Back braces for Kirkey low back vintage bucket seats

[Gumball]

I'm working on the installation of my Kirkey low-back seats (see this thread for how I reshaped them) before sending them over to the upholsterer for leather covers. I like how the Breeze mounts give the seats a nice angle, so wanted to use those - but didn't want to use side-mounts.

In order to do this, I needed to come up with some sort of a back brace that would give rigidity across the back, not just in the center. I'm in the process of doing the metal fab work, but here are some pictures of the cardboard versions.

Each seat has two shoulder-level braces, which completely eliminate rearward flex of the seatback, as well as side-to-side flex as the occupant uses the upper wings as a hand-hold when entering and exiting the car. The 1"x2" tubing will pass through holes in the rear bulkhead and will be bolted directly to the 2"x3" chassis tube. The seat ends of those tubes will have 1 1/2" flat stock that will be gussetted (not shown in the mock-up) and will be attached to the seat via studs that will be mounted to the seatback and protrude through the leather covering. The inside of the seat back will have the stud plates (3"x4" flat stock) to which a pair of perforated weld base studs will be attached. Those stud plates will then be riveted to the seatback and completely covered with padding.

Here are a few pics - I'll post more as I make progress with the fabrication.

http://i845.photobucket.com/albums/ab15/CCRsAC/BackBracesMockUp2_zps2016b30c.jpg (http://s845.photobucket.com/user/CCRsAC/media/BackBracesMockUp2_zps2016b30c.jpg.html)

http://i845.photobucket.com/albums/ab15/CCRsAC/BackBracesMockUp1_zpsede80093.jpg (http://s845.photobucket.com/user/CCRsAC/media/BackBracesMockUp1_zpsede80093.jpg.html)

http://i845.photobucket.com/albums/ab15/CCRsAC/BackbracesMockUp3_zps87b3efd4.jpg (http://s845.photobucket.com/user/CCRsAC/media/BackbracesMockUp3_zps87b3efd4.jpg.html)

[SCFFR]

Great work Chris. Those will be real nice seats when finished.

Ron

[Mike N]

Why not use the style back brace that Kirkey designed for their seats?

16649

It would be plenty stiff and just strong enough so that in a wreck it will bend absorbing energy. My fear with your design is that the tube sections would be too strong behind your shoulder blades and that the seat would deform in an impact and the tube sections would not causing potential back injury. Just my $.02 but might be worth thinking about.

[Gumball]

Mike - why not, indeed. When I started this, I ruled out the Kirkey back braces because of their size and the fact that they would require a huge slit in the rear bulkhead to work as intended. Well, your post got me to thinking and I bought a pair of the Kirkey parts (incredibly thick aluminum) and trimmed them so that they stop at the bulkhead. I'm going to add piece of angle that will bolt through the bulkhead into the 2x3 chassis tube, then serve as a rear mounting point for the back braces by passing a couple button head bolts down through them into the angle.

I'll post more pics once the rest is fabbed up and powdercoated, but here is a shot of the basic fit.

http://i845.photobucket.com/albums/ab15/CCRsAC/kirkeybackbrace3_zpsadcd62ff.jpg (http://s845.photobucket.com/user/CCRsAC/media/kirkeybackbrace3_zpsadcd62ff.jpg.html)

[Gumball]

So, the revised back braces are coming along nicely. Using the modified (shortened) Kirkey-made braces in the above photos, I made a mounting point for the rear bulkhead behind each seat using some 1 1/4" angle. The angle will be bolted through the bulkhead to the 2x3 chassis tube, then the carpet will be installed over it so that just the horizontal portion is visible. That part of the angle has been drilled and tapped so that I can bolt the shortened Kirkey brace to it. The Kirkey brace is then bolted to the seatback using perforated weld-studs that will be riveted to the seat before the seat is covered with padding and leather. When the seat is done, only the four studs will show through the back.

