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Road Tests
The articles are presented with the permission of the publishers and authors with full credits on each.

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Road Tests:

About Ed Miller

1935 Auburn

1935 Bentley

1939 Packard

CCCA Full Classics®:

Alfa Romeo


Derby Bentley


1936 Mercedes-Benz


1935 Bentley 3½ Litre Aerodynamic Sport Saloon, body by Rippon Brothers.

There are two types of Bentleys, a W. O. Bentley is fast, fierce and manly. Its successor is an all together different breed, it is not fierce but rather fast and yet quiet. It is what sports car were eventually going to become. Maybe that is why the successor Bentley is known as the “Silent Sports Car.”

Starting in 1921, W. O. manufactured his cars near London, in the town of Cricklewood. A W. O. Bentley would win Le Mans five times. Walter Owen Bentley certainly was a master craftsman but he wasn’t much of a businessman. One of his admirers was Woolf Barnato. He became one of the “Bentley Boys” who couldn’t stay away from Mister Bentley’s magnificent creations. Woolf drove Bentleys to three of the Le Mans victories. More importantly, Woolf bankrolled Bentley. As heir to the Kimberley diamond mine fortune, this wasn’t much of a strain on Woolf’s pocketbook. Whether Woolf got tired of racing or throwing money down a bottomless pit, is unknown. But in 1931, Mister Barnato’s money ceased flowing into the Bentley coffers. Enter a very nervous Rolls-Royce board of directors. Although Rolls-Royce claimed to be makers of “The Finest Automobiles in the World,” it had plenty of competition. Rolls  feared the aborted Bentley 8 litre would dig deep into the Rolls-Royce market. The British Daimler company offered a competitive twelve cylinder motor car dubbed the Double Six. Another potential competitor, D. Napier and Son, Ltd., produced a fine automobile in direct competition with the Rolls-Royce until 1924 when Napier decided to quit the automotive market and concentrate solely on the manufacture of aeroplane engines. Napier reconsidered its market strategy and was about to purchase the Bentley assets plus a long term service contract with none other than W. O. Bentley.

The possibility of a resurrected Napier coupled with the ability of W. O. to further develop cars for them alarmed the Rolls-Royce board. In a sealed bid auction, using a straw man called The British Equitable Central Trust, Rolls-Royce out- bid Napier for the assets of Bentley which included the W.O. Bentley personal service contract. Before the close of 1931, the assets were transferred to a new company called Bentley Motors (1931) Limited.

Two years later a completely different automobile was introduced to the world. It was a sports car unlike the Cricklewood Bentley. The new Bentley, manufactured at Derby, was much more refined and meant to be a sporty touring motor car   for the upper crust. This is the story of a uniquely bodied Derby Bentley, a 3½ Litre Aerodynamic Sport Sa- loon, body by Rippon Brothers.

A six cylinder in-line engine with a bore and stroke of 3 1/4" X 4 1/2" forming a displacement of 3,669 cubic centimeters or 223.9 cubic inches comprised the new 3 1/2 Litre Bentley. The engine wasn’t new. Rather, it evolved from the Rolls-Royce 20/25 power plant. Typical of Rolls-Royce, every part was meticulously manufactured. The fully machined crankshaft was composed of nitralloy steel, which increases the life of the metal and reduces wear.  This process also increasd its durability. To further improve the crank, the shaft was case hardened to strengthen the metal. This well made crankshaft was held in place by no less than seven main bearings. The crankshaft was fitted with weights combined with a friction damped spring drive and a friction driven flywheel to reduce crankshaft vibration. The crank was encased in a cast aluminum crankcase that was manufactured in two sections. Nonetheless, during the entire run of the Bentley 3 1/2 Litre and its successor, the Bentley 4 1/2 Litre models, the threat of crank- shaft problems loomed large. Therefore, if you desire one of these Full Classic® motor cars never exceed the indicated engine speed limit of 4,500 RPM.

For those who want to know more than they should about the Bentley engine, this diagram hopefully will satisfy your desire. A-Dynamo (Generator), A1-Tachometer connection, B-Starter, C-Tappet covers, D- Oil filler, D1-Oil level indicator, H-Oil pump line, Rm-Rear bearer arms, Y-Front bearer arms

Cl-Coil, Ig-Ignition contact, breaker and distributor, K-Rocker, etc. oil line, Op-Oil pump, Sp-Spark plugs, U-Air silencer, V- SU carburetors, W-Water pump, Wm- return water pipes from induction manifold.

