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RV4 short legs to long legs, input please.

The Rv4 I purchased a couple of years ago was built in 1990. It is a basic wood prop, 150hp version (Dynafocal), fitted with short legs. I love the visibility that the short legs offer on the ground.
"However", after an investigation into somewhat excessive tire wear. It would seem the original builder has miss-drilled the left leg & engine mount. He has then attempted to re-drill. The end result is I need to replace at least one leg & Repair replace the engine mount.
I am aware that short legs & mount are no longer available through Vans, but I can get a new leg (short) manufactured & I would have to have the engine mount repaired & redrilled. I know that a new set of long legs & mount would be the "correct" way to repair it but I am reluctant to go down that path due to the complications & probability of things no longer fitting.
Has anyone got experience in going from short to long's. Am I going to have cowl, airbox, carburetor fitment issues?
I am not a builder as such but my buddy is, however I don't want to stretch the friendship more than I have to.
Any input would be greatly appreciated.
 
I am going through that right now. I had an O-320 on the aircraft with a fixed pitch Kato 3 blade prop. I am installing a Titan IO-340 with a MT 3-blade hydraulic prop. It meant switching to long legs. The motor mount for short legs will not work with long legs so the entire mount and legs had to come off. The issue you will run into if you don't keep short legs is the dynafocal mount for the new legs will not match your center of the firewall holes. I also am starting over with a new firewall (way too many holes) and will have to make new F-443's to fit the new dyanfocal mount. It's pretty involved.
 
Ask Russ..

Ask Russ McCutchen(on here) his thoughts on you ending up with a good alignment after the leg replacement. He was/is the engine mount builder for VANs and the ultimate go-to guy for all this. In the state of your project, and if money not a factor, go long and be done. I have flown both configurations and built my -4 after long was the only style. I wouldn't change it "just because", but the longs do have advantages, and probably hold a slight edge in re-sale.
 
Thank you for your responses guys. I have ordered a new leg & will try the oversize bolt approach. I really don't need any more problems than I have already.
Thanks again.
I am going through that right now. I had an O-320 on the aircraft with a fixed pitch Kato 3 blade prop. I am installing a Titan IO-340 with a MT 3-blade hydraulic prop. It meant switching to long legs. The motor mount for short legs will not work with long legs so the entire mount and legs had to come off. The issue you will run into if you don't keep short legs is the dynafocal mount for the new legs will not match your center of the firewall holes. I also am starting over with a new firewall (way too many holes) and will have to make new F-443's to fit the new dyanfocal mount. It's pretty involved.

Ask Russ McCutchen(on here) his thoughts on you ending up with a good alignment after the leg replacement. He was/is the engine mount builder for VANs and the ultimate go-to guy for all this. In the state of your project, and if money not a factor, go long and be done. I have flown both configurations and built my -4 after long was the only style. I wouldn't change it "just because", but the longs do have advantages, and probably hold a slight edge in re-sale.
 
Short to long gear legs

I had a motor mount break on my 0360 powered RV-4
It would just be an R&R along with new gear fairings. It has been a night mare.

I'm still working on the issues.

I do have the old gear legs yet.

Gary
 
My suggestion would be to have your welder fabricate two half tubes (thickness matching original socket) with an ID matching the leg socket OD. Hog out the original holes in the socket to allow the gear leg to be in the correct position, if necessary. With the leg installed an aligned, clamp one new tube half on the old socket and back drill the hole, then clamp on the second half tube and drill through the whole assembly (with the leg still in the proper position). Grab your welder and then get everything installed and bolted up with the gear properly aligned. Then have the welder tack weld everything up. You can then decide if he will need the mount removed for final welding. Downside the this approach is that you may get distortion of the original socket, due to heat from welding, and it will need to be reamed after welding. Careful Tig welding would minimize that chance. You could also leave one of the half tubes un-drilled and do the final drilling after welding.

You could also make a jig to locate the hole on the leg and just weld small radiused plates over the old holes and drill the first hole using the jig and then just final drill through the assembly for the second hole. Would need a machine shop to make the jig.

I have researched installing new mounts on these older birds and it sounds like a major PITA. I am told the early mounts had a pretty loose tolerance on bolt locations and the likelihood of a new mount lining up is slim. The shop used for mounts changed somewhere in the 2000's and that created a compatibility issue as well.

