Allen keys

An aluminium bracket had to be attached to a curved casting using countersunk head Allen screws in a position out of line of sight, which required bending over to ankle height and fitting and removing the bracket many times.

It was most difficult to locate the key into the head of the screw and also line up the hexagon hole and it often speared out of the fingers and always seemed to fall into an inaccessible place.

The screws had to be pulled up a little at a time, which required many insertions and much frustration until it was discovered by accident that an imperial key of slightly smaller size than the metric hexagon cavity could do most of the tightening, then reverting to the metric size for the final pinch which speeded up the job and removed most of the frustration as it was so much easier to locate into the hexagon cavity.

Frank Wetton, April 2012

Battery cables

The use of an electric starter required heavier duty cables than previously required for lighting and accessories.

When fitting it again it dawned that this most dangerous of cables from a short circuit viewpoint had no circuit breaker or fuse, nor had any car I have ever seen.

Should the cable become detached or rub through its insulation currents of up to 1000 amps could be generated with catastrophic consequences.

Perhaps it is too difficult to fit a 400 amp fuse, which is about what is required, though most batteries are fitted fairly close to the starter motor reducing the risk, but racing cars can require the battery somewhere in the rear.

I am still looking into this as I have seen firsthand what happens when a large spanner was dropped across the terminals of a starter battery for a large V12 diesel generator: it glowed red hot instantly for a few seconds then the battery exploded. Fortunately we all lived to tell the tale, but I have never seen a brown skinned mechanic with such a bleached complexion.

The best place for a circuit breaker is right at the earth terminal of the battery.

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Broken studs

Recently one of the 7mm studs broke which fasten the upper and lower crankcases together and it snapped well below the top surface of the aluminium casting.

In the old days we would have tried to drill a hole in the top surface of the stud down below the casting surface and try to remove it using a wrench and ‘easy-out’ tool. The result was usually a hole which ran off centre because the broken surface of the stud was not flat and if this was avoided the Easy-out snapped off, leaving a hardened tool jammed in situ.

The best approach would be to dismantle the whole crankcase, etc. and file two flats onto the now projecting stub and using a tight fit spanner or vice grips try to remove the stud by unwinding it out.

Not wanting to do the full dismantle job I discovered a new tool at Lee Bros at Parramatta of American origin which works like a charm using a 3/8 reversible variable speed drill, which is called a proGrabit and made by Alden in imperial sizes only. They are not cheap, but saved many hours and it removed the broken stud in 10 seconds. !/4 inch was close enough to 7mm to do the job.

Firstly I turned up a guide bush for an end mill which needed to be a light hammer fit and thus needed a filed angle under the head to allow removal with a punch. This ensured that the broken stud face was machined square, then another bush was fitted with a bore for a 1/8 in pilot drill to make a true guide for the Grabit pilot drill, which is left-handed.

Now the left-handed drill of the Grabit drilled a true hole of the correct size and the tool was then reversed and whipped out the broken stud.

If you Google 'Alden' or 'Grabit' you will find a wealth of helpful hints.

Fitting a New Stud

If there is not enough projection to use the common way of locking two nuts onto the thread of the stud a very effective driver can be made using an acorn or  dome nut into which a small ball bearing is dropped and held by a little grease. These are particularly easy to remove after the stud is seated.

Frank Wetton, 2012

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Ceramic Coating

Ceramic Coating is done by ‘Competition Coatings’, 10 Ferndell St. Granville Tel: 9892 2218 of metal parts, which is a superb protective coating for exhaust manifolds and the like, which are subjected to severe heating and cooling cycles.

They coat them both inside and outside and are a lifetime job.

They can do various colours, but the gloss black and the silver are the most appropriate for our types of cars.

Mine cost about $100, but I think it is worth every cent because nothing else I now of is anywhere near as good as this.

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Circular Mottling

Circular mottling is one decorative finish on aluminium castings.

Bugattis have three types of decorative finish, with the dashboard and firewall and Shell petrol tankers being finished with circular mottling.

Do not be tempted to use valve grinding paste as it hardens to concrete during polishing and cannot be removed without damaging your fine finish.

