Roll cage

[petepecas]

To all,
Do you think a single diagonal 2 inch diam. tube is stronger than an 1 1-2 inch X at the rear roll cage hoop? all being same material, same thickness.

[Grimm]

I think they will both be strong enough to protect you, but I would think the 1.5 X brace would be stronger.

[petepecas]

Yea, I thought so, score tech at san felipe did not...:mad:

[Grimm]

Ya, those diagonals gotta be 2" .120 regardless. So what happened to your racer?

[petepecas]

We entered (Tried to enter:mad:) the san felipe 250 with a stockfull 94 chevy silverado (curb weight 3700 lbs.).
Rulebook says 3000 to 4000 lbs. to use 1 3/4, 120 ga.
I built the main structure w 2 inch,120 chromoly, the x at rear Hoop, side impact bars and x at rear down braces in 1 1/2 120 chromoly.
Rulebook says you need side impact bars if you DONT have steel doors, I do.:confused:
Rulebook says 1 diagonal 1 3/4 brace at hoop and down braces, I tought an x in 1 1/2 would be stronger, guess not.

I learned that you dont wait till race day to get your rig tagged,:o my bad.
We will be back for the baja 500:cool:

[Nick's Trix]

ouch. expensive learing experience. guess that is one of those live & learn type of things.

[chupakabras]

i think the main problem was that combination of 2" to 1.5, because instead of holding when pushing it could penetrate at that point, i don't know if i made my self clear, haha, well, will explain that with some pics later, haha, see yahh. suerte pete,.,

[petepecas]

Yes, it was expensive to haul people and gear all the way to san felo, and, you got a point chup, had not seen it from that angle, in any case, talked to savage on the horn and he said not to chop it yet, he wants to have a look at it personally, will keep you posted...

[straightaxle]

I thought Savage was there in San Felipe when you were in tech in the afternoon. He's the short guy with the long pony tail, cigarette and sunglasses. Didn't he look at it then? We were watching from outside the fence. They were pointing and waving at the bends in the down braces.

We wish the best for you, like you say, very frustrating to bring all the crew and equipment and not be able to run. It's not a question of tube size versus strength, just what they randomly decided to use in the rule book, however the structural design of the cage is more critical. Anything can happen on any given day. The same crew (ARTS) that does SCORE tech was at the Mint race two weeks later, and they were giving me grief about the fuel cell vent that has been the same for 9 years! They had just looked at it 2 weeks before in San Felipe! My favorite was when they said "no coil overs on Class 3" in 2000, and when we get to the Baja 2000 race and there is a 79 Bronco with coil overs on all 4 corners! And it raced that way (for a few miles).

[chupakabras]

just like this past race, they say, this is your last race with these helmets, for the next race come with sa2005 rated helmets,. wtf,. i know, safety first, but, we already test them a few years ago, and we still here to tell the story, :D, i don't know, what can we do. buy new helmets if we want to keep up with score.

[F OFF Racing]

Yes I have a dodge ramcharger that I would like to start installing a roll cage in. I guess by reading I need 2" 120 gauge ??? Also how many points 4, 6 ?

[Blanco]

Yes I have a dodge ramcharger that I would like to start installing a roll cage in. I guess by reading I need 2" 120 gauge ??? Also how many points 4, 6 ?

1st off I have most of the SCORE rules posted.
http://www.class3racing.com/showpost.php?p=7301&postcount=10

& your gonna want at least 6 plus!
Probably more like 8+
Front of the frame
A-Pillar
B-pillar
rear of frame.
ETC.....

[AngerIssues]

1st off I have most of the SCORE rules posted.
http://www.class3racing.com/showpost.php?p=7301&postcount=10

& your gonna want at least 6 plus!
Probably more like 8+
Front of the frame
A-Pillar
B-pillar
rear of frame.
ETC.....


Hi again Bill (with the Ram). It all comes down to what you hope to do with the car. There are some great threads on here with cage pics, etc. If you ever want to race it, the cage must be tied from front-shock mounts to rear, and to the frame. The body must then be tied into the cage or it will start to come apart on ya. Most go so far as "bumper-to-bumper cage, and it does make sense.

If this is a pre-runner/chase truck, some of this is certainly not necessary!

I would say, for a race-truck, you are looking at about 8 points where the thing ties into the frame - front shock hoops, a-pillar, b-pillar (or behind the seats), and rear shock "down bars"... with cross bars at the 1) over the top of the motor (removable), 2) dash (for front down-bars in a "V"), 3) behind the seat (mandatory), and 4)rear-shock mounts.

I'd say check out the pics on here. The green bronco looked pretty nice!!

