awr
06-13-2008, 03:00 PM
I bought a used Mavrikk 1010 head about a month ago.
All seemed in order when I bought it (I got it for a very good price so I wasn't concerned about surprises).
When I got it home I determined that the blade grip bearings and the bearings in the fly-bar mixing arms
had to be replaced. The bearings on the flybar mixing arms were so notchy that the arms would stop every 5 degrees so they had to come out.
The head I have is an older model. I'd like to think that they've improved on their assembly techniques since they made this head as the bearings are press-fit into the bearing block after the parts have been anodized - see my other post on that subject.
The bearings on the fly-bar mixing arms are also press-fit. Press-fitting didn't cause the problem. The problem occured because the manufacturer apparently didn't consider the change in bearing block i.d. when the part is anodized. After the part is anodized the bearing block is too small, so when the bearing is press-fit into the under-sized bearing block it causes premature bearing failure due to excessive compression on the outer bearing race.
The anodized finish on the inside of the bearing block also creates a fit so tight that the bearings don't come out using the usual methods of heating the part in the oven. I had to hammer like heck on two of the blade grip bearings to get them out.
I was able to remove the bearings on the outside of the arms (the bearing furthest from the head), but
the inside bearings were another story. I tried the heat method (i.e. 300 degrees in the oven for 7-10 minutes), with no effect, so out came the punch.
The punch could not make contact with the outer race of the bearing so all I could do was punch out the
inner race. That left the outer race sitting in the arm.
I tried everything I could think of. The problem is the inside diameter of the outside race is about 1 millimeter larger than the barrel of the arm (where the metal insert goes for the mounting bolt), which means there is absolutely nothing to push against to remove the bearing race. It was this fact that led to
the inner race being punched out while leaving the outer race intact.
The solution in this case was to take a 1/4" tap (from a tap and die set) with a fine thread. Of course you'll have to use a different size taps for other bearings, but you only want it large enough to bite into the bearing race without damaging the bearing block.
Thread the tap into the race about 3-5 turns (just enough to ensure it's not going to pull loose. You then have a firm grip on the race at which point you can either pull it out, or tap it out by tapping on the end of the tap.
Worked like a charm - had them out in less than a minute. Of course that was after uttering numerous expletives to the helicopter gods.
Wayne
All seemed in order when I bought it (I got it for a very good price so I wasn't concerned about surprises).
When I got it home I determined that the blade grip bearings and the bearings in the fly-bar mixing arms
had to be replaced. The bearings on the flybar mixing arms were so notchy that the arms would stop every 5 degrees so they had to come out.
The head I have is an older model. I'd like to think that they've improved on their assembly techniques since they made this head as the bearings are press-fit into the bearing block after the parts have been anodized - see my other post on that subject.
The bearings on the fly-bar mixing arms are also press-fit. Press-fitting didn't cause the problem. The problem occured because the manufacturer apparently didn't consider the change in bearing block i.d. when the part is anodized. After the part is anodized the bearing block is too small, so when the bearing is press-fit into the under-sized bearing block it causes premature bearing failure due to excessive compression on the outer bearing race.
The anodized finish on the inside of the bearing block also creates a fit so tight that the bearings don't come out using the usual methods of heating the part in the oven. I had to hammer like heck on two of the blade grip bearings to get them out.
I was able to remove the bearings on the outside of the arms (the bearing furthest from the head), but
the inside bearings were another story. I tried the heat method (i.e. 300 degrees in the oven for 7-10 minutes), with no effect, so out came the punch.
The punch could not make contact with the outer race of the bearing so all I could do was punch out the
inner race. That left the outer race sitting in the arm.
I tried everything I could think of. The problem is the inside diameter of the outside race is about 1 millimeter larger than the barrel of the arm (where the metal insert goes for the mounting bolt), which means there is absolutely nothing to push against to remove the bearing race. It was this fact that led to
the inner race being punched out while leaving the outer race intact.
The solution in this case was to take a 1/4" tap (from a tap and die set) with a fine thread. Of course you'll have to use a different size taps for other bearings, but you only want it large enough to bite into the bearing race without damaging the bearing block.
Thread the tap into the race about 3-5 turns (just enough to ensure it's not going to pull loose. You then have a firm grip on the race at which point you can either pull it out, or tap it out by tapping on the end of the tap.
Worked like a charm - had them out in less than a minute. Of course that was after uttering numerous expletives to the helicopter gods.
Wayne