Winter CMC build

[mattr1548534738]

Last weekend my 86 mustang got a cage, so now its a real race car. I figured its time to post some pictures.

 

I'm building it for CMC1/2. Cobra brakes all around, Maximum Motorsports road and track kit, a little bit of engine work. This weekend I'm going to trim up the wiring harness, which is out of the car right now, and mount the seat. It's going to paint next week (all white) then I'm ready for final assembly.

 

All cage and fab work was done by a good friend of mine who has a fab shop. The whole cage is 1-3/4 095 wall 4130 and fit like a charm. My favorite part about the cage are the boxes we built for base plates. It allowed us to bend tubes, tack weld, pull the boxes out to get a 360 degree weld on the top tubes, then push them back up and finish weld the bottom. Maybe a bit overkill, but labor was free...

 

 

 

 

 

 

 

With some luck and long weekends I should be on track doing shakedowns in January and ready for the first socal event in February.

[Adam Ginsberg]

Matt - welcome aboard!!! Nice to see another SoCal CMC'er! Where in SoCal are you located?

 

Excellent work - very nice welds. Feel free to give me a shout when you have a chance.

[mattr1548534738]

Thanks! I live in Eagle Rock, close to Silverlake. I've been going to NASA races for a few years now helping friends out in different classes. CMC has always looked like lots of fun, and the price is right. How many cars are making it to the events these days? I went to a race up at Buttonwillow early last season to ask class specific questions before I started my build and everyone was very helpful. It seemed like a pretty good showing for the class.

[MHISSTC]

Nice.

Keeping it 4-eyed or going aeronose?

[Trevor571548534737]

Looks good. I like the sierra nevada

[powerslide91]

Man I love fab porn...

 

Looks good!

[liebbe1548534713]

Glad to see a new car being built and not to be a downer, but I have an observation/concern about your car. In the first picture it appears that some of the interior structure has been removed such as the package tray and the sheetmetal below the quarter windows. Maybe I'm seeing the pictures incorrectly, but if so, this is not legal, is it? I bring this up so that you can check this out before you finish the car and can make corrections now instead of later when it would be more difficult.

 

Good luck with your build, and give Ginsberg a run for his money for us.

[cozog1548534733]

Glad to see a new car being built and not to be a downer, but I have an observation/concern about your car.

 

Also:

1. Isn't the tubing supposed to be .120 for a 3000+ lb. car?

2. Shouldn't there be a horizontal bar in the main hoop?

 

I'm jealous you could fab your own cage instead of paying someone else to do it!!

 

Good luck with the racing!

[TurboShortBus]

Also:

1. Isn't the tubing supposed to be .120 for a 3000+ lb. car?

2. Shouldn't there be a horizontal bar in the main hoop?

 

1. Not necessarily:

3001 - 4000 lbs.

1.750†x .120†Chrome-moly / Seamless mild steel (DOM)

No ERW allowed.

15.6.18 Roll Cage Tubing Sizes

For the purposes of determining roll bar tubing sizes, vehicle weight is as raced, but without fuel and driver.

If the car weighs 3000 lbs as measured per 15.6.18, then he's good to go. However, I'd be more concerned about not properly heat-treating the CM after welding it (or so I'm told by my engineer buddy and his welder co-workers, but it could also be nit-picking). I'm going with 0.120" MS for my cage to err on the side of strength as well as to eliminate the need to heat-treat the welded connections.

 

2. He will probably figure it out when the time comes to install the harnesses! It's likely just a quick set of photos prior to finishing the cage.

 

Mark

[KiMifan]

There isn't really a good reason to use chrome-moly in an SCCA/NASA rollcage because the rulebook does not make a distinction in required material size between mild steel and C/M. That is a holdover from NHRA cages, where lighter tubing is allowed if the cage is built using CM. For example, a mild steel rollbar needs to be 1 3/4 x .118 minimum, where a CM rollbar can be 1 3/4 x 0.083. The weight of the car is also not a factor, just the E.T. it's capable of running when determining rollcage specs.

 

You can heat treat welded CM with a torch, but it seems odd to me that you would MIG weld a CM rollcage.

 

Some info on welding CM:

 

http://www.lincolnelectric.com/knowledge/articles/content/chrome-moly.asp

[mattr1548534738]

Thanks for the replies.

 

As far as tubing size and choice, we used what he had at his shop. Ideally I would have used DOM because of cost, but instead we have to heat treat it. It's not a big deal, he has a torch. And I'm really hoping the car dry with no driver is sub 3,000 pounds because the class requires a wet car with my fat ass is 3100.

 

The seat is getting mounted today along with the harness bar. That's the only piece left.

 

I did not remove the package tray, only the two cross pieces that got in the way of the cage. And the rules said I could cut any brackets not used, so I cut the seat belt brackets under the quarter windows. If anyone has experience with tech giving you problems removing either item please let me know. The part under the quarter window had negligable weight, it was removed for exhaust clearence. Thanks.

 

Lastly I'm probably going to cover the headlights with a flat piece of lexan. It's probably not an aero class like I'm used to, but it makes me feel better and that's what club racing is all about.

