Christian Sturms site has a good set of drawings. http://www.supercubproject.com/drawings/main.aspx
We put a set of -18 gear on our J3. Bolted right up.
Wayne
.... my on-going quest for Cleveland approval on the J5.
The actual STC documents leave out the J4 and J5. No idea why. Been on the aircraft for a quarter century.
Why not just do it via 337?
A 337 will be fine as long as you have approval from an STC or a field approval before filling it out. If by field approval the FAA approval box has to filled out. 337 can be done for major repairs but alterations need prior approval.
That doesn't always help.
I got a FA for 26" Goodyears on my C180 a couple years ago--
even though I had scads of previously approved 337's,
it still took 11 months and a lot of prodding the FSDO guy.
Needless to say, this process didn't improve my opinion of the FAA.
Dunno just which cleveland brakes you're trying to get approved,
but my old Univair catalog states that cleveland w&b kit # 199-071 is approved for "J-3 through PA-20".
Had a J3 with a C-90-12 engine that was done many years ago on a 337 but no FAA signature. Called the FSDO and they said it was in the permanent records it was fine. got it in writing and put it in the logs.Yes - a huge percentage of IAs do not understand 337s. I am not a full time mechanic, but still I see bunches of 337s for alterations approved by IAs. This one is just the latest.
It says "installed Cleveland . . . Per Piper kit 199-0170 (from memory)". Then it is signed by an IA - in 1996. Scottsdale FSDO accepted it, without stamping block 3, and sent it to OKC.
Working on approval since May. World's easiest field approval. Dave would do it for free, but this is something the FAA should do - their guidance says "sign it."