Lotus Type 37

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Another favourite car of mine is the Lotus Components Limited – Type 37, variously known as the ‘Three Seven’, and ‘Three 7’ (i.e. as per the graphics painted on the nose-cone of the car on display at the 1965 Racing Car Show).  Graham Arnold in his ‘Illustrated Lotus Buyer’s Guide’, advised of the following: “Actually known as the Lotus 3-7, it was a one-off racing Seven used by Lotus to win the British Clubman Championships after a car called the Terrier, designed by Lotus F1 man Len Terry, had won the Colin Chapman Clubman Trophy! 1965, one off”

John Watson – on his Lotus Seven Register site – has detailed information on the 37 along with other Seven road and racing cars. He has also supplied articles for the Lotus Seven Club magazine and the Historic Lotus Register among others.  It is not my intention to repeat all of the valuable information that John has gathered, but merely to show how the original car was conceived and presented at the 1965 Racing Car Show in all its glory.  John provided me with copies of photos that may have been previously published, and these are shown below.  Credit given where photographer is known.

Many years ago I made contact with Len Terry through a close associate of his from whom I was purchasing some Seven spare parts.  Mr. Terry kindly emailed me, and advised that his association with the 37 was in the design of the rear suspension of the car.  He referred me to his book – co-written with Alan Baker, called “Racing Car Design and Development” from Robert Bentley Publishing. 

Describing his 1967 Shelby CanAm project, Len Terry advises the following:

“For the rear-suspension linkage, I used for the first time on one of my own cars a bottom link of the parallel-arm type.  I did in fact incorporate this earlier on the Lotus 37, which was the Lotus Seven with independent rear suspension, but this car of course was basically a Chapman design.  In my opinion the orthodox linkage (as shown in the sketch) has a basic disadvantage in that, to minimize bump-steer, the designer has to juggle with radius arm lengths and give the rear uprights some castor inclination.  By making the bottom wishbone into parallel arms, I not only reduced the bump-steer but facilitated setting up the suspension by reducing the number of variables.  This system has since been used on other racing cars, Jackie Stewart’s 1969 Matra and the 1970-1 Tyrrells being notable examples”

Note: A sketch is provided in the Terry/Baker book showing the differences in geometry between a triangular bottom link arrangement and the parallel-arm design of Len Terry.

In John Tipler’s book “Lotus and Caterham Seven – Racers for the Road”, he advises:

“A series 2 car was designed by Bill Wells.. It was built by Peter Brand for the 1965 Racing Car Show”.

References to the 37 in other publications all seem to agree on the basic specifications.  The Series 2 chassis was strengthened by more triangulation, and for the rear suspension an Elite differential was fitted along with inboard disc brakes using Girling leading edge alloy callipers.  Fixed length half-shafts picked up the alloy hub carriers and the lower links were the Len Terry designed parallel-arm arrangement.  A pair of short arms each side of the chassis led forward from the hub carriers, picking up on the vertical side chassis tubes and the forward lower ‘A’ bracket location points – these being the same as per the normal Series 2 rear suspension attachment.  Five separate members each side located the rear wheels, but rubber bushes (not rod-ends), provided the necessary amount of compliance for the set-up to work extremely well. 

Front suspension on the 1965 Racing Show car was identical to the set-up on Lotus Seven Series 2 (and later Series 3) road cars, as well as on the original Elite and Lotus 12.  It consisted of a forged upper link fitted with a flexible rubber bush one one end, attached to the chassis on each side. There was a non-removable ball joint on the outer end of each link.  These links created the top wishbone with the anti-roll bar bolted to them. Girling alloy racing disc brakes were fitted on the front wheels outboard. The car was equipped with ‘Wobbly-Web’ mag wheels of 13 inch by 6J profile, fitted with Dunlop Racing tires. The rears were slightly larger width than the fronts.

Note: I have paraphrased (and added) information on the 37 from Dennis Ortenburger as published in his book “Legend of the Lotus Seven”.  Similar to a few other descriptions of the ‘original’ Racing Show 37 appearing in print, he described the front suspension as fitted with double wishbones with separate anti-roll bar. This modification does not seem to appear until the ownership changed from John Berry a year or so later, and is possibly attributed to either Peter Deal or Tim Goss when they owned and raced the car.  The Tim Goss modified 37 as raced by him, was fitted with true double wishbones at the front, with a separate anti-roll bar mounted at the lower front of the chassis with one article advising that they were from the Elan (26R possibly?).

After its return to Lotus following the Racing Car Show, John Berry, Home Sales Manager of Lotus, took over ownership of the car in exchange for his sales commission. He had a very successful racing season with the 37.

