Lotus Elan

Changing gearbox

PostPost by: Gasman » Wed Jul 19, 2006 7:57 pm

Dear all
I'm fed up with my crunching synchro's so have decided to change to a four speed box.
A few questions
I know the clutch plate is different but do I have to change clutch cover as well?
I'm getting my propshaft balanced etc but aim to leave the differential in place (for obvious reasons) are they all the same or more importantly will my speedo remain approximately accurate; probably doesn't matter anyway.
Comments tips etc very welcome


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PostPost by: MintSprint » Wed Jul 19, 2006 8:51 pm

I assume it is an Elan Plus 2 with the Lotus 5 speed box that you are converting to a 4 speed?

I thought the propshafts were different length anyway, so not much point getting your old one balanced, as it won't fit!?

There is a Lotus Parts Bulletin listed under the technical section of the LotusElan.net website that gives the list of parts and a procedure for conversion from 4 speed to 5 speed. Since you're basically reversing this process, I'd have thought that if you read the procedure backwards and refer to the list of parts required, you won't be far off.
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PostPost by: types26/36 » Wed Jul 19, 2006 10:19 pm

Gasman wrote:I know the clutch plate is different but do I have to change clutch cover as well

I fitted the 8.5" clutch plate and pressure plate to my S2 (four speed) and as far as I know these are the ones used with the 5 speed.
The four speed (8" clutch) has a thrust ring fixed on the diaphram fingers and uses a release bearing with a flat face.
The 8.5" pressure plate does not have the thrust ring on the fingers and uses a release bearing with a rounded face.
I was under the impression that the 8" clutch plate and the 8.5"(5 speed) use the same splines on the spigot shaft and it worked but I have read comments that they are not the same.
All I can say there is that it worked for me.
64 S2 Roadster
72 Sprint FHC
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PostPost by: john.p.clegg » Thu Jul 20, 2006 6:01 am

When I changed to 5-speed,my milometer became more accurate (within 1/10 mile in 20 miles) and so suppose my speedometer the same...maybe the reverse in your case?
As for the diffs,no problem there.
Yes the clutch actuating mechanism,bearing,carrier pressure plate etc.etc are different-hopefully you will have all that together in the bellhousing prior to the changeover.....

John :wink:
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PostPost by: sk178ta » Thu Jul 20, 2006 12:22 pm

I have the Lotus 5 speed in my `67 S3 Elan but it`s b******d so I`m switching to a Voight T5. The gearbox will be for sale in 2 weeks. Though needing a rebuild, it`ll only drive in 4th, all the stuff for the conversion is there: bracket, altered propshaft, cluth and cover etc. ?500
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PostPost by: alaric » Thu Jul 20, 2006 9:18 pm

From my experiences with swapping my 5 speed maxi box to a T9, I think the differences are:

    thrust bearing - rounded face on 5 speed, flat on 4 speed
    diaghram spring - has thrust plate fitted in 4 speed case to match the flat thrust bearing
    spigot bearing - the 5 speed input shaft is shorter than that on the 4 speed box, and uses a spigot mounted in an insert in the flywheel - just tap the insert out of the flywheel and use the spigot bearing in the end of the crank shaft - or fit one if it's not there.
    prop shaft - the 5 speed has a sliding spline and a flange at both ends, the 4 speed has a spline that pops into the back of the gearbox. I believe the propshaft on the +2 is about a foot longer than that on the baby elan.
    not sure about the clutch actuating mechanism - never seen the 4 speed version
    clutch plate - the spline on the input shaft is different I believe

Hope this helps. Apologies if the list is incomplete.

I'm still waiting to build my car after the restoration of the bodywork, so can't vouch for the t9 conversion yet. Worth looking at though, but more expensive than a conversion to a 4 speed, and frought with its own set of problems.

All the best.

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PostPost by: Matt » Fri Jul 21, 2006 9:24 am

I'm going to change my 4 speed to the Voight T5 box over the winter.

Any one know if they feel as good as a 4 speeder ?

Let us know how you get on with it in your S3 Jim

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1972 Europa TC
1973 Elan +2 s130/5
1978 Esprit S1
1981 Esprit S2.2
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PostPost by: thor » Sat Jul 22, 2006 9:40 am

I seem to remember being given some advice on a simple solution to sharpen up the feel of my mushy 5-speed box, can someone enlighten me here? involving removal of some rubber joint at the base of the gear stick and subsituting it with aluminium, or something along those lines...
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PostPost by: stuartgb100 » Sat Jul 22, 2006 1:28 pm


I seem to remember a post ( one of Rohan's, I think ) that referred to changing the return spring for a softer/stiffer version.

I've been meaning to pm him for details, but maybe he'll chip in to this thread.

Do not know of your idea. Will be upgrading my Sprint to give it a +2's 5 speed Lotus box this winter, so any tips will be most useful.

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PostPost by: john.p.clegg » Sat Jul 22, 2006 4:55 pm

If you're taking the box apart before the swap,there are some mods you can do that make it a tighter change,and somewhere there is a whole write-up on overhauling/improving the box,someone here will know the one and be able to put their finger on it....

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PostPost by: rgh0 » Sun Jul 23, 2006 2:21 am


The 2 simple things I did with my 5 speed to improve the change (in addition to a total rebuild) was:

1. Replace the gear lever centering spring that pushes the lever out of the 5th / reverse plane with a lighter rated spring. Play with the spring rate and length until it has the right feel for you, I found the Lotus orginal spring much to heavy, prevented selecting reverse by accident but made getting 5th hard work. The spring is located at the base of the lever in the top of the gearbox on the right hand side if I remember correctly, not sure if you can get at it with the gearbox in the car as I have only changed it with the gearbox out.

2. The gear lever is held into its ball socket by a rubber bellows at the base of the lever. I spaced this belows down with washers under the circlip at its top to increase its preload and hold the lever more firmly in place. I have heard of other who have replaced it with an aluminum tube section, the Hollnagel article referred to below shows a further modified the lever to one similar to used on the 4 speed boxes.

I think the article referred to on rebuilding Lotus 5speed boxes is the one below by Victor Hollnagel a Danish Lotus club member. In it he describes in detail a number of other modifications he did to improve the box.


The other thing to be aware of with these boxes is that the clutch plate can hang up on the input shaft and not properly release. If you have problems selecting first gear when stationary you may have this problem. You need to machine a small amount of the hub of the clutch plate so it has enough axial movement on the shaft to properly release. I heard somewhere this was covered in a Lotus service bulletin but it is not covered in the bulletins listed on this site for the 5 speed box - though a lot of other useful information is.

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PostPost by: simonriley11 » Wed Jul 26, 2006 9:27 am

I had my 5 speed rebuilt by Susan Miller as 3rd gear synchro had gone, good job and reasonably priced. The change was better but still not as good as my 4 speed in my Sprint, however it was improved further by changing to the synthetic oil (can't remember the name, look at previous posts) recommended by Rohan. I would say that the change is now about 80% as good as the 4 speed and you certainly notice the improvement in refinement when cruising at 80 mph and changing between fourth and fifth.
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PostPost by: Gasman » Wed Jul 26, 2006 5:22 pm

Thanks guys

My latest theory is along the lines Rohan has suggested in that the clutch plate is not freeing itself up (not enough machined off or some swarf or a burr). Still needs engine out and a free weekend to sort it out...

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