Here are some more pics of the fab process - I'll post more when everything is done and powdercoated and the seats are covered.

http://i845.photobucket.com/albums/ab15/CCRsAC/NewBackBraces2_zps9e9a7c3f.jpg (http://s845.photobucket.com/user/CCRsAC/media/NewBackBraces2_zps9e9a7c3f.jpg.html)

http://i845.photobucket.com/albums/ab15/CCRsAC/NewBackBraces3_zps104bcb49.jpg (http://s845.photobucket.com/user/CCRsAC/media/NewBackBraces3_zps104bcb49.jpg.html)

http://i845.photobucket.com/albums/ab15/CCRsAC/NewBackBraces4_zps3be505c8.jpg (http://s845.photobucket.com/user/CCRsAC/media/NewBackBraces4_zps3be505c8.jpg.html)

[Gumball]

Here's the final product for my seatback braces. The seats are now going to go to the upholsterer and the brace brackets are off the powdercoater.

A pic of all the components:

http://i845.photobucket.com/albums/ab15/CCRsAC/FinalBackBrace2parts_zps89e96afe.jpg (http://s845.photobucket.com/user/CCRsAC/media/FinalBackBrace2parts_zps89e96afe.jpg.html)

A shot of the two angle pieces cleco'd to the rear bulkhead just before I drilled the holes out for larger bolts. I decided to use the 1/8" holes that I originally drilled in the bulkhead and the 2x3 chassis tube to mount the angles to the chassis. After figuring out where the holes needed to be in the angle so that they lined up with the existing holes, I just pulled out one cleco at a time and used a stepper drill to open them up to just beyond 1/4" (the size of the Gr.8 bolts that will hold the angles in place).

http://i845.photobucket.com/albums/ab15/CCRsAC/FinalBackBrace1_zps37ba12e3.jpg (http://s845.photobucket.com/user/CCRsAC/media/FinalBackBrace1_zps37ba12e3.jpg.html)

Here's the passenger side angle bolted in place.

http://i845.photobucket.com/albums/ab15/CCRsAC/FinalBackBrace4mounted_zpsb9fe7901.jpg (http://s845.photobucket.com/user/CCRsAC/media/FinalBackBrace4mounted_zpsb9fe7901.jpg.html)

And finally, I used a piece of .090 flat stock with some clip-nuts that I slid into the open end of the 2x3 chassis tube to hold the angles in place.

http://i845.photobucket.com/albums/ab15/CCRsAC/FinalBackBrace3innerchassismount_zpsb348281c.jpg (http://s845.photobucket.com/user/CCRsAC/media/FinalBackBrace3innerchassismount_zpsb348281c.jpg.h tml)

Everything will be accessible (although tight) once the car is assembled, but I'll do the initial assembly with the body off for ease of working.

The last thing I did today was to make a couple of 7/8" tubes with holes drilled straight through to sit under the leading edge of the seats. The seat bottoms are angled quite a bit and this gives the front the support it needs. The two front mounting bolts pass directly through the tube, holding it in place and giving the mounting points quite a bit of extra rigidity.

[Gumball]

Here is a photo of the brackets installed.

The bottoms are Breeze seat mounts with an added 7/8" steel tube that acts as a filler to get the seat angle correct - the Kirkey's have a multi-angle base. Now that the seats are at the upholsterer, I can take the rest of the brackets to the powdercoater.

http://i845.photobucket.com/albums/ab15/CCRsAC/SeatBracketsforKirkey_zps1dda3537.jpg (http://s845.photobucket.com/user/CCRsAC/media/SeatBracketsforKirkey_zps1dda3537.jpg.html)

[AZPete]

Very nice work. That's why I love this site - innovative solutions by smart guys.
Since my next project is an 818 I'm following the 818 forum where some of the guys are new to FFR and they ask "how high are the seats", "how much leg room" and "where can a radio be mounted" without realizing that they will make their car as they want it. I should send them here to see how guys are innovative and help each other.
Pete