nohoflyer

nohoflyer

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I am building a 7a.

I fit the wings into the fuselage and used drift pins as the instructions call for. I did all the drilling required.

The problem is I can’t get the bottom drift pins out. The top ones were not too hard cause I could tap them out. The bottom ones are inaccessible to tap out because of the gear weldements. I’ve pulled, twisted, adjusted the wing heights to change torques, nada.

Im ready to remove the gear weldements with a cutoff tool and buy new ones just so I can maybe tap those bottom drift pins out.

Any ideas cause I’m REALLY frustrated.
 
nohoflyer said:
I am building a 7a.

I fit the wings into the fuselage and used drift pins as the instructions call for. I did all the drilling required.

The problem is I can’t get the bottom drift pins out. The top ones were not too hard cause I could tap them out. The bottom ones are inaccessible to tap out because of the gear weldements. I’ve pulled, twisted, adjusted the wing heights to change torques, nada.

Im ready to remove the gear weldements with a cutoff tool and buy new ones just so I can maybe tap those bottom drift pins out.

Any ideas cause I’m REALLY frustrated.
Click to expand...
If you haven't tried it already, put the top pins back in and have someone wiggle the wing while you try to pull the difficult ones.
 
Top pins back in like others suggested.

Also try a little PB Blast to help the ‘slide’.

You’ll get it. Take your time and be patient. You’ll learn a lot doing it.

Keep us posted!
 
Consider using a 50/50 mixture of transmission fluid and acetone and put a few drops on the bolt and let it sit for a few minutes.
 
I know there is little room but if you can get a container of sort under the bolt, then put some dry ice with 90% alcohol for just a couple of minutes or so to shrink it. Of course this is after you have put the pins in the top hole first.
I put my main bolts using the dry ice and alcohol and it did help a great deal with installing them.
 
I just replaced my Jeep pitman arm and had to use the special wedge tool to pry it out. It looks like below..
Basically it's wedge with a slot to fit the bolt head or bearing joint. You hammer the wedge and it pries open the bolt
Or you can use the bearing puller if you have the room

Since the commercial wedge in the picture is manufacture for the jeep, a local machine shop can fab something like this if you can't pull out the bolt. The great thing is you can work on the non-landing gear side with all the room.
 

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Bavafa said:
I know there is little room but if you can get a container of sort under the bolt, then put some dry ice with 90% alcohol for just a couple of minutes or so to shrink it. Of course this is after you have put the pins in the top hole first.
I put my main bolts using the dry ice and alcohol and it did help a great deal with installing them.
Click to expand...

Yeah, but he's trying to UNinstall them...
 
If I may offer a bit of general advice? This is where you're going to need to be careful not to booger the s**t out of adjacent structures by prying or wedging or whatnot. Slow down, think things through, and don't get all gorilla on it. They went in, they'll come out, but if you start prying on things, you're likely to just tear up the spars or weldments.

If it were me, I'd back up...put the rest of the pins back in, and try to wiggle the wings a bit as noted. Also an excellent suggestion to get the weight off the gear, so that things are under significantly less external force and freer to move around just a bit.

Thousands of others have used pins just as you have...you can, too. Remember..."make haste slowly".
 
I second Joe's advice...make haste slowly. Removing the bottom bolts in a 7A spar can be a really, truly miserable task, and assembly pins are similar.

Do you have a little space under the head? If so, protect the spar box with an appropriately sized and padded steel or aluminum plate and insert the tip of a pry bar under the edge of the head. I'm talking about a bar two feet long, or more. Lube the bolt as described above, ply out a little, stack another fulcrum plate, repeat. Eventually you'll be able to substitute a wood block for the plates. I plan to make a bar with a forked tip before I do the next one.

Along the same lines, making up a drift with a L-shaped foot may be worthwhile, just so you can bump the pin back a 1/2" or so.

Illustrations for those lucky TW guys who have not had the pleasure. The problem is the two big bolts in the bottom, the threaded end being hidden behind the gear leg socket.

Weldment.jpg

Back side of spar box.jpg
 
Dan, that's very illustrative. First thought that occurs: remove the landing gear mount. Support the plane by engine mount? Not sure if realistic, but would certainly beat damaging main wing spar and mating fuselage surfaces by using wedges.
 
DanH said:
Do you have a little space under the head? If so, protect the spar box with an appropriately sized and padded steel or aluminum plate and insert the tip of a pry bar under the edge of the head. I'm talking about a bar two feet long, or more. Lube the bolt as described above, ply out a little, stack another fulcrum plate, repeat. Eventually you'll be able to substitute a wood block for the plates. I plan to make a bar with a forked tip before I do the next one.
Click to expand...

Exactly what I did on mine, worked perfectly.
 
Why are the drift pins so tight? Maybe worth investigating. On my 7A, the gear weldment bolt holes were slightly off center. I checked them before installing them. Vans allowed me to file the holes off the airplane to eliminate the interference. It would have been a major problem to install or remove wing bolts later.
 
Also, if you're going to pry on something, be mindful of what can be damaged if the pry bar or tool or screwdriver or whatever cuts loose, or the part you're prying suddenly frees up. Will the bar slam down on something? If it slips off, will you damage a nearby part?
 
RV7A Flyer said:
IF you could keep the surrounding part warm at the same time...
Click to expand...
Exactly. Since Al conducts heat so much better than steel, this is difficult. I’d suggest heating bolt and spar, maybe boiling water? The Al hole should expand more than the steel bolt.
 
I’m going to try it today with the help of another builder. Maybe with him wiggling the wing around and getting the pressure off it might work.
 
Just had to back the lower two 7/16" close tolerance bolts out a bit on my 9A this weekend, forgot you had to put the nuts on before driving the bolt in all the way... I rotated the bolts counter-clockwise with a ratchet while applying pressure from the front with a long flat screwdriver levering against the gear weldment. Back when I was at temporary wing attach stage I removed the lower drift pins by similarly backing the pin out just enough to get a vise grip around the head, then pulled on the vise grip while assistant gently rocked the wings up and down. No fun but it eventually worked.
 
Follow up :

A fellow builder (Shado) helped me today. Just some lifting of the wing allowed things to move much smoother. NOT a one person job because the amount of up-pressure required is variable so the helper lifted and jiggled a bit. Funny but when he had the sweet spot, they pulled right out.

Anxiety abated…for now.
 
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I remember installing the wing bolts for the final time. I had them stuck in dry ice for an hour.
Then a DAR showed up to do someone else's plane, so I waited till he left, put the bolts in and started beating on them with a rubber mallet. Didn't want to DAR to see me taking a rubber mallet to the plane. LOL
 
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