Safety Issues

concerning AC's post-war 2 Litre Saloon
Contrary to naive popular opinion, old cars are not less safe in all respects, and may in fact be safer in some ways, depending on which make/model is in question (I could write a textbook on this... but I digress). There are, however, some safety shortcomings on the AC that you should be aware of, and I have suggested solutions to some of them.

Hydro-mechanical brakes
During 1951, a change was made to an all-hydraulic brake system, indicated by chassis number prefix "EH". Earlier ACs have mechanical rear brakes. These sometimes fail to give their full braking force, due to the 'floating' expander units sticking on the backplates. That might be due to improper maintenance if the mounting nuts have been tightened up. There should be a double-coil spring washer under each nut. The nuts should be self-locking, and will probably have to be thin versions due to the short length of the mounting studs. The expanders might need to be removed and fresh mechanical brake grease applied so they can slide freely.

Make sure that the brake rods across the back axle, are not chafing against anything. The longer rod might leave marks on the back of the differential casing. I fitted a slitted piece of fuel hose over the rod. Both rods might also touch bolts securing the axle hasps, when the axle bottoms. Jack up the chassis and see if the rods touch the bolts. If so, refit the bolts with washers under the heads.

Up to 1949 (to chassis EL1239), front brakes were Girling Hydrastatic. Girling dropped this system after a couple of years, so, although fairly advanced in design, they must have given trouble. The pistons are more likely to seize, because they move a very short distance. The shoes have no return springs, but near their base, they have a "bias spring" (or "balance spring"). It is important to have the correct spring, otherwise the brakes might drag, or the linings might lift off the drums (they're supposed to touch lightly when released). Girling part number for this spring is GB38848.

Float chambers spraying out fuel
Problem: If the float chambers are empty, for whatever reason, there is a risk of the needle valve sticking fully open. If this happens, then when you turn on the ignition, fuel will spray out over the engine bay until you turn the ignition off. I found that the later (partly plastic) design of needle valve (that I purchased in 1990) was worse in this respect.

Remedy: Fit packing washers under the floats to prevent the needle valve from opening fully. If you have recently overhauled the carburettors, then the old washers from the jet assemblies are ideal.

Electric fuel pump
A similar problem to that described above can arise if there is a leak between the fuel pump and the engine. The pump will send fuel through continuously until the ignition is switched off. This might present an extra hazard if the leakage occurs due to a crash. If one is able to, then switching off the ignition is the obvious solution. For added protection, a cut-off switch that triggers in the event of a heavy impact (i.e rapid deceleration of the car), could be wired in. The decision has to be made whether this is best wired into the battery or into the ignition. Usually, these are wired into the battery to prevent any fires caused by the electrics, but this would switch off lights in the event of a night time accident and leave the car more vulnerable to a second collision. The main thing is to cut off the supply to the fuel pump to reduce fire risk.

Fuel line
Problem: The fuel tank is mounted high above the rear axle. The fuel pipe emerges from the tank's underside, which means that any leakage from the elbow joints will be more serious than for a top-exit fuel tank. Having a top connection would not make any difference to a leakage further down the fuel pipe, because fuel would syphon out of the high mounted tank.

On ACs up to about 1950, the other end of the fuel line connects to a filter mounted below tank level (on the bulkhead). If you disconnect the pipe (or glass bowl) here, the entire tank contents will pour out. Later ACs had the filter mounted much higher.

If removing and refitting the fuel line, you have to straighten it to extract it, and bend it into shape when installing. This may work harden it and risk a later breakage.

Possible remedies: Installing an isolation valve at the tank outlet would allow you to deal with blockages in the fuel line more safely. Cleaning out the filter (if it's low mounted) will be much easier.

When restoring the car, involving the removal of the fuel line, I would recommend that a new pipe be fabricated, to reduce risk of breakage later. This should have plenty of length, and bends, at its rear end to allow for tank movement/vibration.

Problem: Accelerator (gas) sticks open.

Immediate solution: Switch off engine.

