As you can see the stiffer E24 transmission mount is exactly the same height as the original E30 M3
unit. This is very desirable as it maintains the alignment of the drivetrain. The picture at left also
clearly shows the smaller 6 mm lower stud on the E30 M3 mount compared to the bigger 8 mm stud on the
bottom of the E24 mount. Note the characteristic "cutout" in the original factory mount. The existence
of this cutout means that there is only a small area of rubber that connects the top of the original
tranny mount with the bottom. This is undoubtedly done to decrease vibration. But it comes at a cost
in terms of longevity of the mount, as they often seem to crack right along the section of minimum
cross-sectional area. The E24 mount, on the other hand is the same cross section along it's entire
height. Interestingly, the S14 Gp N tranny mounts, although made of stiffer rubber (higher durometer)
still use the characteristic cutout shape. It must be said that the E24 tranny mounts, in conjunction
with the 740iL motor mounts, do contribute to a significant increase in vibration, especially at lower
RPM's. This is something to keep in mind if considering this upgrade.
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As mentioned above, the E24 mount is the same height as the original S14 mount. However, I also implemented
the 740iL motor mounts, which are 1/4" lower than the original S14 motor mounts. Thus, in an effort to preserve
the driveline alignment, I fabricated these 1/8" spacers to push down the transmission brace. If you think about
it a bit you will realize that lowering the tranny 1/4" would be too much and would not necessarily maintain
the alignment between the crankshaft and the driveshaft. The 1/8" spacer gets it close - the guibo takes
care of any remaining misalignment.
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E24 Transmission Mount
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p/n 23 71 1 175 732
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$15.06 ea @ Nick Alexander BMW
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