Roll Bar Questions
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11 Second Club
Joined: Dec 2002
Posts: 169
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From: Millersville, Maryland
Roll Bar Questions I’m considering installing a 5-point or 6-point Wolfe weld-in roll bar and can’t find answers to a couple of questions.
- I know the cromoly is about 20 lbs lighter than the mild steel. How does it compare in strength since the cromoly wall tubing thickness is 0.095” vs. 0.134” for steel.
- Wolfe says it will clear the rear seats but they are talking about in the up position. Can you still lay the back seat flat (i.e., cargo position) after installing the roll bar? Since I don’t trailer, I want to be able to continue to haul my slicks in the back.
- Is there any difference in the amount of protection between the low-slung door bar and the straight version? Since I would order it with swing outs, I don’t see the straight as being any more convenient.
- For the normal street driving, I plan to remove the door bars. Anybody else do this? Any issues or problems?
6 & 8 Second Club
Joined: Aug 2006
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From: Illinois, RT 66 dragway area
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Stronger, that's why all our 4, 5, 6 second cars must be moly. I'm no expert, but it was explained to be, it has a little more give also, which helps it from ripping apart in an accident.
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Stronger, that's why all our 4, 5, 6 second cars must be moly. I'm no expert, but it was explained to be, it has a little more give also, which helps it from ripping apart in an accident.
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Go with chromemoly. Get a 6 pt. I wont even install a 5 pt, its pointless. Get the straight swing out door bars. They are stronger and will be less hassle in tech. Yes you can lay the rear seats down.
TECH Enthusiast
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From: Evansville, IN
Chrome-moly is stronger than mild steel. It weighs exactly the same, but you can use a thinner wall thickness therefore you save on weight. Just another thing to think about, is that Chrome-moly must be Tig welded. This will give good strength and it is mandatory by NHRA.
I think the tensile strength of 1020 DOM Mild steel tubing is like 80,000 psi. and 4130 Chrome-moly is 95,000 psi.
I think the tensile strength of 1020 DOM Mild steel tubing is like 80,000 psi. and 4130 Chrome-moly is 95,000 psi.
7 Second Club
iTrader: (5)
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From: Gainesville, Florida # of drag strips runs: ?!?!?
Chromemoly is lighter and stronger, but also more expensive, thus the reason some go mild steel for the $$$ savings.
Go with swing-out door bars. They are legal and I also remove mine when not racing for more than a couple of weeks.
BTW, NHRA rules for rollbars are 11.49 in the quarter/7.35 in the eighth and faster. And don't forget the SFI jacket and 5-point harness if you do plan on heading below those numbers to be legal.
Derek
Go with swing-out door bars. They are legal and I also remove mine when not racing for more than a couple of weeks.
BTW, NHRA rules for rollbars are 11.49 in the quarter/7.35 in the eighth and faster. And don't forget the SFI jacket and 5-point harness if you do plan on heading below those numbers to be legal.
Derek
Thread Starter
11 Second Club
Joined: Dec 2002
Posts: 169
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From: Millersville, Maryland
Thanks everyone.
I had been told by several people that the cut is 7.50. However, based on an Internet search, it does seem to be 7.35 for the NHRA. For IHRA and SBRA it seems to 7.50 as best I can tell. However, I don't have a copy of the difinitive rules for any of them. I do know that the rule at one one our local tracks is 7.50 but, then, any track is always permitted to establish its own rules that are stricter than the sanctioning body.
Originally Posted by Villain281H
BTW, NHRA rules for rollbars are 11.49 in the quarter/7.35 in the eighth and faster.
Another thing to consider is that chromemoly with all of it's advantages has about 2 disadvantages. 1 obvious = cost. 2 = It has to be tig welded where as steel can be migged.
Wait, the rear seats fold down? How do I have 2 F Bodies and not know this?
Originally Posted by MADMAN
Go with chromemoly. Get a 6 pt. I wont even install a 5 pt, its pointless. Get the straight swing out door bars. They are stronger and will be less hassle in tech. Yes you can lay the rear seats down.
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TECH Enthusiast
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From: Evansville, IN
Originally Posted by Beaflag VonRathburg
Wait, the rear seats fold down? How do I have 2 F Bodies and not know this?
