[Supras] NAPA motor mounts

[berniek at technicaldevelop.com]

Jim and list:

    A few months ago I went though a similar search, and found the Anchor makes the mounts for NAPA as one of several suppliers.  I spoke with Anchor tech support, a very friendly guy.  He stated that he had one on his desk, and was looking at a crimped steel ring on the bottom half which appeared to be backup protection in case the bonding of the top stud plate to the rubber broke.  The mount was said to be oil filled.  Also found out from independent sources that Anchor is probably the best recognized aftermarket mount supplier.  

    So I ordered the "genuine" Anchor mounts from a local disributor, and found that the top stud plate (about 1-1/2" in diameter) was bonded to the rubber, without backup provisions.  The crimp the tech guy spoke with was to hold the rubber segment to the bottom plate (from which the frame stud protruded).

    By putting the mount in a vise with softwood blocks, I found I could bend the top stud at almost a 90 degree angle with a piece of 1/2 pipe over it since it was pliable.  Apparently there is no backup provision in these mounts.  The stock mounts are much stiffer, and have the black painted overtravel stops bolted between the engine-side mounting brackets and the mount.  The stock mount also has a rubber covered steel projection which backs up against the bracket.  I found that my '90 left side mount had been broken for some time only because of a rust line at the junction of the upper pad and the rubber.  The backup protection must have been keeping matters under control for some time.

    I got a pair of Transdapt Ford flathead buscuits and was going to make up mounts (at least one for the left side) which were captive since they use through bolts and a intermediate plate for the frame side mounting. but never took that project any further.  

    Also got new stock mounts and backup brackets and found the backup brackets to be thicker than the stock '90 pieces, a reassuring finding.  

    Work on a JDM rebuild, the major part of this project, has not progressed due to lack of time, so the mount situation remains unresolved.  Using the Ford buscuits does not address the side thrust due to twisting tendency of the engine (present since the mounts are low and close to the engine) although it addresses the left side lifting tendency perfectly.  So use of the buscuits would require fabrication of a center plate with rings on each side to fit into the circular voids in the buscuit rubber.  

    The Mazda engine is much smaller and much less torquey than a well boosted MkIII, although the lower first gear ratio may offset that difference to a very small extent (the force felt by the mounts is determined by both engine torque output and first gear ratio, since the engine and transmission are bolted together).  

    In the final analysis, I will probably wind up using the stock mounts, but with spacers screwed to the backup plates to make the assembly go solid dynamically with less stress on the mount rubber than in stock form.  At least engine noise wll not be transmitted to the frame at idle and cruise, although metal to metal contact would occur sooner at heavier throttle.  That seems like a good compromise, to keep the stock mount together.

            BernieK