch (one inch).  Turn the adjusting wedges on the front wheels until the brakes just begin to hold.  Move the pedal to the second position and adjust the wedges on the back wheels until the brakes begin to hold.  Move the pedal to position three (depressed to the two inch mark).  The front brakes should be locked and the rear brakes should have very heavy drag.  Obviously some checking and adjustments are needed and road testing may require some fine tuning of the brake adjusting wedges to ensure braking in a straight line.

John Morehead, MARC WA Newsletter April 2018
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Rear Brake Cam Shaft Alert

Reference articles for the maintenance of Model A brakes emphasise the need to keep all
moving parts in good condition to ensure optimum braking.  One part that is sometimes overlooked is the rear brake camshaft that operates the brake cam and the movement of the brake shoes.  This cam shaft is subject to considerable forces and hence will wear in the bushes.

From the start of production to the end of manufacture, three designs of rear brake cam shaft were used.  Up until the mid 1928 (when there was no separate emergency brake), two designs were used.  After this period, a longer 3 & 7/8 inch unit was standard manufacture compared to the initial 2 & 7/8 inch designs.

If the early Model A rear brake cam is to be replaced, check the design before ordering
replacement parts.

John Morehead, MARC WA Newsletter Aug 2017
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Handbrake Rattle

Some years ago, Member Steve Read gave me a tip on how to stop the Model A hand brake from rattling.  I am sure Steve wouldn’t mind me passing it on!

Remove the hand brake lever from the vehicle and dismantle it.  This will all take some time but it is better than driving your Model A with your foot resting on the lever all day!!

You have to remove the button on a 29/31 or the squeeze handle on 28s.  Find a piece of rubber or plastic tube which just fits over the thin wire rod which travels down the inside of the chromed outer.  Make it as long as possible, making sure it doesn’t interfere with the action of the mechanism when together.

Reassemble the chromed lever etc and reinstall into the vehicle.

Before starting this process with 1928 lever type handbrakes, check that it isn’t the actual squeeze piece that is rattling.  If it is, you need to tighten the rivet which it pivots on.  Careful not to tighten it too much or the lever may not move freely enough to work!

Alan Jeffree, MARC WA Newsletter Nov 2012
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Wheel Alignment

The specification for the toe-in for Model A front wheels is only 1/16 inch plus or minus 1/32 inch.  The following method provides a simple and quick way of checking wheel alignment.

Jack up the front axle so that the wheels can just rotate.  At a convenient place on the outer surface of the tyres at the front, mark the surface with soft white chalk in line with the wheels at three positions around the circumference to provide average readings.  If the wheels rotate true then you may only need one position.

With a metal scribe mark a thin line in the chalk, in line with the wheel for, say, one inch and also mark a line at right angles to provide a positive reference point.  Position the reference points on the tyres at a height approximately the same as the centre of the wheel.  Measure the horizontal distance between the two wheels using the marks and a tape measure.  Rotate the wheels to position the marks at the rear and ideally at the same height, taking into account the radius arm and engine sump, as some compromise may be required.  The difference in the readings provides the amount of toe-in (or out).  Repeat at the other positions if necessary.

John Morehead, MARC WA Newsletter Aug 2012
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Tyre Mounting

Start with the tyre and valve stem at the top of the wheel.

(A) Working both ways from the valve stem, press the casing together and down into the rim well – use tyre iron if necessary.  (B) With tyre completely on the rim, raise tyre up (C) until it is centred on the rim and beads seated., then shake the tyre vigorously to clear any folds or creases out of the lightly inflated tube.  Inflate to about 35 pounds (D), tighten nut on the valve stem, then deflate so the tube can settle to a permanent, uniform position and inflate again to 35 pounds.

Re-printed from Western Model A News, Aug 1994
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Tyre Changing

When fitting tyres to your Model A, work from the back of the wheel to save chipping the front where it is seen!  You need to work on a soft lawn or similar so as not to damage the hub cap.  It is best to use a tyre lever which is flat and doesn’t have the raised reinforcing edges.  You can also place a piece of cloth on the lever where it could damage the paint.  Unless a tyre is old and hard, you only need levers to start (two or three positions should be sufficient to get it started, and lift the rest by hand) a rubber mallet will put it on without using levers.

Alan Jeffree, MARC WA Newsletter Jan 2012
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Newly Painted Wheels

If you have a newly painted or powder coated Model A wheel, it is important to remove the coating from inside the stud hole taper.  If this is not done the wheel will not stay tight and you could lose a wheel while driving.  Before installing a newly coated wheel, place the wheel on a flat surface and use an old wheel nut and a rattle gun into each taper until the coating is taken off.  It will only take a few seconds on each of the five tapered holes.  Even after doing this it is important to double check each wheel for tightness if a wheel has been removed for any reason!

Alan Jeffree, MARC WA Newsletter Dec 2011
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Old Wheels

To assess a rusty old Model A wheel:

Before purchasing a wheel which may be usable (or it may be scrap!), visually check it for rust, elongated stud holes, broken or missing spokes, and welds.  Most bent spokes can be straightened as long as they aren’t severe.

