Honda CivicX Rear Motor Mount Design Blog Pt 1

[Vincent@27WON]

Part 2 is live now.

https://www.27won.com/blog/honda-civicx-rear-motor-mount-design-blog-pt-2

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[Matthyahuw]

looks good!
the only thing I'm worried about are the extra forces on the bolt w/o the bushing. is it not laterally torqued each shift?
all that force would snap that bolt at some point...maybe not in months, but years???

If I'm completely wrong, feel free to school me.

When you do release it, will you sell it with 2 or 3 bushings of varying hardness?

 

[Barett@27WON]

looks good!
the only thing I'm worried about are the extra forces on the bolt w/o the bushing. is it not laterally torqued each shift?
all that force would snap that bolt at some point...maybe not in months, but years???

If I'm completely wrong, feel free to school me.

When you do release it, will you sell it with 2 or 3 bushings of varying hardness?

Great questions!
The bolt on the chassis side of the mount is a Class 10.9 M14. The bolt is setup in a double shear clamping with one of the shear planes being through the threads.
Looking at the weaker shear plane through the threads, the average class 10.9 M14 has an allowable shear force of 34,640 lb-force. Yes that is 34K lb-force. We are not worried about the bolt shearing.
We will not be releasing multiple polyurethane duro ratings because that would defeat the design. The entire RMM is designed to work together as one unit, which includes the duro rating of the poly. A softer duro rating would increase the low frequency NVH of the design as well as reduce the reliability/durability of the polyurethane itself. A stiffer poly (which would be borderline rigid) would transmit ALOT of noise to the cabin making the NVH intolerable.

 

[Vincent@27WON]

Great questions!
The bolt on the chassis side of the mount is a Class 10.9 M14. The bolt is setup in a double shear clamping with one of the shear planes being through the threads.
Looking at the weaker shear plane through the threads, the average class 10.9 M14 has an allowable shear force of 34,640 lb-force. Yes that is 34K lb-force. We are not worried about the bolt shearing.
We will not be releasing multiple polyurethane duro ratings because that would defeat the design. The entire RMM is designed to work together as one unit, which includes the duro rating of the poly. A softer duro rating would increase the low frequency NVH of the design as well as reduce the reliability/durability of the polyurethane itself. A stiffer poly (which would be borderline rigid) would transmit ALOT of noise to the cabin making the NVH intolerable.

And that my friends is the epic answer from our lead engineer *mic drop*

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