[mattr1548534738]

Lastly on mig vs tig, I'm not a fan of tig welding roll cages. It makes 360 degree welds that much more difficult. Mig welding 4130 is no problem if you use the right wire, but thanks for the concern.

[TurboShortBus]

There isn't really a good reason to use chrome-moly in an SCCA/NASA rollcage because the rulebook does not make a distinction in required material size between mild steel and C/M. That is a holdover from NHRA cages, where lighter tubing is allowed if the cage is built using CM. For example, a mild steel rollbar needs to be 1 3/4 x .118 minimum, where a CM rollbar can be 1 3/4 x 0.083. The weight of the car is also not a factor, just the E.T. it's capable of running when determining rollcage specs.

This is 50% funny and 50% retarded...I had a conversation about roll cages with a local drag racer about a year ago who just had a full CM cage installed in his Mustang. He recommended that I build my cage out of CM, "Because it's lighter" than MS. I told him that it didn't matter, since CM and MS tubing have to be the same thickness per my class rules, and the weight savings came from NHRA's allowance of thinner walls for CM tubing. All he could say, over and over, was, "But CM is lighter." I eventually had to just walk away.

 

Mark

[TurboShortBus]

Lastly I'm probably going to cover the headlights with a flat piece of lexan. It's probably not an aero class like I'm used to, but it makes me feel better and that's what club racing is all about.

The lexan will still be vertical and recessed, right?

 

7.9.2 All cars must have a minimum of two properly functioning OEM rear brake light assemblies. All other OEM light assemblies may be replaced with facsimiles, plates, covers, or mesh covered cooling duct openings as long as these maintain the stock external appearance. Replacements for recessed lights must also be recessed. Front Turn signals and fog lights may be removed.

Mark

[Al F.]

Excellent stuff and nice progress Matt.

[KiMifan]

And the rules said I could cut any brackets not used, so I cut the seat belt brackets under the quarter windows. If anyone has experience with tech giving you problems removing either item please let me know. The part under the quarter window had negligable weight, it was removed for exhaust clearence.

Exhaust clearance? If you're planning to run the exhaust through the passenger compartment and out the side of the car, you better get a ruling on that first. I think that was deemed illegal a while back, but I could be wrong.

[stevemichael]

I guess this is why people don't post up build pics all the time. The microscope has been turned to this car for sure.

[TurboShortBus]

I guess this is why people don't post up build pics all the time. The microscope has been turned to this car for sure.

The first rule of Fight Club is: You do not talk about Fight Club.

The second rule of Fight Club is: You DO NOT talk about Fight Club.

 

 

Mark

[Glenn]

it would be better to find out all this before he spends more time and money doing it.

 

CMC= exhaust on the outside of the car.

[TurboShortBus]

it would be better to find out all this before he spends more time and money doing it.

Oh, I totally agree, but I have seen some things in photo backgrounds just get nitpicked all to hell.

 

CMC= exhaust on the outside of the car.

I'd be better off pumping mine straight into my helmet vent.

 

I'm not sure if there's a performance advantage or safety disadvantage, but side exhausts coming out of the bodywork just look cool, if for no other reason.

 

Mark

[mattr1548534738]

I posted on the forum so I wasn't building in a bubble. Everything so far has been constructive. I don't want any suprises when it comes

time to tech the car.

 

As far as exhaust goes I was planning on turning up through the

floor and going out the side of the body. Rule 7.24 says I need to exit behind the driver and away from the car. I was told it couldn't go through the floor but i'm not seeing that in the rules. No metal has been cut yet. It's not a performance advantage, I'm just showing off some fabricating. Everything is going to be boxed in and heat wrapped so it's safe.

[Glenn]

if its not in the rules, then you cant do it. consult a Director before doing things like that.

 

i can tell you that you will not be able to run the exhaust inside the car and be legal. if its not a perfromance advantage, there is no reason to do it and you shouldnt have any issue w/ not doing it.

[Adam Ginsberg]

I'm not sure if there's a performance advantage or safety disadvantage, but side exhausts coming out of the bodywork just look cool, if for no other reason.

 

+1.

 

However, as we discussed Matt, it's not legal to have the exhaust come up through the floor.

 

While I can understand your confusion about it not specifically stating that in the CMC rules, I'm going to highlight a sentence in section one of the 2010 CMC rules:

 

The only modifications are those specifically allowed. If not specifically allowed, any modifications shall be prohibited.

 

It's an easy item to miss, as it's the first section, but it's a HUGE component of the rules.

[stevemichael]

if its not in the rules, then you cant do it. consult a Director before doing things like that.

 

i can tell you that you will not be able to run the exhaust inside the car and be legal. if its not a performance advantage, there is no reason to do it and you shouldn't have any issue w/ not doing it.

 

I don't totally agree with you. I have yet to ride in/drive a car with dumps that doesn't get exhaust smell to some level inside the car. Exhaust exiting beyond the body work would be a better situation.

 

I am not bothered by the smells, but some guys are.

[Glenn]

there is no reason to not run the exhaust to the factory location....... or shorter if you can deal w/ the smell.