The main problem with them after passing the above checks, is being buckled.  I close one eye and look down the inside rim from top to bottom.  You can’t do this on the outer edge as the spokes and hub cap tunnel are in your vision.  If you can see all of the outer edge in one plane, it is okay.  If you can not line up the whole outer edge, it is buckled.  A couple of mm out of line, the wheel is still usable – depending on how desperate you are for a wheel.

The wheel could also be egg-shaped and the only way to test for this is to spin it on a hub.  If a wheel passes the above tests, I would take a chance on it.  Not very many wheels I have seen have been egged-shaped.

Alan Jeffree, MARC WA Newsletter Sept 2012
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Wheel Cleaning

Here is a very simple and easy way to clean spoked wheels.  Buy a good brand of “foam
bathroom cleaner” to spray on your wheels.  After spraying, wait a few minutes to let the
cleaner soak in and to penetrate the dirt.  Rinse off with a garden hose and you should have clean and shiny wheels!

Ray Mahony, MARC WA Newsletter June 2013
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Wheel Nuts

When you have had a Model A wheel off, tighten all the wheel nuts just snug then work in a pattern, starting at any one then go to the one opposite and proceed using opposites as you go.  This avoids the risk of distorting the drums.  Recheck them all in a round sequence once tight.

Each time you have a Model A wheel off follow the above sequence, then recheck all wheel nuts after doing a few miles.  It was quite common in “their day” to shed a wheel while driving.  You would be surprised how many Model A backing plates I have seen and the bottom inch has been ground off from losing a wheel and the brake drum has skidded along the road!!

A reminder – if you have newly painted or powder coated wheels take the coating in the wheel nut holes/chamfers off before fitting the wheel (refer to my tip of Dec 2011 Newly Painted Wheels).

Alan Jeffree, MARC WA Newsletter Dec 2012
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King Pins

After servicing and adjusting front wheel bearings, the bearings are checked for excessive play by holding the wheels and assessing side ways movement.  If the play seems excessive then the following checks should be carried out before readjusting the assembled wheel bearings.

Firstly, using a punch or drift tap the head of the locking bolt that secures the spindle (king pin) i.e. from the front of the vehicle.  Then on the back of the bolt use a ring spanner to tighten the bolt nut.  If this procedure has not been carried for some time, you may find that the nut can be tightened.

Next, jam a large screw driver or similar between the spindle housing and the front axle to ensure that it is a tight fit.  Now check the wheel bearing for movement.  If the amount of movement has decreased or eliminated, then the problem is in the spindle (king pin) within the bushes or the eye of the axle and not in the wheel bearing adjustment.

John Moorehead, MARC WA Newsletter Nov 2014
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King Pin Bushes

When replacing king pin bushes. you often find one new bush will not be tight in the stub axle (spindle) and it needs to be tight so you can ream it.

I take the bush out again and melt soft solder over the outside of the bush.  It needs to be over most of the outside but avoid getting solder too close to one end so that you still have a leading edge to get it started.  After soldering, dress off the high lumps.  Large high solder lumps makes it too difficult to press in although some of the solder will be pared-off as you press it into the spindle (stub axle).

When pressing in the bushes don’t forget to line up the bush hole with the grease nipples!

Use a bush driving tool and your vice to push them in or out so you don’t damage or distort the bush.

Alan Jeffree, MARC WA Newsletter Oct 2012
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Front-End Shimmy

If your Model a develops front-end shimmy first check the tie-rod end plugs.  The components should be inspected for excessive wear and the end plugs should be tight enough to compress the internal springs some 25% of their free length.

To adjust after removing the split pin tighten the plug to give the spring compression required.  A large flat blade screw driver can be used.  A simple adjusting tool can be made from a piece of flat bar 5 inches long by 1 inch wide and 1/8 inch thick.  Bend one end at 90 degrees for approximately ½ inch.  This end can then be inserted into the slot in the end plug.

After this work it is advisable to check the front wheel toe-in which should be approximately 1/16 inch.

John Moorehead

A second cause of shimmy can be a sloppy front radius rod ball attached to your gearbox housing.  If you have a rubber radius ball (A-3445), over time it softens with oil and the ball can move around causing shimmy.  One or two Radius ball washers (A-3440-W) can be used instead of the rubber to keep it all tight.  I make my own cupped washers by finding a large flat washer and cup it using a large and small socket all pressed together in an engineer’s vice.  You may need to tighten it a few times over a few months as it shapes itself to the ball.  When I do this modification I use kit (A-3440-RE) which doesn’t have the springs and sleeves as the original kit.

Alan Jeffree
MARC WA Newsletter Dec 2013
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Front-end Excessive Play

Whilst it is relatively easy to detect play or movement in the front wheel bearings and king pin bushes in the front axles, one location that can be overlooked is wear in the top and bottom of the eye of the front axle.  The locking bolt that secures the king pin in the front axle must be kept dead tight to prevent wear in the extremities of the eye of the axle.

