Paul There is the Mercedes coupler i talked to you before ,they have
  several models on EBAY and very cheap,you can design the shaft without
  spline but only an adapted flange cup to meet the coupler and the flexwheel
  as safety in case the rubber fail.I do have an idea of the shaft design with
  this Mercedes coupler.Ths one is for the 550 model http://cgi.ebay.com/**
  ebaymotors/Mercedes-W116-**450SE-W124-300D-T-300TD-T-**Flex-Disc-Kit-_**


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  http://tinyurl.com/3fhm24k


  Jean Prudhomme

Does anyone have dimensions for this type of coupler?  I interested in the
OD and the thickness in particular.

Randy

 used to use own a few bmw 2002's back in the day.  These were used as a flexible coupling between the driveshaft and the output flange on the transmission (called Guibo joints).  Having broken a few and then needed to call a tow truck, I'd never use one on my airplane.

half of the bolts were on the output flange, half on the driveshaft.  When the coupling came apart it was usually spectacular.

Am I missing something-- are you gents suggesting using the flex disc in another manner?
William Mason