Connecting the B and C pillars in a Roll bar?

[BlitzK5]

When connecting the B pillar (middle hoop) to the C pillar (rear hoop) using stringers or horizontal bars (which ever you want to call them) in a roll cage should I weld the bars on the bends from one corner to the other or should I weld them on the flat part (very top). I see most people have been welding them from corner to corner (in the middle of the bend). Does this help out in strength when a roll occurs or something? My main concern is that the OD is smaller in the corner due to the bend and I can’t get a snug fit when joined. There is some space because of the change in OD due to the bend. The corners become less then 2". I’m using 2" X 0.120". I added a picture of someones cage which is similiar to the cage im doing now. As you can sey the pilars are connected by tubes in the cornors and that is what im refering to in my question.

 

[Hossbaby50]

With good copes, welds, and gussets it won't matter really. Or you could do kinda like I did mine. Run the bars for the C pillar along the length of the truck and use a spreader between them.

Harley

 

[mikey_d05]

[hijack]

Harley, how is that slick plastic stuff doing for ya?

[\hijack]

 

[BlitzK5]

Well my pillars are already in place so I cant do that option. So your saying there is no strength advantage of the placement in which these bars are welded on then.

 

[sled_dog]

do not weld on the corners. Nascar dirt track racing and NHRA rules prohibit it for the exact reason you noted, thinning of tubing walls do to bending.

I really find it interesting that UROC's rules are so relaxed in chassis and cage design. I think it is because there has not been a serious injury of a driver yet.

 

[az-k5]

It can be unavoidable to weld to the corners at times. You can make it safer with gusseting.

Sure you can bend the last 6-8" to miss the main bend, but then you have new stress risers to deal with. For our purposes you can hit the bend just as safe due to proper gusseting and load distribution.

 

[Hossbaby50]

[hijack]

Harley, how is that slick plastic stuff doing for ya?

[\hijack]

In the runs I got in before I left AZ it did great. I put alot of weight on them and they helped the panels slide like they are greased up. They also did a good job of distributing the weight of impacts over a larger area and caused less noticable and less severe dents when the truck hit rocks hard enough to dent the panels. The panels rock in my opinion. I really like them and think they are a great option for the casual wheeler that are trying to get on some tighter trails and are trying to keep there rigs somewhat clean.

Harley

 

[70jimmy]

I will have pics of mine up in a few days. Did mine a little different. The B Pillar is a normal hoop from driver side to passenger side. Then I made a hoop that goes from the the B pillar to the windshield and back to the B Pillar on pass side, I then stuck it back in the bender and made a bend right in the middle to pinch the ends in and welded at the B Pillar on top before the bend of the B Pillar starts. Then I ran a bar from driver floor up and angled with windshield and welded to the hoop from B Pillar to windshield. Back is up from driver side rear to above tailgate then angled like the old kayline tops and then to the B pillar and welded on top before bend.

I don't know what is better but I like the look this gave. Some other pretty cool options but I will let the pics speak for themselves. Ok a little more info. Sliders connected to cage using DIY4X caged floor mounts and the sliders are connected to the frame. Sliders are 2" DOM .120 wall and they stick out 3 inches from bottom of door and 3 inches under body they connect to 2" by 3" rectangular.

 

[thor]

do not weld on the corners. Nascar dirt track racing and NHRA rules prohibit it for the exact reason you noted, thinning of tubing walls do to bending.

I really find it interesting that UROC's rules are so relaxed in chassis and cage design. I think it is because there has not been a serious injury of a driver yet.

Where in the NHRA rulebook is that written? My chasis is certified every 2 years by the NHRA and built right off NHRA's drawings. Yet has a node there just like az-k5's.

 

[sled_dog]

NHRA rules in my book say it and my teacher just built and got a car Certified and it was in the rules. What speeds are you running? THe car he built is running low 9s I believe.

 

[thor]

I run 9.80's at 137. 10.0 second and slower do not have to be certified. They sonic test the thickness of the bars in several places, and verify that it matches the cage drawings from the book, and the drawings for ALL sportsman style bars have the halo intersect the main hoop at the corners, the down bars intersect the halo at the corners.

Not to argue, but what paragraph does it say that in? I have never seen it, but that doesn't mean anything cause I'm slow I have only read it a few dozen times.

 

[sled_dog]

I don't have a rule book myself. Here is a quick thing I spotted on the NHRA site.

http://www.nhra.com/contacts/tech_faq.html

The second image, it states that the down bars in the rear of the main hoop must attach to the horizontal portion of the main hoop. Seems to show the halo mounting away from the bends as well, but does not expressly say it here and image is pretty crappy showing it. I will find the quote in my book(mind you it is a quote taken from an NHRA rule book from who knows what year).


Then this article in Hot Rod clearly shows the bars mounting to the bent portions of the cage.
http://www.hotrod.com/techarticles/48019/

 

[thor]

Cool, those drawings on the site are straight from the rule book, Clear as mud. I aint into arguing over it, more just curious. I was refering to the halo and front down bars though not the rear down bars.