Hey guys,
I have an unrelated question about my 91 RX-7. I have had 2 air pump
brackets break on me in the last 2 years. The dealer wants $122 for a new
one. Has anyone had similar problems?
I have a renisis for my RV-7 (was even thinking of putting it into the
RX-7) and can't wait to get it flyable.
I also have a 12 A rotary that came off a flying airplane when it was run
low on oil. Anyone interested?
Thomas
Bend Oregon
Turbo or non turbo?
Were does it crack?
Can you take a jpg of the broken part and send it?
Paul Lamar
Hi Paul,
It's (wish it was turbo) item #7 in this blow-up and they both cracked to
the left of the two left side mounting bolt holes, right at the bend, top
to bottom. My mechanic friend suggested that the belt was too tight but
that belt had an 1" of play when I found the breaks. The air pump turns
over without allot of effort.
I already dropped the bracket off with my welder and didn't think to take
a picture ;(. Engine was happy to run with it broken but it was getting
hammered pretty good.
He is going to add a stiffener plate to cover the mounting holes and around
the bend, on the forward face. He works for beer so it saves me $122!!! and
I hope to never see it break again. Have you ever heard of them breaking?
I'll send a picture of the repair.
Thomas RV-7 in garage/ very slow build
Thomas
Bend Oregon
Common problem with belt driven devices like alternators.
Manufacturing inconsistency in the belt thickness along its length can cause
cyclical loads. It revolves 180,000 times per hour at 3000 RPM.
It does not take many hours to get to the fatigue limit which is in the
millions.
Cyclical loads lead to metal fatigue. Particularly if made from aluminum.
Have your welder build the main bracket from thick 4130. At least 1/4 inch thick.
Smooth and polish the edges. Gusset the adjusting link at least on one side with
1/16th thick 4130.
You can buy 4130 from AC Spruce.
Paul Lamar
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