I just wanted to let you know I started seam-welding my FC. It's a slow process but the results look very promising. It's neat to see the different parts of the unibody extensively fused together. Many parts of the FC seem to beg for this sort of reinforcement.

 

Any new progress???

 

No, I've been really busy with racing season. I hoped to get some work done on it last weekend but the shop was closed down. At least this winter should be a goldmine of production!

 

I did the passenger side door bars today. I went with a simple x to save weight. Even though it is not as strong as nascar style door bars, it is the passenger side... plenty of room between me and the car that hits me.



Also, I started on the base plates for the rear bars. I put the rear bar going to the top of the shock tower for vertical stiffness to reinforce against the spring force. I will be fabricating stiffening plates that tie into the frame rail for added rollover protection.



Some guy at work found this in his desk. Its a pop top from 1981... had to blow the dust off. Sadly, he wouldn't sell it to me.

 

Also, I picked up a 4.33 rear end. It was originally a 4.10 clutch type LSD and he had it rebuilt with 4.33 gears. Although this isn't the 5.12, I needed a 7" NA differential anyway, and got a good deal on it. The car originally had an 8" KAAZ as it was a turbo car.

Do any of the racers that run alternate transmissions feel the 5.12 is necessary if you have gear ratio options in your transmission? Eventually, I would like to get a T5 dogbox.

 

Fantastic build thread. Am watching!

 

The 5.12 is a necessity if you are running a RX-7 box with stock gears or Miata gears. With a dogbox, a 4.10 is fine since you can pick your gear box ratios. This is from experience, not what I have heard.

My 5.12 is up for sale or trade since I bought a Jerico a few months back. Depending on who built the 4.30, I might be interested in that as partial trade or you could come to Dallas and build me a new cage b/c the pictures show you do great work

 

now the fun part is welding 360 all the way around the tube by the roof. I know that some guys cut the top off. do the welding then weld the roof back on.

If you do go for the lop off the top way. There are a few tips you'll want to know about that make it much easyer to reconect the roof.

 

I'm just going to remove the base plates and weld them inside the car, no need to cut the roof off.

 

Hell that's even better.. Didn't know if you had already welded them in.

I must say. your work is very very nice.

 

I just used a hole saw and opened up 1 port or hole above the joint to be welded. You can weld the slug in or just tape over. Great for cage inspection later.

Grreat build but I have to be honest, some stuff is really cool. The FEA and CAD stuff is great. The frame under the car for the driver seat and the aluminum mounts need to be re-thought imho. What is your idea for the partition between the fuel cell and the driver compartment? Rules mandate a partition.

Keep up the good work!

GD

 

You don't need to punch holes in the roof ever. He is using the boxes to gain the clearance before the final welding. I always weld the cage from front to rear in general. The trick for doing the main hoop to halo is to drill holes in the floor or frame box/rail for the hoop to drop down a few inches. Once the top welds are done you lift it back up and slide the mounting plate under the hoop. The plate covers the hole and since it will be welded all the plate it isn't a problem.

 

What would you suggest as an alternative to the seat mounting?

 

This is all opinion. If you have rooom to move the cage around to drop it down, it it not close enough to the original roof to maximize the interior space for the driver. If you did your cage to the maximum driver compartment, then your only alternative is to remove the roof or cut access holes to weld.
Remember that there is a 3' x 2' hole called a sunroof. So a couple of 3" holes at the cage joints are nothing. If your tech inspection requires you to prove the welds, then how do you do this?

My experience is from SCORE, HDRA and rally cars where they ultrasonically check the cage integrity, so inspection holes are an imperative.

Why compromise the floor and drill holes , where there is no cage to recover the integrity? That is chassis structure that should not be compromised. It is harder to do it right than easy.

Answer to the under car seat brace is to utilize the existing seat mount lateral attachments to their best advantage. I incorporated an adjustable mount for a Sparco Pro 2000 all inside the car. You just have to think outside the box. Most seat mounts used just the added cage stucture and did not pierce the floor and compromise any ground influence. You already have the fuel cell hanging too low. Does the front of the fuel cell catch any air that before went through? Rember that any increase in frontal area slows the car down. A fuel cell hanging in the lower air is drag.



