Great idea. I can't wait to see the finished product. That should firm up the back of the seat nicely.

 

As-built change!!!

So, somebody over at the FFR forum suggested that I reconsider the Kirkey back braces. When I started this, I ruled out those out because of their size and the fact that they would require a huge slit in the rear bulkhead to work as intended. Well, that 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.

 

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.

 

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:



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).



Here's the passenger side angle bolted in place.



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.



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.

 

You put more brace on the seat than FF5 on the lower control arms...:weight_lift:

 

What are those large round fasteners with the stud on it?

 

They're called perforated base studs and are available from McMaster-Carr. They're great for things like this as they can be welded, bonded (like under fiberglass or with HSRF) or riveted to the surface. For the seat braces, I'll rivet them to the seat back.

Here's a link to them in the McMaster catalog: McMaster-Carr

 

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.