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

Tips and hints to get a lasting solution.

By Victor HollnagelBa.Sc.Mech.Eng. and Danish club member

Many Lotus Elan owners seemto share the opinion that the Elanis in need of a 5

thgear to keep

revs and noise on acceptablelevels for motorway driving.The last 3 Elan Sprints deliv-

ered from Lotus in 1973 wasactually equipped with the 5-speed gearbox from the slightlybigger +2 version. Furthermore aLotus parts bulletin of 04.09.1974was issued, describing a 5-speedconversion kit for the ElanSprint and theElan +2S 130.

Having

carried out the5 speedconversion on myown Lotus ElanSprint DHC 1973, I willin the following elaborateon my experiences,hopefully inspiring other Elanowners to consider a similarconversion.The Lotus 5 speed gearbox has

got an undeserved reputation ofbeing troublesome. The numberof Lotus Service Bulletins withmodifications could at first glanceseem to confirm that image.

Al ternat ives considered

With that first impression inmind other alternatives wereconsidered,

such as Fords type N/9 gearbox,Fords MT75 gearbox, both of

Sierra fame,and even theAlfa Romeo gearbox used in thetype 105 Bertone Coupe(see the article written by MurrayValentine in Club Lotus News3/1987, page 10).

An important point was to avoidcutting neither in the chassis norin the interior in order to be ableto later convert thecar

back toits originalcondition. Thisappeared to be quite

ambitious, as the chassis is nar-row around the gearbox, and asthe gearlever comes up throughthe floor in a for most cars un-usual forward position.

None of the above three gear-boxes could fulfil these require-ments. Therefore the Lotus 5speed gearbox was further inves-tigated.

Origin of internals

Basically the gears in the Lotus5 speed gearbox are from the BLAustin Maxi being one of the few

mainstream cars sporting a 5speed gearbox at that time.These gears were installed in aLotus designed aluminium cast-ing.

A new input and output sectionwas designed by Lotus to convertthe original transversely mountedMaxi gearbox internals to its newinline position.

Not fragile

The Lotus 5 speed gearbox wasoriginally intended for and used inthe quite heavy new Elite (2240

lb/1016 kg) with its powerful 2 litre16 valve type 907 engine devel-oping 160 HP, all of which whendriven in anger took the stresseson the gearbox close to its limits.

This might be the reasonfor the reputation of the gearboxof being somewhat fragile.

In a 1558 ccm, 126 HP and1540 lb/700 kg Elan Sprint loadsare immensely reduced comparedto the Elite.

One of the above mentionedlast 3 original 5 speed Elan

Sprintsproduced in

1973 wasactually

exported to Denmark and boughtby Mr. Claus Gaarde; a long timeDanish Lotus enthusiast. Clauscould inform me, that he afterrebuilding the gearbox himself in1984 to the latest specifications drove 150 000 troublefree kilome-tres with the box behind a slightlyuprated 140 HP Twin Cam en-gine. Claus kindly lent me all histechnical information (parts list,service manual and service bulle-tins) on the box. Claus also had anearly complete gearbox as spareparts, which I was invited to ex-amine.

After going through all this in-formation I could see no reasonwhy a Lotus gearbox should notbe able to work satisfactory in mySprint as well.

Elite and Elan versions

The version of the gearbox usedin the new Elite has a longeroutput section and the clutchhousing has a different engineflange compared to the version ofthe 5 speed box used in the Elanand Elan +2. But the centralgearbox section carrying the

gears is the same on the Elite andElan variants.

