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Jeremy
11-26-2006, 01:41 PM
After some trial and error as well as searching the available designs I have come up with a chassis brace that took all of the flex out of my car. The first edition is a piece of 1 inch tube running from side to side where the subframe meets the subframe connectors. It also has some angle braces running fore and aft. It is currently welded in but it is too low.

I have a design that will be 1/4 inch lower than the subframe connectors and still go from side to side. It is a combination of the factory bracing on a first gen convertible and the g brace made for early Mustangs.

My question to those that want to chime in, should I make the center section bolt in, like the first gen f body's or make it one solid, welded in piece as I originally planned. I have checked and there is nothing that the 14 inch by 14 inch center section will be in the way of for servicing. The only potential problem is that I won't be able to drop the exhaust as it will hit. If exhaust needs servicing I will have to put a joint somewhere in between the down pipes and the end of the subframe.

If I make the center section removable, it will add some fabrication time and some minor expense. The mounting bolts will also be a potential source of flex.

I am wanting opinions as to wether it is worth it. If I weld it in solid, the exhaust will be have to be threaded in from rear to front versus up and down if it is removable. This is if I want to maintain one piece from the down pipes to the mufflers. If I cut the pipes and add a joint, then it really is not a problem.

Let me know what you think. I hope to finish cutting the pieces to length tomorrow and dropping everything off at the welders.
I'll post pics as I get things built. While this may not be for everyone, for those that don't want to stay stock, it will do wonders for you chassis rigidity. The current one, which is no where as beefy as the final one I plan to build, already got rid of all my squeaks and rattles. The dash no longer creaks when going over driveway cuts. Bumps are completely soaked up by the suspension now and the car rides really soft with the ws6 springs.

Rick Dorion
11-26-2006, 03:11 PM
Sounds great. For removeability you can use a ball/cone setup to drop out the center exhaust.

dipren443
11-26-2006, 04:44 PM
Sounds excellent. Look forward to seeing pics/drawings of the setup. I have been contemplating a brace of this type and can't wait to see your solution :geek:.

ks71z28
11-28-2006, 10:21 AM
You've been on this for a while, wheren't you doing the under tray? Let me see a pic and i can compare it to my camaro to see if any conflicts, also what sf conectors are you using as a height reference?

Keith

Jeremy
11-29-2006, 03:10 AM
The belly pan was no where near as stiff and heat buildup was a big problem.

I have CE bolt in subframe connectors that I welded in. They helped some, but the brace helped a lot more.

The brace is in and done. I do want to go back and grind the welds smooth and paint everything. I am also considering gusset plates for the joints, although it may be a bit of overkill.

In the pics you can see that I tried to add some strengthening ribs to the 1/4 inch plate. I am not sure I like the look of them plus they added 1/2 more height to the brace. I will probably cut another 1/4 plate a little smaller on each side with an x in the middle and weld this to the exisiting plate. It should look better and probably be just as still as the two pieces of angle iron.

The goal was to tie everything in to the existing braces on the floor pan and then box the tranny tunnel. All pieces were cut a little tight and had to be persuaded into position.

Chirs Alston chassis works is working on something similar for use with their subframe connectors. It bolts in at the front and rear of the subframe connectors but would have hung a little lower as it uses 1 inch round tubing through out.

Without the added ribs on the plate, I was 1/4 inch lower than the subframe connectors. When I double the thickness of the plate, I will be 1/2 inch.

https://static1.pt-content.com/images/noimg.gif (http://img297.imageshack.us/my.php?image=p1010267le5.jpg)

The first pics showed a side view giving the overall layout of the brace.

https://static1.pt-content.com/images/noimg.gif (http://img137.imageshack.us/my.php?image=p1010268lt3.jpg)

This pics shows the vertical piece tying the brace to the rear subframe support.

https://static1.pt-content.com/images/noimg.gif (http://img227.imageshack.us/my.php?image=p1010269kk0.jpg)

Here you can see the front tie in points. The angle piece was done before the brace and did a lot to help rigidity by itself. I left it there as this was a large space and I wanted to make everything nice and stiff.

https://static1.pt-content.com/images/noimg.gif (http://img97.imageshack.us/my.php?image=p1010270em6.jpg)

A close up of the rear angle braces.

https://static1.pt-content.com/images/noimg.gif (http://img97.imageshack.us/my.php?image=p1010271hb3.jpg)

A pic showing everything.

Does it work? Yes. Over all road surfaces bumps now pass with little affair. The car is much less twitchy in corners and tends to wander less on badly rutted roads. It truly rides better than either my 04 crown vic company car or my wife's 05 Taurus.

Structurally it just feels a lot more solid. The dash doesn't shudder any more over bumps.

Over extreme driveway cuts, I still get a little groaning in the area above the windshield. The only thing I can figure is that the suspension must really reach the limits of its travel and put a lot more stress on the frame. If I take the same driveway cuts at less of an angle (more straight on) the groaning is gone.

I wil continue to explore how I can get rid of the popping above the windshield. I definitely want to check the spot welds in the roof area as I have heard that on the t top cars they can work loose which might explain some of the noise.

But overall I am very happy. Over normal road surfaces the t tops don't rattle anymore, the doors don't seam like they are loose in the openings, no more dash shimmy, and the car is much more predictable in corners. There is one corner around here that has a bump mid corner. Before the car felt like it wanted to hop to the side when hitting the bump but now it passes with a little thump.