Installed 180 Landing Gear

How to keep the Cessna 170 flying and airworthy.

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Re: Installed 180 Landing Gear

Post by GAHorn »

Aryana wrote:No sweat. Edit your post and delete mine!
OH NO! We need to keep a trail-of-evidence whenever Bruce makes a mistake. We only edit-out mine! :twisted:
Bruce Fenstermacher wrote:
Aryana wrote:
Bruce Fenstermacher wrote:What am I missing. If you put shims (washers) under the gear leg at the top, which is what you would do to raise the wing on that side to level the wings, you are also changing the caster of the wheels.

The problem here is that most likely the problem is to much positive caster. Adding shims to the top of the gear would only add more positive caster. So it wouldn't help.
I might be completely confused, but I think you meant to say camber, not caster?
How-CasterAngle.gif
Well I was thinking camber but wrote caster. Starts with a C. I guess we are now all confused. :?
(Knowing Bruce's moderator skills.... I'll give this about 24-hours before he finds a way to enter my domain and wipe out this archiving-quotation.) :lol:
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Re: Installed 180 Landing Gear

Post by wingnut »

Bruce Fenstermacher wrote:What am I missing. If you put shims (washers) under the gear leg at the top, which is what you would do to raise the wing on that side to level the wings, you are also changing the caster camber of the wheels.

The problem here is that most likely the problem is to much positive caster camber. Adding shims to the top of the gear would only add more positive caster camber. So it wouldn't help.
Well............actually, when you add or remove shims at the gear leg attachment, you are not changing the symmetry of the gear in relation to each other. We call it "shimming the gear", but you are actually doing is shimming the fuselage. When you "shim the gear", you are really shimming the fuselage up or down.
Del Lehmann
Mena, Arkansas
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Re: Installed 180 Landing Gear

Post by cessna170bdriver »

wingnut wrote:...Well............actually, when you add or remove shims at the gear leg attachment, you are not changing the symmetry of the gear in relation to each other. We call it "shimming the gear", but you are actually doing is shimming the fuselage. When you "shim the gear", you are really shimming the fuselage up or down.
When I was there 3 weeks ago it took Brett 3 tries of explaining that to me very slowly before I finally got it. :?
Miles

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Re: Installed 180 Landing Gear

Post by Bruce Fenstermacher »

gahorn wrote: OH NO! We need to keep a trail-of-evidence whenever Bruce makes a mistake. We only edit-out mine! :twisted: ......

(Knowing Bruce's moderator skills.... I'll give this about 24-hours before he finds a way to enter my domain and wipe out this archiving-quotation.) :lol:
I make mistakes all the time and you guys read many of them. A big weakness I have is I read what I intended to write, not what I actually wrote. And I do proof read every post I make several times.

And if you look back at my original post you will see I did correct my mistake and for continuity of the thread left the mistakes in place but lined out. In doing so I left evidence of the mistake yet corrected it and left Aryana's post pointing out my error. I guess that is the superior moderation skills George is talking about. :lol:

As for editing out George's posts, there is only so much a line out can accomplish. :twisted: But I've never edited out his posts, perhaps he has? :wink:
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Re: Installed 180 Landing Gear

Post by Bruce Fenstermacher »

Gear shimming effect on chamber.jpg
I agree with Del, shimming the gear is a wing fuselage/wing leveling procedure.

However, shimming a gear to adjust the fuselage and or raise a wing by adding shims under the gear does increase the chamber as you can see in the lower drawing in which only one gear is shimmed compared to the upper drawing. In fact if you look close shimming one gear side changes the chamber positively on both wheels.

I concede that the positive chamber change may be negligible and practically undetectable. Del would know better, I have yet to shim or even shimmy a gear leg. :wink:
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Re: Installed 180 Landing Gear

Post by canav8 »

Ok. now that we all agree on what I am doing. I am trying to shim the axles on the gear for toe in and camber. I bought $1K worth of shims. It turns out I could have made my own but I wanted to see the actual thickness of the shims in the 100 series service manual. As it turns out the shims that were on my 170 do not have part numbers but when measuring them with original part numbers and sizes I believe I have the shims for a 172 or 182. they are very thin and there is many of them. The original shims are much thicker. I will also share as some posters have mentioned about position of gear leg at the fuselage. The correct way to set this up is to have the gear leg resting all the way back against the aft portion of the fuselage extrusion. I am not interested in leveling wings so no shims are added under the landing gear. The camber is way off and requires max amount of shims to get close to the 100 series manual numbers. The problem you run into is there is a max thickness of shims you can use. I took pictures and will post when I get home.. Thanks to all that have contributed. DOug
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Re: Installed 180 Landing Gear