Use a champagne cork pushed into a tubular tool with a shank for mounting in a drill chuck and coarse sand of about 46 grit as the abrasive- use washed sand as beach sand contains salt and will corrode the surface soon after the job is done.

Mount your aluminium panel onto a sheet of chipboard, which is usually very flat unless stored against a wall in damp conditions. Fit all the disks previously cut out for instruments and switches or make new ones if you threw them out earlier, and hold them in place with a wood screw.

Do the polishing on a drill press and definitely not a milling machine, as the latter is too precise in pitch and the finish does not look right.

Draw horizontal lines in soft pencil with vertical pitch a tiny bit more than half the diameter of the cork. Start at the left hand with the first circle being partly on a piece of scrap aluminium the same thickness as the panel, then make the second and subsequent circles just over half the diameter of the cork to the right as judged by eye.

The correct and accurate vertical spacing can be assured by clamping a strip of wood to the drill press table and using it as a guide while sliding the panel and chipboard support along. Eye-judged horizontal pitch spacings look good.

Sprinkle the sand over the panel and use only light pressure and slow speed on the drill.

After a few circles a projection at the centre of the grinding face of the cork will form and this must be cut off with a very sharp knife or removed by dragging a piece of plywood with coarse sand paper glued on under the cork with a very light pressure  on the drill.

Do not be tempted to use any type of clear varnish on the finished surface as certainly a white oxide will form over time and the varnish cannot be removed to polish it off. Wattyl advice was to grind it off and start again.

Best to use a car wax polish containing carnauba wax and polish with a soft cloth, which you are sure contains no sand nor grit.

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Cleaning castings

A call from Noel Mackintosh about cleaning castings dredged an almost forgotten memory about using a molasses solution to clean rust off steel parts.

It seems to use natural bacteria to do the job and does not affect any metal at all, even aluminium, but it is slow-taking about a week to do the job, depending on the thickness of the rust film.

The parts come out of the soaking bath so clean that they rust very quickly again in the atmosphere and need an almost immediate spraying with INOX, which I have found to be better than WD40, or undercoating.

At about this time, some 40 years ago, there was a Finnish product on the market which promised bacterial cleaning of oxides from all castings. I tried it and it worked very well being faster than molasses, but it very quickly disappeared from the market.

Molasses concentration is not critical and today I would use about one pound per gallon of water (1/2 Kg per 5litres) and grease should be washed off with solvent first.

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Cooling water in Blocks

Some cylinder heads are notorious for cracking the valve seats due to poor heat transfer. Six cylinder Fords and three-valve Bugattis have this fault.

I am modifying my Bugatti block, which has an integral cylinder head, using a copper pipe gallery from the bottom of the block to above the valve seats position and squirting a portion of the water to the block via brass jets to where it can do the most good. This is hidden inside the block and is a bit tricky to fit.

It dawned on me that every car I have ever seen takes the coldest water from the bottom of the radiator and feeds it via a pump to the coolest part of the block, ie the lowest level, usually by some type of spreader manifold.

This does not make sense as the cylinder walls are much cooler at the bottom due mainly to adiabatic expansion of the gases and some heat loss through the cylinder walls to the coolant, but the maximum cooling is required at the top.

Bill had also noticed this aberration and told me that the latest F1 Ferrari fed the coolest water to the cylinder head. Clever Italians engineers.

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Alignment
dowel pins & drilling

Using dowel pins to align components

The four hole in the casting above had been drilled and tapped on the workbench and the corresponding countersunk holes in the bracket drilled in the correct places at the same time. That was the easy part.

When the casting was bolted under the flywheel and the bracket hand held around it, it became quite difficult to align it so the screws could start in their tapped holes and without cross-threading them.

The trick was to fit them together on the bench and between two of the screws drill a ¼ inch hole for a dowel pin of sufficiently light fit that it could be removed by hand.

A dowel pin was then made with a bullet shaped end so that when the casting was installed and the bracket offered up the dowel pin bullet head found its hole with a bit of wriggling and when inserted fully the screw holes were then aligned.

