Tips – Chassis

 

Chassis

Clutch Pedal Free Play
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

 

 

Clutch Pedal Free Play

You don’t want to drive your car without any free movement or play in the clutch pedal before it starts to disengage the clutch. The clutch pedal must have at least 1” free movement or play at all times. As the clutch facings wear, this play gradually becomes less, and, if not adjusted back out, will result in clutch slippage and a burned-out clutch.
The free play is adjusted by removing the clevis pin on the clutch actuating arm, below the clutch pedal. Screw the clevis rod out to increase pedal movement, to compensate for wear. Replace clevis pin and cotter pin.
Make checking the clutch pedal clearance and adjustment (when needed) a part of your routine maintenance checklist, and have a Model A Day!

Jm Cannon, MARC WA Newsletter June 2020
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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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