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It seems nobody has written a book on the complete history
of the Hewland gearbox despite the fact that it is a critical
component of racing cars from the late 1950’s to the
1980’s.This lies in complete contrast to the numerous
shelves of books providing even the smallest details on most
racing engines ,marques and courses.
However,
what technical data that survives is sourced from magazine
articles especially from the English magazines including
Autosport and Motor Sport. Never-the-less an Authoritive book
on Hewland gearboxes would be very helpful to restorers of
historic racing cars and especially members of eligibility
committees.
The
trustworthy author, Doug Nye, did write the Hewland Gearbox
story for Autosport magazine in 1968 and covers the technical
details of the development of the transaxle from its origins
in 1959. This newsletter item is
a summary of that and I thank VHRR, member Ken Zinner for
assisting with the research.
Mike
Hewland ran a small engineering business at Maidenhead in the
UK and his range of specialties was gear cutting. By chance,
the head of a racing team (UDT) running Cooper F2 cars, Bob
Gibson-Jarvie, sought some help from Hewland as significant
gearbox trouble was being experienced. The results of this
request were two-fold with six successful gearboxes being
designed and built in 1959 and Hewland finding himself in the
gearbox business.
It
is interesting to note that at this time the Citroen box in
the Cooper Climaxs in Australia were also giving trouble as it
was designed to “pull” the car along and in this
configuration was used to “push” the car along with
reverse stress loads splitting the alloy case. Bill Paterson
attmpted to solve the problem by employing extended external
bolts and Austin Miller disgarded the Citroen boxes and used
the VW based Porsche 356 box with great success.
Meanwhile,
Eric Broadley of Lola Cars was impressed and commissioned
Hewland to build a gearbox for his new rear-engined Formula
Junior cars. This was the first Hewland transaxle being VW
based and 12 were made during 1960-61. The VW box was well
made in a cast magnesium and with it’s strength and
lightness was chosen over the Renault and Citroen. Known as
the Mark 1, the VW bearing carriers , selector rods,
differential, crownwheel and pinion were retained however
straight cut gears and a removable cap-end allowing a quick
interchange of gears were introduced. Of course, it went into
rear engined racing cars upside down and was strong enough to
service the tranformation from “pusher” to “puller.”
The
story continues in 1961, a year that saw the introduction of
the 1500cc capacity for formula 1 and the rapidly growing
popularity of 1100cc Formula Junior. With the resulting
reduction in top speeds designed as a safety measure, the
engineers were concerned in managing the vast torque of the
high revving small engines. Consideration was also given to
lowering the centre of gravity of the cars as a way of
increasing cornering speeds which is where the races would be
won.
Mike
Hewland was in a most advantageous position because the
inverted VW gearbox had the output shafts above the input
shaft from the clutch thus already providing the lowest center
of gravity. He captured the torque of the engines with
his Mk 2 (1961) and the Mk 3 (1962) boxes with 5 gears and
enhancements which included a design clear-up and a reduction
in weight of 10lbs.
Under
pressure from chassis designers who found the rear selector
rod increasingly difficult to accommodate in future slim-line
cars, the Hewland team formulated the Mk 4(1963) with 5
forward speeds, a Ford Consul differential and a forward
facing selector rod on the right hand side. As a result,
drivers found gear changes more positive and mechanics found
ratio changes much easier. This model found universal
acceptance and established the brand.
Two
additional models followed in 1964 with the release of the Mk
5 for the high torque Cosworth Ford engine and the Mk 6
(4 Speed) for Formula 3 (1000cc) and used later on Formula
Ford cars. By this time, nearly 900 units were racing on
circuits world wide.
Coming
back a little, in 1958 Cooper cars were showing their
potential to challenge Vanwall, BRM and the Continental
marques with their increased reliability. Jack Brabham had
visited the ERSA factory in Paris where
Citroen housings were made and advocated strengthening
measures to the casting. Jack was also concerned with lowering
the centre of gravity of
Coopers as his experience was telling him that cornering speed
would be critical to lap times. The Citroen box could not be
used upside down and the input shaft sat well above the
output drive shafts making a negative issue. To solve this
complexity, he cabled Ron Taurenac in Sydney and the reply was
prompt, “Jack, you have forgotten your speedway days, use a
spur gear.” So, working with Jack Knight (hence the name
Ersa Knight) Jack extended the bell-housing to contain a shaft
from the clutch with a spur- gear linkage to the input
shaft thus lifting the gearbox against the engine and allowing
the whole engine-transmission assembly to sit lower in the
car. The 1959 World Championship followed.
As
was stated at the beginning of this article, there is no
single definitive history of the development of the Hewland
gearbox and the reports in the various magazines from the MK
VI onwards become a little confusing.
By
1965, Formula One had gone to a 3 Litre engine capacity and
the use of V8’s required stronger gearboxes with internal
oil pumps to ensure adequate lubrication and temperature
control. Designs based on the VW were now superseded and Mike
Hewland developed his own case with these concepts. Given the
name LG500 (because it was a large gearbox) it was aimed to
accommodate the American 5000cc engines and the first 4 speed
example was used by Eric Broadley in the
Lola T70.
The
contemporary report from Doug Nye indicates that the
Australian Paul Hawkins (the same bloke that terrorised South
Melbourne in his Austin Healey) persuaded Hewland to invest in
the production of LG’s and an initial 30 were made to cover
pattern and tooling costs. Hawkin’s vision of the Formula
5000 was correct and nearly 500 of these units were sold, with
the design offering an alternative 5 speed model.
The
Nye story then introduces another Australian who needed
stronger transmissions for his F1 cars. He commenced with the
5 speed version of
the
MK IV (nominated the HD for “Hewland Design”) but soon
found its limitations and commissioned a new and heavier model
for his BT19. This of course was Jack Brabham in 1966 and the
box was designated DG because somebody leaned over Mike
Hewland’s shoulder at the drawing board and commented “
That’s a different gearbox.” The initials stuck!
However, there is a report that the initials came from
Dan Gurney who incorporated this model into his eagles.
In
this same year, the Mark 7 was created as an adaption of the
MK 4 with 6 speeds for the 1000cc Formula 2 class. New
customers for the DG included Cooper,BRM and McLaren for their
F1 cars and a big demand developed in America for the Can–Am
and Indianapolis series.
With
67 employees and numerous sub-contractors, the Hewland Company
by 1968 was bigger and more successful than Mike had ever
expected. Two additional models (the FT 200 for F2 and the FG
5 speed for F1) were added to the range, but production was
aimed at filling orders for the 3 and 5 litre cars.
Today,
Hewland Engineering Limited has annual sales of seven million
pounds and makes a wide selection of transmissions including
the Mk8/9 which replaced the famous MK4. Updated manuals are
available for all models. Mike Hewland is still alive and is
widely regarded as “the father of motor racing
transmissions.” The company’s interesting website is www.hewland.com
- Written by Roger James
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