GD

 

Absolutely opinion, I guess in 23 years of cage building I've learned that you don't need to get the cage so close to the chassis everywhere that is nearly impossible to weld all the way around a tube. It all depends on rules but many places you don't want to cage up against the body, its better to bridge the gap with some gussets and use the cage and chassis as elements of a beam. The A pillars are one such place.

And even without a .125" thick, 30-50 sq in plate welded over it, try to tear a piece of metal with a round hole punched in it.

And I can make the main hoop close enough to the roof that you can't get a piece of paper between them but in sportscar racing the top of the windshield is where the hardest hits usually occur if the car goes shiney side down.

 

Opinoin is true. Rules also govren most of us too.

The up side of cutting off the top makes for nice even welds, ease of getting it right to the edge and it's easyer to skin the top to get some of the weight off the highest point of the car. Or replacing it with a Carbon.

But then again...rules rules rules....lol

Sorry for the thead jacking.... build on!

 

There is a lateral front seat mount beam in stock form, and there are two pads on either side of hte floor for the rear seat mounts. Connecting the two rear mounts on the floor and laying a thicker .125 x 2.00" top on the front,would make a decent base for either the aluminum mounts you have or a front to back piece of aluminum angle on the sides of your seat. Anything on the inside of the car.

GD

 

Wow. Only 23 years? In every car, buggy or truck I build, maximum room around the driver usually mandates that the cage be fabbed right up against the roof, or door, or floor. My car is made for me and my sons and we're all 6'3" and 200lbs. So we need all the room we can gain between the cage and helmets.

Besides, I don't want to compromise the integrity of the roof by cutting it off. Worse, IMHO, than a 3" hole.

When the tech inspector asks you if the cage is welded all the way around, has he ever said ,"Show me?"

I do Tech Inspection for local off road promoters and I ask the tough questions.

GD

 

I've ever had a techy say "show me" although I wish they would do things like that. 99.9% of the time you can see all of the joints with a mirror or a close eyeball even though you couldn't get a welding torch in the finished area. I've cut old cages out of cars that have had a full 3/4" of a 1.75" tube not welded. The drag racers and off road guys take cage inspection a lot more serious than SCCA or NASA ever has, there are some pretty scarey "pro" built cars running around SCCA events.

Half the fun building a cage is trying figure out the right sequence to weld it in so you can get all the way around every joint. With a little planning you can have people scratching their heads on how it was done. I've gotten quite good at welding while upside down looking in a mirror

Back to the OP's build! Thanks for your work in tech, SCCA could use more like you.

 

Like I said before “opinions differ”,
Oldschool is true and tried.
But there are new better ways to do things. Just look at any Pro car built by factory teams. (I’m not talking about armature rank SCCA and NASA). You will see cages that tie the suspension in as well as make a safe capsule for the driver. So the roof is mostly used for looks.

Off road/rally cages are built to protect the driver in a crash with the road, trees, cliffs and maybe a car.

Road race/circle track cages are protect the driver in a crash with walls, other cars and the road.

Not saying your opinion is wrong, and don’t want to jack this tread anymore.

 

Like I said before “opinions differ”,
Oldschool is true and tried.
But there are new better ways to do things. Just look at any Pro car built by factory teams. (I’m not talking about armature rank SCCA and NASA). You will see cages that tie the suspension in as well as make a safe capsule for the driver. So the roof is mostly used for looks.

Off road/rally cages are built to protect the driver in a crash with the road, trees, cliffs and maybe a car.

Road race/circle track cages are protect the driver in a crash with walls, other cars and the road.

Not saying your opinion is wrong, and don’t want to jack this tread anymore.

 

In my nine years as an official with SCCA's World Challenge I can honestly tell you that 99% of what I saw doing annuals was impressive and our inspections very thorough.

 

SCCA Pro is a whole different ball game. Come out to a club race and you get to argue with tech guys about a liter being more than a quart for an emergency catch can.

 

I spun these little guys up today. I don't have much experience on a lathe, so this took a while.





I made a mess...



And filled this trash can up.



Happy holidays and cheers!

 

good to see some work getting done.

I will hopfully make it down there after finals are done. The next two weeks are going to be just crazy intense.