AC Ace and Aceca Bumpers and Overriders

Standard, or an extra?

For the 1956 season, AC made changes that the motoring press recorded at the Earls Court show. Motor Sport's show report of November 1955, covering the AC stand, number 130, says of the Ace:

Overriders for the bumpers, a Fram oil filter and Michelin X tyres are now standard on the Ace, the price of which rises by £85.

and of the Aceca:

Bumpers, demister and heater are now standard on the Aceca, the price of which has risen by £160, to £1,375 basic.

Read that carefully, because it says two different things about the two cars. On the Aceca, bumpers became standard. On the Ace, it is the overriders for the bumpers that became standard, and the sentence is silent on the bumpers themselves. The word now in both sentences implies neither was standard before the October 1955 show.

The price rises quoted are for the whole package of changes at each stand, not for the bumpers. Do not read £85 or £160 as the price of a bumper set.

A dealer listing for a 1958 Aceca describes its tubular bumpers as rare, which is consistent with many cars never having been ordered with them.

Two patterns of overrider, and when they changed

There are two distinct overriders.

The early pattern was a special item bought in by AC. A member who has studied them describes a family resemblance to the overriders used on the AC two litre saloon and on the contemporary Lea Francis, while noting that neither is identical. It mounts on a bracket with two holes. It was fitted to roughly a hundred cars, with the same member giving figures of both 99 and 121 at different points, so the archive records the range rather than a single number.

The later pattern is the same item as fitted to the Standard Eight, and mounts on a single bolt.

The changeover can be dated more closely than most things on these cars. An Aceca that left the works on 27 August 1955 was photographed arriving in Chicago in October 1955 still wearing the early overriders on dual tube bumpers, while photographs taken at Thames Ditton in the same month show the later style. The estimate offered on the forum is late September 1955. The same member had originally supposed the change was caused by the introduction of the Aceca's tubular bumpers, and withdrew that explanation when the Chicago photograph appeared.

Because the correct early items were unobtainable for decades, many Aces now wear Ford E93A or E493A upright overriders, from the Anglia, Prefect and Popular, which are visually close and still remanufactured. If your car has those, they are a substitution rather than a fault, but they are not original.

Chrome plated steel, not stainless

Original bumpers and overriders were chrome plated steel. One Aceca is recorded as arriving with chromed steel tubular bumpers, another member has original overriders awaiting rechroming, and the club's own reproduction overriders were made as steel pressings, triple chrome plated.

Front and rear overriders are described as identical to one another apart from slightly different hole centres.

Stainless steel bumpers exist for these cars and are a modern substitution rather than a reproduction of the original specification. A small private batch of mirror polished stainless Aceca bumpers was made in 2022 from patterns taken off three original cars. Only three sets were made and the archive has not established whether those patterns still exist.

Cars that left without them

At least one car can be shown to have left Thames Ditton without rear overriders, and the evidence is better than usual. A left hand drive export Aceca delivered to Sweden, chassis AEX 31, was found during restoration to have no real trace of overriders. Its owner then obtained photographs from the son of the original owner showing the car on Swedish import plates in its first weeks, and those photographs show no overriders fitted in its first summer. The forum record describes a mounting bolt present at the front but no evidence of the mounting holes for the rear distance tubes.

Competition was raised as a possible explanation and then ruled out. The original owner's family had no memory of the car ever racing, and a contemporary that was raced in Sweden and Denmark carried a full set.

A census of surviving early cars was compiled on the forum, sorting them into those with correct early overriders, those with none, and those with later or substitute items. It is useful, but it records the present state of surviving cars rather than verified original fitment, and sixty years of repair and substitution sit between the two. The photographs of AEX 31 are valuable precisely because they are period evidence of what the car actually left with.

A separate report on the forum describes another early Ace showing no mounting holes in the rear body panels and no brackets for rear overriders, while noting that some earlier cars clearly had them. The archive has not established whether that is the same car described under a different chassis form.

The brackets, and how they mount

The overrider bolts onto a bracket that is a snug fit inside it. The bracket is about 180mm long, 4mm thick and 20mm wide, widening to 40mm at its widest point. The early type has two mounting holes, the later type a single bolt.

