Rebuilding, uprating and fitting a Lotus 5-speed gearbox ...

Rebuilding, uprating and fitting a Lotus 5-speed gearbox to the Lotus Elan.

Tips and hints to get a lasting solution.

By Victor Hollnagel

Ba.Sc.Mech.Eng. and Danish club member

Many Lotus Elan owners seem Sierra fame, This might be the reason Prices
to share the opinion that the Elan and even the for the reputation of the gearbox
is in need of a 5th gear to keep Alfa Romeo gearbox used in the of being somewhat fragile. Elite Lotus 5 speed gearboxes
revs and noise on acceptable type 105 Bertone Coupe
levels for motorway driving. (see the article written by Murray In a 1558 ccm, 126 HP and are obtainable for realistic money,
Valentine in “Club Lotus News” 1540 lb/700 kg Elan Sprint loads
The last 3 Elan Sprints deliv- 3/1987, page 10). are immensely reduced compared due to them being frequently
ered from Lotus in 1973 was to the Elite.
actually equipped with the 5- An important point was to avoid swapped for the later used Getrag
speed gearbox from the slightly cutting neither in the chassis nor One of the above mentioned
bigger +2 version. Furthermore a in the interior in order to be able last 3 original 5 speed Elan 5 speed gearbox for improved
Lotus parts bulletin of 04.09.1974 to later convert the
was issued, describing a 5-speed car Sprints reliability. Only the mid gearbox
conversion kit for the Elan produced in
Sprint and the back to section can be used from these
Elan +2S 130. its original 1973 was
condition. This actually Elite versions, though. The Elan
Having appeared to be quite
carried out the ambitious, as the chassis is nar- exported to Denmark and bought needs to use a clutch housing
5 speed row around the gearbox, and as by Mr. Claus Gaarde; a long time
conversion on my the gearlever comes up through Danish Lotus enthusiast. Claus with a Twin Cam engine flange
own Lotus Elan the floor in a for most cars un- could inform me, that he – after
Sprint DHC 1973, I will usual forward position. rebuilding the gearbox himself in and the short gearbox output
in the following elaborate 1984 to the latest specifications –
on my experiences, None of the above three gear- drove 150 000 troublefree kilome- section which has the gear lever
hopefully inspiring other Elan boxes could fulfil these require- tres with the box behind a slightly
owners to consider a similar ments. Therefore the Lotus 5 uprated 140 HP Twin Cam en- placed in a position as far forward
conversion. speed gearbox was further inves- gine. Claus kindly lent me all his
tigated. technical information (parts list, and as close to the central gear-
The Lotus 5 speed gearbox has service manual and service bulle-
got an undeserved reputation of Origin of internals tins) on the box. Claus also had a box housing as possible. Both the
being troublesome. The number nearly complete gearbox as spare
of Lotus Service Bulletins with Basically the gears in the Lotus parts, which I was invited to ex- clutch housing and the output
modifications could at first glance 5 speed gearbox are from the BL amine.
seem to confirm that image. Austin Maxi being one of the few section are unique to the Elan
mainstream cars sporting a 5 After going through all this in-
Alternatives considered speed gearbox at that time. formation I could see no reason version, and unfortunately
These gears were installed in a why a Lotus gearbox should not
With that first impression in Lotus designed aluminium cast- be able to work satisfactory in my these parts are no
mind other alternatives were ing. Sprint as well.
considered, longer available
A new input and output section Elite and Elan versions
Top: Ford N/9 was designed by Lotus to convert from Lotus. There-
Middle: Ford MT 75 the original transversely mounted The version of the gearbox used
Bottom: Alfa Romeo Maxi gearbox internals to its new in the new Elite has a longer fore quite stiff
inline position. output section and the clutch
such as Ford’s type N/9 gearbox, housing has a different engine prices varying
Ford’s MT75 gearbox, both of Not fragile flange compared to the version of
the 5 speed box used in the Elan between £ 750
The Lotus 5 speed gearbox was and Elan +2. But the central
originally intended for and used in gearbox section carrying the and £ 1500 are
the quite heavy new Elite (2240 gears is the same on the Elite and
lb/1016 kg) with its powerful 2 litre Elan variants. asked for Elan +2
16 valve type 907 engine devel-
oping 160 HP, all of which when 5 speed gearboxes
driven in anger took the stresses
on the gearbox close to its limits. depending on