Post by canav8 »

Arash. Shims are placed under the landing gear leg to raise the gap between the gear leg and the fuselage. By doing that it
raises the wing on that side. you only do this if the wing tip to ground distance is more then 3 inches different from each other. If you look at the 170 IPC on the landing gear page you will see the call out for the shim. It is actually a washer you put on.
Last edited by canav8 on Sun Apr 09, 2017 3:04 pm, edited 1 time in total.
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Re: Installed 180 Landing Gear

Post by c170b53 »

Doug, just to build our database. I mentioned about .025 at each end of the leg when in the extrusion. What was yours? Any idea what the change in toe in is, between all the way forward and all the way aft?
I placed mine in the middle, I wanted some room between the steel and aluminium.
Jim McIntosh..
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Re: Installed 180 Landing Gear

Post by hilltop170 »

The way I keep the landing gear adjusting devices straight in my mind is:

-Wedges are installed on top of the gear leg at the outboard gear box and are tapped in place with a forked drift that will straddle the wedge anchor bolt to securely fix the gear in place without any vertical play. Wedges should be tapped into place, then secured with the bolt. Do not try to drive in the wedges by tightening the bolt. You will strip out the nut plates and be in for a miserable job replacing them. Shims can be added under the wedges if needed. Once wedges/shims are installed, wing leveling measurements can be made.
-Washers are placed under the narrow top end of the gear leg between the gear leg and top of the inboard landing gear support block. The vertical landing gear bolt goes thru the washer. Washers are only installed to level the wings before gear alignment is attempted or installation of P-Ponk gear beef-up kit. It may take several tries installing the gear, wedges, and washers to get the wings level to your liking. Once wings are level, the P-Ponk kit can be installed.
-Shims with various tapers are bolted between the lower end of the gear leg and axle to adjust wheel camber and and toe-in. They should be installed last after wings are leveled.

As far as I can tell, there is no way to adjust caster which is fixed by the forward sweep of the gear leg.

Also, the gear should be placed against the aft side of the outer gear box prior to aligning the wheels as this is where the gear will migrate with braking.
Last edited by hilltop170 on Mon Apr 10, 2017 7:29 pm, edited 3 times in total.
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Re: Installed 180 Landing Gear

Post by n2582d »

Richard,
That's about as clear as one can explain the three sets of shims on the 170's landing gear. Here's an annotated illustration from Fig. 26 in the IPC:
Click to Enlarge
Click to Enlarge
c170b53 wrote:Doug, just to build our database. I mentioned about .025 at each end of the leg when in the extrusion. What was yours? Any idea what the change in toe in is, between all the way forward and all the way aft?
I placed mine in the middle, I wanted some room between the steel and aluminium.
Jim, for what it's worth my lady leg gear measure almost exactly 6" wide where it comes through the outboard extrusion. My extrusion measures around 6.125" wide. So with my rudimentary trig I figure the most one could change the toe in would be 1.2º.
Bruce Fenstermacher wrote:I agree with Del, shimming the gear is a wing fuselage/wing leveling procedure. However, shimming a gear to adjust the fuselage and or raise a wing by adding shims under the gear does increase the camber ... .
I concede that the positive chamber change may be negligible and practically undetectable. Del would know better, I have yet to shim or even shimmy a gear leg. :wink:
Bruce, I was thinking the same thing. As I have my gear out I measured the distance from the center of inboard bolt hole to where the gear rides in the outboard extrusion at 6" and from that point to the middle of the tread at the base of a 6 X 6.00 tire at 42 7/16". If you shim the gear at the inboard end 1/8" it should change the camber on that gear by slightly less than 1.2º -- so if you only do one side to raise a wing the net effect would be half of that or .6º on each gear.
Last edited by n2582d on Fri Apr 07, 2017 3:52 pm, edited 1 time in total.
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Re: Installed 180 Landing Gear

Post by gfeher »

