Just an update on the AEC Doughnuts. They were installed last week
on my Sierra at annual. It took the shop one day for the
installation of all three sets. They found the installation
instructions extremely helpful. The discs were pre-mompressed for
about 4 days under a heat lamp which prepared them for the install.
The end result is a smoother taxi and softer landing. I can highly
recommend these.

Bob Palamara
'72 Sierra
9707L



--- In musketeermail@yahoogroups.com, "Michael Rellihan"
<rellihan@...> wrote:
>
> I thought I had posted an update on this, but I now can't find it.
Here is
> my understanding of current status on the AEC cushions.
>
> - AEC designed the cushions to the upper end of the range of the
permissible
> Durometer hardness (per their PMA), to assure long life.
>
> - There have been no problems with installations on the fixed gear
planes,
> nor with the Sierra nose gears. These are all the smaller diameter
cushions
> having the single centered bonded metal disk. There have been
several posts
> on the installation process, and there are some photos on BAC
(including an
> Igloo cooler "heater" and a pre-compression rig). If the
> pre-heating/pre-compression process is followed (as outlined in the
Service
> Manual), the job goes problem-free.
>
> - There have been several installations on the Sierra main gear.
Two owners
> experienced problems with achieving adequate pre-compression. It is
> believed that the non-machined upper inside surface of the main
gear housing
> casting can vary in thickness as much as a quarter of an inch.
With the
> upper-end hardness of the new rubber, and the two-sided metal
bonded discs
> on the larger-diameter cushions, it is apparently possible to have a
> stack-up of circumstances that makes it impossible to get enough
installed
> compression on the Sierra main gear.
>
> - AEC has addressed this by ordering more of the large cushions
having a
> Durometer reading on the lower end of the permissible range (in the
PMA).
> They will resume sales of the Sierra main gear sets by configuring
marked
> sets. These will have several of the softer cushions at the top of
the
> stack, and the harder ones beneath. The softer rubber will be up
inside the
> upper gear housing, where it will be more protected from the
elements (sun,
> ozone, solvents, etc.). The AEC original-design hardness cushions
will be
> placed in the lower exposed positions, and will be better able to
withstand
> the environmentals as intended. The combined cushion stack will
enable
> proper pre-compression, even if a thicker casting is encountered.
It will
> also function as a sort of variable-rate spring, to provide a good
ride even
> while the cushions are new and stiff.
>
> I'll ask Kamran for an update on resumption of sales of the retract
main
> gear sets. Sales of the smaller-diameter fixed gear (and Sierra
nose gear)
> sets have continued, though at a very slow pace. Several of those
success
> stories have been posted on BAC and MML.
>
> Just as a reminder to those who are contemplating a cushion
change: The
> large roll pins that secure the stack tube to the compressor plate
are
> supposed to be checked for straightness during the cushion work (as
> described in the shop manual). Many are found deflected due to
previous
> hard landings. The original MilSpec pins are obsolete for design
and
> manufacture, and are generally unobtainable. There is a
superseding MilSpec
> for a stainless-steel version of the pins (per the US Qualified
Procurement
> List). These are standard hardware parts, and the superseding part
is
> perfectly legal to use. I actually found a company to make me some
of
> these, so we would have a source. Of course, I had to have a
minimum
> quantity made, and I am frankly still well in the hole on the deal
(though I
> have sold maybe a dozen sets). If you are planning a gear donut
project,
> please consider purchasing a set of pins to have on hand. I have
them
> listed in the BAC Classifieds along with my other items, and they
are very
> inexpensive.
>
>
> _____
>
> From: musketeermail@yahoogroups.com
[mailto:musketeermail@yahoogroups.com]
> On Behalf Of bpalamara1
> Sent: Tuesday, January 24, 2006 11:13 AM
> To: musketeermail@yahoogroups.com
> Subject: [musketeermail] Alternator
>
> Has anyone used the new AEC Doughnuts? It's about time as they
are 34
> years old.
> How long should it take a good mechanic to do a retract?
>
> Bob Palamara
> '72 Sierra
> MC96
>
>
> _____
>
>
>
> [Non-text portions of this message have been removed]
>







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