Prevention: The centre carburettor has no return-spring of its own, so if the throttle couplings come loose, that centre thottle might stick wide open. It is therefore a good idea to install a return-spring for that centre carb. Also, make sure that the flexible couplings between the throttle spindles are clamped tightly so that they cannot slip.

Old tyres
The most important safety components (excluding the driver) are the tyres. This is one area where one should not economise. The problem with very old collectible cars is that tyres often get too old before they wear out. Sometimes you can see the aging in the tyre-walls, but sometimes a good-looking tyre can be hiding deterioration internally. In my teenage years when I first took over my AC and returned it to the road, I picked the best out of the two sets of tyres I had to hand. I did not realise that one had been painted to look like new, and this tyre failed with a huge tear next to the rim, allowing the inner-tube to bulge out and strike the inner wing each time the wheel revolved.

Vintage Tyres suggest that tyres have a useful life-span of 10 years, but this reduces to 6 years if they are not being used.

After my tyre failure scare (back in '85), I ordered a couple of new Mabor General tyres. 17 inch tyres had been obsolete for many years, and these had just come onto the market. These new tyres were distorted. This gave the appearance of a buckled wheel, made them hard to seat on the rim, and also were hopelessly out of balance. Subsequently, Firestone 550 x 17 inch tyres became available to special order, and these were far better (although mine still needed dynamic balancing).

Since then, many more 550 x 17 tyres have come on the market. Back in the days when 17 inch tyres vanished, a few owners changed to the 670 x 16 size that AC had adopted from 1950 onwards. These are a tight squeeze in the spare wheel compartment, if you do make the change on an early AC.

16 inch rims also give the option of fitting radials. Radials provide far more grip, greatly reduce "tramlining", reduce the alarming angles of drift when taking sweeping bends fast, and reduce rolling resistance (better fuel economy). On the downside, you have to be sure not to over-stress axles and wheels by using all the extra cornering power. Also, the appearance might suffer if you can't find any the right size and look. Many radials currently fitted to ACs are undersize, for their outside diameter. Apart from changing the appearance, this affects castor-trail and steering offset, and one has to be careful that the handling has not been dangerously compromised. I have noticed that Avon were commissioned to produce a radial version of the 670 x 16 tyre, made to resemble the old cross-ply tyres. This is the Avon 670R16. It's expensive, but has had very good user reviews from classic car owners.

In the USA, Excelsior tyres have a range of radials made to look like cross-plies (bias-plies), and this includes a 550R17 which might be suitable for the early 2 Litres, but I don't know of anyone using them. I'm tempted to try them when my AC is back on the road.

Safety belts
AC used to recommend Britax cross-over, 3 point belts. The short section of belt being secured from the opposite side of the transmission tunnel to the person using the belt. These short sections can be bolted to the steel rear floor panel, with a thick reinforcing plate underneath to spread the load. Clearly, this floor panel needs to be very secure if used this way. The steel floor is bolted to the alloy cross-member behind it, and to the main plywood floor panels along its front edge (and with woodscrews to the sillboards along each side).

The lap-belt can be bolted to the alloy cross-member that is just below the rear seat cushion, again with a thick steel reinforcing plate behind the alloy.

Securing the shoulder belt presents a problem since the AC does not have a full B pillar from floor to roof. I've seen belts attached to the wooden cantrail, but I have reservations about this approach. Although it might be strong and stiff enough to do its job (provided a securing bracket is very firmly screwed on with several large woodscrews), one can't use bolts to attach the seatbelt to it. Also, in the event of a roll-over, or other serious crash, the cantrail might come adrift, and then the belt could then fatally injure the wearer.

AC recommended attaching it near shoulder height to the B pillar, by making up a suitable angle bracket. On my AC, the shoulder belt was secured low down on that alloy cross-member near to the lap-belt anchorage. This is not recommended practice, since the belt is at an unfavourable angle behind the seat, and will not function well in a crash. When considering the strength of attachment brackets, note that the force that it may have to withstand can exceed 20 times the weight of the person wearing the belt.

