So I'm looking to eventually get a cage in a future track car build and a 'extreme street' build when my two projects are done and though I might try my hand at welding it myself. I have a friend that can teach me the basics of welding cages, but would like some info on some issues. I have a friend with a homemade roll cage in a Superbird and it had badly aligned doors that would not shut properly. He decided to that the cage was a pain due to the way the previous owner put it in, decided to cut it out. After removing the cage, the door alignment issue they had went away and now shuts properly. I want to avoid some of these problems and looking for some advice.

Should cages be welded with drivetrains in them?
Does the car need to be planted on all four corners or supported on jacks/lift?
Will having all the suspension done first affect the geometry or not an issue?
Steel vs chromoly?

Thanks for any info you have.

After seeing my friend wreck at 135mph and the cage welds holding I only could suggest having a professional chassis shop put in a cage.

Reread your post how the amateur put in a cage and there were issues. But those who are chassis builders here please answer his questions for the better of the forum. Also the link below is one of the best chassis builders and has some good information.

https://www.youtube.com/watch?v=SQw9DFo8R5A

A unibody car needs to be properly supported. How that's done depends on if it's a running car on it's wheels, a bare shell or somewhere in between.

Suspension done? Stock, struts & 4 link or somewhere in between? A chassis car is built to the suspension locations. A stock suspension, full body car is built to support the original locations.

Chrome-Moly, but that requires TIG welding and proper fitting.

You can learn the basics sitting at a table with a MIG running beads. But when you get inside of a car, in all kinds of positions, on a round piece of tube, it's not the same. Learning how to fit, plan, make it symmetrical, fit tight to the body, weld places you can't get to, make it look right, use a tape, plumb line, angle finder and a level is 80% of it.

Have you fabricated anything out of steel before? A race car is not a good beginner project.

Make sure the car you are starting with is straight and not a parallelogram to start with, especially if its unibody and you're tying into the shock towers, even if it hasn't been in an accident. Its pretty hard to pull it back into spec once its caged, and the wheel alignment isn't working out. My friends frame Jig is made out of I-beam with that is at least 10" on the web.

Have a pro do it. If you want to learn, watch the pro.

Some things in race cars are not worth risking your life over, especially race and safety equipment
I know of a good young roundy round racer that was killed in his car at the old Riverside raceway in Riversdide ,CA back in the mid 1970 when one of the bars broke loose in a wreck and pierce his body above the left kidney
Be safe, don't die young over bad decisions

Build it yourself but be sure to wear a mask, don’t want to die from Covid.

I'll chime in here. We have an endurance racing car. One of our team members is a great welder and did his own circle track car... however he didn't want to do the cage in the endo car, said at our speeds he didn't want to be responsible. Plus we wanted to make 100% sure we'd pass tech. Suck to get the car all set up and fail tech. If you are racing this car and it needs to pass tech and you have never done this before, take it to a shop. Our cage cost about $3500

this is why... this is our car after going from 3rd to 2nd by mistake...this is only at maybe 89mph. The cage held up great and is being used in the new car.

Think of this, NASCAR requires mild steel for a cage, 4000 pound cars going 200 mph that wreck a lot. Ask yourself why?

There are also rules on where the loop behind your head goes and it's relationship to where the driver's seat is at etc. A chassis guy will know all the fitment rules and get it right the first time.

Self-taught types just starting out can make a weld that looks ok with a little practice, but do they really know if the weld is strong enough? Look at the guys who narrow their own rear ends at home for the first time and the spring perches break loose on the starting line.

I will add, your helmet cannot be w/in 2 inches of any bar. Before you or anybody welds a cage in, get in the car with your helmet on and see where your head is. It would suck to get it all welded up and your head be too close to the bars...

I built almost everything on my car. The one thing I farmed out to a professional? The 6 point roll bar!

I paid a local race car shop to do it and they thought of things I didn't because it is something they do every day.

Amazing looking welds and peace of mind for me.

Yeah, and anything quicker than 7.50s is required to be 4130. Why?

I don't want to dissuade anyone from building their own car, engine, trans, rear or whatever. But you have to be realistic about your skills and abilities. No one is born being Jerry Bickel or Don Ness. They have to learn and build on their skills to where they can do what they do. Some people become good accountants or lawyers so they can pay people to build them cars.

