The International Cessna 170 Association

A customer just sent me a pair of reconditioned gear legs. They both have the hole that's drilled completely through.
The gear we removed were also the knock-kneed type, but only have a dimple for the brake line retainer to clip into place.

I can find or fab the brake line retainer straps, but the IPC doesn't mention what type fastener attaches the retainer straps to the gear leg/hole. Anybody know?

The holes in the gear legs are countersunk on both sides (top and bottom), so was thinking if I make a strap, I would dimple it so the dimple will nest into the countersinks. This way, the fastener wouldn't have much stress on it, and I could use a soft rivet to fasten the retainer to the gear leg. Micro-shave it flush on both sides.

Or I could make retainers out of half hard stainless, and dimple the retainer to clip into the countersunk holes, installed with some PR1440 sealant, maybe avoiding a fastener through the gear leg.

Thoughts?

Del,
It looks like KRN has straps, p/n 0541104, in stock. Like you wrote, the IPC clearly shows a fastener for attaching these clips but it doesn't spell out what that fastener is. I think one can come up with a reasonable guess looking at the Cessna 120/140 IPC. Here's a screen shot:Item 16 is a AN435-6P-16 rivet, (now superseded to MS20435). This is a 3/16" dia. 1" long carbon steel round head rivet. (Anyone know how the thickness of the 120/140 gear compares to the early 170 gear? You'd obviously need a longer rivet if the gear is thicker.) I found the information on this rivet here. The only thing I wonder about here is if they used a round head rivet on the 170 why are the holes countersunk? Anybody know if the 120/140 holes are also countersunk? Bruce, did you happen to get a picture of this clip on the gear leg of N4039V?

Personally, I think I'd want something less permanent in there than a steel rivet. How about AN3 bolts or AN525 screws with two of these repair washers to fill the countersinks?

Del-
I hear you saying the legs have one hole on each leg. They were the early early gear for serial numbers 18003 to 19219. The later A Model gear had a dimple top and bottom.

I have tried in vain to upload a picture but my normal routine of take picture, email it to myself in reduced size, and upload it is not working today. I’ll keep trying.

The parts manual shows a maybe 1/2” wide strap bent 180°into a “U” and with long enough legs to go around the brake line with a rubber bushing (1/4” vacuum hose?), and holes for a rivet (I would rather have a bolt). The strap goes the long way to the hole, in other words, the strap can either be longer or shorter. The parts manual shows it longer. I think stainless steel would be a great idea for the strap. The originals are carbon steel.

Del, my 1955 170B uses the dimpled straps. If I remember correctly I purchased NOS replacements from Air Repair. Might be worth checking them out.

I believe form the factory the brake line strap was riveted to the leg. Of course the first time maintenance was required the rivet got replace with a screw. In any case, what ever held the strap to the leg is not specified in the IPC.

Del, with your first option, I'd be concerned about dissimilar metal corrosion between the soft rivet and the hole, especially given that I understand the hole area was prone to failure in the past. Your second option is more like the Cessna's later version on the dimpled knock-kneed legs on my '52 model. The clips on mine can move/float a bit, but it's never been a problem. The clips don't come anywhere near to falling off. In order to prevent the clips from scratching the paint on the legs, I've put small strips of silicone tape between the legs and the clips. Works very well. If I were you, I'd just try to find a set of the later clips.

Del... what about a different approach.... Why not use the previous gear-leg spring-clips ...but instead of using a rivet or bolt/screw... how about just drilling a small hole thru the clips’ dimpled area and running a loosely fitted cotter thru the clip and gear leg?

In any case, steel, iron and aluminum do not have large electrolytic issues according the charts I’ve seen.... what about a soft aluminum rivet?