Once the screws were started the dowel pin was removed until the next trial fitting of the bracket.

One dowel pin was sufficient, but more complex jobs may require two or more.

Drilling in alignment

Sometimes it is necessary to locate existing tapped holes to a new casting for drilling exactly in alignment.

It is almost impossible to find the centre of a tapped hole by measurement, even if studs are fitted to the tapped holes and measurement made from the outside of the studs, then deducting one stud diameter from this measurement.

There are three reasons this may not be very accurate:

1. The studs may not be full diameter, especially at the thread
2. The original holes may not be in a line
3. It seems that centre-punching introduces its own errors in positioning

An effective way is to make up false studs which are a loose fit in the original tapped hole. Do this in a lathe, then turn a sharp point at the outer end and the stud just long enough to protrude about ½ mm above the surface.

Fit the studs as above, locate the undrilled casting exactly, the tap it with a leather hammer or wooden mallet so that the sharp points make centre-pop marks in the casting.

If the studs have tiny flats filed next to the sharp points they can be unscrewed with a small needle nose pliers.

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Drilling square holes

A recent video from China shows this being done using a special drill. Actually the idea is at least 50 years old and may be much older than that.

It involves the use of lobed shape drills and requires a pilot hole of larger than usual size.

A lobed figure is a shape of constant diameter, which is not circular and a little sketch will explain better than words.

Because it is constant diameter it will roll true on a flat surface but be all over the place in a vee block. It is only a matter of putting cutting teeth at the ‘points’ to convert the shape into a drill.

Lobed figures are commonly created in centreless grinding operations as used for roller bearing rollers, and many years ago I produced almost perfect pentagons when setting a rolling machine to roll tiny sheet metal cover plates for AA batteries-they should have been circular!  

Making the drawing showed up another characteristic that a lobed figure is possible only with an odd number of lobes.

Precision drilling

Sometimes you may need a precision ground pin of exact size, either tough or hardened. One or two–offs are expensive at a machine shop but perfect pins can be made simply by buying a twist drill of the correct size, and they are obtainable is size ranges of 0.1mm, and hacksawing off the length required from the shank.

Jobbers pattern drills have longer shanks than normal drills if required.

I was amazed that cutting a drill shank was possible but the shank is tough while the flutes are hardened. As proof look at an old drill with the shank damaged by slipping in the drill chuck. Harden by heating to red heat and dropping into a cup of oil, or water if greater hardness required.

Exhaust Manifolds

A call from another member prompted these tips.

The idea was to make a manifold from steel tubing something like the Bugatti style ‘bunch of bananas’, which is simple, elegant and effective.

The flanges for mounting to the head and exhaust pipe can be water jet cut if you make a drawing, and for the latter a three or four-bolt design is better than the bug two bolt style which blows gaskets regularly.

The gasket faces of the flanges need to be machined smooth and then small circular grooves machined into the face to extend gasket life greatly.

The manifold flange which mates to the exhaust pipe flange should be assembled loosely and bolted up to the exhaust pipe flange and tack welded in situ, removed then welded fully. This will assure excellent alignment.

Tube bending is best left to the experts as it requires proper equipment to do it neatly, hence a drawing is essential. This is NOT pipe bending.

Most manifolds are attached to the block or head with nuts screwed onto studs mounted into the casting, which are a source of problems as they freeze into the casting and snap off easily and are very difficult to remove.

If this happens you could try the Grabit tool mentioned earlier, but give it every chance by soaking the studs to be removed in “Blaster”, available from Blaster Group P/L, 30/8 Victoria Ave in Castle Hill. Tel” 9894 7360.

It is far better than ‘Penetrene’ or WD40.

If replacing the studs, go the whole way and make them from 316 Stainless steel.

Throw away all the manifold nuts and make special ones from hexagon brass longer than usual so they completely cover the stud, which will stop the usual protruding part of the stud growing by rusting and stripping the thread of the nut as it is unscrewed, and if the nut freezes onto the stud the brass threads will strip in preference to the stud.

While you are at it make a few spares and keep them in glove box or car tool kit.