I would not be afraid to upsize the hole in the leg if you can get it to be clean, round and straight.

Larry
 
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Larry, how do you align the leg??

On which drawing or place in the manual do I find that?

Finn

sorry, both my 6 and 10 had pre-drilled legs, so I have never done the leg alignment routine. I know it is in the manual somewhere for the 4 and 6. I believe it is usually done upside down. You need equal length and also adjust for toe.
 
She got legs...

The Rv4 I purchased a couple of years ago was built in 1990. It is a basic wood prop, 150hp version (Dynafocal), fitted with short legs. I love the visibility that the short legs offer on the ground.
"However", after an investigation into somewhat excessive tire wear. It would seem the original builder has miss-drilled the left leg & engine mount. He has then attempted to re-drill. The end result is I need to replace at least one leg & Repair replace the engine mount.
I am aware that short legs & mount are no longer available through Vans, but I can get a new leg (short) manufactured & I would have to have the engine mount repaired & redrilled. I know that a new set of long legs & mount would be the "correct" way to repair it but I am reluctant to go down that path due to the complications & probability of things no longer fitting.
Has anyone got experience in going from short to long's. Am I going to have cowl, airbox, carburetor fitment issues?
I am not a builder as such but my buddy is, however I don't want to stretch the friendship more than I have to.
Any input would be greatly appreciated.

G'Day Pete,
I mulled going to long legs many moons ago when I upgraded my Four from an 0-320A to a Hot-Rod E2D with 175HP.
After much gnashing of teeth I decided to stay with short legs, found a guy on this site to swap mounts/legs (conical-dynafocaL) and installed the new engine. If you order your prop from MT, they can make the blade lengths whatever you desire.
I like 69" props on short leg RV4's, really shouldn't be a problem.

The short legs have many advantages, not the least of which is fixing what ya got and not having alot of extra work.
:)
V/R
Smokey
 
Thanks Smokey, yes I am keen to keep the short legs. The visibility is excellent. I think I have it all under control now. Just waiting on freight in this new Covid world.

G'Day Pete,
I mulled going to long legs many moons ago when I upgraded my Four from an 0-320A to a Hot-Rod E2D with 175HP.
After much gnashing of teeth I decided to stay with short legs, found a guy on this site to swap mounts/legs (conical-dynafocaL) and installed the new engine. If you order your prop from MT, they can make the blade lengths whatever you desire.
I like 69" props on short leg RV4's, really shouldn't be a problem.

The short legs have many advantages, not the least of which is fixing what ya got and not having alot of extra work.
:)
V/R
Smokey
 
Thanks Larry. This is the route I have decided to take.

My suggestion would be to have your welder fabricate two half tubes (thickness matching original socket) with an ID matching the leg socket OD. Hog out the original holes in the socket to allow the gear leg to be in the correct position, if necessary. With the leg installed an aligned, clamp one new tube half on the old socket and back drill the hole, then clamp on the second half tube and drill through the whole assembly (with the leg still in the proper position). Grab your welder and then get everything installed and bolted up with the gear properly aligned. Then have the welder tack weld everything up. You can then decide if he will need the mount removed for final welding. Downside the this approach is that you may get distortion of the original socket, due to heat from welding, and it will need to be reamed after welding. Careful Tig welding would minimize that chance. You could also leave one of the half tubes un-drilled and do the final drilling after welding.

You could also make a jig to locate the hole on the leg and just weld small radiused plates over the old holes and drill the first hole using the jig and then just final drill through the assembly for the second hole. Would need a machine shop to make the jig.

I have researched installing new mounts on these older birds and it sounds like a major PITA. I am told the early mounts had a pretty loose tolerance on bolt locations and the likelihood of a new mount lining up is slim. The shop used for mounts changed somewhere in the 2000's and that created a compatibility issue as well.

I would not be afraid to upsize the hole in the leg if you can get it to be clean, round and straight.

Larry
 
Gear legs - tires

Hi Peter,
Years ago Smokey told me about 380-150-5 tires from Desser for my RV4. They’re a bit larger (you just have to make a bigger hole in your wheel pants to fit them), and they raise your prop off the ground more, as well as improve ground handling - especially on grass strips, etc. I’ve installed these on all 3 RVs I’ve owned in the past and they’re a great improvement I think !
 
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