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Old 12-06-2012, 06:34 PM
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mach4 mach4 is offline
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Join Date: Jul 2011
Location: San Diego County, CA
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Having confirmed that the rough idle was due to my urethane filled motor mounts by installing a set of new ones, I decided to get a new set of motor mounts and fill them with a very soft urethane to see if that is the solution to keeping a smooth idle and yet preventing a collapse of the mounts. My original urethane was a Shore A 75 and the new urethane is a Shore A 30 which I sourced from Reynolds Advanced Materials. This chart shows the scales and some representative materials.

Compared to the original filled mounts the Febi mounts showed a permanent compression just within 3 weeks of use. So I'm going with Meyle for the new set. The Meyle are perfect for filling with urethane because the flashing from the casting of the rubber covers the sides and provides a perfect void for filling. Notice the difference below.

All that is necessary is to create a plug for the mounting hole that will contain the urethane. I used silicone mold release so that the plug could be removed easily. (Urethane is a great bonding agent) Here they are ready for pouring.

After pouring there is a 24 hour cure time.

The engine is out of the car right now for a transmission swap, so it will be awhile until I can report on the results of this latest motor mount strategy.

Here are the finished mounts

Attached Thumbnails
380SL Diesel Conversion Project-mounts-1.jpg   380SL Diesel Conversion Project-mounts-3.jpg   380SL Diesel Conversion Project-mounts-2.jpg   380SL Diesel Conversion Project-mounts-4.jpg   380SL Diesel Conversion Project-mounts-5.jpg  

Current Stable
  • 380SL (diesel)
  • Corvette C5
  • Manx
  • Baja Bug
  • F350 Powerstroke
  • Auburn Boattail Speedster replica

Last edited by mach4; 12-06-2012 at 07:03 PM. Reason: add image
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