Lotus Elan

5 Speed box: A little bit of the old "Vince Reynard magic"..

PostPost by: vincereynard » Fri Aug 23, 2019 7:28 pm

I think there may be some confusion creeping in here between the 5 th/ Rev Gate protection plunger (and spring) and the 5th/Rev detent.
912-aug.-23-20.16.jpg and


A - is Jon's third mod.
It can only be access with the box out (far as I know) otherwise the chassis is in the way. It prevent inadvertant selection of 5th / Rev.

B - is Jon's forth mod.
It stops 5th jumping out (on the overrun). It can be easily access under the box via the big domed nut.
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PostPost by: JonB » Fri Aug 23, 2019 8:19 pm

McMaster replied to my query:

Hi Jon,

Thank you for considering McMaster-Carr for your purchase. However, we will not accept orders from your facility due to the cost of complying with US export regulations.

Aaron


Didn't know simple compression springs were on the US embargo list. Pretty unimpressed. :evil:
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PostPost by: Mick6186 » Sat Aug 24, 2019 7:15 am

On my 5 speed I thought I would remove the Bush in the gearstick and weld it up to make a more positive change. This resulted in a noticeable increase in noise transmitted so I went back to a stick with a Bush. Much better,
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PostPost by: nmauduit » Sat Aug 24, 2019 7:54 am

vincereynard wrote:I think there may be some confusion creeping in here between the 5 th/ Rev Gate protection plunger (and spring) and the 5th/Rev detent.
912 Aug. 23 20.16.jpg


A - is Jon's third mod.
It can only be access with the box out (far as I know) otherwise the chassis is in the way. It prevent inadvertant selection of 5th / Rev.

B - is Jon's forth mod.
It stops 5th jumping out (on the overrun). It can be easily access under the box via the big domed nut.


thank you for the clarification : I was thinking along the line of spring B... though the symptom being that I have a hard time disengaging the 5th, esp. when the gearbox is hot (highway...), rather than jumping out. Said gearbox has been overhauled by a usual s..... (rather than someone who knwos what he is doing, I still curse myself every time for my ignorance back then), I already have added a washer, without a drastic difference, I did not want tu push my luck with too many washers and risking stripping the threads... Do you think it's worth trying to swap the spring for a weaker one, or rather to take the gearbox out for a proper inspection (esp. slot alignement), scheduled down the road, but not just yet ?
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PostPost by: JonB » Sat Aug 24, 2019 8:38 am

Well you know the thread on the dome nut is quite long, so try adding a couple more washers first. Or just undo it a bit at a time and check the action with the car in the garage. I was a bit hasty and cut 1/4 inch off the spring (way too much) so it was jumping out of 5th. Fortunately the bit I cut off wasn't lost so I was able to restore it by pushing both parts into the hole. :roll:
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PostPost by: nmauduit » Sat Aug 24, 2019 10:56 am

JonB wrote:Well you know the thread on the dome nut is quite long, so try adding a couple more washers first. Or just undo it a bit at a time and check the action with the car in the garage. I was a bit hasty and cut 1/4 inch off the spring (way too much) so it was jumping out of 5th. Fortunately the bit I cut off wasn't lost so I was able to restore it by pushing both parts into the hole. :roll:


I'll try one more washer then - but in the garage or cold it's stiff but more or less fine, it's more when hot that it does not disengage easily, which is why I'm suspecting something more...
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PostPost by: c.garde » Sun Aug 25, 2019 10:03 am

Hello gent and nerds,

Just returnet from sunny Tuscany I read this discussion with interest.
Allow me to chime in:

I discussed the issue concerning strong dome spring more than a year ago. I am sure that this can still be found.
As I recall I ended up reducing the preload and rate with about 30 %.
This included mods. both of length/ ? of spring and elongation of dome nut.
All in all not very systematic.
An easier approach might be to find a shorter and weaker spring . Supporting this with spacers as necessary will make it easy to find the balance.
Lotus modified the retaining cuts in the shaft at a later date. ( I had already done this during my first rebuild, that is before BL and lotus introduced this new shaft )
This will of course have an impact of the jumping out issue and can only be addressed during rebuild..
As I concluded these modifications resulted in a whole new. experience. with a much more consistent weight of gearshifts. - and still no jumping out , nor unwanted engagements.
Allow me to recommend Victor Hollnagels discussion .
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PostPost by: vincereynard » Sun Aug 25, 2019 2:58 pm

c.garde wrote:Allow me to recommend Victor Hollnagels discussion .
Best regards c.garde


+1 for that. An essential read for 5 speed box fans.
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PostPost by: john.p.clegg » Sun Aug 25, 2019 7:54 pm

But do not follow .

