The International Cessna^® 170 Association

blueldr wrote:Rebushing a set of original rudder pedals in a helluva lot more work and expense than installing a set of the later model plastic pedals that never wear out.
IMHO,Unless you're a stickler for originality. the plastig pedals look better too.

You're sure right about the work (time) involved. Good thing I didn't charge myself an hourly rate! I probably wouldn't have done it if I had to pay someone to do it.

Richard Pulley,
Are you sure that the rudder pedals are made of a weldable aluminum alloy? Some alloys, if welded will crack right along the edge of a weld.

I assumed the weld I photographed above cracked because it the aluminum was heat-treated rather than the type of alloy. If I annealed the pedal before welding would that take care of the cracking issue or is the type of aluminum alloy simply unweldable?

I would suspect that the rudder pedals are made of 2024 alloy or 24ST and I do not believe that it is classed as a weldable alloy.

I just traded pedals left and right. The former right side pedals still had round holes and the left ones were a bit sloppy but not at all cracked. Feels better from where I sit. Good for another 50 years I think.

The plastic rudder bar bushings are symmetric top to bottom and do indeed need longer bolts.

Those later model rudder pedals (square tops) look good on square tail 172"s. I changed mine out many years ago. I like them since the area your shoes rub on don't show wear.

Arash.....
Two items immediately come to mind. First, please be careful when reassembling your master cylinders...those little piston return springs that encircle the plunger shaft? Make absolutely certain they are installed correctly. If not (upside down), your brakes will function properly at first, but won't be able to refill themselves when the fluid in the line needs replenishment. You may already know this. Second, and you've probably already figured this out, when you install the new-style plastic rudder pedal bearings, the rudder pedal bay dust covers will no longer fit properly because of the height difference. I hate them, but went back to the stock aluminum bearings for this exact reason. Just got to keep 'em lubed. Was planning on flying down to KHAF this week anyway....maybe I'll stop by your hangar, see what you've got going on.

Aryana wrote:

.......Now this is just the ticket. In addition to my IA, I have a really good sheet metal guy who can help me do this.

Are the steel bushings only held captive from moving outboard in the pedal by the riveted plate, but are free to move inboard? The steel tube the pedal mounts to would prevent the bushings from moving inboard, but I wanted to make sure I understand your repair before I ask my IA to help.

Not quite sure I understand the question yet. Steel bushing???
It been a few years ago, but here is my recollection. I bored out the existing oblong holes to a larger diameter. Not enough to remove all traces of oversize, but enough to locate the new bushings. Then I turned the new bushings on a lathe. The bushings were 2024 aluminum, which is what I assumed the pedals were made from. The bushings are flanged, with the small diameter sized to be a close fit in the new bores of the pedals, and the outer flange sized to rivet to the pedals with correct edge distance. This gives twice the bearing area on the shafts compared to the original pedals, with the same material. I suppose that I also had to fabricate longer shafts, since the pedals are now slightly wider. Now, I don't believe that using aluminum bearing surface is really the best choice for this application, but I was trying to maintain the original design features. Another case where Cessna surely didn't imagine that these airframes would be in service anywhere near this long.
Hope this makes sense now!

Aryana wrote:But speaking of those piston return springs, does anyone know what the part number is and/or where to buy em?

Fig. 59-13 in the 170B IPC shows p/n 0541148. $7.50 from Premier Aviation.

Steve, that's nice work. I suppose you could have used bronze for the bushings, or even steel. I'd rather wear out the shaft than the bushing. The shaft is just a hollow 5/16" OD steel rod. If you could lock the shaft to the pedal you'd design out this entire problem. Then the bearing would be the shaft inside the pedal lever T. This is a great thread. My pedals aren't badly worn, but better to fix them before they need it.

Arash, you probably made the right decision about the carburetor. Not a bad idea to rebuild these things every few decades. I said "probably" because you never know how the new carb will work compared to the old one, with a different venturi and different main jet and whatever else changed in all those part number supersedures.

I've done the flap roller job. I used the McFarlane upgrade roller kit. It took a while, not just to install the rollers, but also to clean and repaint the flap tracks and to re-set the flap cable tensions. You might want to consider having some large nylon washers on hand to make your own "wear washers" that run on the sides of the flap tracks.

Arash
The new carb looks really good. I see they have new castings. What is on the "warning label" ?
Dan

I can only image flying 500 hours a year!
The warning label wasn't as strong as I thought it might be as it was probably written by a lawyer.

a job well worth several hours spent on your elbows...

Arash-
Is the indicated airspeed in your first picture normal for cruise or were you in a descent? I never see more than 105mph ias at 2500rpm.

Not Arash, but I can bank on 115-120mph straight and level indicated at 2450 RPM in 56D (stock 52 B). I ferried a friend up to Danville, VA to get a 1949 A model for an annual at our field, and he said that he was only getting about 105-110mph at the same power settings. Neither airplane has wheel pants, though I have smaller tires (6.00x6 versus 7.00x6 on the A model). No green on either airplane.