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View Full Version : Possibly taking on a hangar queen J3C-85, any advice?



IainR
10-06-2020, 10:30 AM
Good day all
I have recently come across a J3C-85 which has been in the back of a hangar for 18 years. This will (hopefully) be my first J3 having flown super cubs and various other bits and pieces for years I've been on the look out for something like this but am nervous none the less! Any advice on things to look out for or mods that are must do/nice to do that may well have not been done (eg univair struts, grove disc break conversion, any more?)? Having not flown for so long I am going to be getting the engine opened up and checked as well as the components serviced so will be a good time to do any additional work.
Any advice appreciated!

bob turner
10-06-2020, 10:41 AM
There are no must-do mods. The struts will save money in the long run if you choose Univair. The brakes are only necessary if the originals have failed.

Carefully check for fuselage corrosion, and if wood spar, take a good look at spars. I personally would borescope the engine, and if no serious corrosion can be seen, I would pre-oil and start it.

When you disassemble an engine these days, mechanics want to send all the pieces out. You will get a reground crank and cam, new lifters, re-machined case, new pistons and valves, often new cylinders. Twenty grand. A lot of it is driven by lawyers - but these engines are lawn mowers. They do not generally fly apart, and only quit when the fuel stops flowing.

IainR
10-06-2020, 10:49 AM
Thanks Bob!

behindpropellers
10-06-2020, 12:38 PM
Good day all
I have recently come across a J3C-85 which has been in the back of a hangar for 18 years. This will (hopefully) be my first J3 having flown super cubs and various other bits and pieces for years I've been on the look out for something like this but am nervous none the less! Any advice on things to look out for or mods that are must do/nice to do that may well have not been done (eg univair struts, grove disc break conversion, any more?)? Having not flown for so long I am going to be getting the engine opened up and checked as well as the components serviced so will be a good time to do any additional work.
Any advice appreciated!

Find a good cub mechanic to look it over prior to purchase. 18 years isn't bad but in the wrong environment a lot of damage can happen.

Tim

Taledrger
10-06-2020, 06:31 PM
Find a good cub mechanic to look it over prior to purchase. 18 years isn't bad but in the wrong environment a lot of damage can happen.

Tim

You can't beat that advise!!!

I love an 85hp J3 !!!

bob turner
10-06-2020, 08:26 PM
I agree 100% with those guys. However . . .

I bought my first Cub in 1962. Blackwell said $1200. I glanced at it and wrote the check. Then I grabbed a duster pilot to teach me to fly it. They told me later they were laughing at me for not negotiating. I got my license from those guys - didn't even know I was taking a checkride until Talmadge Barber handed me a shot of whiskey and said "congratulations." Very close to 5000 hours in it since then, mostly trouble-free. Eight landings today.

Since then, two more Cubs, two Stinsons, a Mooney - all pretty much by staring at them from ten feet. Don't regret any of them. Helped with two Stearmans, a Waco, several Super Cubs . . . the only ones that did not work out well were the ones that were already a done deal by the time I got there. Always check the empty weight in Super Cubs, especially highly modified birds.

When someone asks for advice, my first comment is to check the paperwork, data plate, alterations, total time, and fly it. That, apparently, does not apply here - at least the flying part. But you should not pay a premium price for an aircraft that has not flown in two decades - it may need $20,000 worth of work! Or worse, a new fuselage! But there is a chance that it is ok, and that you could fly it out of there after a good inspection and pre-oiling (easy; we just hook pressure up to a galley plug and pump until it squirts out all rocker arms).

One of the Stinsons came from my Chief Pilot at America West. We bought it sight-unseen. Beautiful aircraft. It is now up in Alaska somewhere -

For me, buying Cubs is like meeting a new co-pilot. You can almost tell by the way they look at you when you shake hands, whether it will be an easy trip or not.

Taledrger
10-06-2020, 10:01 PM
For me, buying Cubs is like meeting a new co-pilot. You can almost tell by the way they look at you when you shake hands, whether it will be an easy trip or not.

Bob, I didn't Quote you completely, but ... if I've learned one thing in all these years ... A lot of these airplanes where not very old when "we" were buying our first ones .. and lets face it, it was a heck of a different world then.. things are different now ..

We were buying 25 year old airplanes. Folks today are buying 70+ year old airplanes ... major difference.

I've never had a "pre-buy".. never had a problem, post purchase.. I've spent my life in aviation.. owned several airplanes.. as much as I "buy" the airplane, I "buy" the seller.. You can tell a lot about the airplane if you study the seller..

