[GreenKeys] M28 skintight motor questions

[Chris Elmquist]

Hi Don...

Yes... it seems like the motor is very similar to a standard 28 and indeed
much of the stuff in the standard 28 manual seems to match.  The only
difference appears to be the lack of oiler ports on the end bells.
Without those, it would seem to imply that there are oil free bearings
in there although they may have just had a plan to replace motors rather
than lube them.

I've email'd Paul at RTTY Electronics to see what parts he may have.
I'm OK with pop'ing for a new motor if he's got one else whatever parts
I can get to rebuild this one.  The resilent mounting rings are clearly
shot so have to find a way to replace those at least...  and as long
as it's torn down, I'd look at replacing the bearings in the motor too
since at least one of those is likely the source of the screeching.

Chris N0JCF


On Monday (01/16/2012 at 12:09PM -0600), DR HOUSE wrote:
> Chris,
> 
> I always thought the motor unit on a "skintight" was the same as the
> standard.
> Obviously it is not.  I have to look up the documentation on the LMU-3.
> I have three "Compact" 28KSRs here. One is civilian and two are
> military.
> I also have a spare motor unit for them.  THEY ARE different as all
> of the
> electrical components other than the motor itself are on the side of
> the motor
> mount rather than under the motor.
> 
> "More as I get to it and it happens"
> 
> Don
> 
> 
> On 15 Jan 2012, at 4:27 PM, Chris Elmquist wrote:
> 
> Gang,
> 
> Finally getting some time to work on the M28 "skintight" that I acquired
> last summer over 4th of July weekend.
> 
> The main driven gear has a flat worn on it so I removed the motor to
> get to that and while I had the motor out, looked it over and spun it
> by hand.  It spins freely and coasts for a while so I powered it up.
> Runs OK except for a gawd awful screech...  just like a police siren.
> Bearings are probably not too good.
> 
> While looking for oilers, of which I found none...  I also found that
> the rubber bushings that isolate the motor from the mount are pretty
> well shot.  One has the appearance of melting while the other is rock
> hard and cracking.
> 
> Photos here,
> 
> https://picasaweb.google.com/117891262011490779403/M28skintight?authuser=0&authkey=Gv1sRgCOmKpKLzxtnBiAE&feat=directlink
> 
> It doesn't seem like these bushings are easily removed from this
> motor...
> are they normally a replaceable part?
> 
> And then the lack of oil ports is very puzzling.  Was this intended to
> be an oil free motor?  One photo shows the motor p/n which is 151795.
> Another of the photos shows what could be an oil port but the casting
> is completely solid there with no hole...
> 
> Do I need to replace the motor to get new bushings or ???
> 
> Thanks and 73,
> 
> Chris N0JCF
> 
> -- 
> Chris Elmquist
> 
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-- 
Chris Elmquist