One technique to reduce or eliminate this play is to fit oversized kingpins.  The eye of the axle may need to be carefully reamed to result in a tight fit of the oversized pin.  The king pin bushes in the axle will then have to be reamed to achieve a firm sliding fit between the king pin and the bush.  New locking bolts should be installed.

There were three styles of locking bolts used from the start of production up to mid 1929 and the Style No. 3, which is a cotter pin type with a single large nut, was used until the end of production.

Also the securing nut should be positioned to the rear as it acts as a stop.

Some years ago the writer used this technique on our Model A front end and this source of play or movement was eliminated.

The Model A Ford Club of South Australia provides oversized king pins on an exchange basis.  In the past the oversize pins were approx 0.008 inch oversize.  For current  availability, details and price contact:

Model A Ford Club of SA, PO Box 202, North Adelaide, 5006 or visit their web site

John Moorehead, MARC WA Newsletter June 2017
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Rear Axle Thread Repair

Considering the age of our vehicles, it is not uncommon for the 5/8 inch UNF 18 TPI threads on the rear axles to become badly worn.  Even with a new nut, if it cannot be tensioned to the specified amount of 100 foot/pounds, then the correct way to fix the problems is to fit a new axle.

After removing the hub check the condition of the axle taper, key way and key.  Also check the internal taper within the hub.  It is the taper fit that does the work as demonstrated by the force normally required to remove the hub.  If these components are in good condition then the following techniques have been used to repair the axle thread in situ.

  1. The root diameter of the original 5/8 thread is approximately 9/16 inch.  Carefully file the axle thread so that the diameter is 9/16 inch.  The footprint of the original thread may be visible.  With a 9/16 inch UNF die which is also 18TPI, cut a new thread.  Fit a new 9/16 inch nut and tension to 90 foot/pounds.  This reduced diameter will be satisfactory as mentioned previously; it is the taper lock that does the work.
  2. This method requires careful alignment and attention to detail.  Using the centre bore in the end of the axle, drill a pilot hole using say a 1/4 inch drill the full length of the axle thread and into the taper section for approximately one inch.  Drill a second pilot hole using a 3/8 inch drill.  Cut off the damaged axle section.  Enlarge the pilot hole to the correct size for a 5/8 inch UNF tap and cut the internal thread.
    Finally screw a high tensile 5/8 inch bolt with sufficient thread to go into the axle and long enough to match the original axle length.  Use Loctite or similar compound and the head of the bolt to ensure it is dead tight.  Cut off the new bolt to the required axle length.
  3. Weld up the damaged axle thread and dress by filing to enable sufficient metal to cut an adequate 5/8 inch UNF thread.  Fit a new nut.

The above techniques are only repairs.  Why not have some fun and remove the differential and fit a mechanical sound axle.

John Moorehead, MARC WA Newsletter Nov 2017
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Shock Absorber Servicing

Do not forget to check and service the original Model A shock absorbers.  Ford recommended the fluid and needle valve setting be checked every 5000 miles.

The Model A ‘Houdaille” double acting shock absorbers operate on the principle of hydraulic resistance.  Shock absorber fluid is forced from one chamber to another by the movement of the lever arm.  The needle valve setting is important to control the rate of flow between chambers.  Originally the fluid used was 90% glycerine and 10% alcohol to prove the required viscosity.  A suitable fluid is available from Veteran, Vintage, Classic Lubricants (Penrite) and Model A Parts suppliers.

The shock absorber fluid should be replaced and filled to approximately ¼ inch below the filler plug.  Average setting of the needle valve is between is achieved by opening the valve (anti-clockwise) approximately one quarter and three eights of a turn off the closed position.  This is only an initial setting and by screwing the needle out further will provide a softer ride.

It is important to clean the components of the tubular shock links used between the lever arm and the chassis.  The internal parts should be greased regularly.

In later years Ford used an alternative shock link commonly called a “dog bone “which incorporate rubber balls for movement.  This design is often used in lieu of the original tubular unit.  A light coating of graphite powder can be applied to the rubber components for lubrication.

John Moorehead, MARC WA Newsletter Oct 2017
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Speedometer Repairs

REPAIR AND MAINTENANCE OF STEWART WARNER MODEL A
OVAL SPEEDOMETER

On the last MARC run to Gin Gin I noticed that the odometer was not working.  The drive cable was sound as the speedometer drum was indicating correctly (well almost!!).
Whilst there are numerous articles/instructions for the dismantling and repair of the Model A speedometer, I decided to contact an instrument firm that I have used in the past for motor cycle chronometric speedometers.  My contact said “ no problems” and they are familiar with the Model A units.

A few days later after replacing some bushes and general maintenance, the unit was returned and at a reasonable cost.  The speedometer works well and the speed indicating drum is surprisingly steady.

My contact is Aisat Instruments, Welshpool and can be contacted on (08) 9350 5545 and I would certainly recommend this company.

John Moorehead, MARC WA Newsletter July 2016

PS. Ian Steer has also used Aisat with success.
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