Lotus Elan

In house research: flex donut coupling improvements

PostPost by: Geoffers71 » Sat Apr 19, 2014 7:43 pm

I'll be interested in finding out how much they are as I'll be needing 4 myself soon :D
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PostPost by: au-yt » Sun Apr 20, 2014 1:39 am

I will be interested to see how you get on with the development and testing.
are you planning to use a car or test jig?

Cheers
Graeme
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PostPost by: lotustastic » Fri Apr 25, 2014 9:05 pm

Actually both, but a testing jig until
My elan gets on the road for further road testing. This really starts as a personal endeavor to find a better, more modern material that can have longevity as well as an improved design which eliminates the common failure points on the current donuts increasing safety. I'll be fabbing my second prototype in the next week as although the first was a very good start, I want to improve the bonding strength between the metal and polymer. I've found a way to improve this dramatically.
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PostPost by: lotustastic » Tue May 06, 2014 3:28 am

Hello,

I've made the second prototype with a tougher pu rubber grade and much improved bonding to the metal interleaves. With that said, I am looking for anyone that has a few used rotoflex couplings with the interleaves "metalastik type"(they can be considered unusable, broken, rubber split and look like rubbish) and are willing to donate as I need them mainly for the metal bolt bosses and plate inserts for a comparison study. I'm in the U.S. (TN) and of course willing to pay shipping.
If so, please PM me.

Things are looking good.


Thanks!

David D.
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PostPost by: StressCraxx » Tue May 06, 2014 3:54 am

There is no cure for Lotus, only treatment.
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PostPost by: Mike harris » Tue May 06, 2014 12:29 pm

HelIo,
I'm also looking into changing to cv joints;

Anyone any thoughts or experience with the TT propshaft with metalastic shock absorption ?
Perhaps a compromise compared with the spyder shafts or rigid CV shafts


Also seen Lotus Australia looking into volvo dohnuts
http://www.lotus.org.au/ddc/

image.jpg and
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PostPost by: Quart Meg Miles » Tue May 06, 2014 9:53 pm

Mike harris wrote:
Also seen Lotus Australia looking into volvo dohnuts
http://www.lotus.org.au/ddc/

Wow, $A33 against $A160 for the Metalastics! The compensation for slightly different width and hole diameter looks a small price to pay and perhaps someone should produce a kit. I wonder if they would compress to the smaller radius of the early drive shafts (I've just fitted my car's eighth new set of doughnuts).
Meg

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PostPost by: Elanman99 » Wed May 07, 2014 6:28 am

I think that in regard to using couplings designed for propshaft applications, one needs to bear in mind that they are designed for much less angular deflection than Rotoflexes.

The Volvo ones shown are proving successful but a Lotus 61 has very small suspension travel than an Elan. The Elan driveshaft is exceptionally short compared with the majority of other cars that have IRS and that fact puts the couplings (whether Rotoflexes or CV types) into an area where not many couplings are available.

Ian
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PostPost by: Chancer » Wed May 07, 2014 10:35 am

Also be aware that a propshaft joint will only see one third or so of the maximum torque loading that a driveshaft joint could.

Someone quite rightly will point out that the torque multiplied by 3 (or whatever the final drive ratio is) is shared between 2 driveshafts so only 1.5 times as much, not when using my patented clutch plate unsticking technique it isnt :lol:
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PostPost by: Quart Meg Miles » Wed May 07, 2014 5:41 pm

Thanks Ian, I was about to ask that very question about angles.

And Chancer, I was going to Google the Volvo part to find what it was used on and hadn't realised it was a propshaft item. Although the Lotus 61 is comparable in torque it doesn't have the lifetime requirement of an Elan so combined with the angular problem it might not be suitable. It would be an interesting experiment to try, though, in just one place and probably cheaper to do than buying one Metalastik!
Meg

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PostPost by: StressCraxx » Wed May 07, 2014 7:14 pm

The allowable angles, torque capacities and service factors are available from the manufacturer. It is an engineered product same as any other power transmission coupling.

Meyle is the manufacturer of these couplings.
http://www.meyle.com/EN/Locations/MEYLE-USA.html
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PostPost by: vernon.taylor » Mon May 26, 2014 1:16 pm

Any news on this ?

Merci et @+

Vernon
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PostPost by: lotustastic » Tue Sep 16, 2014 2:00 am

Project is still going although more slowly than expected along with my elan restoration due to work requirements and personal issues...Although material is white, it will be tinted black. I will update as soon as possible. Attached is a pic of one of the experimental prototypes for fitment....

Thanks

David D.
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PostPost by: trw99 » Tue Sep 16, 2014 7:25 am

Looks good, David. Well done!

Keep it up.

Tim
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PostPost by: Quart Meg Miles » Tue Sep 16, 2014 9:56 am

It looks good enough to eat, I love white chocolate.
Meg

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