Friday, September 12, 2008

Engine Mounts

In early 2007 we began working on a solution for the severe engine rocking inherent in the Elise/Exige. Shifting problems and exhaust failures can clearly be attributed to this excessive motion - it has also maligned a LIDbone or two. I made the following post last summer:

We've been vexed by the large engine movement in our cars. To address this
issue, we're experimenting with transmission mounts. These direct replacements
have stiffer polyurethane bushings that reduce engine/transmission movement,
which results in more precise shift performance and better throttle response.
The pictures below show our second generation prototypes that we've tested in
our cars. As it turns out, we have much more work to do to insure that it is a
solution that can work for most of the community. We'll keep at the R&D
because this is one problem we aim to sort! No ETA on the final product....

Unfortunatley these caused far too much cabin vibration. I think most NVH engineers at Lexus would have had a coronary if they drove our car with these two mounts. Without question they improved the shifting action of the Spyder by dramatically reducing the rotation. But the high levels of shake & rattle sent us back to the drawing board for street driven cars.

Earlier this year we sorted a new solution which comprised of metal inserts that took up the recesses in the stock rubber mounts. It was another clever idea from our friends at BurkeBuilt but it turned out to be too expensive to produce. We tested this solution on track and it worked very well.

Enter Innovative Mounts: We've now found a solution that should meet our needs for dramatically reduced engine rotation AND minimal vibration into the cabin. Innovative Mounts has been building mounts for the sport compact market for over 10 yrs. Their kit includes mounts for all 4 locations. Though we considered changing only the front and rear mounts, Tim@Innovative highly discouraged us. They have found this will create more stress on the remaining 2 mounts as well as transmit too much vibration. One of the key features of their PUR bushing is the tapered end design which helps reduce vibration transmission through the attachment points.
We will be testing a set on our car this week or next. We expect to have them available in 2 flavors of stiffness: Street & Track.

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