The International Cessna^® 170 Association

I powder-coated my gear legs and engine mount when I rebuilt my 170 about 4½ years ago. (Also the elevator & elev trim rods, cabin steps, lifting and tie-downs eyes, rocker covers, exhaust cross-brace, oil cap, and dipstick.) The shop I used beadblasts then uses a phosphoric acid? bath chemical conversion (similar to alodine for aluminum) in lieu of a conventional spray-on primer.

just changed out the gear legs this weekend. Thought I'd spotted a crack at the top rear axle bolt hole maybe a year ago, decided to just keep an eye on it (I wasn't too worried, this is heavy 180 gear). While I watched it grow I got another set of gear magnufluxed and painted up. A guy I know just piled up his 180 last month when one of his gear snapped on landing (NTSB ANC04LA001) so I figured it was time to quit watching the crack grow....

point is, the crack reflected thru the powder-coat just fine. I have reason to suspect the crack preexisted the powder-coating so I'm not sure if it would've been visible if it had cracked afterwards.

regarding the gear, I changed from 0.760" forward swept 180 gear to 0.680" 180 gear without any rake. Moved the axles back about 2.5". I really liked the old set-up but this looks nice too. Sure was easier to align.

regarding engine mounts, Atlee Dodge powder-coats his if you don't specify otherwise. He's a pretty well-regarded repair station so it must be OK then, huh?

As an aside, ...the axle bolt holes should be chamfered to remove the sharp edges in order to diminish the likelihood of cracking. The lower bolt holes on some 170 gears were originally AN5's which were enlarged to AN6's when solid axles and other mods were performed. After the holes were enlarged, they should have been chamfered.
Axle attach-bolt holes are important items to inspect at maintenance time.

Spiro,how do you like the way it handles on the ground with those new gear legs? Do you notice a difference?
My ragwing has the heavy (.760") late-model 180 gear legs. Puts an awful lot of weight on the tail. I've always thought that the early 180 legs with less forward rake would be a better set-up for a 170,the mains would not be as far ahead of the CG so any ground-looping tendencies would be minimized.
When my gear legs were installed by a previous owner,they noted on the 337 that the mains were moved forward 3". So with 2-1/2" less rake,your gear should put the mains about 1/2" farther forward than stock 170 legs. That should be ideal.

Eric

hi Eric,

I haven't flown it yet with the new gear. Probably be another week or two, I'm trying to take advantage of a bunch of hanger time I've got this month.

my only concern is the greater possibilty of nosing over. With that heavy forward swept gear and double pucks I could really brake hard and not worry about it at all. Never had any problem with ends wanting to swap with the old gear.

there's no forward rake at all on this early 180 gear so it comes out of the fuselage at the same angle as all the 170 legs. I don't know exactly what the specs are but it measured out pretty close to 2.5" on the bench and figuring the airplane in 3-point attitude.

- paul

I just looked thru my paperwork,& realized that I made a mistake.When the stock gear on my 170 was changed to the late (.760") 180 gear,the mains were moved forward about 3-1/2". My information on 180's indicates that the gear legs were swept forward 3" starting with the 1955 model. I therefore believe that the early 53-54 legs are about 1/2" farther forward than stock 170 legs. I My information indicates that the leg thickness was increased from .650" to .700" in 1957. The heavier (.760") (185) gear legs were used on 180's starting in 1964.
This information is from Joe Stancil's "skywagons-r-us" website database,so it's not official,but I believe that it's acurate.
Useless trivia maybe,but it might be useful to someone.

Eric

I measured about 2.5" without taking terrible care. I could have easily been 1/4" off, maybe even 1/2".

>> When the stock gear on my 170 was changed to the late (.760") 180 gear,the mains were moved forward about 3-1/2".

"about"? How accurate was that measurement? In 3-point, or level? That late 180 gear is also probably longer than the stock 170 legs.

>> My information on 180's indicates that the gear legs were swept forward 3" starting with the 1955 model.

Stancil's write-up is good but it's not meant to be 100% technically accurate, his 3" may be an approximation. I've seen several different figures bandied about, usually with inches and degrees seemingly interchangable. Let's be careful about restating data from a questionable source.

awhile back, on this board, somebody mentioned they had a Cessna gear leg drawing that would have this info on it.

When the gear legs were changed out,the 3-1/2" farther forward location of the mains was measured in the level position,when determining the new W&B figures. My measurements when I re-weighed the airplane this last spring verify this--the arm for the main wheel axles with the stock gear legs is 21",with my late 180 gear the arm for the mains is now 18.5".
You're right about restating data from a questionable source,but Stancil's data is useful in deciding which gear legs you may want. However,in my opinion,anytime this major of a change is made,for W&B purposes the airplane should be re-weighed & re-measured--the changes shouldn't be just "calculated",whether your data is questionable or official.

Eric

>> the 3-1/2" farther forward location of the mains was measured in the level position .... the arm for the main wheel axles with the stock gear legs is 21",with my late 180 gear the arm for the mains is now 18.5".

21 - 18.5 = 2.5", so I'm confused.

FWIW, my arm w/ the late 180 gear was measured at 18.75". I'll remeasure w/ the "new" legs next time I get it in the hangar, got another plane in now.

Oops,that 21" was a typo--22" is the arm for the main wheels with the stock 170 gear. You gotta excuse my typo's,I'm not much of a typist,more of a "hunt'n'pecker"!

Eric