The flip side of Bob's First Officer analogy is, he spent along time "learning from his "Captains" ... and passed it on!

This was pretty much the OP (original poster) first post.. Congrats for asking your questions!! Shows your interested in knowing all you can..

As I said earlier... 85hp J3 !! Awesome !!

IainR
10-07-2020, 03:54 AM
Thanks for the time everyone. I am busy with the logbooks etc and so far nothing overly startling. I am really trying to look out for items that are possibly going to cost a fortune as I get her airworthy so that I can make a fair offer. I had a Twin Comanche which I inherited from my father for a number of years and every now and then some obscure thing would catch us out at annual time and cost a small body part! I now fly my grandfathers Tri-pacer which while softer on the pocket also everynow and then throws a surprise cost. Trying to minimize the surprises as much as possible!

JimParker256
10-07-2020, 09:26 AM
Trying to minimize the surprises as much as possible!

Aren't we all, my friend... Aren't we all! And no matter how "perfect" the airplane you buy, or what "pristine" condition it may be in when you buy it, ALL airplanes throw us surprises every now and then. It's nature's way of asking "Do you REALLY want to be a pilot?" LOL

The good thing about a Cub (or any other very "basic" airplane) is that even the big surprises are smaller than with more complex airplanes. Other than the engine, most other things can be put right with copious applications of sweat and blood (plus small-to-medium infusions of capital, of course).

Good luck to you! Hope brings you many hours of happy flying!

Charlie Longley
10-07-2020, 07:40 PM
https://youtu.be/JdyRNhffDJM

IainR
10-08-2020, 03:43 AM
Having had a chat to my local engine shop, I believe that C85 engine parts are hard to come buy, can anyone confirm this? The shops recomendation was if it needs a over haul, turf the 85 and put in a O200.

Crash, Jr.
10-08-2020, 10:37 AM
C85 parts are hard but not impossible to find. Don's Dream Machines has the STC to overhaul the C85 with O200 crank/pistons/cylinders. As far as I know there is no STC to install a full O200 in a J3.

bob turner
10-08-2020, 11:09 AM
My impression (I am currently running three, have a spare, and supervising an assembly) is that everything except the crank and rods is available from someplace near Fresno. The crank STC is expensive but worth it. I finished one 200 hours ago and am delighted.

Univair has an STC for the O-200 in the J3. Check the J3 Cub forum for details.

IainR
10-09-2020, 01:47 AM
My impression (I am currently running three, have a spare, and supervising an assembly) is that everything except the crank and rods is available from someplace near Fresno. The crank STC is expensive but worth it. I finished one 200 hours ago and am delighted.

Univair has an STC for the O-200 in the J3. Check the J3 Cub forum for details.

Thanks Bob, what crank STC are you refering to if you don't mind my asking?

bob turner
10-09-2020, 11:04 AM
There are two STCs to put the O-200 crank, rods, and pistons in a C-85. Notpositive, but I think Don's Dream Machines and ECI? Bought mine in 1995 for $1200, balanced it for $300 more. Things have changed since then.

Installed it two years ago, and am deliriously happy.

BC12D-4-85
10-09-2020, 11:19 AM
http://www.aircraftspecialties.aero/stc-kits/?sort=alphadesc
http://www.donsdreammachinesllc.com

Mine came from the first link. It works.

Gary

IainR
10-10-2020, 02:04 PM
There are two STCs to put the O-200 crank, rods, and pistons in a C-85. Notpositive, but I think Don's Dream Machines and ECI? Bought mine in 1995 for $1200, balanced it for $300 more. Things have changed since then. Installed it two years ago, and am deliriously happy. Thanks very much for the info, do you know if the O-200 STC allows the installation of higher compression pistons to take a C-85 up to 90hp? I seem to remember reading somewhere that it could be done but am not sure if its possible on type certified aircraft.

BC12D-4-85
10-10-2020, 02:17 PM
The C-85 Stroker STC's increase the compression from 6.3:1 to 7:1 via longer piston stroke in a similar cylinder. That creates a ~C-90 equivalent due to increased displacement (188>200 ci) and C-90's compression. The C-85 and C-90 cams are slightly different (the STC's retains the C-85 cam). Continental has a SB (M47-16 Supp. 1) that approves converting a C-85 to C-90 as well using C-90 components. There is an unapproved mod that retains the C-85 pistons with the Stroker STC. It raises the compression further to about 8.5:1 but requires chamfering the upper piston to eliminate interference fit.

