Replying to Topic 'another CEL'
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Originally posted by SteVTEC
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Originally posted by mpulse1
This may not even happen on all V6 equiped cars as there's a +/- 15% variability in powertrain mount stiffness (this is caused by natural variations in a rubber compound, and is not from a lack of engineering talent).[/b]
+/- 15% sorta seems like pretty lose specs. True, that wouldn't be an engineering issue, but rather a bean counter issue on how much the engineers are allowed to spend on engine mounts. The tighter the specs, the more expensive the part. So it looks like these are just cheapo engine mounts with lots of variation in them - enough to cause problems on some cars. hmmmmm....
Hopefully Mazda will consider tightening the specs of the engine mounts for the 04's.[/b][/quote]
The +/-15% is an industry wide accepted tolerance on natural rubber stiffness.
I'd have to talk with one of our chemists, but I believe the +/-15% comes from two sources. The first is that being natural rubber, there is a certain amount of natural variation. The second deals with the difficulty in mixing natural rubber compounds.
When designing engine mounts we take into account that +/-15% when doing gross motion analysis of the powertrain. Most of that is to make sure nothing bangs into anything else under the various load conditions.