I'm sure the Pike family would send you pics of their Ramcharger. It is very very nicely done with "big" stuff!

ken

[lucasdalebultema]

Sorry to hear that you didn't get to race. I don't know the backgrounds of everyone on here but I was wondering if you had done any analysis of which would actually be better. I'm a mechanical engineering student and I could probably do a Finite Element Analysis on the 1.5" cross versus a single 2". Then you could bring something to them and show them qualitatively that your design is better (assuming it is).

I could probably then use this for a class project in the future too!

Lucas Bultema
Assistant Captain
Wayne State University Formula SAE Team

[Grimm]

If your X had been 1.75 you would have been fine because your vehicle weight was less than 4000. 1.5 is a pretty small tube though, i can see there concerns i guess. But I still think it would have held up.

[AngerIssues]

do a Finite Element Analysis on the 1.5" cross versus a single 2".

Uh... Yeah! That is what I would do!

Now where do I start? :confused::confused::confused::confused::confused: :confused::confused::confused::confused: he he

(let us know how that comes out... I can check your math) :D

[lucasdalebultema]

I would probably run through a couple different scenarios and see if the X would be best or not based on the properties of the metal. If you had an idea where your loading came from that would be great. I'll try and do something up in NX5 as soon as I can. I need to remake some control arms and pullrods today for our mini formula car but tomorrow and Friday I have off so I can probably try to figure it out then.

What size tubing is in question and what size tubing do they claim you need to use? OD? ID? Wall Thickness? 4130? Any other info about the material would be great.

[petepecas]

I had 1.5" 120 ga. replaced with what they wanted, 2", 120 ga. single diagonal, from top of "B" pillar to bottom of opposite "B" pillar.

I already changed everything to meet their criteria, I gotta race!!, the B500 is 10 days away:eek:
but I do appreciatte the interest and effort you are willing to put into this:)
If you still want to go ahead with the analisis, just out of curiosity, would be interesting...

Pete

[tsm1mt]

To all,
Do you think a single diagonal 2 inch diam. tube is stronger than an 1 1-2 inch X at the rear roll cage hoop? all being same material, same thickness.

Just FYI, one of the issues with a 2" cage and a 1.5" diagonal is the change in tube size.

It's right up there with why a gusset is better placed on the outside of a joint, than in the middle (lay the gusset onto the side of two pieces of tube and weld - you make a "L" not a "T") - the small tube will want to punch through the bigger tube.

It's in this spirit that for non-critical areas in my new car, instead of dropping tube size to save weight/cost, we're dropping wall thickness.

2x.095 (or even .083) instead of 1.75x.120 perhaps, when I'm adding an over-kill tube to 2x.120 parent material.

[AngerIssues]

I would probably run through a couple different scenarios and see if the X would be best or not based on the properties of the metal. If you had an idea where your loading came from that would be great. I'll try and do something up in NX5 as soon as I can. I need to remake some control arms and pullrods today for our mini formula car but tomorrow and Friday I have off so I can probably try to figure it out then.

What size tubing is in question and what size tubing do they claim you need to use? OD? ID? Wall Thickness? 4130? Any other info about the material would be great.


I think, as of late, they have required 4130, and been subject to some major criticism because of it. I don't have the wall thickness in front of me. having done the move, I've misplaced my rule books. Only SCORE requires you order them and wait for them to arrive. Check BITD.com - who has "on-line" rules.

[Ckrue689]

With score techs, it all depends on whether or not they got laid the night before...

[gunit]

I think, as of late, they have required 4130, and been subject to some major criticism because of it. I don't have the wall thickness in front of me. having done the move, I've misplaced my rule books. Only SCORE requires you order them and wait for them to arrive. Check BITD.com - who has "on-line" rules.


For the main cage SCORE requires all to be .120" wall. Under 4000# 1 3/4" min and over 4000# 2" min. Material can be either 4130 Chromo or DOM. Must be seamless tubing.

The weight is measured wet with fuel and at least 1 spare tire.

[azdirtworx]

so, usually what do these bronco weigh roughly?? over 4000? and just for argument sake, to just go ahead and run 2"????

[gunit]

so, usually what do these bronco weigh roughly?? over 4000? and just for argument sake, to just go ahead and run 2"????


It is pretty hard to build a Bronco class 3 and have it come in under 4000# in race trim. The rule book measures the weight "as raced" including fuel, spare tires, safety equipment etc. but without driver, see page 32 in the SCORE rule book.

It would not make sense to build it out of 1 3/4 and then fail tech by a couple of #'s. Your investment of time and materials will be worthless to race class 3. You could race other series but the value of the car will be much less. Why do that to yourself? When you are starting from scratch it's not that big of difference in cost or effort so you should use 2".