Information sometimes becomes lost or modified over time, and specifications regarding the 37 are no exception.  Some photographs show the 37 as original, combined with how it was under the ownership of Tim Goss, while others show extensive modifications to the car in subsequent ownership. Like the 7X, (and many Lotus Seven road cars) the 37 was heavily modified by subsequent owners after its original build by Lotus.  One photo on the Lotus Seven Register shows it fitted with a Holbay valve cover – possibly a rebored 1600 c.c. engine? One Lotus Seven book advises that it had a 116E 1340cc screamer engine fitted from new, but possibly the source of the information mixed this up with the Cosworth Ford 109E racing engine? Others – as per John Watson – advise that it was a Ford 116E 1500cc Cosworth Type IX engine, producing 120 BHP. Cosworth documents that the IX produced 125 BHP at 7000 rpm. Note: Ortenburger’s source of information also advises that the engine produced 125 BHP.

Lotus 37 Braking System

The dual master cylinder brake set-up of the 37 with a balance bar arrangement, is a good example of Lotus making use of ‘off the shelf’ items to cut costs.  By joining together two Ford 100E aluminium brake pedal brackets with a full length pedal pivot pin, *and cutting off a lug from one of the brackets to fit the pedal box area, a strong arrangement for holding the brake pedal was achieved quite cheaply.  One additional bracket was welded onto the top far right of the frame, where the second altered 100E bracket was located to further brace the assembly. It is possible that a second Lotus Seven clutch pedal was used in place of a regular brake pedal to allow for the correct spacing for ‘heel and toe’ braking/accelerating. A Lotus Seven clutch pedal fitted with a brake balance bar pivot sleeve (which holds the movable spherical bearing), provides the ideal spacing between the three pedals. 

Note: *Lotus also trimmed off another unused lug on this same bracket for cosmetic reasons (and added lightness?).

For anyone deciding to copy this arrangement on their Seven, Tilton Engineering in the U.S. manufacture a compatible brake balance assembly for welding on to a pedal which is almost identical to the Lotus arrangement.  Unfortunately the Ford 100E cast pedal bracket is as rare as hens’ teeth these days (2022). Mike Brotherwood had a few in stock pre-pandemic.  Caterham in the ‘80s had some brackets newly cast as replacements (part no. 74018 – Hydraulic Clutch – 4 Lug), but it is not known if they still produce them.  The pedal pivot pins require removal in order to fit a single pin that connects both brackets together for obvious safety reasons.  The additional small steel frame bracket – to be welded on to the frame to secure the second 100E cast bracket in place, can be sourced from Arch Motors or Xtra Special Sevens.

A photo of a Series 1 Seven from the Simple Sevens website, shows a modification to the car to provide dual master cylinders with a balance bar.  A metal plate has been used to further secure the master cylinders together. 

References.

Some photographs courtesy of Ferret Fotographics

Lotus Seven Register (web site).  Produced by John Watson

Historic Lotus Magazine no. 90 Autumn 2017, celebrating the Seven. Back issues available from the Historic Lotus Register

Legend of the Lotus Seven by Dennis Ortenburger.  Osprey Publishing

Lotus and Caterham Seven – Racers for the Road by John Tipler. Crowood Publishing

Illustrated Lotus Buyer’s Guide by Graham Arnold. Motorbooks International

Lotus Seven by Graham Arnold. Haynes Publishing

Lotus Seven and/or The Lotus and Caterham Sevens by Jeremy Coulter. Motor Racing Publications

The Story of Lotus 1961-1971 Growth of a Legend by Doug Nye. Motor Racing Publications

Lotus by Chris Harvey. Osprey Publishing

About the author

William Fayers

Welcome to the Anglo Canadian site for information on the Lotus Seven and the racing derivatives. My interest in this quirky little car began during high school in England, and has continued to this day. With the purchase of a Series 3 - too long ago than I care to remember - I have collected as much information as I could from the always very helpful owners, companies, racers, and mechanics who dedicated so much of their time to this fascinating little car. A number of Formula1 drivers started their careers racing a Seven. Gordon Murray, the exceptional designer and engineer originally with Brabham/MRD Formula 1 and designer of the McLaren Formula 1 road car, includes it in his list of favourites. If you have any stories or advice on maintaining the Lotus Seven, please drop me a line.

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About Author

William Fayers

Welcome to the Anglo Canadian site for information on the Lotus Seven and the racing derivatives. My interest in this quirky little car began during high school in England, and has continued to this day. With the purchase of a Series 3 - too long ago than I care to remember - I have collected as much information as I could from the always very helpful owners, companies, racers, and mechanics who dedicated so much of their time to this fascinating little car. A number of Formula1 drivers started their careers racing a Seven. Gordon Murray, the exceptional designer and engineer originally with Brabham/MRD Formula 1 and designer of the McLaren Formula 1 road car, includes it in his list of favourites. If you have any stories or advice on maintaining the Lotus Seven, please drop me a line.

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