To round out Richard's explanation, the shims as he's described them (axle shims, p/n 0541111-2 and 0441139-5 and -6) also adjust the wheel toe in/toe out. Each shim has a complex taper - it tapers in two directions 90 degrees apart. When installed, it tapers vertically to affect the camber, and horizontally to affect the toe in/toe out. So you need to keep that in mind when trying to adjust one (e.g., camber) and not the other (e.g., toe in/out). It can get confusing when tring to keep the orientations of the tapers in mind when adjusting just say the camber without affecting the toe in if you have more than one shim on that axle.
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Re: Installed 180 Landing Gear

Post by lowNslow »

I think the confusion is that in the parts manual there is both a "shim" and a "wedge" on the outboard bracket. Number 6 is a shim which you can add more if necessary, number 4 is the wedge.
6 = shim          4 = wedge
6 = shim 4 = wedge
Here are the instructions for installing the gear provided by Pponk.

Steps to Installation

1) Hoist the airplane.

2) Install your gear in the aft position. This should leave you 1/16th to 3/32nds inch gap between the gear and the front of the bracket. If the gap is larger than this, check the rear portion of the bracket that touches the landing gear to see if it has compression damage due to years of use and striking objects with the landing gear. (Inspect for stress fractures and cracks in any compressed areas.) A symptom of "too large a gap" is a chronic "clunk" when you land or take off. Tightening the shims is only a temporary fix for the problem...the "clunk" usually comes back.

3) Install the wedges and shims so that they do not push all the way in and bottom out. If they bottom out, install an extra shim. (Parts Manual allows more than one shim. You also may need a thicker wedge.) There are 2 sets of shims and wedges holding each set of gear in place.

4) Tap the forward wedge lightly with an aluminum punch and hammer to set the wedge. Screw your 1/4" bolt up snug to the wedge.

5) Repeat this procedure for the rear wedge.

6) Tap the forward wedge again lightly with a punch and hammer to reset the wedge, and again snug up the 1/4" bolt.

7) Repeat this procedure for the rear wedge.

Note: Do not over tighten this bolt...it is there only to keep the wedge from backing out. DO NOT POUND IN THESE WEDGES, THINKING YOU WILL KEEP THE GEAR FROM MOVING. You only will damage the outboard brackets (and keep me in business).

Steve Knopp
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Re: Installed 180 Landing Gear

Post by ghostflyer »

Well done "low and slow" this is exactly what I was talking about but somebody has put my wedges on the bottom under the spring . I am thinking of redoing my spring correctly with the wedges .
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Re: Installed 180 Landing Gear

Post by c170b53 »

Ghost flyer, humm, could it be that living down under is the reason your wedges are upside down? :oops:
if you've lived this long with the wedges installed on the bottom, maybe just keeping an eye on it until there's an in service issue that forces your hand might be the best option. Are there holes in the casting for the wedge retaining bolts should you wish to reverse them? You probably know there's anchor nuts on the inside of the extrusion for those bolts as well. Drilling new holes probably won't hurt the extrusion but I would ream them to size to ensure they have the best chance of a good life.
Jim McIntosh..
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Re: Installed 180 Landing Gear

Post by canav8 »

c170b53 wrote:Doug, just to build our database. I mentioned about .025 at each end of the leg when in the extrusion. What was yours? Any idea what the change in toe in is, between all the way forward and all the way aft?
I placed mine in the middle, I wanted some room between the steel and aluminium.
Hi Jim. The proper way to place the gear is all the way aft in the fuselage extrusion. In-fact Steve Knopp of Pponk advocates putting a Delrin wedge infront of the gear leg so it will not move. I did not do that but it makes sense. The gear will move aft through use not forward. The only problem when everything is tight, You can change the toe in a very small amount. If the gear moves due to difficult landings like heavy crosswind landings and braking, the gear will eventually move aft. I measured the Toe In at your request and with the 180 Gear installed I got 1.1 degrees toe out from full forward to full aft in the extrusion. By mounting the gear aft it actually makes a requirement to add additional shim at the wheel. The shim at the wheel easily will handle the gear to fuselage mounting changes. Now that I have the correct shims that are much thicker then the ones I had on there originally it will be easier to get the correct geometry. The bigger issue is the Camber. I have the max thickness in Shims and I still do not have the Camber in the call out of the 100 series service manual. It is going to just mean heavy outer tire wear on the outside of the tire. The whole problem will correct itself when I hang the TCM IO-360 on her this summer. D
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