lotus gearbox 5sp

PostPost by: oligoni » Tue Sep 27, 2022 12:29 pm

Hello,
By chance , I have The gearbox 5 sp # 165.
The former owner told me : sometimes I have to do the double clutch !!!
I thoroughly cleaned the gearbox.
Before mounting it on my + 2 130s (1974), I would like to be sure that it is working properly.
On youtube, I found a series of very well done videos on the subject.
but, it is a 1976 Elite gearbox. https://youtu.be/7UzvAcUsaHA
The main body of the box is really similar.
Can you confirm this?
And if so, does anyone have a copy of the workshop book (gearbox)?
Thanks ,
Olivier
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PostPost by: nmauduit » Tue Sep 27, 2022 1:34 pm

Hello Olivier,

there is an interesting article you can find on the Golden Gate Lotus website : https://www.gglotus.org/ggtech/elan-5spd/elan-5spd.htm (nb: if your gearbox is an early one, it is likely to have the narrow bearing which was upgraded later, you may want to consider that while it's out).

I sometimes do have to "double clutch" to engage 1st when standing still, or rather engaging second then first when standing still. And I'm still experiencing difficulties to disengage from 5th when hot (sadly my gearbox was "overhauled" by one of the usual suspects, rather poorly, I now sure know better than trusting away when in a rush...)
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PostPost by: mbell » Tue Sep 27, 2022 6:24 pm

I've not watched the videos (yet) but the Elite/Eclat is the same basic box apart from:
1) Different tail housing
2) Uprated input bearing
3) Changed angles on the synchro 's and other minor changes (oil drilling on gears etc)

The rebuild process is the same.

It could be worn synchro's or something unrelated like badly adjusted/functioning clutch. You need to decide whether just to clean it, filled with some good oil (e.g. Redline MTL/MT90), fit it to the car and try it out. Or spend some money and rebuild it now.

I've changed the forth gear synchro on mine successfully and have little to no gearbox experience. It the second easiest one to change and requires specialized tools to get it apart. See:
viewtopic.php?f=37&t=50390&p=370099&hilit=+tools#p370099

nmauduit wrote:I sometimes do have to "double clutch" to engage 1st when standing still,


Same on my gearbox. Which I believe has had recent (miles wise) rebuild before I got it, but that also had other major issues.

nmauduit wrote:And I'm still experiencing difficulties to disengage from 5th when hot


You likely need to reduce the preload on the 5th gear detent, this is one of the few things that can be done with the box in place. You remove the dome nut and then add extra copper washer or change the spring. This reduces the effort, but can still be stiff.
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PostPost by: oligoni » Tue Sep 27, 2022 7:30 pm

Thank you . nmauduit , mbell , Rdracer,

Your answers reassure me and will help me in the difficult way of restoration.
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PostPost by: nmauduit » Wed Sep 28, 2022 12:25 pm

mbell wrote:
nmauduit wrote:And I'm still experiencing difficulties to disengage from 5th when hot


You likely need to reduce the preload on the 5th gear detent, this is one of the few things that can be done with the box in place. You remove the dome nut and then add extra copper washer or change the spring. This reduces the effort, but can still be stiff.


Thank you for your reply: I've been experimenting a bit along that line, and just recently added a 3rd (!) alloy washer, which I consider the absolute maximum before shortening/swapping the spring (which shows some signs of having been ground in the past, possibly a dirty fix from those who "overhauled" the box ?) - on that topic I also noted that the plunger itself had a machined flat side (rather than cylindrical - I suppose thie is ok) but more importantly a rather sharp V-shapped locking tip (rather say a spherical dome of sort): is this stock or could this make it lock harder than designed for ?
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PostPost by: mbell » Wed Sep 28, 2022 7:25 pm

nmauduit wrote:I also noted that the plunger itself had a machined flat side (rather than cylindrical - I suppose thie is ok) but more importantly a rather sharp V-shapped locking tip (rather say a spherical dome of sort): is this stock or could this make it lock harder than designed for ?


I don't think I paid a lot of attention when messing with mine, the plunger might not even have come out. I do think you are correct that it is quite sharp V shape thou.

So maybe changing the shape might also lowers the effort. I know that balls or ball shape heads are commonly used. I guess the only risk is it getting stuck in 5th, popping out of gear or the new part gets stuck. Not sure if there is an off the shelf one available from a different box that could be used or if you need a lathe to make one up.
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PostPost by: gwiz22 » Mon Oct 03, 2022 9:31 pm

Hi Mbell
I had the same sticking in 5th problem. I drafted a piece for Club Lotus at the time. It's attached. I hope it helps.
Graham
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5 Speed Gearbox Mod.doc
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PostPost by: nmauduit » Tue Oct 04, 2022 12:34 pm

gwiz22 wrote:Hi Mbell
I had the same sticking in 5th problem. I drafted a piece for Club Lotus at the time. It's attached. I hope it helps.
Graham


Thank you for your input, looks like this refers to a dome type detent (while mine is inverted V shaped), I'll try to experiment with a dome type when I get a chance (I had the car off to a track day this sweek-end, but did not get to try the 5th as I took it there on a trailer)... My washer stack being now of 3 high I won't add any more (would rather swap or shorten the spring). All this can be done without draining the whole box, only a couple spoons being lost when taking the domes nut off.

Mbell : getting stuck in 5th because of a plunger/detent too strong should easily enough be resolved by undoing the bottom domes nut I suppose, so trials and errors along that line is not overly time consuming. Looks like I'm going to take the gearbox off one of these days, so I may investigate further when that time comes.
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