Bill, et al
Thanks for all the comments. I am glad the information was useful.
Bill, I haven't actually experienced any seal damage during the installation process so I haven't pursued any other techniques or means of protecting against the snap ring grooves. There certainly are cases where sliding the O-rings past discontinuities in a cylinder will damage the O-rings. The nose gear strut is a good example. (see attached) Here the bolt holes need to be blocked off to prevent the O-rings from getting a slice taken out. The nose strut has other factors that would promote damage to the O-ring. For example, the O-ring cross section is very small relative to hole or gap to be spanned. It becomes completely unsupported as it passes the hole.
Certainly the slightest burr on the snap ring groove could cut a seal. I imagine minor damage to the groove could even be introduced during snap ring removal. The scratch removal/honing with the sand paper strips should clean up and knock down the groove corners a bit. If my luck ever changes and I catch the snap ring groove damaging a seal, I would probably look into fabricating a nylon split ring to sit in the groove while the piston assembly and end plugs are inserted - a similar concept as with the strut holes.
I rebuilt all cylinder at about 350 hours. About half have made it another 1,000 hours without any issues.
good luck to all with all those rebuilds. Once you have it down, it should become a very infrequent maintenance task.
Chris
Chris Zavatson
N91CZ
360std
From: William Rumburg <lancair403@verizon.net>
To: lml@lancaironline.net
Sent: Sunday, July 3, 2011 8:46 AM
Subject: [LML] Re: LNC2 Hydraulic Cylinder rebuild procedure
Chris-
Thanks for taking the time and effort to make your hydraulic cylinder rebuild presentation. It's excellent.
You noted that sliding the end caps, with new o-rings, back into the cylinder can be 'challenging'. Yes, there is a real possibility of damaging the new o-rings as they're forced into the cylinder across the snap ring grooves. I rebuilt my own cylinders last year with excellent results, except that one of the door cylinders has a slight leak around the shaft and will have to be rebuilt again. I'm sure it was a result of o-ring damage as I forced the end cap into the cylinder across the snap ring groove, despite generous lubrication. Do you think that inserting a suitable piece of plastic mylar into the cylinder to cover the snap ring groove while pushing the end cap into place would act to prevent such damage?
Bill Rumburg
N403WR (Sonic BooM)
----- Original Message -----
Sent: Saturday, July 02, 2011 11:34 PM
Subject: [LML] Re: LNC2 Hydraulic Cylinder rebuild procedure
Johannes,
Try this link:
Chris
Chris Zavatson
N91CZ
360std