Prices

Elite Lotus 5 speed gearboxesare obtainable for realistic money,due to them being frequentlyswapped for the later used Getrag5 speed gearbox for improvedreliability. Only the mid gearboxsection can be used from theseElite versions, though. The Elanneeds to use a clutch housingwith a Twin Cam engine flangeand the short gearbox outputsection which has the gear leverplaced in a position as far forwardand as close to the central gear-

box housing as possible. Both theclutch housing and the outputsection are unique to the Elan

version, and unfortunatelythese parts are no

longer availablefrom Lotus. There-fore quite stiffprices varyingbetween 750and 1500 are

asked for E lan +25 speed gearboxes

depending oncondition. Actually you are

paying these prices only for the

clutch housing and for the outputsection, because the centralgearbox section carrying thegears can as mentioned earlier be used directly from the Elitegearbox, which should be

possible to get for 100 to 250depending on condition.

Output housings: At topfor Elan and below Elite

When buying an Elan 5 speedgearbox remember to get thepropshaft with integral sliding

spline at the gearbox end and thegearbox mount too, as theseparts are unique to the Elanversion as well.

Top: Ford N/9

Middle: Ford MT 75Bottom: Alfa Romeo

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My own way to the Elan 5

speed gearbox was to put an adin Club Lotus News. For 1100 Iended up buying a dismantledgearbox with a couple of newgears and with the convenientpossibility to inspect the boxsinternals too. My intention was todisassemble and renovate thegearbox anyway.

However this appeared tobe no cheap experience. Buttake it as a hobby, considerwhat other people spend ontheir hobbies (what did yourwife spend on shoes lately?)and enjoy the originality of theconversion which is done justlike Lotus did. If done prop-erly, it should raise the valueof your car too.

Equipment

To carry out the conversion it isnecessary to have good work-shop experience, to be patient,and to use plenty of commonsense.

You should have access to ahydraulic press and have com-mon workshop tools. It is

also necessary to be able tomake up a couple of special partsand tools to get the job doneproperly. You should get hold ofthe original section F from theElan +2 workshop manual and allthe Lotus service bulletins regard-ing the 5 speed transmission. Itwill be of great help to you, if youhave a parts list, too.

On that basis you should beable to make a well functioning 5speed gearbox and even enjoyingthe pleasure of doing the jobyourself.

Lotus vs. Ford box

The Elan is normally equippedwith a Ford gearbox first used inthe Ford Corsair 2000E. Henceits often referred to as the Ford2000E gearbox. This gearboxweighs 33 kg with its cast ironclutch- and gearbox housing. TheLotus box weighs only 27 kg withits aluminium housings. By fitting

the Lotus box you are addinglightness to your car, just asColin Chapman prescribed.The gear ratios of the first 4

gears are nearly the same in theFord 2000E and in the Lotus box:The biggest difference is foundbetween the ratios of the 1

st

gears; the Lotus boxs 1st

(1:3,20)is 7% lower the Ford boxs 1

st

(1:2,97) giving a slightly easier

and less clutch stressing startfrom stand still with the Lotus box.The other ratios are the same

within 3%, a difference you willhardly notice. In top gear at 130km/h revs drops form 4600 rpm inthe (Ford) direct 4

thgear to 3700

rpm in the (Lotus) 1:0,80 ratio 5th

gear, giving a very useful 900 rpmdrop and reduction in the noiselevel on longer journeys. Thelayout of the Lotus 5

thgear as an

overdrive is confirmed by thegearknob badge: 1 2 3 4 O/D.

Numbers and markings

In the bottom of the gearboxhousing a series number isstamped.

Some of the gearbox housingswere machined to odd tolerances,and were fitted with oversizebearings, which are no longeravailable. These boxes are identi-fied by OS stamped beside the

series number. Try to avoid theseboxes as they are more difficult torebuild.

From series number 1492 andon the angle of synchromesh on1

stand 2

ndgear is changed from

5 to 6 to improve synchromeshlife and action.

From series number 2174 andon a nice trust needle roller bear-ing for the 1

stspeed gear and an

accordingly revised 1st

speed gearis used.

From series number 2016 andon a smaller roller bearing is usedat the rear end of the counter-shaft. In my opinion a slightlyretrograde step.