condition. Actually you are

paying these prices only for the

clutch housing and for the output

section, because the central

gearbox section carrying the

gears can – as mentioned earlier

– be used directly from the Elite

gearbox, which should be

Output housings: At top
for Elan and below Elite

possible to get for £ 100 to £ 250
depending on condition.

When buying an Elan 5 speed
gearbox remember to get the
propshaft with integral sliding
spline at the gearbox end and the
gearbox mount too, as these
parts are unique to the Elan
version as well.

Lotus vs. Ford box Numbers and markings for a much stronger standard size

ball bearing with a ring to com-

The Elan is normally equipped In the bottom of the gearbox pensate for the slightly smaller

with a Ford gearbox first used in housing a series number is outer diameter. This change

the Ford Corsair 2000E. Hence stamped. greatly enhanced the rigidity and

it’s often referred to as the Ford Some of the gearbox housings location of the input shaft, and the

2000E gearbox. This gearbox were machined to odd tolerances, lifetime of the input shaft bear-

weighs 33 kg with its cast iron and were fitted with oversize ings. If your gearbox does not

clutch- and gearbox housing. The bearings, which are no longer have this modification, you can

Lotus box weighs only 27 kg with available. These boxes are identi- make it yourself, if you have

Elan propshaft with inte- its aluminium housings. By fitting fied by “OS” stamped beside the Input shaft
grated sliding spline the Lotus box you are ”adding series number. Try to avoid these

lightness” to your car, just as boxes as they are more difficult to
My own way to the Elan 5 Colin Chapman prescribed.
speed gearbox was to put an ad rebuild.

in Club Lotus News. For £ 1100 I The gear ratios of the first 4 From series number 1492 and Top: New strong ball
ended up buying a dismantled
gears are nearly the same in the on the angle of synchromesh on bearing + ring
Ford 2000E and in the Lotus box: 1st and 2nd gear is changed from
gearbox with a couple of new
gears and with the convenient The biggest difference is found 5° to 6° to improve synchromesh Bottom: Early narrow
possibility to inspect the box’s between the ratios of the 1st life and action. ball bearing
gears; the Lotus box’s 1st (1:3,20)
From series number 2174 and
internals too. My intention was to is 7% lower the Ford box’s 1st on a nice trust needle roller bear-
disassemble and renovate the (1:2,97) giving a slightly easier ing for the 1st speed gear and an access to a lathe. To make room
gearbox anyway.
for the wider bearing you will
However this appeared to
be no cheap experience. But Vehicle speed have to spigot the input shaft
slightly and deepen out the
take it as a hobby, consider
what other people spend on Final drive ratio: 3,778 pinion: 9 cr. wh.: 34 recess in the input housing.
their hobbies (what did your Tyre dynamic radius: 281
wife spend on shoes lately?) mm tyre dimension: 155/80R13 To improve lubrication of
and enjoy the originality of the 1st
conversion which is done just the needle roller bearing
like Lotus did. If done prop- 9 2nd 3rd 4th 5th Rev. between the 1st motion and
erly, it should raise the value 9 the 3rd motion shaft, two holes
of your car too. Gearbox eng. rpm 57 km/h 8 were introduced in the 1st
Lotus 1000 61 14 20 28 35 8 motion shaft radially through
Ford 1000
Lotus 6500 14 20 28 -
Ford 6500 91 133 182 229 53 the land beside the teeth of
55 the gearwheel.
91 130 182 -
If your input shaft does not
Equipment and less clutch stressing start accordingly revised 1st speed gear have these lubrication holes, you