".Modifications
Selector shaft finger
The standard selector shaft fingerhas round sides, which gripinto the selector fork?s square cutouts
with straight sides. The 3rd/4thselector fork is made of brass andhas narrowed down sides. Consequently
the sides of the selectorfork cut-out are deformed leadingto a sloppy gear change.
The solution is to make up aselector finger with a square headand straight sides just like the
selector fork cut out, which it gripsinto. Make the revised finger froma piece of Uddeholm ?Arne? steel,
which can be hardened andtempered to the right strength andhardness. The selector shaft is
modified to take the now Allenscrew secured selector finger. "

...as you will lock-up the 5th/Reverse selector...

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PostPost by: JonB » Sun Aug 25, 2019 8:31 pm

vincereynard wrote:
c.garde wrote:Allow me to recommend Victor Hollnagels discussion .
Best regards c.garde


+1 for that. An essential read for 5 speed box fans.
Elan_Lotus-Maxi_5-Speed_Rebuilding-Upgrading-Fitting.pdf


Agreed, and I did read it some time ago. Some of the mods I have done as you can see, and some not (mostly because I lack the tools and / or confidence to pull the box apart). What else can I do to improve it without full on disassembly?

For example: I'd love to fit a concentric clutch slave, but I do not know how to make up the plate to mount it on. Hollanger just says "A console plate was made up to take up the new clutch cylinder." Nice for him I suppose but not so easy for the rest of us? Anyone know where I could get a plate?
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PostPost by: vincereynard » Sun Aug 25, 2019 10:29 pm

I must admit I did not find your clutch particularly heavy Jon.
Well I did not notice it, so it must have been OK.

Search the forum , I'm sure it has been a topic before.
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PostPost by: JonB » Mon Aug 26, 2019 7:51 am

I've asked about the clutch before, Vince - after I measured the weight needed to depress the pedal at 23 kilograms. There was a consensus around the springs in the pressure plate hardening over time, so I bought a NOS plate to be fitted when the box goes back in. I did check master and slave cylinders to make sure they are the correct bore (they are), and I asked about the concentric clutch mount plate but there were no replies. Unsurprising as it is a very specialist part.

One thing that made a huge difference to the feel of the clutch was the replacement of the pipe with a braided pipe. This cured the stickiness and freed the action up a bit, but it's still heavy. I recall you posting on the inadequacies of the standard actuating lever. There's a picture where you show how the ideal placement of the pivot is so far off its actual position - third shot down:

viewtopic.php?t=39331&f=37&start=15#p274366

That's one of my "reference threads" by the way. :D

[edit, after some searching about]

  • kstrutt1 said (on the subjkect of the Saab slave cylinder support plate) "my drawings should still be in my folder in the files section". This in an archive post viewtopic.php?t=7155&f=16&start=0#p30139 - where's the files section?
  • nmaudit discusses fitment of a concentric cylinder here: viewtopic.php?f=37&t=32719 - some talk of getting additional plates made up but no actual news, plus some additional machining required on the gearbox? So perhaps not a bolt on modification?
  • My thread where I first asked about the plate: viewtopic.php?f=37&t=42331 (unsuccessfully as it turned out)

    So for me, not having access to a lathe, the problem is acquiring the mounting plate.
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PostPost by: nmauduit » Mon Aug 26, 2019 8:28 am

I did a concentric clutch adaptation based on the Hollnagel paper for my street S4, mostly for reliability purposes in my mind. I wanted a 100% reversible mod just in case, so did not modify the front lid of the gearbox to hold the concentric clutch, so used a machined a plate with the same bolt holes to that end. Total thickness was calculated and adjusted with a blank mounting so that the travel of the concentric clutch could accomodate disk use with some margin on both sides, it was quite straightforward actually (maybe I was lucky). I opted for a Saab 900 clutch ($50), but there are other parts out there fror the same purpose (Titan, Burton ... no affiliation, not tested by myself). The pedal is quite firm though (and rather binary, in that it engages on 10-15mm from what my foot remembers), but I have installed an heavy duty clucth (170+ ft.lb holding torque, just in case...). Maybe the master cylinder could be swapped for a longer, softer pedal...