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Grinding a steering ball

BUGATTI steering arms have the ball end integral with the arm, and no doubt others makes use this system rather than a removable ball fitted with a taper and nut.

As the arms are bent, it is not possible to fit them to a lathe chuck for a regrind if they are not too worn. Discard any that are worn through the case hardening and do not be tempted to weld them as the arms are of heat treatable steel and likely to crack and snap off like carrots-not a healthy type of steering arm.

I have ground them by hand by using a mounted point about one inch diameter with a spherical recess in the working end and holding this in a chuck of an electric motor running at about 1500 rpm.

The trick is to blue the ball with a large Texta felt tip pen to check where the grinding is taking place, noting that there is no grinding taking place right in the centre of the tool and cutting progressively more towards the outer diameter.

Constantly measure the ball with a micrometer or dial vernier and hasten slowly.

The final touch is to tear off a 1 in square of emery cloth and push it into the grinding tool recess and polish the whole ball end this way. A slightly worn grinding tool works best. Start with #120 grit, followed by #220 and #400.

I have managed to recover a ball end within one thou with care using this method.

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Split Pins

Sources

Vintage cars require mostly smaller sizes. Usually these are available in coarser sizes only and are often too long, at least for Repco and Bunnings.

A good source of stainless steel in smaller diameters and lengths is from an aircraft supply shop located in most of the aerodromes where smaller aircraft are serviced, such as Archerfield, Moorabbin, Bankstown and Parafield.

Alternatively they can be ordered from Aircraft Spruce and Speciality from USA, who ship next day after receipt of order. Look them up on Google.

TIP: Americans call them 'cotter pins'.

Split Pin Fitting

As pins are fitted through castellated nuts, which hide to drilled hole in the bolt until almost fully tightened. This can be a problem if the bolt is in a difficult position, as they always seem to be.

The tip here is to file a line across the threaded end of the bolt, which corresponds to the line of the pin hole and in more difficult cases to also mark the bolt with a coloured mark on the tip of the bolt close to the hole position.

Sometimes the pin hole does not expose enough in the groove of the castle nut to allow the split pin to enter. This can happen because it is a new installation or a thicker washer has been used in the assembly or a shim has been fitted to get a correct clearance elsewhere.

Rather than fitting a smaller diameter split pin, the tip is to tighten the nut fully and mark which slot just aligns with the pin hole either from seeing the pin hole partly exposed or by the filed mark you made previously on the end of the bolt.

Remove the nut and file down that groove for the pin a little more.

For more severe cases the nut may be faced off in a lathe or simply filed off a bit on the clamping face.

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Turning a ball on lathe

If the ball end is removable it will be easier to make a new one from case hardening steel and heat treat it after machining.

Turn the ball oversize by hand and with a bit of practice this is not too difficult.

Finish turn the ball using a hardened silver steel tool in the form of a tube with a sharpened end, which looks like a wadding punch. A diameter of about half the diameter of the ball is about right.

Mount this tool in the tool post and move it to engage the ball to be cut always pointing it towards the centre of the ball.

This produces a very accurate ball which can be finished off with emery cloth.

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Water Jet Machining

Bill Smith told me about this one.

To cut complex shapes, such as a steering wheel blank in stainless steel or a car nameplate, water jet machining is a relatively cheap and very effective way and does not distort the job as does grinding, nibbling, or jig-sawing.

The pattern required is done by computer graphics and can be modified easily and also permits scanning of an existing sample.

The blank material is placed on a machine bed in the form of a mesh to allow the water jet to pass through the cut and the pressure used is about 30,000psi and is fed with a stream of fine garnet abrasive.

It is incredibly accurate and holes can be done as the program turns off the jet while the head traverses into position and starts on the hole.

The cut edges are slightly rough but easily cleaned up with emery.

The only disadvantage is that the cut edges are slightly tapered, but this is negligible for thin materials.

Almost any material can be cut from ceramics, metals, plastics, wood, to gasket materials, so long as they would not be water damaged.

The company Bill and I have used has stopped trading, so look up others in Yellow Pages.

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