The International Cessna 170 Association

Another point to remember is the added weight on the tailwheel. It is not inconsequential. If you have a tail pull handle installed, you'll notice it. The added weight also might make bringing the tail up a bit longer. The stiffer gear has me running just a bit lower tire pressures. Tailwheel geometry is altered a bit so taxiing is just a bit different. All in all, I don't think it's adding much Takeoff roll, but I don't have any numbers. But who cares about function. It looks awesome!!!

Triplepac wrote:Another point to remember is the added weight on the tailwheel. It is not inconsequential. If you have a tail pull handle installed, you'll notice it. The added weight also might make bringing the tail up a bit longer. The stiffer gear has me running just a bit lower tire pressures. Tailwheel geometry is altered a bit so taxiing is just a bit different. All in all, I don't think it's adding much Takeoff roll, but I don't have any numbers. But who cares about function. It looks awesome!!!

Thanks for posting Triplepac and welcome to the Forums. You are absolutely correct. The proper way to shim these is having the aircraft at flight or level attitude. It does not mention that in the service manual but the tail weight is 170lbs in my case. I made sure I had the aircraft level before doing this as well. After doing a lot of investigation, I found that the axle shims I had on the gear were for a 182. They are considerable thinner and perfect for fine tuning but they are not the correct ones. The problem was the shims were painted and I could not identify what part numbers they were. Of coarse there was no logbook entry either. I needed significant shim for the toe in and camber especially on the right side. I went around and found some NOS about half the price of Cessna.
Doug

ghostflyer wrote:Please be aware the gearbox to fuselage shims do have a effect on gear alignment also. If you have a excessive axle to gear leg shims then look at the gearbox to fuselage shims also. These are sometimes called wedges.not much in the manuals about this .

Ghostflyer, Are you referencing the washers that go under the gear leg and the extrusion? I know that is used for wing leveling but I was hoping this conversation was regarding Landing Gear Axle, Toe IN, and Camber. Are you refering to some other shim that will influence the alignment of the gear here? I am just trying to follow. Thanks, Doug

My left hand leg was nearly inpossible to align when it was suggested that have a look at the wedges that are contained in position buy 2 bolts . These wedges sit under the gear spring . I pulled out the main bolt that holds the gear spring to the box section [replaced with a new bolt ] and removed the wedges also. There was great amount difference in thickness between the wedges. So I swapped the fore and aft wedges around . This fixed my issue with alignment . Wing tip height is about 3/4 in difference . This job is very labor intensive ,but using greased slip plates under the wheels helpfull.
PS. put the main bolt in first before tapping in the wedges into position .

Wedges are on the top of the gear leg. They need to clamp the gear leg tightly against the bottom of the opening thru the bracket. These wedges are not for setting alignment.

Sorry, just checked and my wedges are on the bottom of the spring and they were about 40 thou difference in thicknesss. They had to be tapped into position as i was told do not let the bolts that hold them into position be used to pull them into position . I am not despairing over this as I have found many differences over the years with Cessna models not conforming to the parts book or manuals. However I am not convinced my gear box is the original either.its similar but not exact to,another 170. The rivet plan is different . My aircraft flys very well hands off and lands straight and no issues except the pilot is getting old and cranky.

Well, I think that just before you torque the attach bolt and tighten the wedges, you can move the gear slightly fore and aft which could help if you had a toe in / toe out issue. If you have a reason to remove the gear, likely you'll have a reason to check alignment even if you didn't think you mixed up the shims

Ghostflyer, if you indeed have the wedges underneath the gear legs and not on top, and have clamp bolts underneath the gear leg to hold the wedges in place and not on top, it sounds like the outer gear box extrusions have been installed upside down. The wedges are supposed to be on top of the gear. I agree wedges under the gear make more sense as the gear loads are up, not down, but that is not how the planes are designed. Wedges under the gear would be almost impossible to access too, must be a real pain. But, since the gearbox is as it is, I would not worry about it too much if everything else seems to be ok.

There should be no shims fore or aft of the gear leg, there is some fore-aft clearance that makes it look loose and allows slight rotation about the upper gear bolt, but it is made that way and should not be constrained.

Sorry if I've confused things, I should have been more explicit. If the gear leg has been removed, it may on reinstall, be placed in a different position than removed (even though P-Ponk suggests it should be placed aft in the gearbox casting) which will likely make a difference in alignment, requiring adjustment of the shims between the leg and wheel axle.
I just thought that Ghostflyer had made a mental error over the gear wedges but if he didn't, yikes that's messed up.

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.

Firstly , I should have realized that my aircraft is different to what we have had in the past . I thought when we were doing the wheel alignment I had a bent left hand leg . It wasn't, it's the airframe that's "bent". Plus the gearbox has been messed with over the years . The workman ship with riveting ,spacing is very good and everything has been coated in zinc chromeate .it looks factory fresh. The leg was positioned in the most forward position and then the fuselage gearbox to leg were added and tapped into position and then secured with bolts. Then the main bolt was added . Alignment was only possible with swapping the wedges around as they were of a different thickness and adding some axle to leg shims . The alignment of the wheel is not perfect but within limits and aircraft handles ok. Wear on the tire is normal as I have gone through 1 tire since the aligment and the new tire is wearing correctly . My wings are 3/4 inch difference in height and that's within limits .
When I said the aircraft is "bent " , it's not perfect due to 10,000 hrs of flying in the bush and rough strips but I think every aircraft is not exactly aligned as it came out of the factory .it fly,s remarkably well hands off and even better than some factory fresh Cessna 172,s that we have reassembled from the shipping container.

You say you have 185 gear legs? So they would be .750 of an inch thick? how do you find them for the type of flying you do? The reason I am asking is because I have a brand new set of 185 gear legs sitting in the hangar and was thinking of putting them on. I do like the 180 gear that I presently have but do find it a little soft in some of the places I go.

I have nothing to compare as I haven't flown a 170 with another set of legs .they are stiff or harsh but I am happy with the limited flex, but run 8.00 tires so they offer some bounce. It lands differently to a Cessna 180 and bit more squirrelly .but if you have 180 legs fitted ,I would stick with them and sell the 185 legs and make some money .

Had another look today at the gaps at the front and back of the gear leg to the outboard gearbox extrusion sides. There's about .025 gap front and back thus the positioning of the gear leg probably doesn't make much of a difference to the toe-in, toe out.

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.