viewtopic.php?f=37&t=32719&p=220424&hilit=concentric+clutch#p220424

Image

[edit, after reading the edit above]
So for me, not having access to a lathe, the problem is acquiring the mounting plate.


it's been 5 years now, I don't recall all the details - one forumer asked me then if an extra plate/setup could be machined for him, I checked and it could then, but now my machinist would have forgotten the details and most likely has not kept his notes, so a check on engine + gearbox would be needed for proper fit. I would think it is quite likely one should use the services of a machine shop (lathe) or well equiped friend workshop to ensure proper fit :

Image

in my case a bit of turning was done to ensure registration of the slave clutch to the plate. The tube seen on the photo is pressed out for installing the concentric slave insead.

If lost in the jungle one always can do a lot with a file, a vice, a square and caliper... but for my pride and joy I went to the solution that seemed most reliable at the time.
Last edited by nmauduit on Mon Aug 26, 2019 9:05 am, edited 3 times in total.
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PostPost by: JonB » Mon Aug 26, 2019 8:43 am

nmauduit wrote:I wanted a 100% reversible mod just in case, so did not modify the front lid of the gearbox to hold the concentric clutch, so used a machined a plate with the same bolt holes to that end.


Do you mean to say the concentric slave could be fitted direct to the gearbox by virtue of tapping some bolt holes in the front face?

Do you have any drawings showing the dimensions of your mounting plate?

The pedal is quite firm though (and rather binary, in that it engages on 10-15mm from what my foot remembers), but I have installed an heavy duty clucth (170+ ft.lb holding torque, just in case...).


I suppose it would be better with a standard clutch. How heavy is yours? I measured the weight required to depress my clutch by using a piece of timber. Put one end on the clutch pedal, and use a suitcase weighing gadget hooked to the other end. Then pull the gadget and read off the weight registered when the pedal moves. Doing this I got 23Kg.
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PostPost by: nmauduit » Mon Aug 26, 2019 8:58 am

JonB wrote:Do you mean to say the concentric slave could be fitted direct to the gearbox by virtue of tapping some bolt holes in the front face?

Do you have any drawings showing the dimensions of your mounting plate?


my saab 900 clutch is held to the adapter plate by the small allen screws (I think I remember I rotated it a bit to make sure the bleeding port would be on top at an angle, so extra holes were made and one shows on the photo), the big allen screws are attaching the adapter plate on top of the original cover, with small columns in between to transmit the clamping pressure.

the stock setup shown on Vince's photo shows the tube that needs to be taken out (press fit) - in my case I think a true flat was machined on the cast stock cover where the tube exits, as well as a registering diameter for better locating the slave, the adapter plate fitting around the stock cover, and clamping pressure goes through the 4 small columns between the back of the adapter and the stock cover. Actual slave longitudinal location comes mainly from adapter plate thickness (17.1mm + plate thickness is the total setup thickness, the 17.1 being the result of fitting the plate to the stock cover after registration machining).
Image
If I want to reverse the setup I'd need to press back the original tube into the cover (probably glue it as well, press fit was not very strong iirc).

no drawing or dimensions, only what was documented on my post on the forum then (I don't recall the thickness of the stock place, but rather than a hefty block it was decided to use a plate and 4 columns, 17.1mm long, to get the clutch bearing at the right location

JonB wrote:I suppose it would be better with a standard clutch. How heavy is yours? I measured the weight required to depress my clutch by using a piece of timber. Put one end on the clutch pedal, and use a suitcase weighing gadget hooked to the other end. Then pull the gadget and read off the weight registered when the pedal moves. Doing this I got 23Kg.


I suppose also - I opted for the Helix heavy duty (QED supplied it - no affiliation) as I wanted all chances on my side for a durable solution.

I find mine ok except after 1 hour of stop and go in traffic jams... for these I eventually got the habit of doing a lot of 1st/neutral/1st gear changes, so that I don't need to hold the pedal for too long. I haven't calibrated the pedal pressure, car is away for the moment - I may do it for curiosity
Last edited by nmauduit on Mon Aug 26, 2019 12:32 pm, edited 1 time in total.
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