Design changes

Beside the above mentionedchanges an important change ofthe odd narrow, large outer di-ameter ball bearing at the inputshaft was made. It was changed

for a much stronger standard sizeball bearing with a ring to com-pensate for the slightly smallerouter diameter. This changegreatly enhanced the rigidity andlocation of the input shaft, and thelifetime of the input shaft bear-ings. If your gearbox does nothave this modification, you canmake it yourself, if you have

access to a lathe. To make roomfor the wider bearing you willhave to spigot the input shaftslightly and deepen out therecess in the input housing.

Elan propshaft with inte-

grated sliding spline Input shaft

Top: New strong ballbearing + ring

Bottom: Early narrowball bearing

To improve lubrication of

the needle roller bearingbetween the 1

stmotion and

the 3rd

motion shaft, two holeswere introduced in the 1

st

motion shaft radially throughthe land beside the teeth ofthe gearwheel.

If your input shaft does nothave these lubrication holes, youcan drill them yourself. Grind offthe hard surface with a smallstone in a Dremel or equivalent,making a slight grub, buy a nor-mal 3 mm brick-wall drill, grind itsside down to 2,5 mm, and you areable to drill through the rather

hard steel using a little oil forcooling. Much cheaper thanbuying a new shaft with holes

for 150. Remember to carefullygrind off the sharp edges, notdamaging the bearing surface

inside the 1st

motion shaft in theprocess.

Vehicle speed

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 eng. rpm km/h

Lotus 1000 9 14 20 28 35 8Ford 1000 9 14 20 28 - 8Lotus 6500 57 91 133 182 229 53Ford 6500 61 91 130 182 - 55

1st

motion shaft puller2,5 mm lubri-cation holes

3rd

motion shaft support Bearings

The gearbox contains 4 ballbearings, 3 roller bearings and 5needle roller bearings. They areall of RHP or Torrington origin.

Only 2 ball bearings and 4 nee-dle roller bearings are standardcatalogue items, the other 6bearings are special.The way to get hold of all the

bearings is to contact a bearingspecialist company with the right

UK contacts. Provide the list ofthe bearings, and they should beable to source them all for you.The 6 special bearings will not

be cheap. Be prepared to pay inthe region of 500 for all of the12 bearings.

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Modifications

Selector shaft finger

The standard selector shaft fin-ger has round sides, which gripinto the selector forks square cut-outs with straight sides. The 3

rd/4

th

selector fork is made of brass andhas narrowed down sides. Con-sequently the sides of the selector

fork cut-out are deformed leadingto a sloppy gear change.The solution is to make up a

selector finger with a square headand straight sides just like theselector fork cut out, which it grips

into. Make the revised finger froma piece of Uddeholm Arne steel,which can be hardened and

tempered to the right strength andhardness. The selector shaft ismodified to take the now Allenscrew secured selector finger.

Lever pivot

The lever for the 5th

gear andthe reverse gear is secured at itspivot point with a tiny circlip whichis reported to easily slip off. Thesolution is to make up a new pivotpoint and securing system of a

turned down M10 bolt of 8.8 steelquality. This bolt is secured by aM6 Allen screw. By tuning thetolerances it is now possible tohave a secure and free turningpivot without sloppiness.

Selector line up

The cut outs in the selectorforks and in the 5

th/rev. lever

should be aligned in neutral;otherwise the gear lever cannotbe moved across the gaiter freely.In my case the cut out in the

5th/rev. lever was about 0,7 mm

out of line. This was compensatedby making up new retainers (seedrawing position 18) for the inter-lock plate with 0,5 mm eccentricholes and threads. It was nowpossible by turning the retainers

to move the bracket with the5

th/rev. lever until its cut out was

aligned with the selector fork cutouts.

Support ring

The input shaft and the 1st

mo-tion shaft are mated with splinesaround the above mentionedheavier ball bearing and a rollerbearing. The inner ring of theimproved ball bearing only sits onthe spigotted end of the inputshaft. The alignment of the matedshafts to the ball bearing and the

support of the inner ring of the

ball bearing can be enhanced bymaking up a support ring filling upthe remaining space between the1

stmotion shaft spline and the

inner diameter of the ball bearing.

