The International Cessna 170 Association

At annual I removed wheel fairings and back plates to install some 8.00 x 6 tires. Still to be determined brand of tire im going to as most of my flying is from asphalt with some grass strips included. But the thing I noticed most was the 5 washers on the back side of the lady legs (1953 B Model) attacthing the solid aluminum axles. Can't be right? Can anybody stear me the way of the proper bolt and nut An numbers. Top two bolts are of smaller diameter. Also whats the most popular brand of 8.00 X 6 or 8.5 x 6 tires.
Brent yocum with new to me 170B

The top bolts are AN5-23A or NAS145-41 and the bottoms are AN6-24A or NAS146-42. The NAS bolts are recommended for ski installations and require a special washer as well.

As a new owner you may want to download the C170B parts manual https://support.cessna.com/custsupt/dyn ... dynVal=477
Its FREE!

I use Michelin tyres and tubes . I replace the tube each time I replace the tyre because tubes wear also. We have many brands of tyres on aircraft that come through the shop and have found Michelin’s are the slowest to loose pressure over time and have the best wear characteristics. Those Tundra tires from Alaska look and work great but wear so quickly on hard surfaces and cost a arm and a leg. My axle attach bolts are all the same size and are all MS bolts . Those axle attach bolts will be all different lengths because of the different thicknesses of the shims for alignment.

Thx for the info! My plane has the lady legs and no shims on either side.

Really, no shims. Is that even possible? I'd be looking into that.

BTW 8.50x6 are not on the TCDS so if you care, your looking at fishing around for paperwork to make them legal. 8:00x6 are on the TCDS.

I installed Air Trac 8.00x6 4-ply tires in June 2015 and have been extremely satisfied. They're much softer than the Michelin 7.00x6-6s they replaced, so they make landings a bit bouncier, but the softness is good on dirt and grass. I run 20-22psi operating mostly from concrete, and the tires have been wearing very well. I could run lower pressure, but I haven't experimented with it.

Really no shims. Seems to track straight. But again it’s new to me. I only have about 3 hrs in the 170.
What kind of toe in is desired?

Well , I don’t have any shims either and mine is ok on the ground as well (or so I think so). I’ve checked the alignment a few times didn’t need to re-adjust. I do have some of the outside wear pattern but it’s surviveable.

Byocum wrote:Really no shims. Seems to track straight. But again it’s new to me. I only have about 3 hrs in the 170.
What kind of toe in is desired?

Zero Toe-in at 2,000 lbs is recommended by Cessna.

No shims with proper alignment would indicate a nice straight fuselage and straight gear, either from the factory or with proper rebuilds along the way.

No shims on my C180 either and it was wadded up into a ball by a tornado before I got it.

lowNslow wrote:The top bolts are AN5-23A or NAS145-41 and the bottoms are AN6-24A or NAS146-42. The NAS bolts are recommended for ski installations and require a special washer as well.

As a new owner you may want to download the C170B parts manual https://support.cessna.com/custsupt/dyn ... dynVal=477
Its FREE!

Karl,
What special washers? Looked everywhere, but couldn't find anything about a special washer.

These NAS bolts are a high strength bolt, and have a radius between the underside of the head and the bolt shank.
A special washer with a countersink that provides relief for the radius is required. Without the special washer, the regular washer can dig into the radius which creates a stress riser and compromises the bolt.

The 5/16 countersunk washer is NAS143-5C, which has been superceded by MS20002C5.
The 3/8 countersunk washer is NAS143-6C, which has been superceded by MS20002C6.

Karl

Thank you for posting the C170B parts manual link, very helpful.

Kevin

sfarringer wrote:These NAS bolts are a high strength bolt, and have a radius between the underside of the head and the bolt shank.
A special washer with a countersink that provides relief for the radius is required. Without the special washer, the regular washer can dig into the radius which creates a stress riser and compromises the bolt.

The 5/16 countersunk washer is NAS143-5C, which has been superceded by MS20002C5.
The 3/8 countersunk washer is NAS143-6C, which has been superceded by MS20002C6.

Thank you for the information.
Looks like your plane is a little older than ours, which has a serial # of 18118.