Accounts of how the bracket attaches differ in their wording and the archive gives both rather than smoothing them over. One describes the bracket as bolted through the aluminium body by two bolts, with front brackets bolting directly to the bodywork and rear brackets needing aluminium spacers. Another describes front and rear brackets bolting to the chassis, with the distance tubes exiting through the bodywork. The reconcilable reading is that the bracket passes through the aluminium skin and picks up on structure behind it, but no drawing or clear statement has been found and the archive does not assert it.

Distance tubes are fitted only at the rear, in short and long pairs, two of each per car. A detail of works practice worth knowing when yours do not look square: the ends of the distance tubes were simply parted off at the factory, so they slope slightly as they exit the bodywork, and everything comes into alignment once the bolts are pulled up.

Brackets were mostly painted in the same black used on the chassis, though there are examples painted to match the coachwork.

The advice from someone who has fitted a set is to leave every fastener loose until the whole assembly is in place and aligned, then tighten in stages, checking as you go. The rear is more of a fiddle than the front.

Fasteners

One assembly, two thread standards. The fastener schedule recorded for an Ace is:

• Eight 5/16 inch UNF screws, three quarter inch underhead, hex head, overrider to bracket
• Four 5/16 inch BSF bolts, one and a quarter inch underhead, three quarter inch thread, front bracket
• Two 5/16 inch BSF bolts, two and three quarter inches underhead, and two of two and a quarter inches underhead, one inch thread, rear brackets
• Eight 5/16 inch BSF Aerotight nuts
• Sixteen 5/16 inch plain washers
• Eight 5/16 inch UNF cage nuts and cages

Note the mix of UNF and BSF on a single assembly. The same member who recorded that schedule observes that original fastener specifications varied significantly between cars, which is consistent with everything else about hand built production at Thames Ditton.

Getting them now

The AC Owners' Club commissioned a reproduction of the early pattern overrider in 2018 and 2019, made as steel pressings with welded mounts and triple chrome plated, in a final batch of eighty units, which is twenty car sets. One person inspecting them noted that the plating is less robust on the back face and recommended a clear protective lacquer before fitting. The club is the place to ask whether any remain.

A club member has fabricated overrider mounting bracket sets, front and rear, supplied self finished, advertised in the club magazine. There is no website.

The later pattern overrider is still made for the Ford cars it was shared with, as a chrome plated upright pattern item, and is available from small Ford specialists. Those listings make no mention of AC.

At least one stainless bumper manufacturer states that it will tool from a customer's original sample, though its own AC listing covers the 428 only.

The archive could not identify any chrome plater or brightwork firm advertising AC Ace or Aceca work specifically. There are competent classic platers, but naming firms that merely do classic cars would be padding.

What is not established

• Whether full width bumpers ever became standard on the Ace. The Motor Sport report says overriders did for 1956 and is silent on the bumpers themselves.
• Any period price for bumpers or overriders as an extra. None was found.
• Who originally manufactured the early AC pattern overrider. One maker was suggested on the forum and never confirmed.
• What the bumper end caps were made of, and whether front and rear differed. The question was asked on the forum and never answered.
• Whether Ace and Aceca tubular bumper bars interchange. The 2022 reproduction was patterned from Acecas only, and its maker noted that front and rear differ slightly from each other.
• Whether the Ace Bristol's bumper fittings are identical to the AC engined Ace. Owners of Bristol engined cars use the same parts in the forum discussions without anyone remarking on a difference, which is suggestive but not a statement.
• Anything about the Greyhound's bumper parts, or whether they share anything with the Ace and Aceca.
• Whether a car could be ordered without bumpers as a factory competition option. Cars without them plainly exist, but no listed delete option has been found, and since bumpers were an extra to begin with, without may simply be the un-ordered state.
• Any corrosion or fatigue problem where the steel brackets pass through the aluminium panels. The galvanic risk is obvious in principle but the archive found no restoration account, club note or condition report documenting it for these cars, and will not assert it unsourced.

The period evidence on standard fitment is Motor Sport's Earls Court show report of November 1955, covering the AC stand. The detail on patterns, brackets, fasteners and the cars that left without overriders comes from AC Owners' Club forum threads on Ace overriders and on Aceca bumpers, running from 2012 to 2022, in which members compared their own cars, brackets and period photographs. Supplier information is from the club and from specialist suppliers' own listings. No individual member is named here.