To carry out the conversion it is from stand still with the Lotus box. is used. can drill them yourself. Grind off
necessary to have good work- The other ratios are the same From series number 2016 and the hard surface with a small
shop experience, to be patient, stone in a Dremel or equivalent,
and to use plenty of common within 3%, a difference you will on a smaller roller bearing is used making a slight grub, buy a nor-
sense. hardly notice. In top gear at 130 at the rear end of the counter- mal 3 mm brick-wall drill, grind its
km/h revs drops form 4600 rpm in shaft. In my opinion a slightly side down to 2,5 mm, and you are
the (Ford) direct 4th gear to 3700 retrograde step. able to drill through the rather
rpm in the (Lotus) 1:0,80 ratio 5th

gear, giving a very useful 900 rpm Design changes hard steel using a little oil for

drop and reduction in the noise cooling. Much cheaper than

1st motion shaft puller level on longer journeys. The Beside the above mentioned buying a new shaft with holes
layout of the Lotus’ 5th gear as an changes an important change of
You should have access to a overdrive is confirmed by the the odd narrow, large outer di- 2,5 mm lubri-
gearknob badge: ”1 – 2 – 3 – 4 – ameter ball bearing at the input cation holes
O/D”. shaft was made. It was changed

hydraulic press and have com-

mon workshop tools. It is

3rd motion shaft support for £ 150. Remember to carefully
grind off the sharp edges, not
also necessary to be able to damaging the bearing surface
make up a couple of special parts inside the 1st motion shaft in the
and tools to get the job done process.
properly. You should get hold of
the original section F from the Bearings
Elan +2 workshop manual and all
the Lotus service bulletins regard- The gearbox contains 4 ball
ing the 5 speed transmission. It bearings, 3 roller bearings and 5
will be of great help to you, if you needle roller bearings. They are
have a parts list, too. all of RHP or Torrington origin.

On that basis you should be Only 2 ball bearings and 4 nee-
able to make a well functioning 5 dle roller bearings are standard
speed gearbox and even enjoying catalogue items, the other 6
the pleasure of doing the job bearings are special.
yourself.
The way to get hold of all the
bearings is to contact a bearing
specialist company with the right
UK contacts. Provide the list of
the bearings, and they should be
able to source them all for you.

The 6 special bearings will not
be cheap. Be prepared to pay in
the region of £ 500 for all of the
12 bearings.

Modifications up through the tunnel in a rear- Gearbox mounting plate
ward position in relation to the cut According to Lotus fitting in-
Selector shaft finger out in the tunnel and the tunnel struction the gearbox mounting
console. This is compensated for plate for the Lotus box should be
The standard selector shaft fin- by making up a new gearstick mounted to the chassis in holes
ger has round sides, which grip with an offset rubber bush house, drilled in new positions. I pre-
into the selector fork’s square cut- with the gearlever welded to the ferred to make up a new gearbox
outs with straight sides. The 3rd/4th front of the bush housing. The
selector fork is made of brass and original gearstick is disassembled modified
has narrowed down sides. Con- at the concentric rubber damper,
sequently the sides of the selector original
fork cut-out are deformed leading to move the bracket with the the lower gearstick part is care-
to a sloppy gear change. 5th/rev. lever until its cut out was fully straightened, a M10x1 thread Gearbox mounting plate
aligned with the selector fork cut is cut at the end of it, the conical
The solution is to make up a outs. mounting plate which made it
selector finger with a square head original possible to use the existing holes
and straight sides just like the Support ring in the chassis instead.
selector fork cut out, which it grips The input shaft and the 1st mo- modified
tion shaft are mated with splines Concentric slave cylinder
into. Make the revised finger from around the above mentioned The clutch originally uses an
a piece of Uddeholm “Arne” steel, heavier ball bearing and a roller outside mounted slave cylinder,
which can be hardened and bearing. The inner ring of the too close to the exhaust manifold.
tempered to the right strength and improved ball bearing only sits on On hot days and in town traffic
hardness. The selector shaft is the spigotted end of the input this situation often leads to
modified to take the now Allen shaft. The alignment of the mated cooked clutch fluid and a mal-
screw secured selector finger. shafts to the ball bearing and the functioning clutch release.
support of the inner ring of the
Lever pivot
Support ring
The lever for the 5th gear and
the reverse gear is secured at its
pivot point with a tiny circlip which
is reported to easily slip off. The
solution is to make up a new pivot
point and securing system of a

