I have read that if you have sub-frame connectors on a convertible, you can do away with the Tunnel Brace that all we convertible owners know about. This tunnel brace really inhibits your ability to have an x-pipe and still maintain some ground clearance once adding spacers for the Tunnel Brace to go back on.

QUESTION: I am installing weld in subframe connectors from Global West, the ones designed for convertibles. Would this mean I can do away with the Tunnel Brace? I was also contemplating welding on some braces from the sub-frame connectors, that can cross over and bolt into the holes that originally were for the Tunnel Brace. This would form sort of a cross pattern of support under the car, and I was wondering if anyone else had some knowledge or ideas about this topic, specifically if you own a convertible.

This concept of forming a cross pattern off the subframe connectors comes from looking at subframe connectors designed for fourth gen owners. I think this would work quite well in conjuction with the first gen difficulties.

Let me know your thoughts. My plans are not for racing this car at all, but I would like to be able to remove the trans tunnel brace without effecting the rigidity of the cars platform.

Hi Jon,
I don't know about replacing the X-brace. And I wasn't aware that GW had sub frame connectors designed specifically for convertibles! I'll be checking THAT out...I thought they just had the "one size fits all" type.
On Monday after Thanksgiving, my car goes to the shop for sub-frame alignment and GW subframe connectors, as well as a few suspension tweaks. But I am leaving the X Brace on the car. The subframe connectors are just for some additional strength and structural support to get rid of the last of that slight 'convertible shimmy" over road irregularities. I also have the cocktail shakers installed, which I know some people get rid of to save weight. I don't race either, but I want a car that handles and rides correctly. Even if that means I make a few compromises with my exhaust choices...which I will be faced with in January when we install the GMPP 385 Fastburn. Just my .02
There are a few others here with convertibles that know a lot more than me! You'll be hearing from 'em. smile.gif

Check out my replies in this one...
http://www.camaros.net/forum/ultimatebb.php?ubb=get_topic;f=7;t=005906

Sub frame connectors will most likely be a better replacement for the X-brace than they are for the cocktail shakers but I have driven a '69 without the X-brace and when I drove over RR tracks I thought the windshield was going to pop out of it's frame. The dash and cowl area looked like rubber. There are so many exhaust solutions available. You don't need 3" pipe and an X pipe may be a power adder at some point but you can spend the same money else where with the same or better results. The other thing I haven't spoken up too much about but I read a lot about here is "nobody carries an exhaust kit for the ragtop". It seems nobody thinks about the local muffler shop any more. I don't see that kits are that much less expensive and a good muffler guy can do wonders under your car... I have 2 1/2" under my X-brace with about 1/2" of shimming. I'm not 100% happy with the job, I think the pipe will fit without shimming the brace... Bob Spears has an X-pipe and 2 1/2" pipe and I believe his X-brace is slightly shimmed...

The bottom line is the ragtop isn't as rigid as a coupe in stock form. Add sub frame connectors to both and the ragtop still isn't as sound as a coupe. Start removing any of the factory designed support and the ragtop is only going to fall further behing the coupe... If you are building a real race car out of your rag then put in a cage and then throw away the X-brace and cocktail shakers... Well don't throw them away, maybe sell them on ebay!!

Okay, all very good points. What about remaking the brace and designing it more closely to the drive shaft, and dropping an x-pipe exhaust connection right below the brace. I understand I can shim the brace down lower and keep the exhaust above it, but what about routing the exhaust above a custom brace?

By the way, I am planning on having a local muffler shop bend me a custom system. I just think if I was going to ever drag something, like over a speed bump, I'd rather it be the exhaust as opposed to the the convertible brace shimmed down and get caught.

This will be a redo on the exhaust system. The current system incorporates Delta Flowmaster 50 series, and yes they are kinda long for the convertible. The system currently does not sweep up quick enough over the axle, so when loaded down on the Power Tour I was banging the pipes when the rear suspension had heavy travel upward from a dip in the road with a load of gas.

Since I'm having the pipes redone, I'm trying to fiqure a way to get an x-pipe connection as opposed to an h-pipe. Maybe I just need to stick with an h-pipe, for at least that could be bent down around the drive shaft a little easier.

Keep your thoughts rolling in. I appreciate another's point of view.

Question??

Anybody ever thought about making the tubes that fit in the area in question out of the squashed tubes I think Spin-Tech sells for added clearance??

pdq67

Right now my brace is the lowest point on my ragtop. I've only had it scrape 2 times since I lowered my car almost 2 yrs ago. I ride around with 4 in the car all the time and a full trunk.

The oval tubes may be a good resolve to getting the pipes in the tunnel.

Maybe Bob is lerking and will post a pic of his X-pipe...

I built this center section for my 67 Firbird convertible this Christmas break. I used 2 1/2" mandrel bend pipe and a cross over system from Summit. It is not an X pipe but heck, the crossover is only 2" Long so I think the pulses wil share both pipes effectively. The trick to fitting my pipes up into the tunnel above the body stiffener was to bend the crossmember back up to it's original position. It is real tight but it fits and does not rattle!
http://www.tootechracing.com/Car%20Section%20Index.htm (Scroll down to the Firebird exhaust section.)