Structural Integrity

[SySt]

I have a question for anyone who may know the answer. In the process of fitting up my LS6/T56 setup I have needed to remove both OEM transmission mounts (frame side). To do that I simply drilled out the spot welds. I also removed the bracket that holds the handbrake lever using the same method. So now I have weakened the transmission tunnel.

I removed a good amount of material from the "c-channel" that the front of the seat rails bolt to. Basically the c-channel no longer exists on top of the transmission tunnel.

Basically, I know I have weakened the unibody. The question is, what is the most feasable way to regain that lost strength. And is it even something to worry about?

 

[cjsupra90]

Can yo take some pics of what is left on the car from what you removed. The visual will help out substantually in figuring options for you to do.

 

[SySt]

Yeah, I can post some up tomorrow night. I may throw in some subframe connectors and a cage before it comes out, but I want to drive it next summer and that just means more money...

 

[SySt]

Here is a pic of what has been removed.

 

[supra90turbo]

Once you have it squared away to where it all works, start welding in some steel that will take the shape that the material you removed did, only modify it to what will fit with your setup.
Just re-create the factory-type bracing, but in a fashion that will work with your modifications.

 

[cjsupra90]

unless the pic is deceiving, it looks like you cut out a lot more then needed. I'd just trim out and plate off just whats needed to clear the shifter housing from the section that you removed and reweld it back in.

 

[cjsupra90]

Another option is to get some like 1" X 2" or what ever would fit in where you cut rectangular 4130 chromoly tubing. Some .058 wall 4130 would be more then stronge enough to rebrace the section back.

 

[SySt]

The pic is not deceiving, the rear of the transmission is tilted down. Once up at it's proper height it does not look like I cut more than I needed to. I was kinda thinking 10pt cage and subframe connectors but that would be expensive as I am not a good welder.

So just weld some sheet steel where I took it out? What about the "c-channel"? The shifter inhibits the route the channel takes from the factory.

 

[cjsupra90]

Ok, add the c-channel back attached behind the section that is left that extends to the seat mounts. Basically move it back to where the front edge is located where the back edge is and extend it down the sides of the tunnel.

Best bet would probably be to find another car in a salvage yard and remove the complete section that goes from floor to floor up over the tunnel and weld that back in.

 

[cjsupra90]

visual aid (sorry, my paint skills arent the greatest)! this should help incase my last post didn't quite make sense.

 

[SySt]

I know that is still not as strong as the original peice if I do that. Though I do have access to rectangular/square tubing at my work with 1/8" wall for free... That should work right?

 

[Zach]

I say just brace the underside of the car well when you make the tranny crossmember. My dad's triumph is a convertible and the original transmission tunnel was fiberboard. Yes, fiberboard. I'm not condoning Triumph's engineering practices, but I don't think you have much to worry about, just make a sturdy crossmember and reinforce the crossmember where it joins to the body.

 

[SySt]

Shit man, i'd love to use a fibre-glass body/floor. I can build a perfectly rigid tube-frame. I am an aspiring engineer with lots of resourses when it comes to the racing world. However I am trying to deal with my car as cheaply and as easily as possible. This design will not last, trust me once my car is done and has ran for a summer you will see. I beat the living SHIT out of my car. I will crash it many times to come. I will fix it just as many.

 

[Yellow 13]

Shit man, i'd love to use a fibre-glass body/floor. I can build a perfectly rigid tube-frame. I am an aspiring engineer with lots of resourses when it comes to the racing world. However I am trying to deal with my car as cheaply and as easily as possible. This design will not last, trust me once my car is done and has ran for a summer you will see. I beat the living SHIT out of my car. I will crash it many times to come. I will fix it just as many.

You sound like me lol.

 

[SySt]

Let's put this in physical terms. Last summer cost me a windshield, a front lower ball joint, a steering rack, a set of tires, a set of wheels and a turbo.

 

[trucker]

wow...hey have you gotten your engine mounts done yet?

doing a sbc swap soon(parting out my "mock-up) car as we speak

going old school at first, motor will eventually end up in daughters mk2(thats gonna be a pain in the ass) fancy shit later

i'm digging thru your threads right now, you seem to be the only one documenting this kind of swap, plz keep it up!

 

[SySt]

In a few days I expect I will have the motor mounts completed. I will definitly share pics and specs in my build thread.

 

[trucker]

thx...btw arent lsx mounts diff than early small blocks?

 

[SySt]

Yes, they are. However I purchased and are using about half of the mounts off ebay. Basically, the mounts I am using are older SBC style. Once you see the pics you should be able to make some easily based on mine.

 

[trucker]

cool...any timeframe on this...? i've been talking about it for like a year now..ready to get started as soon as i get setteled into new job(which i took so i would have more time at house to work on supe)