Tom,

 

1.  Because of the design of Matco wheel and bearings, the wheels must be bolted up tight - that is, while the plane is up on jacks, the axle nuts must be tight enough that an attempt to spin the wheels means that they make no more than 1/4 to 1/2 turn.  Loose wheels can cause damage to the bearings and their surfaces as they are rattling around. 

 

2. You should try to maintain about 50 psi in the mains and about 38-40 in the nose.  Low inflation pressure can lead to premature wear on the inner tubes and ultimately a flat tire.

 

3. Inspect nose tire for "cupping" - an uneven outer edge.  Cupped tires can lead to apparent vibration at certain rolling speeds.

 

4. Alignment of the mains can be mechanically checked, however the wear pattern on the tires may be revealing.

 

5. You should check the damping of the nose gear.  - usually 2 steel plates with grease between them placed under the nose wheel.  There should be reasonable resistance (damping) when you try to turn the wheel by hand.    If not, the strut may have to be rebuilt or serviced.  You may need weight on the nose gear so the "self-centering" mechanism is not engaged when the wheel is turned.

 

If you accomplish these tasks, you have passed "Lawn Dart Landing Gear Maintenance 101".

 

Grayhawk

 

PS  You could always remove the rotors and check them for "warping" against a flat surface (laminated composite wood shelf material from Lowes or Home Depot).

 

Before I go and over engineer a problem, I thought I would get every ones expert advice first.  It clearly has worked well for me in the past. (Thanks Grayhawk) 
 
I have what feels to be a classic case of warped rotors, but that isn't it.  About the last half of the roll out I start to get a vibration from the right main gear.  Or at least I think it is the right side.  Thinking it was an easy fix I replaced the rotors with a new set.  I think it is better, but that could be just in my head.  The vibration is much worse under braking, but does exist while just rolling.  As most vibrations, it seems to have a peak intensity at a certain speed. 30-50 mph I would guess.  This has the original rubber cushion landing gear.
 
So, here are my ideas..
 
Bad tire that is out of balance?  Waaay out of balance. They are Chang Shin tires, so maybe I got what I paid for.  haha
 
Out of Alignment? This aircraft has had the service bulletin completed regarding the main gear reinforcement.  Could this have caused an alignment issue? 
 
Nature of the beast?  It has had this problem from the day I purchased it, so maybe it is just me. Although I hope not!
 
Would love to hear some ideas or past experience with this.
 
Thank a ton!
Tom McNerney
N54SG

--
For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html