Lotus Elan

5 Speed clutch

PostPost by: mbell » Mon May 15, 2017 2:52 pm

If it helps you're making me feel a lot better about my decision just to refit the existing clutch in my car!
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: vincereynard » Mon May 15, 2017 5:10 pm

mbell wrote:If it helps you're making me feel a lot better about my decision just to refit the existing clutch in my car!


Happy to be of service. :D

I done some measuring and calculate the flywheel should 144mm from the gearbox face.

I'll put the new bits together and see if they fit.
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PostPost by: NickD » Mon May 15, 2017 9:25 pm

The Elite front cover will work with either type of input shaft bearing. No changes were made to the main casing when the bearing was changed - the smaller diameter and thicker later bearing just had a steel sleeve fitted to increase the outside diameter from 72mm to 76.2mm. I've kept the original thin outer bearing on mine, but the later bearing is at least a readily available alternative should the thin bearing become unavailable.
The 5 speed clutch cover didn't have the centre thrust plate, but was otherwise pretty much identical to the 4 speed one. It also used a round-faced release bearing.
New Borg & Beck clutch plates used to come with a label in the box which said that the centre boss should be shortened (by 5mm, I think) to provide clearance, so this could explain the difference between a new and used plate.
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PostPost by: rgh0 » Tue May 16, 2017 11:07 am

The five speed lotus gear box / bell housing was designed without a thrust face fitted to the clutch pressure plate spring. Some of the pressure plates for a 5 speed box have a radius machined in the fingers where the round release bearing nose fits and some do not. This appears to make no difference to the clutch function.

The flat thrust face fitted to the diaphragm spring fingers was only used on the four speed box clutch assembly. This used a different flat faced thrust bearing and a different height carrier for the bearing. Mixing 4 speed and 5 speed parts leads to problems and many people including suppliers don't understand the subtleties of the differences, so your "original" installation may not have been correct.

cheers
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PostPost by: gjz30075 » Tue May 16, 2017 6:38 pm

I was thinking of reusing my 4 speed clutch (HD pressure plate with platen and appropiate throwout
bearing) when fitting my 5 speed. I wanted to use it because of its heavier clamping force.

Rohan, are you saying this arrangement won't work?

As a caveat, I should say I'll be using a modified 4 speed bellhousing with a spacer so the distance
front to back (gearbox) is the same as a 5 speed bellhousing.
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PostPost by: vincereynard » Tue May 16, 2017 7:22 pm

gjz30075 wrote:I was thinking of reusing my 4 speed clutch (HD pressure plate with platen and appropiate throwout
bearing) when fitting my 5 speed. I wanted to use it because of its heavier clamping force.

Rohan, are you saying this arrangement won't work?

As a caveat, I should say I'll be using a modified 4 speed bellhousing with a spacer so the distance front to back (gearbox) is the same as a 5 speed bellhousing.



Here is a shot of them both together. So obviously this installation did work but it was very heavy! Although this would not have been helped by having a 3/4 slave instead of a 7/8!

I shall fit it all together in a day or so at the position it will be at when fitted. Then check where the release sits and therefore the arm angle.

The new is 14mm shorter in depth so the release would be 14mm further down the dreaded tube and I am concerned it will be too close to the end. Especially as the centre protrudes further backwards.

I am working on a bellhousing "length" 200mm, does this correspond with your measurements?

Rohan, thanks for confirming that the straight fingers work the same. I was about to ask the supplier the same question.

p1050191.jpg and


BTW Grizzy gave me a NOS driven plate, but I received a new one with the rest, so if it is any good to someone drop me a PM. Freebie natch.
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PostPost by: gjz30075 » Tue May 16, 2017 7:32 pm

Vince, I'm at 190.5mm
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PostPost by: NickD » Tue May 16, 2017 7:59 pm

Vince,
So what release bearing and carrier did your existing setup use with that 4 speed cover? Was it the standard 5 speed carrier and round-faced bearing? If so, I'm surprised that there was room to squeeze it all in. Doesn't the tube actually end up going through the thrust pad and is there much clearance?
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PostPost by: vincereynard » Wed May 17, 2017 4:27 pm

gjz30075 wrote:Vince, I'm at 190.5mm


Mine is definitely - 198mm + 1/16 closer plate (1.5 mm) - Total 199.5 mm. Are you using the 5 speed flywheel? Although I have not tested it yet by putting all the bits in the correct place, I can see having 9 mm less room could cause problems.
p1050224.jpg and


NickD wrote:Vince,
So what release bearing and carrier did your existing setup use with that 4 speed cover? Was it the standard 5 speed carrier and round-faced bearing? If so, I'm surprised that there was room to squeeze it all in. Doesn't the tube actually end up going through the thrust pad and is there much clearance?


Yep, the standard dubious lash up! As the tube fell out when I upended the box I cannot be sure but I imagine it must have got through the thrust pad as there would not have been any other possibility.

As I have said before, (a number of times), considering the mess Toad was in I'm surprised it went as well as it did!
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PostPost by: gjz30075 » Wed May 17, 2017 6:09 pm

Vince, I will be using the 4 speed flywheel and I have a 4 bolt bronze input shaft bushing of which I had
the o.d. turned down slightly to provide a press fit in the flywheel. That is what I plan to use for the
gearbox input shaft support.

I mocked all this up with a spare short block and using a remote MGB pedal box which has a clutch pedal
and MGB master cylinder, I was able to work the pressure plate (withOUT the platen) and rounded
throwout bearing and achieve suitable results. However, I really want to use the pressure plate currently
in my car ( WITH the platen) and throwout bearing because of its slightly heavier clamping force. I was
hoping for enough room in the bellhousing for this.
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PostPost by: mbell » Thu May 18, 2017 12:38 am

If it helps this is what my clutch setup looks like for reference....
Attachments
20161123_154913.jpg and
5 speed clutch
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: vincereynard » Thu May 18, 2017 3:33 pm

Here is a shot of the flywheel / clutch in its fitted position 144mm from gearbox face.

p1050227.jpg and

This is where the release bearing will set "at rest". Note the damage to the tube indicating where it was with the old 4 speed cover.

p1050229.jpg and

I have had to chop about 5mm off the length of the tube as it was damaged. I am now concerned that it will be too short!

What is the maximum stroke of the slave cylinder?

Finally a shot of where it will all sit. With the 5 speed having no centre thrust, using the same lever means the pushrod attaches a bit too far back, losing mechanical advantage. Tight bludgers!
p1050233.jpg and
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PostPost by: rgh0 » Fri May 19, 2017 11:32 am

The thrust bearing carrier for the 5 speed was different to the 4 speed do you have the right one considering the wrong clutch pressure plate was used ?

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PostPost by: vincereynard » Fri May 19, 2017 1:45 pm

rgh0 wrote:The thrust bearing carrier for the 5 speed was different to the 4 speed do you have the right one considering the wrong clutch pressure plate was used ?

regards
Rohan


Who knows Rohan.

screenshot-from-2017-05-19-14-36-33.png and


However I'm told by someone more knowledgeable than myself that -
the "4" has a smaller bore to match the 2000E and smaller OD to match the carrier. The "4" carrier would have to be bored out to fit the "5" tube and a sleeve to fit the bearing.

Also, going by the depth of the bit that connects with the "D", it looks correct.

Regards
Vince
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