It might be possible to fit the stalk type of attachment, by bolting it to the side of the transmission tunnel. This must not be bolted to the separate piece of tunnel that runs between the front seats, as this is only lightly screwed to the wooden floor panels. The rear end of the transmission tunnel is integral with the rear footwells, and would be much stronger, but you need to make sure that nothing fouls the propellor-shaft.

There is a specialist in the UK who can make and install a seatbelt system for classic cars: Quickfit Safety Belt Service. UK law allows us to install retracting belts with chrome buckles and brackets. It might be possible to hide the belt reel behind the side trim panel alongside the rear seat cushion, and making a slot for the belt to feed through (between armrest and side trim)?

Whatever the arrangement, mounting brackets need to be strongly screwed to the wood frame - I would suggest woodscrews of no.10 x 1 1/4" or larger and at least 4 screws per bracket. That would give a strength of more than 2 tons force. Ideally, a bracket would be needed just above window rail level for the loop supporting the shoulder belt, although just below window level might be satisfactory. For the support brackets, it might be possible to have them wrap around the hinge pillar, for a more positive support, and maybe make use of the hinge bolts plus wood screws? The shear-strength of the hinge bolts works out at about 0.5 ton each for mild steel, or about 0.6 ton for grade A2-70 stainless (which I've installed on my AC).

It might also be possible to install rear belts by making slots in the rear shelf into the boot, feeding the shoulder belt through and bolting the reels under the shelf? Many other classic cars have used this approach. As mentioned many times across this website, ash timber makes a stronger frame than a steel one, and ash is even stronger still in an impact. Ash's resilience also reduces the effective strength requirement. Any steel mounting brackets will need a fairly large base to spread the load across the surface of the wood, permitting at least 4 large screws to be used.

By contrast, thin sheet steel needs localised reinforcement to take seatbelt anchors.

When I've completed my AC restoration, I'll show details of my seatbelt installation.

Old data on seatbelt strengths shows that they could withstand loads over 3.5 tons spread across all of their mountings. Allowing at least 2 tons per fixing, provides a big safety factor. If the steel rear floor is fully bolted/screwed down, I estimate it can take 9 tons load in a forwards direction.

Semaphore indicators, AKA trafficators, have become a fun novelty and it is nice to keep them in operational order. They are of little practical use nowadays since most motorists are not familiar with them. It is advisable to add flashing indicators, but the semaphores can be kept in service too. This is done by installing two flasher units, one for left and the other for the righthand flashers, enabling both systems to operate together.

Rather than drill new holes in the wings, flashers can be mounted on brackets attached to the bumpers. At the front, this is easy since there is lots of room to mount them discreetly under the front bumper. At the rear of the car, it is more awkward since the ground clearance is very low, so extra lamps have to mounted above the bumper. One then has to be careful that they don't obscure the tail lamps from any angle. Rear reflectors are also recommended, and are mandatory in the UK. Having them mounted in the wings, and thus sloping, might make them less effective.

Suicide doors
Some features of old cars only become a problem because most people are not familiar with them. Doors hinged at their rear edge, may have presented some dangers to start with, but need greater care these days when one has passengers unaccustomed to these doors. This is an extra reason why seat-belts can be a great help, so that one's passenger will be secure even if the door was to open. Either way, it is advisable to familiarise passengers with the door handle, so that it does not get confused with the window-winder.

I have noticed that most ACs have had their internal door handles fitted the wrong way round. That is, almost horizontal rather than near vertical. I'm not sure if this is by mistake, or as a measure to prevent one from accidentally pushing the handle forwards?

Windscreen brackets
From about mid 1948, the windscreens were mounted in a metal frame. Many of these were secured to the body with small brass angle-brackets. These brackets were screwed and soldered to the brass windscreen frame, and screwed to the body's wood frame. These brackets appear to have been hand made from strips, and the act of folding them may have work-hardened them to the point of cracking at the fold. Two of mine broke after removing the screen from the car, and a gentle force applied to some of the other brackets reveals cracks.

It may be worth checking that your brackets are not about to fail (or already broken). A much better approach to fixing in the windscreen, might be to cut brackets from rolled angle-girder? Ideally, you would need to remove the windscreen to remedy this issue (so that soldering can take place), but it might be possible to securely screw new brackets on?

