Okay, my car is at the shop right now getting an SCCA/NASA legal cage put it. My cage builder asked me what I wanted to do and presented me with a few options on changing the interior of the car a bit.

We already gutted the doors, relocated the door handles and riveted 20gauge breadrolled aluminum to the open areas of the doors.

Here's what he wants to do next, and its got me worried.



^ this is the robispec car, see how they gutted the rear seat brace? Well he wants to do the same thing but take it a step farther. He wants to cut out the headboard area and around the fenders, then he wants to weld-in a flat sheet of 20gauge sheetmetal with some beadrolling. I'm worred that this will weaked the structure of the car and possible cause some unwanted flex?

I will be utilizing a cage similar to RobiSpecs, so the safety is not as big an issue, but I dont want to damage the performance of the car

 

I'd probably be more concerned with rule sets than damage to the cars rigidity...and maybe even your budget for the project as well. I'd also say if you go this route, you'll probably want to make sure your cage ties into the rear shock towers, and probably also want to have a strut tower bar so that everything back there is boxed & triangulated.

Check out the build pics in this thread if you haven't already, posts 39 & 42 are the pics that are relevant to your questions:

https://www.evolutionm.net/forums/mo...car-build.html

Dave

 

Your cage builder is already working on your cage and youre worried now? What concerns me is that youre worried at this juncture. Because if your cage builder has actually built SCCA legal cages in racecars that actually race with the SCCA, than you should have nothing to be worried about. When youre paying someone to build you a SCCA legal cage, you pick a cage builder who has actually built SCCA legal cages in racecars that actually race with the SCCA. Otherwise, youre going to second guess everything they do, and youre going to end up asking everybody and their mothers. If youre worried, you should contact your SCCA tech inspectors and see what they say. It all comes down to the rules.

 

he is not so familiar with the evo, let alone imports. He deals more with muscle but he is my sponsor and any chassis or frame work, including the cage is free of charge. I've just never seen this done, thought I would ask before we went ahead and cut everything out.

The rear strut towers are boxed with a strut tower bar and a bar connecting the towers welded in. There is also an X brace on the rearward struts.

He thinks it will be fine, I dont see why not, I just wanted a 2nd opinion from racers who have experience with this car

 

Basically we would be doing this for extreme weight savings. We are also going to skin and pin the trunk with custom fasteners. The carbon hood is getting skinned with a strapping to stop flex and aerolatch pins.

I'm even considering an aluminum dashboard.. Its legal in NASA TT from what I have been told. This would save a good amount of weight imo

 

If he has done cages before, he should be able to look at the rules and build something legal for your class. I race my not-an-Evo in a class that does not allow tie-ins to the suspension at all, has to be welded to the trunk floor, as an example of stuff you need to check the rules for. But I am not doing SCCA so I can't help you with specifics for your car.


Does SCCA do a hp/weight ratio for determining what class you are in?

 

The class is NASA TTU. He's building the cage to meet both SCCA and NASA spec for TT

 

I think I will probably stay away from this just to be safe. I will cut out the seat braces and put a nice piece of beadrolled sheetmetal to cover the openings and fuel pump covers.

Otherwise the cage should look like a regular cage with an extra X-brace. An X-brace on the passenger door and Nascar style bars on the drivers side.

Any other suggestions/comments?

 

Dont take any of this the wrong way. Bottom line is that a cage is something that is taken very seriously. So im not going to advise you on it because its a serious matter. Besides, your cage builder should be the person who answers your questions, not us. Thats the whole point of having someone do the work for you. But the impression im getting from you is that he is not sure. I highly recommend you find someone in your area who has actually built cages for racecars that actually race with NASA/SCCA. Talk to as many racers in your area. Find out who built their cage, and get their feedback on their cage builder. You need to do some homework on this. Eventually you should be able to find someone you can trust. Then contact the cage builder and ask them if they will be willing to give you some feedback. Keep in mind a lot of people claim a lot of things. There are many build threads posted all the time on a lot of forums. Then one day some racers take a look at their cage and they scratch their head because...

 

Its not so much the cage builder that's questioning this its me. He knows what he's doing. I guess I'm not sure if I like the idea of hacking up a unibody like that. Especially on a car as expensive as the Evo. I think we will stick with a basic design.

Our original design was just like RobiSpecs cage, then we came across their thread and we decided that was the way to go. I'm a little bit fanatical when it comes to weight reduction, lol. We will stick with a basic cage. I've wrecked a car with a failed cage. It hurt

 

robis cage is a minimalist cage, meeting the NASA TT rules and essentially not much more.

if you read the rules you'll see all the bars he has are called out specifically. the cage i'm building in my car is nearly identical to robis as well, but only because i'm also doing a cage that meets the rules and only 2 tubes extra. also i'm not doing the X bars on the passenger side, i'm doing the nascar bars because i have a passenger seat. you will want to cut the rear seat back "V" section out in order to have the proper roll hoop supports to the rear strut towers, but even that can be done without cutting it out completely.

in my car we cut the entire trunk out where the spare wheel sits, because the fuel cell is sitting in there. i'm not cutting any other sheet metal out beyond that because the car is already light enough. (my car should be 2600lbs with the cage)

and i definately wouldn't be worried about cutting about the car, cause once you put the cage in theres really no going back anyway.


*oh, and don't worry about cutting to much of the car out if your racing TTU. you have a power to weight limit anyway for that class so spending a ton of time cutting metal out and remaking the parts is only going to make you de-tune the car. for example, at my weight, i'm only allowed about 420whp. currently i'm making roughly 600, and have a lot more on tap once the weldon pump gets here.... HAHA i'm going to have to tune it on wastegate to meet the rules.

 

As long as you can tie the cage into the rear shock towers you should be fine. We're doing it on this evo x we're building for wctc.



Car is a little farther along now. I'll have to post a thread about it sometime soon.

-Peter

 

why is everyone welding to the floor pan on their cages? Does SCCA or Redline require this because NASA TT does not. They recommend you weld to the strut mounting point which is what I am doing

 

on the evoX the rear tubes are directly above the rear subframe attachment bolts..and the lower flore tubes are welded to the flore directly above the front of the rear subframe. We use these to make the car MUCH stiffer.

 

is this something I should consider on the CT9A chassis? Right now our plan is to box the rear strut tower mounts and weld to those. Where you have your cage mounted is where I currently have 3 plates (2 on both sides of the frame and 1 on top) that hold my harnesses in securely. Maybe I should re-design this?