Custom Roll Bar

Tech tips and how to's

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RCMike
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Re: Custom Roll Bar

Post by RCMike » Sun Jun 23, 2019 3:03 am

speedbug78 wrote:
Sat Jun 22, 2019 11:17 pm
What about you scca guys? I see you running roll bars. What are your requirements? How do they fit your cars?

Thanks for the ideas! It makes me think and will turn out better in the end.
One is I think 12 point, I think the other is 18 or 20...

If I did not know better, I would think they were trying to build a tube frame car..lol

I will see if I can get some photos tomorrow, we are breaking one down for paint, to take it back to historic livery..

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Mike Unger
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Re: Custom Roll Bar

Post by Mike Unger » Sun Jun 23, 2019 8:11 am

It sounds like you are thinking about occasional trips to the drag strip with your road car so you are probably planning what you need. When I hear racing a roadster I immediately think road racing a sports car. If you use chrome moly the welds need to be normalized. You may already know this but I thought I'd mention it since you mentioned using 4130.

Here's the minimum design for a SCCA road racing cage. These are minimums and as Mike mentioned more bars or strategically placed bars are often used to stiffen the chassis. For a roadster the tubing would need to be 1.5" 0.095 DOM as a minimum.
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Mike Unger

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speedbug78
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Model: 2000
Year: High Windshield-68-70

Re: Custom Roll Bar

Post by speedbug78 » Sun Jun 23, 2019 10:47 am

If you use chrome moly the welds need to be normalized.
I'd rather not turn this into a thread about welding, but NHRA limits us to gtaw welding of 4130, but requires no additional normalization of the weld. Typical practice that I see (and have done) is to weld with ER70 filler and just let the weld air cool.

Here is a welding web discussion about it: https://weldingweb.com/showthread.php?6 ... 0-Rollcage
Cars:
'69 2000
'66 VW Baja
'97 F150
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Mike Unger
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Re: Custom Roll Bar

Post by Mike Unger » Sun Jun 23, 2019 12:17 pm

speedbug78 wrote:
Sun Jun 23, 2019 10:47 am
If you use chrome moly the welds need to be normalized.
I'd rather not turn this into a thread about welding, but NHRA limits us to gtaw welding of 4130, but requires no additional normalization of the weld. Typical practice that I see (and have done) is to weld with ER70 filler and just let the weld air cool.

Here is a welding web discussion about it: https://weldingweb.com/showthread.php?6 ... 0-Rollcage
Sounds like you're all set then. Have fun!
Mike Unger