Welcome to last year :willy:

Is it me, or does the spec sheet listed under the "Fire" project look like the spec sheet for SN65?

Hi RR,

Thanks for the input.

I agree with everything you posted. 100%. Well... maybe 95%

The overall chassis modifications will be evaluated before the roll bar is added. The roll bar is only being installed as a safety measure to satisfy certain sanctioning bodies. We are expecting 1/4 mile times to be somewhere in the 10's and we don't want to be kicked off the course because we are sans roll bar.

But, just because it is mainly a safety item, does not mean that we are not going to use it to our advantage. It’s main function will be to tie together and reinforce the rear suspension mounting points and reduce flex in this area of the chassis.

The roll bar is being modified from the original sketches. Yes we are eliminating the scissor truss from the sides of the cage. After mocking things up, we felt it was a bit of over kill. But, I will argue the benefits of this type of design. There are two major benefits of this type of truss. First it is almost as effective (at maintaining the distance between two points) as a straight pipe between the bottom legs of the roll bar. Also, it reinforces the major legs by reducing their unsupported span by 50%.

Today we work on the firewall / cowl reinforcements. When these are complete, we will test and see just how far these modifications have taken us.

Hi Jeff,

Damn... This sounds so familiar. I just can not put my finger on it, but I am sure I have seen something like this being done before. :-)

It is not you. We are currently debating the drive train for "Fire". I want to drop in a blown 5 litter (we have a nice, built 5.0 engine with a power charger on it sitting in the shop right now). Wayne wants a Roush stroked 351 (427). We are also working out the trans and rear end.

I think I will defer to Wayne on this one. If he wants a 427 with a paddle shifted 4R70W and a 9" Detroit locker rear, then who am I to argue. It is only money, right. :-)

After all, I am getting my turbo straight 6 with a manual 6 speed and a 9" posi rear.

Bob, Have you seen this? Chasis Stiffening
W.

i have that kit..... took all the peices out to look at em.... thats as far as that project has moved. my coupe has nice original rust free floors, so the mustangsplus kit was much more logical than vert braces and floors. if the kit stiffens it up 75% of what SN65 has accomplished i will be happy.

Yes I have seen that kit.

While the Mustang's plus kit does address some major issues, we are hoping to take things a bit further.

The inner convertible rocker assemblies add a huge amount of stability to the rockers (in two directions). The Mustang plus kit gets most of its strength from the short channel they weld to the bottom of the rocker.

They are adding a torque box, which is a major structural item. And, adding it in two pieces makes for an easy installation, but I wonder what gage material they are using and if there box is actually as strong as the factory design. The torque boxes we added are very heavy items with a number of contours that help in the overall strength. Also, the factory inner rocker reinforcements pass through the factory torque boxes and are tied together well making for a very strong assembly.

Also, the shape of the steel contributes greatly to the overall strength. And the way it is attached makes a difference in the strength. I prefer spot welds to stitch welds for almost all connections. Even though we will weld an edge to seal the seam and clean things up a bit, we always spot weld the material together before we seam weld it.

That is basically it for the Mustang’s Plus kit. They do box the end of the frame rail to the rocker, but that connection adds little to the overall strength of the chassis.

In our plan, the convertible seat pan assemblies are a major item. They tie the frame rails to the rockers and the rockers to each other, adding a tremendous amount of strength not only to the floor, but to the overall chassis assembly.

When done, we will have added about 180 to 200 lbs of steel to a 2,500 lb car. I am predicting a 90% reduction in chassis twist/flex on our test platform. At that point, we will have a chassis that can handle the high performance drivetrain and suspension modifications we intend for the car.

Sound like a plan???

Currently, we have reduced torsional deflection by 70%. We started with 1.062" of deflection and are now down to .319". Not bad so far.

Here are some photos showing the rocker, floor pan mods

http://sn65.com/images/Fire%20&%20Ic...9-27%20011.jpg

http://sn65.com/images/Fire%20&%20Ic...9-27%20012.jpg

http://sn65.com/images/Fire%20&%20Ic...9-27%20038.jpg

Here is a photo showing the cowl, firewall, shock tower reinforcements.

http://sn65.com/images/Fire%20&%20Ic...0-09%20027.jpg

We need to add the final shock tower brace and weld the floor to the rockers before we can take our final "test". After that, we can add the cage and see just how much we gain at that point.

Also, we are working on a modified Monty Carlo bar that not only helps maintain the distance between the shock towers, but also helps reduce overall front clip deflection.

Installing the converible items to your rust free floors would not be that big a project.

To install a convertible inner rocker on a coupe or fastback is pretty simple. First, you would remove the stock seat pans. Next you would drill a series of holes in the floor pan all along the inner rockers (about .75” away from the rocker). Then you cut the floor pan away from the rocker (we recommend a plasma cutter, but it can be handled by a “saws all”.). You just pull it along the inside edge of the rocker and you are done in a flash). Use an air chisel to remove the strip still attached to the rocker, and, after a bit of grinding, you are ready to rock.

At this point the inner rocker (trimmed and formed to mate up with the rear torque box) just slides into place and sits right on top of the floor. The lip of the inner rocker reinforcement slips down into the slot you just cut and everything is ready to weld in place. Granted, there are quite a few spot welds, but welding is the fun part, isn’t it?

At this point, welding in the convertible seat pans (top and bottom) is a snap. Just position as desired (we shifted ours back about 1.5” for additional leg room) and weld in place.