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1. 06:44 PM - Alternator Belt (Karol Hansen)
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Just wanted to share the following with all regarding alternator belt findings:
Using Vans supplied Plane Power Alternator, and Vans supplied I0-540 Engine
with an LW 12227 double pulley flywheel, my findings are that a Gates XL 7325
is the belt of choice. The Alternator came in a fairly recently purchased FF
kit (few months ago) and the Install Instructions say: "For 7 1/2 inch ring
gear support pulley locally purchase XL7300 Gates (not supplied)". A Dayco 15355
(Gates XL 7355) does come with the kit but it is way too long and meant for
a 9-3/4 inch ring gear support pulley.
After some web searching on VAF I found that this discussion had been been covered
not too awful long ago with the conclusion being that a Gates XL7328 was the
belt of choice. I bought both a 7328 and a 7320 (only 3/4 inch difference
in total length) and tried them both. First tried the 7320 which is 32 5/8 inch.
No matter which way you held your jaw it wasn't going to go on - not without
hurting something! The 7328 (33 3/8 inch) did go on but I found that I could
tighten it all the way to maximum travel on the V-1004 arm and still rotate
the pulley too easily without the engine/flywheel turning. That's for a new
belt. Once broken in and the belt has stretched, it would be out of capable
travel adjustment range. What is the BIG DEAL you say? NOT interested in removing
the spinner and the prop just to install a different belt after one hour
of flight is my answer. Back to the store, got an XL 7325 and bingo - fits on
the flywheel and alt. with just a bit of difficulty, but once tightened there
was still about 1/4 to 3/8 inch travel on the V-1004 arm for adjustment. Log
book size entry time!
For those that are unfamiliar with how to, or how much to tighten the belt, PlanePower
does include instructions that are good on their website. If I might
add a tip that has worked well for me over the last 15 years: A new belt is a
bit slippery as NEW. This will change over the first few hours of operation
- the belt will also stretch a bit after these first few hours. So, what I like
to do for the initial setting is snug the alternator down to the point of being
able to put a 1/2 inch breaker bar with appropriate socket ( 3/4 inch - PlanePower)
on the alternator center nut and in turning the breaker bar just slightly
(10 - 20 degrees) it should almost turn the flywheel, hence the engine
crank. For now this is good enough. Tighten and safety wire. Then after just
a couple hours of flight and the belt is stretched to basically final form
and no longer slippery, I like to tighten it just enough to perform the same procedure
as above but have it actually turn the alt. and crank together, no slipping.
No over tightening! Also these rules do not apply to an oil or fluid
contaminated belt!
If the belt is tightened too much, we will have alternator bearing and/or other
issues, and if we don't tighten it enough it can slip causing premature belt
wear and possibly poor to little output at the alternator.
***When making these adjustments be sure to put a few 1/2 inch bolts/washers in
the crank to hold the flywheel in place (as in symmetrical with the crank flange)
unless of course the prop is already bolted on.
SORRY if this has already been posted somewhere, I couldn't find it and thought
it might help some of you. It's also during the weekend, so PlanePower is closed
- they may have already discovered these Gates numbers, I'll give them a
call tomorrow One thing is for sure - their recommended Gates XL7300 would not
have worked on my set up! The Revisions from Plane Power that I have are dated:
8/27/12 - maybe they have an updated one.
Rich Hansen
RV-6A sold
Rv-10 Fitting Cowl, Panel Ordered!
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