Windscreen glass
In the USA, laminated glass for improved windscreen (windshield) safety was established much earlier than in Europe. Here in the UK, "safety glass" could be either laminated or toughened (tempered). The cost of laminated glass in the UK was extremely high, and thus toughened glass remained the standard for most British cars up to the 1970s or so.

This needs to be kept in mind if you do any work on the window glass of an AC 2 Litre (or most other British classics of the period). If you cut or drill into it, it will disintegrate with a bang. If it is not constrained by a frame, it might explode! Damaged toughened glass will have to be renewed. New ones have to be cut prior to heat-treating. In service, the main drawback is that a breakage will shatter the entire pane leaving you with little or no visibility. Later versions (from circa 1970s) had small zones that remain see-through after breakage. Laminated glass, as well as maintaining visibility, might provide increased strength against heavier objects penetrating the car. That assumes one uses a suitable grade of laminated glass designed for windscreen use. It might be worth considering an upgrade to laminated glass for the windscreen, especially if restoring the car? But please use a reputable supplier that deals with car's glass. Pilkington still offers this service in the UK.

I was reminded of the above dangers when watching an American restoration garage on TV, trying to drill the front screen from a 1953 Morgan. Removed from its frame, it burst and sent glass flying some distance. Tempered/toughened glass has a built-in stress that stores a lot of energy!

Rear lighting
Some of the worst accidents involving classic cars result from being struck from behind by a faster vehicle at night time. That may be caused by a combination of speed differential and the rear lighting of the old car. Tail lamps of vintage and classic cars might be mounted relatively close together, close to the ground, possibly obscurred by parts of the car from certain view angles, and less bright than modern lamps. Rear red reflectors are mandatory in the UK regardless of the car's age, but these are not always mounted at full car's width or else are mounted at a slope.

With the AC 2 Litre, the tail-lamps do give the car's full width. They are, however, mounted low, and the bumper is also very low, presenting problems on where to mount additional lights and reflectors (they can't be mounted under the bumper without risk of being damaged if the back of the car grounds). With the earlier style L461 rear lamps there is just enough space below them for mounting the reflectors below tail-lamp level. With the later style L488 tail-lamps, these are even lower down and so reflectors may need to be mounted slightly inboard (as long as they don't obscure lights from view angles). Or else be wing mounted but keeping the reflectors upright.

Halogen bulbs are available to brighten these old tail-lamps or better still, modern LED lamps - bright but with low current consumption. An additional option might be mounting extra brake-lamps inside the rear windows, as long as these don't reflect inside the car. Cleanliness of lenses is important, so be sure that soot from the exhaust pipe is not going to keep coating a lense.

Self-flashing LED bulbs for trafficators are also available, and the AC's trafficators are perfectly situated for viewing from the rear. This solves the problem of where to mount extra lamps. For the front of the car, one can get combined side-lamp/amber flashers to fit in the existing side lamp sockets.

Wheel nuts
Torque settings for wheel nuts are hard to find for older cars like the AC. And the wheel-brace in the toolkit does not give much leverage. My dad insisted that most folk over-tighten them and he relied upon the small wheel-brace. He never had any wheel fall off, but I realise that this is not a wise safety philosophy to wait and see if disaster strikes! When, as a youth, I took over the family AC (in the 1980s), I still used the wheel-brace, but added a tiny drop of oil to the threads, thus increasing the tension in the tightened stud. However, don't lubricate the thread if you tighten with a larger wrench, or to a given torque setting (usually quoted for dry threads).

I checked out typical torque setting data for some classic cars with 1/2 inch studs, and these were fairly consistent at 75 to 80 lb-ft (approx. 100 to 110 Nm). Also some argue that torque-wrench tightening lacks accuracy (which is true), but I think that even tightening between the set of nuts is more important than a precise measurement.

Just remember to carry a wheel-nut wrench with enough leverage for tackling a roadside wheel change.



Website started 29th December 2006