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


  Yes i know on the car you do have lot of bending action and twisting
  but it have one model which have a steel cage and all bolting are
  lineup to the same circonference so if it fail it keep turning the
  shaft ,we can use a strongger one similar to the Mercedes 500 and
  built a similar cage and will be stronger and will keep the sungear
  shaft driven in case it fail.The steel cage bolted to the flexwheelIt
  worth to make one and test it.There is the picture of the one i am
  talking and the 500 Mercedes which i am sure is more stronger then the
  one you had on your car.

  Jean Prudhomme


A simpler way to solve the problem of failure of the rubber joints is to
use the clutch/ e shaft pilot bearing to locate the
psru input shaft. That way the rubber only sees torsional loads and NO
radial loads. A failure would still allow the prop to keep turning
although with considerable vibration.

chris smale

    
It is a biggest problem with Tracy damper rubber bushing which is been hold by the bolt who are atached only one side of the flexwheel and when the rubber fail the bolts tend to bend and damage the flexwheel.  With the steel cage over the coupler similar to the one i send a photo at least the rubber pce attached to the flywheel are been hold by the cage and the flexwheel so if it fail all the rubber parts will stay in place on the flexwheel part and no bolts bending and no damage to the flexheel and you wont have much vibration and the fact the sun gearshaft is holded  by the e shaft and stay aligned.These coupler are warranty to 12000 milles on car and with the upgrade one the life should be much much longer.


Jean Prudhomme