A Few Minor Improvements, Hints and Tips

Bryan Moseley
1998 – 2005

This article is based on the author’s experiences with AC 3000ME chassis number 177, and other ACOC members’ experiences. All information is given in good faith, but no responsibility is accepted for errors or omissions.

A few minor changes to the car can transform its driveability and reliability. These include the following, all of which can easily be effected:

- fit larger section rear tyres. Many cars in the club now run 195/60 VR14s to the front, and 215/60 VR14s to the rear. The latter size was made by BF Goodrich but is now discontinued. The more commonly available 225s are too big for the rear wheel arches unless the upper rear wishbone or its chassis pick-up point is modified, so a compromise is to fit 205s at the rear. The improvement in stability and handling is marked.

- fit a low-friction throttle cable. The best design was pioneered by Robin Rew. The difference in throttle control, particularly at small throttle openings, is remarkable. It has been said that the original AC item would have disgraced a push bike!

- turn the carburettor through 90?. Robin Rew pioneered a ‘cut-and-weld’ inlet manifold which turns the carb to its correct position relative to the car, so that the float bowl faces forwards. This entirely cures the fuel starvation noted during long right hand bends in the Autocar Road Test of March 1980. It also cures the problem of a reluctance to restart when hot, possibly due to fuel vapourisation. Exactly why remains one of life’s minor mysteries.

- fit a replacement air filter, perhaps a K&N or a Pipercross. This allows the inlet manifold to breathe more freely and also allows much better engine bay access. The carb may need rejetting to compensate for all the extra air getting in to the engine.

- remove the cylindrical muffler pipes from the Thames Ditton exhaust system and replace them with open straight-through pipes (although of course retain the triangular mufflers!). Again this allows much better engine breathing, with little increase in noise. This modification does not apply to the Scottish cars, which had a rather different silencer arrangement. Some members have gone further, replacing the triangular silencers with off-the-shelf straight-through ones, although a disadvantage is that this introduces a mild steel element into an otherwise stainless system. For the final touch, tubular exhaust manifolds can be fabricated to replace the Ford cast iron ones which help to strangle the engine and crack into the bargain.

- fit Goodridge braided steel flexible brake lines and Mintex brake pads. The feel of the braking system will be improved considerably. Unfortunately there have been recent stories of these not meeting MOT requirements as the tester can’t see if they are perished.

Routine servicing is simple but must be carried out as stated in the Owner’s Handbook. Ignore the chassis grease points at your peril! A worthwhile, possibly even essential, move is to run the gearbox on a top-notch fully synthetic oil such as Mobil 1, which reduces wear and prolongs the life of the ‘box. As the engine and gearbox sumps are close together consider running the engine on Mobil 1 if this route is chosen. The oil is expensive, but is much less expensive than a gearbox rebuild. A suspicion remains that a number of chain failures have been caused by chips of metal from the gearbox circulating into the chain case and then jamming the pistons on the chain tensioner (see above). It is therefore very worthwhile changing the gearbox oil every year (at least), even though the oil itself is likely to still be effective. Paying £3000+ for a gearbox rebuild and then not paying £32 for 4 litres of gearbox oil every year is something of a false economy! Another worthwhile modification is to fit a magnet in the gearbox sump. AC did carry a magnetic sump drain plug in their stores for a while, but if this is no longer available the middle of the standard sump drain plug can be drilled out and a small cylindrical synthetic magnet fitted here. The author used epoxy resin to bond the magnet (which was a close fit) into the hole. Ensure the completed item is no longer than the original, or it will foul the gearbox internals, and clean the swarf off every year at the oil change. If all is well only very fine metal particles should be present.

The rear wheel bearings need infrequent tightening. A disquieting lurch under hard cornering, followed by the discovery that one of the rear uprights is loose is the usual chain of events. The split pin which holds the large castellated nut in the centre of the hub can be removed, the castellated nut tightened, and the handing should be restored without the difficulty and expense of replacing the bearing. Original wheel bearings are now virtually impossible to obtain, but a modification to use one that is available has been made with some success by club member Steve Hall.

Two parts which wear comparatively rapidly and can make the steering sloppy and the car quite nasty to drive are the top steering universal joint, and the plastic bush which carries the steering column where it passes through the front bulkhead. Both are easy to replace, and accessible from the front hatch.

The clutch slave cylinder is fitted on the top of the bellhousing on the offside of the engine. Ensure its feeder pipe is fitted in the lower threaded joint and the bleed nipple is in the upper threaded joint. The factory fitted them straight from the box with these two reversed, so it’s almost impossible to bleed the clutch properly. The reason seems to be that if the bleed nipple is fitted in the top thread the cylinder won’t fit into its box!