Spacer

Put a 1mm plain washer overthe selector link pin (position 4) tospace the selector link out fromthe gearbox side. This will take up

excess sideways sloppiness inthe gear lever when it is in the1

st/2

ndgear position.

Offset gear lever

An offset gearlever should bemade up like the lever used onthe original 2000E 4 speed gear-box, but the offset should be tothe front instead to the rear. Thereason for this is that the gearlever from the Lotus box comes

up through the tunnel in a rear-ward position in relation to the cutout in the tunnel and the tunnelconsole. This is compensated forby making up a new gearstickwith an offset rubber bush house,with the gearlever welded to thefront of the bush housing. Theoriginal gearstick is disassembledat the concentric rubber damper,

the lower gearstick part is care-fully straightened, a M10x1 threadis cut at the end of it, the conical

rubber spring is cut down, suit-able spacers made up, and thenew forward offset gearlever

can be assembled. The rubberbushing used is a part from the

rear suspension A-arm outerbushing. The mounting of the new- disassembled - gearlever to thegearbox is now much easier too.The photo should give the generalidea.

Gearbox mounting plate

According to Lotus fitting in-struction the gearbox mountingplate for the Lotus box should bemounted to the chassis in holesdrilled in new positions. I pre-ferred to make up a new gearbox

mounting plate which made itpossible to use the existing holesin the chassis instead.

modified

original

Gearbox mounting plate

Concentric slave cylinder

The clutch originally uses anoutside mounted slave cylinder,too close to the exhaust manifold.On hot days and in town trafficthis situation often leads tocooked clutch fluid and a mal-functioning clutch release.

To overcome this a SAAB 900concentric slave cylinder wasmounted inside the clutch hous-ing, doing away with a lot of themechanical parts. A console plate

was made up to take up the newclutch cylinder. The necessaryhydraulic lines, fittings and anoutside bleed screw had to bemade up too.

original

modifiedSupport ring

1 mm spacer here

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Assembly

It is wise to make a trial assem-bly of the gearbox with the oldbearings to check the functionand free running of all the parts.Shift through all gears and turnthe shafts. For my part on my trialassembly I found the input shaftbinding and loosing up for every180 turned which was tracked

down to an out of true 1st

motionshaft. I had to have a new shaftfitted!

When fitting bearings to thegearbox housing, always heat upthe housing with a heat gun.When heated, aluminium expandsthree times as much as steel.This should assure you correctand much easier fitting of thebearings.The gearbox housing should be

thoroughly cleaned before as-sembly. Nowadays ball and rollerbearings are dimensioned notonly by the loads, but by the

cleanliness of the lubricant aswell. Even the smallest amount ofdirt can greatly reduce the life-span of your expensive bearings.It pays well off to be thorough.

When tightening the big nuts atthe 3

rdmotion shaft and on the 2

nd

motion shaft, the workshop man-ual says that you should put thegearbox in 1

stand 3

rdgear at the

same time, locking up the gear-box. I would advise you not to usethis method, because you putimmense loads on the gear

teethes and the shafts. Insteadtake a surplus synchroniser collarring and have it bolted up in a toolwith a lever arm. This tool can beused to carefully hold back the 2

nd

motion shaft on the 5th

gear syn-chroniser mechanism while tight-ening down the nuts, withoutoverloading the gearbox.The baulk rings can present a

slight problem, as they have to be

of the correct angle, which asmentioned earlier was changed. Itshould be possible to feel if thebaulk ring fits properly to the coneof the corresponding gear wheel. Ihad to go through a couple of setsbefore I had a full set of the cor-rect angle baulk rings.To eliminate the risk of the

bearings rotating in the gearboxhousing when the gearboxreaches working temperature, ordue to bad tolerances, always useLocktite bearing securing fluid. Becareful not to drop Locktite intothe bearings.

