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How do I extend front seat back

rv8_builder

Active Member
Hi Rv8tors,

I temporarily installed the front seat back last weekend and it just barely contacts the "tall pilot" weldment. I haven?t riveted it together yet and need to extend it about 1" if using the stock hinge location.

Anyone done this before that can offer some advice on how to extend it :confused:

DSC02706.JPG
 
seat back extension

This one, IMHO, is a no brainer.

the vertical rails are a very simple part and you should just make new ones. The time invested in scabbing on extensions just isn't worth it, and you will see it every time you get into the airplane.

You could try recutting the ones you have, but I suspect they'll still be too short ;-)
 
If you move the bottom seat hinge a similar distance back, things should work out fine with what you have.
 
Andre,
I had the same problem. I ended up doing two mods, for the most utility. First, I installed a second hinge, 1.5" further aft of the stock hinge mounting point. This will allow use of the stock seat back when placed in the rearward hinge. The second thing I did was to make an extra seat back, two inches taller than stock. This can be used in either hinge point. See photos
Charlie Kuss



Note the added section to the taller seat back in the photo below



Taller seat back rear view



Close up of the section added to the top of the seat back




The next 3 photos show my floor skin with the two hinges mounted. FYI, all those extra dimpled holes are because I made my floors removable with flush #8 screws.

Top skin with hinge pin located in the "extra" seat back hinge located 1.5" further aft.



Next photo shows the bottom view



This photo show close up of one leg nut plate and mod to stiffener angle for the nutplate. This nutplate secures the hinge pin when used in the rear hinge point for the seat back.

 
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If you move the bottom seat hinge a similar distance back, things should work out fine with what you have.

Jon,

Can you please confirm that moving the bottom of the seat back aft doesn't create any interference issues with the rear control stick.

Andre,
I had the same problem. I ended up doing two mods, for the most utility. First, I installed a second hinge, 1.5" further aft of the stock hinge mounting point. This will allow use of the stock seat back when placed in the rearward hinge. The second thing I did was to make an extra seat back, two inches taller than stock. This can be used in either hinge point. See photos
Charlie Kuss

Charlie,

Did you use normal "hardware store" aluminum angle to make your taller seat back?

Thanks for the advice guys.
 
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Andre and Nico
Yes, there is an interference with the rear stick. It's very easily resolved by getting an RV4 rear stick. It's bent already and works perfectly, although it needs to be cut off slightly. Also, the front seatbelt anchors will need to be shortened if you move the seat back bottom the maximum distance aft. If the seat is placed as far aft as possible, then the top horizontal angle will have to be moved down to clear the seat back brace.
Good luck
 
Charlie,

Did you use normal "hardware store" aluminum angle to make your taller seat back?

Andre,
I purchased a length of 6061-T6 "structural" aluminum. You can identify structural aluminum, because it has a radius in the inner vertex. Architectural aluminum has a sharp corner on the inside. It should never be used on an RV.
You should be able to purchase it locally at a metal supply shop.
I'm 6'4" tall, so I added a "filler" aluminum sheet at the top.
Charlie Kuss
 
Andre and Nico
Yes, there is an interference with the rear stick. It's very easily resolved by getting an RV4 rear stick. It's bent already and works perfectly, although it needs to be cut off slightly. Also, the front seatbelt anchors will need to be shortened if you move the seat back bottom the maximum distance aft. If the seat is placed as far aft as possible, then the top horizontal angle will have to be moved down to clear the seat back brace.
Good luck

Andre,
I purchased a length of 6061-T6 "structural" aluminum. You can identify structural aluminum, because it has a radius in the inner vertex. Architectural aluminum has a sharp corner on the inside. It should never be used on an RV.
You should be able to purchase it locally at a metal supply shop.
I'm 6'4" tall, so I added a "filler" aluminum sheet at the top.
Charlie Kuss

Thanks for the info guys. I'll try to source some "structural" aluminum locally to replace the side angles. I'm 6'7" tall so its important I get this one right :D
 
Andre
It looks like you'll need the seat as far aft as possible. In that case, you don't have to replace the angles. You will in fact have to move that top horizontal down and therefore your angles will be long enough.
Best regards
 
Andre
It looks like you'll need the seat as far aft as possible. In that case, you don't have to replace the angles. You will in fact have to move that top horizontal down and therefore your angles will be long enough.
Best regards

Thanks Jon,

I'll try that before replacing the side angles.
 
Thanks Jon,

I'll try that before replacing the side angles.

Andre & Nico,
I agree with Jon. Look at my first post again. You will note that I said that moving the hinge back 1.5" will allow you to use the stock seat (as is). I made the long seat back to allow shorter pilots to sit further forward (use the stock hinge point). I tried to attach this photo yesterday, but ImageShack was doing site maintenance. This is the rear view of my extended seat back.

tallerpilotsseatbackrea.jpg


If you decide to make an extra seat back, use 6061-T6 or 2024-T3 aluminum.
Charlie
 
Andre & Nico,
I agree with Jon. Look at my first post again. You will note that I said that moving the hinge back 1.5" will allow you to use the stock seat (as is). I made the long seat back to allow shorter pilots to sit further forward (use the stock hinge point). I tried to attach this photo yesterday, but ImageShack was doing site maintenance. This is the rear view of my extended seat back.

tallerpilotsseatbackrea.jpg


If you decide to make an extra seat back, use 6061-T6 or 2024-T3 aluminum.
Charlie

I’m at this point on a QB 8 and would love to see images of how you extended the seat back and hinge location. Is there a limit to how far I can cut the belt anchors back?
 

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Doug,
If you decide to make a second, longer seat back, I would suggest simply modifying the holes in the seat back(s) rather than chopping up the seat belt mounts. That way, everything still works out, when/if you let one of your "vertically challenged" buddies fly from the front, with the taller seat back located in the stock position.
Thanks for PMing me, to let me know that the two photos were MIA. I've re-posted them, along with 5 more, to my original post on this thread.

Charlie
 
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Stock & Tall Seat Back Comparison

Note that on the tall seat back, I had to reverse the position of the second from the top, cross piece of angle. This is done so that it won't foul the cross bar on the "tall man" [WD-823] weldment.



Front view comparison

 
I've found that I actually like the taller seat back, even when positioned in the rear hinge location.

Charlie
 
Tall pilot

I’ve looked over many threads on the subject.
This one is definitely helpful. I’m 6’5.

I plan to install standard hinge and aft hinge as described in this thread. I already have the standard seat back bar but will order the tall pilot one too. I’d rather build the options in for all possible positions than regret going 1 way or another.

My question on the tall seat back…
Can I use the tall one for all combos ie either hinge location either seat back support? Edit: I see previous mentioned the tall seat back can be used on either hinge, I’m not clear on the taller extended seat back mod working with which seat back support, tall support only or both? end edit.
Or, Will I need two seatbacks to go back and forth? If so I’ll need to upholster two seat backs.
 
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