Gary

Hardtailjohn
10-10-2020, 11:06 PM
I remember when talking to the guy from A S S, he said they were putting out somewhere around 93hp.
John

BC12D-4-85
10-10-2020, 11:14 PM
Seems to feel about right John. C-90 rated 2475 and 5 min. 2625 @~95hp. C-85 rated 2575 and the Stroker STC retains that limit. It's the added torque that counts I suppose.

Gary

WhiskeyMike
10-11-2020, 08:10 AM
The most important check is the wing struts. If it has original struts, then extreme caution is advised. You can land OK with a dead engine, a broken tail wire or inoperative brakes, but not a missing wing. Before sealed struts there was a mod that went on almost every "Cub" banner plane J-3, PA-11, PA12, PA-18 called Bradley safety straps. I lost a friend in Mount Pleasant TX due to strut fork failure, and I've seen loads of water drained out of struts when drilled to weld in the Safety strap bushing. As a minimum, make certain they actually did the strut punch test and didn't pencil whip it. Better yet, install sealed struts. Enjoy your Cub, and spend your money on gas before engine upgrades. The 85 flies well as is.

IainR
10-30-2020, 09:37 AM
Well I pulled the trigger and have bought her. Now to get her up and running again! Thanks for the help on the thread much appreciated. By the way the unusual "N number" is because she is in South Africa.

5196751968

Paul Heinrich
10-30-2020, 10:10 AM
Simple beauty.

Fine art is always worth preserving.

Crash, Jr.
10-30-2020, 10:10 AM
Wow, what a pretty example of a J3! You definitely got a good buy on that one

behindpropellers
10-30-2020, 10:59 AM
Looks like a really nice bird!

Tim

mbsyvers
10-30-2020, 11:28 AM
I purchased a J3C-65 last fall that hadn't flown in 15 years. I bore scoped the cylinders and found them to be rust free. The differential compression test was performed cold prior to me ever running the engine. three cylinders were77 over 80, with the last at 73 over 80. I pulled the lift struts, removed the forks and bore scoped and the picture showed clean gray steel. This certainly could have gone the the other way, but am hoping you find yours to be in great condition also. Mine came with the C-90-8 and aluminum spars. I soloed an 85 J3 22 August 1965.

IainR
11-01-2020, 11:00 AM
Thanks all! I'm sure I will have a fair few questions as I embark on this adventure.

IainR
11-06-2020, 01:59 PM
http://www.aircraftspecialties.aero/stc-kits/?sort=alphadesc
http://www.donsdreammachinesllc.com

Mine came from the first link. It works.

Gary

Gary having had a look at the aircraft specialities website it states no increase in performance, did you find that to be the case or did you get similar performance to the Don's Dream Machines STC?

BC12D-4-85
11-06-2020, 02:26 PM
Gary having had a look at the aircraft specialities website it states no increase in performance, did you find that to be the case or did you get similar performance to the Don's Dream Machines STC?

Iain the first link claims no increase because it limits their need to change published performance and fuel consumption data. I believe Don's testing showed an increase to the mid-upper 90's hp. That's what I found as well. Power and fuel consumption increased....it has to because the displacement goes from 188 to 201 cubic inches and compression from 6.3:1 to 7.0:1. Move more air through the engine and power/fuel increase.

Earlier I had a C-90 fresh overhaul in a PA-11....static rpm with optical tach checker about 2335. Same prop Sen AK76-2-40 transferred to the Taylorcraft static is 2440. The Taylorcraft has a better airbox (new and tight), air filter (Donaldson), exhaust system (C-150 mufflers), C-90 cam and lifter bodies (per Continental's current 1960 SB 47-16 data), so is better than the Piper exhaust and whatever. Over TCDS static limits but good for floats. Basically the STC turns a C-85 into a C-90. I am pleased.

Gary

IainR
11-06-2020, 02:38 PM
Thanks very much for the info Gary!

dgapilot
11-06-2020, 04:29 PM
Surprised nobody mentioned it, but there is no such thing as a J3C-85! There are J3C-65s that have C85 engines installed.

There was a question about the O-200 STC from Univair. Keep in mind that that STC is only eligible an airplanes with metal spars and a specific fuel tank in the wing. It doesn’t work for wood spar wings! It has also been said that the prop specified in the STC makes for a bad combination of prop, engine, and airframe.


