Roll Bar, might finally be defeated!

1fastredsc · 06:44 AM

Well, i took some measurements of the mounting plates on the front leg of my roll bar. I wanted to make sure that i was doing this right and that my chassis wasn't tweeked or something. So my measurements revealed what i had been afraid of all along, and that's that the left leg, the one that i couldn't get to fit right was not angled correctly compared to the other leg. So, i think something in my head snapped over the weekend. Next thing i knew i had the roll bar mounted on a big bench vice, with that one left leg mounting plate bolted to a large peice of angle iron and the oxy torch sitting next to me (balls to the wall or nothing at all right?). I got my dad and uncle for help, and while i cooked one section of the leg they gave constant pressure on opposite ends of the bar (i did this as opposed to only having one end of the angle iron sitck out because i didn't want to stretch the bar outwards, i wanted it to stay fixed in it's location, but twist in it's place about 20-30 degrees or so clockwise). Well just when the section of bar began to mildly glow they were able to twist, very slight twist. And then, this was the advice of one of the welders here at work, i slowly but steadily cooled it down with the torch still on it, by measuring with an infared temp gun. When it got to about 700 degrees, i switched torches with a propane torch my dad had already lit and shut off the oxy/ace torch. From there on i slowly cooled it off with the propane torch to 340 before i just let ambient air cool it. From 700 to 340 or so it took about 20-25 minutes, so this was a slow process. The welder told me that doing this will prevent the area from cracking or becoming a weak point. I hope i did it right, after 3 hours of letting sit in the garage, i took a rust removing wheel and removed the excess carbon from the area that the torch left behind and removed the paint that got a little cooked. I'll up date when i fit it to see if it finally fits correctly. Although i already eye balled it and compared to what it was (you used to be able to eye ball it and tell it wasn't right) , it looks perfect now. To any of the welders/metalurgists, you guys think i should let an experienced welder heat treat the area correctly before i paint and mount or is what i did sound sufficient?

Jamie79SC · 12-10-2003, 08:14 AM

In my opinion, you're all set, (as long as the car stays right side up). :-)

vash · vash's Garage

it's just mild steel right? unless it was sometype of chrome-moly, you did it right.

1fastredsc · 12-10-2003, 12:52 PM

I think it is mild steel, but i have no way to test, i looked up in a welding book afterwards and they said that chrome-moly is ferrous metal like steel (magnetic). Is there another way to tell the difference? The shop that i bought it from is positive that it's chrome-moly because the full race cages are, but they rarely sell roll bars so i'm starting to doubt there judgement. BTW, it's a saftey devices roll bar, the high end model with all the extra trimmings.

vash · vash's Garage

oh crap, how do you tell if it is chrome moly? damn i cant remember, i know chrome moly is hella lighter, so maybe it is, with all the 911 guys being all weight concious. go and ask the mechanical engineer students down at your local NMSU. i know if it is CROMO it will have to be full annealed. that is heated up in a big ass oven, and allowed to cool slowly. that may be why the welder had you progressively cool the thing down. but that may be too localized. on our MINIBAJA car we built the frame up with cromo. we full annealed it, and that thing was tough. we crashed and dented a motor mount section, and because the race was coming up we just welded a replacement section on, and we did what you did with the slow cooling. bouncing around on the race it cracked at the new member. we actually lost to NMSU (i went to UTEP) because of it. the bar stock we had, was labeled every so many feet with the numberical designation of the particular type of cromo we were using. i am sure your cage is painted. i bet it is chromo, the roll cage i installed into an early bronco was friggen heavy. it is your call, i bet you wont have anyproblems at all, unless a car goes through alot of cyclic loading when racing around. just so you know, full annealing relieves the metal of any internal stress placed on it by work hardening (you and your people bending it). i seem to remember it realigning the metals crystalline structure. ???it has been awhile.

hey when does school start for you? NMSU? wat major?

cliff

1fastredsc · 12-10-2003, 01:40 PM

One month, jan 14, and i'm an ME. Um, i wonder how hard it would be to find someone with an oven that can anneal the structure assuming that it is chrome-moly. I just called up the shop and i asked my friend who works there to call safety devices and make positively sure that it really is chrome-moly. So lets see what happens, for now i'm still going to put it in this weekend and make sure that it fits snug.