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TECH Enthusiast
Joined: Jul 2003
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From: Evansville, IN
Depends on who you talk to. To achieve the full strength benefits of any welding process, you should stress relieve, but its not always feasible or worth it. Thin walled material does not really need to be stress relieved(under .120" wall thickness). I would almost bet that all the sponsers out there making chrome-moly parts, none are stress relieving parts. I could be wrong though. All the highend drag cars have chrome-moly roll cages, and you cant stress relieve the entire car. You just have to know how to tig weld and use the proper materials(gas, wire, tungsten). Here check out this link. Its on Lincoln Electrics website and it discusses welding 4130. This should answer all your questions.
http://www.lincolnelectric.com/knowl...hrome-moly.asp
I made my own fully adjustable, double rod ended, chrome-moly Lower control arms and panhard bar. They are working great on my car. Hope fully a cage will be next on the list.
http://www.lincolnelectric.com/knowl...hrome-moly.asp
I made my own fully adjustable, double rod ended, chrome-moly Lower control arms and panhard bar. They are working great on my car. Hope fully a cage will be next on the list.
Last edited by smoknta; Jun 16, 2007 at 12:42 AM.
Originally Posted by smoknta
Depends on who you talk to. To achieve the full strength benefits of any welding process, you should stress relieve, but its not always feasible or worth it. Thin walled material does not really need to be stress relieved(under .120" wall thickness). I would almost bet that all the sponsers out there making chrome-moly parts, none are stress relieving parts. I could be wrong though. All the highend drag cars have chrome-moly roll cages, and you cant stress relieve the entire car. You just have to know how to tig weld and use the proper materials(gas, wire, tungsten). Here check out this link. Its on Lincoln Electrics website and it discusses welding 4130. This should answer all your questions.
http://www.lincolnelectric.com/knowl...hrome-moly.asp
I made my own fully adjustable, double rod ended, chrome-moly Lower control arms and panhard bar. They are working great on my car. Hope fully a cage will be next on the list.
http://www.lincolnelectric.com/knowl...hrome-moly.asp
I made my own fully adjustable, double rod ended, chrome-moly Lower control arms and panhard bar. They are working great on my car. Hope fully a cage will be next on the list.
Nice info there. That answered a couple questions I had.
6 & 8 Second Club
Joined: Aug 2006
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From: Illinois, RT 66 dragway area
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Never seen anyone worry about stress relief either. Actually, I doubt if anyone even asks when they get stuff welded.
Never liked the removable bars, yes I know they are legal, but don't trust them. Small hijack ?? Has anyone seen a car roll over or flip with them. I would love to see or hear, how they hold up in a real crash. Madman??
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Never seen anyone worry about stress relief either. Actually, I doubt if anyone even asks when they get stuff welded.
Never liked the removable bars, yes I know they are legal, but don't trust them. Small hijack ?? Has anyone seen a car roll over or flip with them. I would love to see or hear, how they hold up in a real crash. Madman??
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Ed swingouts are going to be the way to go if you legitimately drive your car. If the cage is done right you can take the bars out and its like having nothing in the car at all.
Wouldnt buy a prefab entire kit though, they tend to not tuck away nearly as well as they could if you bend it for the car. Come by the shop and look at Ashleys car in the next couple of days or Waynes he is right around the corner. 10 pt full cages Tysons put together and not in the way at all
Wouldnt buy a prefab entire kit though, they tend to not tuck away nearly as well as they could if you bend it for the car. Come by the shop and look at Ashleys car in the next couple of days or Waynes he is right around the corner. 10 pt full cages Tysons put together and not in the way at all
Thread Starter
11 Second Club
Joined: Dec 2002
Posts: 169
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From: Millersville, Maryland
Originally Posted by AshWS6
... Come by the shop and look at Ashleys car in the next couple of days or Waynes he is right around the corner. 10 pt full cages Tysons put together and not in the way at all
Sorry, but I don’t recognize the screen name. I think I know which shop you are referring to but I’m not certain.
I plan to go the Eastern F-Body thing at MIR on Saturday. I figure that would be an ideal place to look around at different bars and cages that people have put in.
BTW, I met Tyson a couple of years ago when he did my drive shaft loop.