You have to work with someone to learn fabrication skills and things specific to doing race car work. Talk to people who have done it and have them show you around a car. A mentor or an advisor who isn't an idiot is almost a necessity for those just starting out. You have to learn how to make stuff out of metal. It's all just metal.

You should know your own abilities and mechanical aptitude. You should be very familiar with the roll bar/cage section of the rulebook. If you are able to do it, then do it. It's rewarding to do a project like that, learn how to do it and build on your skills.

Read the rule book. Look at lots of other cars. Use the right material. Make sure the joints fit very tight. Add extra bars , gussets. Tie the cage to the body at the A pillars, B pillars, cowl, any where you can. Tack everything before any final welding. If you have any question on welding, have someone that you have seen their work do the final welding. Designing to drop tha tacked cage thru the floor to gain access to all upper welds is a good idea. Take your time, no hurry. I built and designed my cage myself. It got good comments from the Division 3 tech director who certed it and a few well known chassis guys to boot. I am not a tig welder. I bent most of the tubes, fitted them all and tacked it. Had a professional weld it all up.
Doug

Perfect example there, cross bar has to be welded first, then the brace diagonal welded in next. It goes together in steps, something a person with experience will know. PPPPP, proper planning prevents poor performance.

if I understand you correctly, I thought a few years back, the above was changed, in that they now wanted the diagonal bar one piece, and the cross bar two pieces?

And the the reply earlier about needing two inches of clearance between any bar and the helmet, is that a written rule or common sense, although the 2" is somewhat arbitrary?

On the MS vs CM for Nascar, I thought there were three main reasons, cost, weight savings is not overly important, and the fact the stock cars get banged up over the course of a season and put back on the track, and MS can handle that, and welded CM, although a stronger material, doesn't like repeated abuse, and hard to tell when its near its useful end.

Mild steel will give and bend (absorb) when hit. CM will crack over time, the reason for the X-ray requirements. My first car was MS but was hard to sell, the two I have now are CM because that’s what the racers want. Remember the number one rule, triangulation. Your 50 pound head in a 5 pound helmet flopping around to close to a bar in a wreck is not good. I don’t think 2” is far enough away, remember Dale Earnhardt. these are just my opinions.

My thoughts, and experience for what it is. Mig Welding on a table with nothing in the way, and using clean new metal, is a skill that does not take too much time to master. Welding a cage in a car upside down, getting sparks down your neck, and trying to get the undercoat and paint off well enough for a good weld is a lot bigger challenge. First is look at the cage two ways, making the car safe, NHRA rules lay that out, second, making the chassis stronger and stiffer without adding too much weight is the next challenge. I always weld on jack stands, car leveled, and make sure the doors still work and gaps fit well during the process. For most cars and home building mild steel is the way I would go. Moly is lighter and stronger, but also more brittle, and higher level welding skill is required. I have built several cages over the years, I remember one that when welding in the frame connectors, I got a spark down my shirt, and in pushing the creeper to try and get away from it, I hit one of the jack stands, and to my surprise, it simply slid out form under the car, and the car just sat there on three jackstands. I took that to be a test that the car was square and stiff as it needed to be.

I have a 64 dodge NSS car that we built at the tech school where I retired from as a teacher. The last project the students helped me with on the car was a moly cage. The welding instructor who was helping made the students fit the joints so a .010 feeler gauge would not fit in the joints before he would let them be welded. The welding instructor did most of the upside down, curled into a ball welding. My issues is as a 64 years old, I can not see well enough to weld in those positions anymore. Moly cage saved 100lbs, and made the car a lot more consistent, in 60 foot times. Since moly is so much lighter I added a little tubing here and there to make it stiff. The other issue was the original cage was built as a leaf spring car and over the years had been changed to a 4 link. The cage had bars were they were not needed, and needed bars in other places. The redo, fixed all those issues. And I was proud that the NHRA tech inspector who certified the new cage commented on the good quality of the job.

The other issue is resale value, if it is a good job, a moly cage car will always bring better money on resale.