turned down M10 bolt of 8.8 steel ball bearing can be enhanced by rubber spring is cut down, suit- To overcome this a SAAB 900
quality. This bolt is secured by a making up a support ring filling up able spacers made up, and the concentric slave cylinder was
M6 Allen screw. By tuning the the remaining space between the new forward offset gearlever mounted inside the clutch hous-
tolerances it is now possible to 1st motion shaft spline and the ing, doing away with a lot of the
have a secure and free turning inner diameter of the ball bearing. mechanical parts. A console plate
pivot without sloppiness.
Spacer
Selector line up
Put a 1mm plain washer over
The cut outs in the selector the selector link pin (position 4) to
forks and in the 5th/rev. lever space the selector link out from
should be aligned in neutral; the gearbox side. This will take up
otherwise the gear lever cannot
be moved across the gaiter freely. 1 mm spacer here
In my case the cut out in the

excess sideways sloppiness in was made up to take up the new
the gear lever when it is in the clutch cylinder. The necessary
1st/2nd gear position. hydraulic lines, fittings and an
outside bleed screw had to be
Offset gear lever made up too.

5th/rev. lever was about 0,7 mm An offset gearlever should be can be assembled. The rubber
out of line. This was compensated made up like the lever used on bushing used is a part from the
by making up new retainers (see the original 2000E 4 speed gear- rear suspension A-arm outer
drawing position 18) for the inter- box, but the offset should be to bushing. The mounting of the new
lock plate with 0,5 mm eccentric the front instead to the rear. The - disassembled - gearlever to the
holes and threads. It was now reason for this is that the gear gearbox is now much easier too.
possible by turning the retainers lever from the Lotus box comes The photo should give the general
idea.

Assembly teethes and the shafts. Instead Be sure to use a magnetic bot- fied tolerances. They are of great
take a surplus synchroniser collar tom drain plug to catch steel importance to the function and
It is wise to make a trial assem- ring and have it bolted up in a tool deposits from the oil. I ended up shift quality of the gearbox.
bly of the gearbox with the old with a lever arm. This tool can be using one from a Triumph Spitfire
bearings to check the function used to carefully hold back the 2nd gearbox as it was NLA from Use the best synthetic gear oil
and free running of all the parts. motion shaft on the 5th gear syn- Lotus. you can get, for instance Castrol
Shift through all gears and turn chroniser mechanism while tight- TAF-X. The gearbox will take 1,7
the shafts. For my part on my trial ening down the nuts, without You will need an approx. 15 cm litre.
assembly I found the input shaft overloading the gearbox. longer speedometer cable. A
binding and loosing up for every cable specialist firm should have You should now be able to en-
180° turned which was tracked The baulk rings can present a the answer to that. joy motoring in your Elan even
down to an out of true 1st motion slight problem, as they have to be more when cruising long dis-
shaft. I had to have a new shaft of the correct angle, which as Otherwise do exactly as stated tances in 5th gear!
fitted! mentioned earlier was changed. It in the Lotus workshop manual,
should be possible to feel if the and be careful to keep the speci-
When fitting bearings to the baulk ring fits properly to the cone
gearbox housing, always heat up of the corresponding gear wheel. I
the housing with a heat gun. had to go through a couple of sets
When heated, aluminium expands before I had a full set of the cor-
three times as much as steel. rect angle baulk rings.
This should assure you correct
and much easier fitting of the To eliminate the risk of the
bearings. bearings rotating in the gearbox
housing when the gearbox
The gearbox housing should be reaches working temperature, or
thoroughly cleaned before as- due to bad tolerances, always use
sembly. Nowadays ball and roller Locktite bearing securing fluid. Be
bearings are dimensioned not careful not to drop Locktite into
only by the loads, but by the the bearings.
cleanliness of the lubricant as
well. Even the smallest amount of All bolts and nuts should be
dirt can greatly reduce the life- secured with Locktite for bolts,
span of your expensive bearings. especially the long Allen bolt
It pays well off to be thorough. securing the input shaft to the 1st
motion shaft. It is critical if it works
When tightening the big nuts at loose. But it won’t if you are
the 3rd motion shaft and on the 2nd careful.