vash · vash's Garage

damn i used a foundry for the mini baja car near canutillo. i cant remember the name, but i will call a buddy that knows them. the ovens are about the size of a racquet ball court (hell with my spelling) and they are running all the time. they didnt even charge us, because they just tossed our frame in with abunch of their stuff. if i get a hold of my buddy, i will pass the contact over to you, so you can work some mojo on them for a freebie. (hint: act sad,....and poor). if you are a ME, you better enlist for the mini baja team. i think they bumped up the briggs and stratton motors from 8hp to 22hp. whoa! someone can get hurt...besides you're a car freak too.

aigel · aigel's Garage

If it is a Safety Devices roll bar, it is NOT chrome moly.

HTH, George

1fastredsc · 12-10-2003, 02:03 PM

Yeah but i'd be kicked off the team for being the one ********* who had to try and slap on a k03 turbo and some nitrous. LOL, thanks aigel, i really hope your right.

aigel · aigel's Garage

Remember, 1fastredsc, I am the one that has bought a used safety devices bar with the feet missing and need to weld new feet on it. No problem, I thought, I am Dr. Mig but then I got pretty scared when realizing the bar may be chrome moly. Hence I talked to Stable Energies and they assured me (just like their online material from SD shows) that the bars are mild steel, close to DOM stuff used here.

I sent you a PM / email, I need some help with the feet dimensions!

Cheers, George

1fastredsc · 12-10-2003, 02:17 PM

sure, i'll measure mine up for you just let me know, i'm going to have to repaint so it'll be awhile before i can actually weld and bolt it in. What's DOM stuff btw?
EDIT: I've been itching to use the new machinist quality rulers that just came in

.

aigel · aigel's Garage

DOM is abbreviation for Drawn over Mandrel. It is a fabrication method for seamless piping, I guess. I am unsure why there is no DOM chrome moly, but it probably has to do with material characteristics.

I appreciate your help with the dimensions! I need to get the car ready for tech inspection for next years DE season!

George

1fastredsc · 12-11-2003, 11:25 AM

OK, wonderfull news, the shop called safety devices for me and as aigel said it's mild steel. Appearantly chrome-moly is only offered in there full race cages as the bada$$ model. (i'm doing the happy dance as i type) Anyhow, i'm going to post some pictures of what i did this weekend, for the next unfortunate soul who pays this much for a damn roll bar and finds out it doesn't fit correctly.

aigel · aigel's Garage

Great news!

The reason my roll bar has it's feet missing is the fact that it was a poor fit. The PO welded it in place because he wasn't able to fit the nut plates underneath! To take it out he didn't want to mess with the tons of welds on the feet...

I still think that this is the nicest roll bar out there, the way it bolts to the sills and not to the floor and the way it hugs the inside of the car. But I would be majorly disappointed, if I had paid 600+ bucks for something that doesn't fit well.

I have seen many complaints about other bars not fitting right either. Mainly stuff that bolts to stock drilled holes or has otherwise to fit to tight tolerances. I think the DAS bar is another candidate there. Of course, if you have something that bolts into the center of your back area with much space given, it is easier to fit...

G

1fastredsc · 12-11-2003, 06:06 PM

This is for aigel and any others in the future that may find help from this info.

Excuse my horrible drawing.

aigel · aigel's Garage

THANKS!!!

So, it is 4.5mm thick material. That means 3/16 is real close! Excellent. That is still thin enough to be easy enough to bend up with a torch.

I hate to be a pain, but what are the hole diameters? I mean, I have the nut plate and hardware and can just make them big enough, but I am curious.

Thanks again for the great input! I'll keep you posted how the fabrication / install goes.

G

aigel · aigel's Garage

The taped area is where you tweaked it? That should be just fine! George

1fastredsc · 12-12-2003, 11:56 AM

****, i forgot diameters!
It's been two years since mech drafting class and i'm already slipping.
They are 11mm.

dad911 · 12-12-2003, 12:28 PM

You may consider adding a diagonal bar while it's still out of the car.

aigel · aigel's Garage

Quote:

Originally posted by dad911
You may consider adding a diagonal bar while it's still out of the car.

Alan:

It comes with a diagonal bar that bolts in place. This bar has bolt in diagonal and harness bar.

Cheers, George