The crankshaft actuates overhead valves via rockers and pushrods from a camshaft running at half the speed of the engine. The cam- shaft is driven by a set of bronze helical gears and held in place by seven plain bearings high in the crankcase. Near the front of the camshaft is an additional cam which, together with a se- ries of spring plungers balances out unevenness in torque which maintains silent operation of the timing gears.

Both head and block were of cast iron. They were individual units, though the cylinders extend two inches into the block. A conventional one intake and one exhaust valve serve each cylinder. The head is of cross-flow design. This means the fuel enters from one side and the exhaust out the other. This promotes uniformity of fuel mixture and more complete scavenging of the exhaust gases.

An unusual lozenge shaped combustion chamber provides better combustion. Although the first few Bentley 3½ Litre cars had pistons wearing four rings, the lowest of which was a scraper ring, the remainder of the run did just as well with three rings, the lowest continuing duty as a scraper ring. The aluminum alloy pis-tons wear skirts that are split in order to deal with expansion and contraction.

The connecting rods are both drilled and have external piping in order to allow pressurized oil to flow from the big ends to the gudgeon pins. The rods are nickel-steel forgings in the shape of an “I.” The connect- ing rods used shimmed steel backed metal shell bearings. Shimmed connecting rod bearings had not gone out of style. When a connecting rod bearing starts to wear, a mechanic would replace the shim with a new shim of appropriate thickness rather than scrape the bearing. Incidentally, maximum oil pressure is 32 P.S.I. Typical oil pressure when the engine is warmed up is 20 P.S.I. at 2,000 RPM. At idle, expect 5 to 7 P.S.I. of oil pressure. If it falls lower, turn the ignition off and tow it to your nearest Bentley mechanic.

The fuel system starts at the rear of the vehicle with an eighteen imperial gallon gasoline tank. An imperial gallon is approximately 20% greater than a U.S. gallon. Two imperial gallons act as a reserve. This re serve gasoline is contained in the same tank. A separate and longer tube is used to bring it forward. This tubing is brought into play by a separate switch on the dashboard. Twin 13/8" Skinner Union (S.U.) side draft carburetors mix the gasoline and air. As with any other S.U. carburetor, you can entertain yourself periodically by unscrewing the top cap and adding a few drops of sewing machine oil. Twin S.U. pumps force gas forward. They may be operated individually or in tandem. Just like any other S.U. electric pump, if both pumps stop working, tap one or both smartly once or twice. It will get you a few miles further down the road.

The spark is provided by a twelve volt system. The distributor has an automatic advance plus a manual advance for unusual situations and for cold starting. The 3½ Litre Bentley engine was rated at either 114 or 115 HP @ 3,800 RPM, depending on which book you happen to be reading.

The clutch is a typical 10½ inch single driven dry plate. It is mechanically operated. The transmission is more interesting. It consists of four forward and naturally one reverse gear. The top two forward gears are synchronized. Stop rubbing your eyes, you read correctly. Only the top two gears are synchronized. This can lead to some frustration in shifting, particularly from first to a non-synchronized second using a double clutch method and then upward through the gears without double clutching. However, Bentley Motors recommends that at a stop, the driver initially accelerate not in first gear but second. First gear is reserved for starts on your typical San Francisco street. To further confuse we colonials, the gearshift lever and hand brake are located to the far right, fortunately so is the steering wheel.

An open driveshaft with universal joints have needle bearings that required infrequent maintenance. The rear axle is of the full floating variety. Within the casing are off-set hypoid bevel gears which reduce the noise level which used to be associated with the rear-end. The rear-end ratio is either 4.1 to 1 or an optional and rare 3.9 to 1

The leather encased springs and shackles are lubricated by a centralized lubricating system. A handle located under the dash should be ap- plied once a day to lubricate numerous parts of the chassis. Occasionally inspect the “U” bracket bolts that secure the springs to the axles as they can work loose. Along with the springs come hydraulic double acting shock absorbers. The front pair of shocks are combined with a unique articulated triangular shaped tubing. Its purpose is to resist torsional displacement of the front axle during hard braking. Eighteen inch wheels are combined with 18 X  5.50 splined wire wheels, often covered by discs.

Steering is by worm and nut with a fast turn lock to lock of 2.6. A turning circle is typical of the day at roughly forty feet.

Brakes are encased in twelve inch drums. They are internal expanding mechanical brakes. 178.8 square inches of brake lining area is available to bring the Bentley to a halt. If you add the emergency brake lining area, you have 232.8 square inches. A fascinating brake feature is the brake assist. It is mechanical and complicated. It derives its power from the transmission and it would take more pages than Classic Lines magazine has to adequately describe.

