Crankshaft balance

"stol" wrote in message
ups.com...
I'm curious about how you have 0.4 ips vibration problem?

Pistons and rings are not part of crankshaft balance.
Pins bearings?

Let me set some things straight for ya. Any good racing machine shop
can balance a motor far better then the vast majority of FAA approved
places. In fact Lycoming can't even built a crank for some models they
produce that won't break, and they have killed people this way. So much
for the FAA keeping a close eye on quality... As for nitriting and heat
treating, this is an every day detail in the racing market and is down
to a science, not black magic... Pistons and rings and circlips are
part of the rotating/reciprocating assembly and need to be balanced
too. Good shops even add in a factor for the weight of oil that clings
to the balanced mass to get it perfect.


Well Excuse meee..........!!!!

Circlips? Are you referring to piston pin circlips? They are not used in
Lycomings or Continental aircraft engines.
Tell me which models of Lycomings break cranks? I don't want to fly behind
those.

I'm still wondering what the pin bearings are.

Please direct me to to a engineering reference or paper that discusses the
factor that discusses the weight of oil that clings to the balanced mass.
Otherwise that is somebody's guess.. their own black magic.
Kent Felkins

"stol" wrote in message
ups.com...


R2. You need more than a scale for the rods. A rod is suspended by
each
end and in turn the big ends and the small ends are weighed, the C.G.
is
deduced. In other words the rotating and the reciprocating masses are

measured. Auto guys will then make up a bobweight of nuts and bolts

equal to the rotating part which they add to the crank throws and that
is
then spun on a dynamic balance machine

///////////////////////////////////////////////////////////////

This is correct to a point. I have balanced more engines then I care to
remember and I have never had a motor where I didn't weigh all the rods
as is. For instance if you have 8 rods and 7 weigh in at 580 or so
grams and one weighs 640, you can grind /machine /rub / pray,,, what
ever you want to do there is no way you can remove from the big end or
small end to get "that" heavy rod balance with the other seven. So the
point I was making is one could gram out the parts at home to find out
pretty darn fast is they have a bad match of stuff. Once the motor gets
to a quality auto machine shop they will put the rods on a fixture and
duplicate big end and small end weights.


gee.... a fixture... What does a quality auto machine shop use? A CNC
machine?

Kent Felkins

"stol" wrote in message
oups.com...

/////////////////////////////////////////
Look close at the Lyc / Cont cranks and you will see balance marks on
the rod throw end. As you have pointed out they don't have counter
weights so thats the only logical place to correct a large imbalance
that happens during the crank forging process.

Yes, you have noticed the factory and aftermarket balance marks. Have you
ever checked the depth of material removed? How deep is the nitride layer
usually?
What do you do about the bifilar dampers that most higher horsepower
crankshafts have?
It is a misnomer that these are commonly called crank counterweights.
You install new bushings and rollers? Do you balance with them
installed on the crank? What about a Lycoming ring gear?

btw, thanks your three posts in "setting me straight".

Kent Felkins
Felkins Aircraft Ltd.
FAA CRS WNKR918K
Tulsa Oklahoma

"stol" wrote in message
oups.com...

/////////////////////////////////////////
Look close at the Lyc / Cont cranks and you will see balance marks on
the rod throw end. As you have pointed out they don't have counter
weights so thats the only logical place to correct a large imbalance
that happens during the crank forging process.

Yes, you have noticed the factory and aftermarket balance marks. Have you
ever checked the depth of material removed?
How deep is the nitride layer usually?
What do you do about the bifilar dampers that most higher horsepower
crankshafts have?
It is a misnomer that these are commonly called crank counterweights.
You install new bushings and rollers? Do you balance with them
installed on the crank? What about a Lycoming ring gear?

btw, thanks for your three reply posts for "setting me straight".

Kent Felkins
Felkins Aircraft Ltd.
FAA CRS WNKR918K
Tulsa Oklahoma

Kent Felkins
Felkins Aircraft Ltd.
FAA CRS WNKR918K
Tulsa Oklahoma

/////////////////////////////////////////

I was just giving out my two cents worth. After all this is the Rec,
Aviation, " HOMEBUILT" site. I would never post something like this on
the rec. aviation "certified" site. After all the FAA knows all.I still
think Lycoming murdered 13 people by selling a inferior product and the
FAA was in bed with them the whole way. I have owed several certifeis
planes in my life and I never want to see a yellow tag again. Those
things have tried to kill me a couple of times and the funny thing is
the Feds didnt even investigate the repair stations involved. Now I
will head at and fly my homebuilt plane powered by a Firewall forward I
designed and built. The air is good and thick at -34f. Peace and Merry
Christmas from Jackson Hole Wy

Ben
www.haaspowerair.com

Here is some more discussion about balancing:
http://groups.google.com/group/rec.a...9345c98a2408b1

here are some links to the Lyc mess. I am amazed you are in the
industry and have not heard of this fiasco..

www.bizjournals.com/wichita/ stories/2005/02/14/daily30.html

Another link to bad cranks....

eaa563.org/Newsletters/ 2002%20News%20Letters/0203/vol9issue3.pdf

more bad "CERTIFIED cranks

www.machinedesign.com/ASP/viewSelectedArticle.
asp?strArticleId=58969&strSite=MDSite&catId=0 -

Better yet just google " Lycoming crankshaft recall" Your sig line
shows you are a FAA repair station.. Ya mean the feds didn't notify you
of this major failure???



Kent Felkins
Felkins Aircraft Ltd.
FAA CRS WNKR918K
Tulsa Oklahoma