Lotus Elan

Rotoflex couplings - Thickness

PostPost by: Seveneer » Fri Aug 19, 2011 7:26 am

Hello
The manual says that the shafts should be fitted on the high sides of the bosses. In this way, the Rotoflex has a thickness of 46.5mm. With the central shaft properly aligned on the diff and wheel ( using some sand bags in the trunk to lower the car ! ), there is not enough space to insert the Rotoflex. Hence, a difficult work. It would be very easy however to fit the Rotoflex with the shafts on the low bosses, as the Rotoflex has then a thickness of 40mm and finds its space with no trouble between the shafts.
My question is : why must the shafts apply on the high bosses ? I see no reason why the Rotoflex would not work properly if fitted with the shafts on the low bosses. Has anyone already tried this ?
Thanks for the comments !
Louis Lempereur
Belgium
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DSCN2423.jpg and
Thickness of 46.5 or 40mm depending on assembly !
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PostPost by: types26/36 » Fri Aug 19, 2011 7:40 am

Seveneer wrote:My question is : why must the shafts apply on the high bosses ? I see no reason why the Rotoflex would not work properly if fitted with the shafts on the low bosses.


Well according to the manual the length will not be correct.
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rotoflex.JPG and
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PostPost by: nebogipfel » Fri Aug 19, 2011 7:44 am

Seveneer wrote:My question is : why must the shafts apply on the high bosses ?


Presumably that's the way the Lotus engineers designed it? :)

edit: and as Brian has kindly posted item 2 (above) :wink:
Last edited by nebogipfel on Fri Aug 19, 2011 8:21 am, edited 1 time in total.
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PostPost by: cliveyboy » Fri Aug 19, 2011 8:11 am

You gents have beaten me to answering some of the pointers but here are my thoughts:-

By fixing the shafts to the high side you are giving extra clearance between rubber and shaft. When the rubber goes into compression it will balloon out slightly and also as it is getting twisted alot this can be enough to foul on the shaft. Its probably not too much of an issue on the Elan with its three legs but if it was mounting onto a solid flange(disc) it probably would be.
I think the main issue is the position of the suspension when installing a rotoflex will be different to its position when being driven. I would asume that in normal driving conditions the rotoflex would be in a fairly neutral condition although it is being wound up hopefully there would be little misalignment. i.e the shaft flanges and rotoflex are all running relatively parallel to each other.
If you install the rotoflexs the other way around you are asking the rotoflexs to compensate for an extra 6.5mm (1/4?) of movement . That could mean the rubber is always seeing greatly increased forces in use and will wear out much quicker or the forces will simply be too much and destroy themselves straight away.
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PostPost by: cliveyboy » Fri Aug 19, 2011 12:22 pm

I have just seen Rotoflexes retailing for ?80 each.
I think there might be a lot more sets of solid drive shafts been sold in the future.

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PostPost by: Seveneer » Fri Aug 19, 2011 2:56 pm

Clive
I don't think the shaft would touch the rubber if mounted on the low bosses.
The only difference I see would be that the shaft would pull on the Rotoflex instead of pushing, ie the length would be 3mm too short instead of 3mm too long when the car is in neutral position. So, no big deal. Of course, when the car is low or jumps, then the pull on the Rotoflex would be more, as you say. May be that is the reason ?
Anyway, by taking away the steel band and replacing with a hose clamp, it is possible to adjust the diameter and fit the bolds, but what a painful job ... It took me a whole day to do one side. I was hoping to get tricks to save time on the other side !
Thanks for the good advices. My S2 is very original, and I like to keep it like that, with all its typical Lotus troubles ( noisy windows, rain water leaks, etc ... ) which are part of the fun ! I am not ready for solid shafts yet !
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PostPost by: elansprint71 » Fri Aug 19, 2011 9:58 pm

Seveneer wrote:Clive
I don't think the shaft would touch the rubber if mounted on the low bosses.
The only difference I see would be that the shaft would pull on the Rotoflex instead of pushing, ie the length would be 3mm too short instead of 3mm too long when the car is in neutral position. So, no big deal. Of course, when the car is low or jumps, then the pull on the Rotoflex would be more, as you say. May be that is the reason ?
Anyway, by taking away the steel band and replacing with a hose clamp, it is possible to adjust the diameter and fit the bolds, but what a painful job ... It took me a whole day to do one side. I was hoping to get tricks to save time on the other side !
Thanks for the good advices. My S2 is very original, and I like to keep it like that, with all its typical Lotus troubles ( noisy windows, rain water leaks, etc ... ) which are part of the fun ! I am not ready for solid shafts yet !
Louis


I'm not sure if you fitted the Rotos back to front but if you did; we look forward to reading your empirical observations.
Let us know when you submit and fit the Mick Miller shafts. :wink:
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PostPost by: billwill » Sat Aug 20, 2011 12:44 am

This topic describes my method of fitting the doughnuts; which makes it much easier to do. Be sure to read the text messages following the photographs.

elan-f14/replacing-the-doughnuts-t16456.html
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