The Bentley, also referred to as Bensport, rests on a 126 inch wheelbase. The chassis weighs 2,510 pounds. There were no Bentley bodies. The purchaser contracted with a body builder of his choice. A light body probably added as little as 700 pounds, a heavy sedan body, an estimate 1,100 pounds and the Aerodynamic Sport Saloon, an estimated 900 pounds.

Entry may not be impossible, but the driver’s side is blocked by both the hand brake and the gearshift lever. Better to enter and exit from the passenger side. Here there is more leg room between the “A” pillar and the leading edge of the front seat than some modern cars. The bucket seats are among the best of their generation. They are well formed and supportive. Not only are there individual adjustments for each front seat that brings them either closer or further away from the dashboard but there is a rake adjustment. Seat rake is the angle of the entire seat in relation to the floor. There is a depression under the driver’s feet to provide slightly more room to maneuver. In the rear of the compartment, the back of the seat has insufficient padding. Yet leg- room is adequate, particularly since the first few inches of your feet can be placed under the back of the front seat without discomfort as there is a sunken foot well in the floor for each rear passenger. However entry to the rear compartment is poor. The armrests are beautiful but seriously inhibit ingress and egress.

Once the family is settled in the Bensport, a simple ritual of starting the Bentley commences. Switch on the ignition by turning the right hand lever on the switchbox to I & C. If starting from cold, set the mixture control, located around the horn button to Start. Manually retard the ignition about one-quarter of its quad- rant which is also located around the horn button.

Depress the starter and the engine comes to life. There is no raucous roar but subdued mechanical sounds can be heard from under the bonnet (remember this is a British beast; bonnet is British for hood). Move the mixture control from Start to Run.

Finding second gear can be chore. To the novice there is no feel for where the gears are located. Once found and with clutch depressed, the Bentley accelerates smoothly out onto the street. Second gear feels just like any second gear. In this case it is used as a first gear except when climbing hills. Therefore the initial gear feels extremely long legged, which it is. At 15 MPH, a shift into third gear is fairly quick and smooth. At 25 MPH the gear lever finds itself in fourth gear. Accelerating down old U.S. 41 in Bonita Springs, Florida at 45 to 50 MPH is a pleasure in the 3 1/2 Litre Bentley. The steering as heavy, even at speed. Yet there is no discernible play. Turning left into a gated community, you discover just how quick the steering is. It is quite easy to over steer this Sport Saloon. At 2.6 turns lock to lock the steering may be heavy but it is also fast. Bumps and dips don’t seem to particularly bother the Rippon bodied car. Coming to a stop sign, the brakes don’t have much feel and are fairly heavy, but they stop the roughly 3,500 pound car in a straight line.

Once back on the open road the Bentley is allowed to accelerate through the gears. First gear hasn’t come into play. At the next stop light, the gear shift is placed in first and off we go. Shift into neutral with clutch depressed, pause, clutch as you shift into second gear with a small crunch. It works, but starting in second is much better, particularly on the teeth of the gears. What will she do? About 18.5 seconds in a race from 0 to 60 MPH combined with a top speed of about 91 MPH. Not the best, but excellent performance for the period.

As we head back to the Bentley’s garage, respect for “The Silent Sports Car” has been earned. It is silent, relatively easy to drive and comfortable, specially for a pre-WWII luxury sports car. There is only one Rippon bodied Aerodynamic Sport Saloon extant but there are other Derby Bentleys out there for you. Try one, you will probably like it.


Engine: Six cylinders, inline
Displacement: 3,669 c.c./223.9 c.i.
Valves: OHV
Bore & Stroke: 31/4" X 4½ "
Compression Ratio: 6.5:1
Main Bearings: 7
Brake Horsepower: 114/115 @ 3,8500
RPM Electrical: 12 Volt Lucas, coil
Induction System: Twin HV4 13/8" S.U. side draft c
Carbs Fuel System: 16 gallons plus a 2 gallon reserve
Fuel Pump: Twin electric S.U. fuel pumps
Clutch: 101/2" single drive dry plate
Gearbox: 4 speed, synchromesh on 3rd  and 4th
Rear end: 4.1:1 or optional 3.91:1, hypoid
Wheels: 18 inch wire wheels with splined hubs
Tires: 18 X 5.50
Brakes: Mechanical boosted 12 inch drums
Brake lining area: 178.8 square inches
Steering: Worm and nut
Wheelbase: 126 inches
Chassis weight: 2,510 pounds

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