Sent from my iPhone using Tapatalk

IainR
11-16-2020, 04:40 AM
52364

Out of interest (possibly) A lot of guys both on this forum and off advised (with years of experince and full respect) flying the J3 away if everything seemed fine. Engine compressions were good, turned over sweet (having been torn down now everything was still pretty much in spec) so all in all seemed like I wasted my time tearing down the engine, until the crank went for NDT. It was very badly cracked, engine shop recons if I had run it, it could have said cheers at any time! The joys of buying old aircraft with unknown histories.

mvivion
11-16-2020, 09:43 AM
52364

Out of interest (possibly) A lot of guys both on this forum and off advised (with years of experince and full respect) flying the J3 away if everything seemed fine. Engine compressions were good, turned over sweet (having been torn down now everything was still pretty much in spec) so all in all seemed like I wasted my time tearing down the engine, until the crank went for NDT. It was very badly cracked, engine shop recons if I had run it, it could have said cheers at any time! The joys of buying old aircraft with unknown histories.

Actually, I’ll offer congratulations! This is an excellent time and place to discover that crank flaw. The alternative could really suck. Good luck on the rest of the project, and good job using an abundance of caution!

MTV

Techteach
11-16-2020, 01:18 PM
You may not think finding the crack is a good thing, but it really is. I know of someone losing their entire prop off a C-85 (yellow tagged crank) due to crank failure. Thankfully, it was a perfect example of a deadstick landing onto the nearest farmer's field with no damage.

JP
11-17-2020, 09:47 PM
Sounds like a bad prop strike in the past. In general a lot of the older cranks were tender and had very, very minuscule cracks from various misadventures over the years. The one in my 1959 C-90 had 3.

When the oil would get warm you would get a bit of seepage that would land on the windshield. The tiny cracks were discovered during overhaul of the bottom end and a new crank was acquired. The nice people at Aircraft Specialty Services said that as a practical matter it was highly unlikely that the crank would have come apart suddenly absent attainment of an RPM well beyond the capability of the engine (in which case you likely had a bigger problem at hand). Sounds like yours was on the other side of the spectrum so enjoy the security of the new crank.

Oh, I only have one small piece of constructive criticism of your purchase. The tires are too damn small. Please fix that, too. :lol: Otherwise, geniet die vlieg in u nuwe vliegtuig en baie geluk!

IainR
11-18-2020, 02:32 AM
Sounds like a bad prop strike in the past. In general a lot of the older cranks were tender and had very, very minuscule cracks from various misadventures over the years. The one in my 1959 C-90 had 3.

When the oil would get warm you would get a bit of seepage that would land on the windshield. The tiny cracks were discovered during overhaul of the bottom end and a new crank was acquired. The nice people at Aircraft Specialty Services said that as a practical matter it was highly unlikely that the crank would have come apart suddenly absent attainment of an RPM well beyond the capability of the engine (in which case you likely had a bigger problem at hand). Sounds like yours was on the other side of the spectrum so enjoy the security of the new crank.

Oh, I only have one small piece of constructive criticism of your purchase. The tires are too damn small. Please fix that, too. :lol: Otherwise, geniet die vlieg in u nuwe vliegtuig en baie geluk!

Baie dankie Oom! ek is besig om die tires reg te maak, moenie worry nie!

Wag2+2
11-19-2020, 09:42 PM
je spreekt nederlands?

behindpropellers
11-19-2020, 09:59 PM
52364

Out of interest (possibly) A lot of guys both on this forum and off advised (with years of experince and full respect) flying the J3 away if everything seemed fine. Engine compressions were good, turned over sweet (having been torn down now everything was still pretty much in spec) so all in all seemed like I wasted my time tearing down the engine, until the crank went for NDT. It was very badly cracked, engine shop recons if I had run it, it could have said cheers at any time! The joys of buying old aircraft with unknown histories.

It's great that you found the cracked crank. You might have a desire to tear the whole plane apart. If possible, just focus on making it safe to fly. Get a year or two of flying in before you proceed. You can slowly rebuild a cub by doing one wing one year, then the other wing....and so on.

Tim

IainR
11-20-2020, 01:18 AM
je spreekt nederlands?

Net 'n bietjie Afrikaans, maar dis amper die selfde. South Africa has 11 official languages, English and Afrikaans (a spin off of Dutch) being the only two languages of European decent, the other 9 are all of African decent and quite different!

IainR
11-20-2020, 01:19 AM
It's great that you found the cracked crank. You might have a desire to tear the whole plane apart. If possible, just focus on making it safe to fly. Get a year or two of flying in before you proceed. You can slowly rebuild a cub by doing one wing one year, then the other wing....and so on.

Tim

Thanks Tim, the rest of the Cub is actually in really good condition. It would seem, I have to have her x-rayed in the next bit and then will know for sure