motion shaft, the workshop man- Generally, Locktite only works
ual says that you should put the when the surfaces are clean and
gearbox in 1st and 3rd gear at the free from oil and grease.
same time, locking up the gear-
box. I would advise you not to use The sealing compound to use
this method, because you put on the gaskets is Hylomar or an
immense loads on the gear equivalent not drying up RR
specification sealing compound.

Acknowledgements a brand new 5th gear pinion speed gearbox in an Elan (you sourced all bearings and welded
among numerous other important will have to cut a little in the chas- the balancing weights properly
This project could not be tack- bits and pieces. sis and move the engine and onto the propshaft.
led without invaluable help from gearbox a bit forward. It has been
many friends and specialists: Alan Voight supplied many NLA done a couple of times with good Torben Valerius provided the
items. results and it’s not expensive). possibility to have some gearbox
Nick Abbott at the Bull and surfaces cleaned up in a big lathe
Butcher in Turville sold me the Michael Taylor sold me a nice Claus Gaarde supplied his at his disposal.
gearbox, provided a nice meal, a used Elite gearbox, a new input complete Lotus literature on the
pint of Breakspears bitter and bed housing, not to mention finding a subject and the opportunity to Frank Thrusholm - last but not
and breakfast on my visit to col- gearknob with the all important have a thorough look at the hard- least - took the trouble to read the
lect the box in England. “1-2-3-4-O/D” shift pattern badge ware. proofs on my ramblings.
to enjoy.
Pat Thomas at Kelvendon Peter Kjul, Niels Johansson and Thanks to you all!
sourced a much needed new 1st Murray Valentine, Australia Henrik Andersen provided knowl-
motion shaft. kindly sent me his absolutely edge of material and heat treat-
thorough an detailed 10 page ment for the selector shaft finger,
Paul Matty Sportscars sourced description of how to fit an Alfa 5

Lotus 5 speed gearbox bearings

Pos. # Qty. Bearing Make Type Inner di- Outer Width Width of. Outer
drawing flange diameter of
ameter diameter
flange

41 Ballbearing RHP 6207 35 mm 72 mm 17 mm - -

5 1 Rollerbearing with flange RHP 17LRJ30 30 mm 72 mm 16 mm 4 mm 3”

8 1 Needlebearing, caged ? ? 20 mm 26 mm 12 mm - -

14 3 Needlebearing, caged Torrington FWJ 354025 35 mm 40 mm ≈ 24,5 mm - -

14 1 Needlebearing and Torrington TE-160-680 27,15 mm 40 mm 35,3 mm 3,9 mm 55,55 mm
aksialneedlebearing with
innerbushing

23 1 Ballbearing with recess RHP 2LJ11/16 11/16” 68,7 / 12,6 mm 8,5 mm -
59,5 mm
in outerring

24 1 Rollerbearing RHP 14RJ11/16 11/16” 68,8 mm 16 / 12 mm - -
(innerring /
with different with of outerring)

inner- and outer ring

31 1 Ballbearing RHP 6006 30 mm 55 mm 13 mm - -

41 1 Rollerbearing RHP 1DXXLLRJB30 ≈ 30 mm 55 mm 25 mm - -

45 1 Ballbearing, RHP 3LDJT20 20 mm 47 mm 20,5 mm 4 mm 52 mm

double with flange

Engine rpm

Final drive ratio: 3,778 pinion: 9 cr. wh.: 34

Tyre dynamic radius: 281 mm tyre dimension: 155/80R13

1st 2nd 3rd 4th 5th Rev.

Gearbox km/h eng. rpm
Lotus 130 - 9292 6360 4636 3687 -
Ford 130
- 9316 6475 4636 - -

Lotus Elan 5 speed gearbox shafts, bearings and gearwheels