All bolts and nuts should besecured with Locktite for bolts,especially the long Allen boltsecuring the input shaft to the 1

st

motion shaft. It is critical if it worksloose. But it wont if you arecareful.

Generally, Locktite only workswhen the surfaces are clean andfree from oil and grease.The sealing compound to use

on the gaskets is Hylomar or anequivalent not drying up RRspecification sealing compound.

Be sure to use a magnetic bot-tom drain plug to catch steeldeposits from the oil. I ended upusing one from a Triumph Spitfiregearbox as it was NLA fromLotus.You will need an approx. 15 cm

longer speedometer cable. Acable specialist firm should havethe answer to that.

Otherwise do exactly as stated

in the Lotus workshop manual,and be careful to keep the speci-

fied tolerances. They are of greatimportance to the function andshift quality of the gearbox.

Use the best synthetic gear oilyou can get, for instance CastrolTAF-X. The gearbox will take 1,7litre.You should now be able to en-

joy motoring in your Elan evenmore when cruising long dis-tances in 5

thgear!

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Acknowledgements

This project could not be tack-led without invaluable help frommany friends and specialists:

Nick Abbott at the Bull andButcher in Turville sold me thegearbox, provided a nice meal, apint of Breakspears bitter and bedand breakfast on my visit to col-lect the box in England.

Pat Thomas at Kelvendonsourced a much needed new 1

st

motion shaft.Paul Matty Sportscars sourced

a brand new 5th

gear pinionamong numerous other importantbits and pieces.

Alan Voight supplied many NLAitems.

Michael Taylor sold me a niceused Elite gearbox, a new inputhousing, not to mention finding agearknob with the all important1-2-3-4-O/D shift pattern badgeto enjoy.

Murray Valentine, Australiakindly sent me his absolutelythorough an detailed 10 pagedescription of how to fit an Alfa 5

speed gearbox in an Elan (youwill have to cut a little in the chas-sis and move the engine andgearbox a bit forward. It has beendone a couple of times with goodresults and its not expensive).

Claus Gaarde supplied hiscomplete Lotus literature on thesubject and the opportunity tohave a thorough look at the hard-ware.

Peter Kjul, Niels J ohansson andHenrik Andersen provided knowl-edge of material and heat treat-ment for the selector shaft finger,

sourced all bearings and weldedthe balancing weights properlyonto the propshaft.Torben Valerius provided the

possibility to have some gearboxsurfaces cleaned up in a big latheat his disposal.

Frank Thrusholm - last but notleast - took the trouble to read theproofs on my ramblings.

Thanks to you all!

Lotus 5 speed gearbox bearings

Pos. #drawing

Qty. Bearing Make TypeInner di-ameter

Outerdiameter

WidthWidth of.flange

Outerdiameter of

flange

4 1 Ballbearing RHP 6207 35 mm 72 mm 17 mm - -

5 1 Rollerbearing with flange RHP 17LRJ 30 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 andaksialneedlebearing with

innerbushing

Torrington TE-160-680 27,15 mm 40 mm 35,3 mm 3,9 mm 55,55 mm

23 1 Ballbearing with recessin outerring

RHP 2LJ 11/16 1

1/16 68,7 /

59,5 mm12,6 mm 8,5 mm -

24 1 Rollerbearingwith different with ofinner- and outer ring

RHP 14RJ 11/16 1

1/16 68,8 mm 16 / 12 mm

(innerring /outerring)

- -

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

41 1 Rollerbearing RHP 1DXXLLRJ B30 30 mm 55 mm 25 mm - -

45 1 Ballbearing,double with flange

RHP 3LDJ T20 20 mm 47 mm 20,5 mm 4 mm 52 mm

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 - -

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Lotus Elan 5 speed gearbox shafts, bearings and gearwheels