[Blanco]

Savage (SCORE tech) would not even look at my Bronco when I told him my cage is 1.75 :(Broncos are difinetly over 4000 lbs.

[azdirtworx]

aight.. thanks fellas...2" it will be...:D

[Ckrue689]

so does anyone know if there were any special edition Bronco II's that had a V8? that would be friggin sweet if you could swap in a 5.0 and be legal...

on that note, is there anyway that they will allow a smaller V8 being that the FS broncos have a 351??

[straightaxle]

Never was a V8 in a BII, but the Explorer's had them later on.

[Ckrue689]

yeah, I know. just thought Id ask because they had a BII that had a chopped top with a soft top...

too bad though...

[broncodan74]

so does anyone know if there were any special edition Bronco II's that had a V8? that would be friggin sweet if you could swap in a 5.0 and be legal...

on that note, is there anyway that they will allow a smaller V8 being that the FS broncos have a 351??

Better off going with an early Bronco. The later years even came with 351's! I'm currently building a '68! :D

[Broncodawg]

Not flaming at all, but Early Broncos never had 351s, even as an option.
Weren't available until early 80s FSBs, I believe. Many 351s live in EBs now tho.:D

[AngerIssues]

Savage (SCORE tech) would not even look at my Bronco when I told him my cage is 1.75 :(Broncos are difinetly over 4000 lbs.


Just a few days ago I found my original weights.

Front: 2340 (avg)
Rear: 2400 (avg)

That is 4740, but I will tell you this is BEFORE I cut the rest of the bed out to make room for the Kings, batteries, and other stuff that I did AFTER the weights. I kept track of each piece, weighed them seperately, and recalc'd. I don't have the FINAL weight of this 1985 FSB, but I can safely say I didn't lose 700 more pounds.

Short of a monster-truck-style body-glass, I don't think it would be possible to get below 4000.

[broncodan74]

Not flaming at all, but Early Broncos never had 351s, even as an option.
Weren't available until early 80s FSBs, I believe. Many 351s live in EBs now tho.:D

Ah crap, I new that... :confused: Thought I saw 351's listed in my Chilton's manual from 75-77...

[straightaxle]

Back to the topic of cages, how in the world did they pass this cage? I know it was at BITD and not SCORE, but check out the rear down bars. I guess it also didn't matter since the truck only did 4 miles at Vegas to Reno before it turned into a carBQ. It started life as stock class Super Duty, and it was STOCK! They didn't even put shocks on it. They think the exhaust caught the brush on fire when they got stuck.

[azdirtworx]

wow, now that can ruin your day.... especially with not bringin any hotdogs.....

[petepecas]

Won't let me open the link to photo from straightaxles reply:confused:
asking to log on, but, but, I AM....

[Blanco]

Won't let me open the link to photo from straightaxles reply:confused:
asking to log on, but, but, I AM....

http://www.thewebwheeler.com/forums/images/smilies/6.gif You try clearing your cookies?

[petepecas]

Thanks Cam, maybe my office computer needs attention, the home PC let me open the pic.

Back to the topic, yea, those rear down bars look like grab bars for a fire truck! I guess they will let anything run in BITD:eek: Poor guys didn't get to try their roll cage:(

[Ckrue689]

Back to the topic of cages, how in the world did they pass this cage? I know it was at BITD and not SCORE, but check out the rear down bars. I guess it also didn't matter since the truck only did 4 miles at Vegas to Reno before it turned into a carBQ. It started life as stock class Super Duty, and it was STOCK! They didn't even put shocks on it. They think the exhaust caught the brush on fire when they got stuck.


Talk about "Heat Treated" eh?

[Blanco]

Talk about "Heat Treated" eh?

http://www.thewebwheeler.com/forums/images/smilies/20.gif

[chupakabras]

maybe those rear down bars were intended for contingency purpose, i mean, for the crew to have something to hold on, haha, just kidding, well they look pretty much like the cages found on some police trucks in tijuana,.

[Broncodawg]

The burned truck was brand new, made it five miles before catching fire.
Two women racing desert for their first time ever and one is Charlie Daniel's hot daughter. The team is Charlie Daniel's racing and she has raced circle tracks for a while now and decided to get into desert. Says she will build a new truck and try again in BITD.

[Ckrue689]

The burned truck was brand new, made it five miles before catching fire.
Two women racing desert for their first time ever and one is Charlie Daniel's hot daughter. The team is Charlie Daniel's racing and she has raced circle tracks for a while now and decided to get into desert. Says she will build a new truck and try again in BITD.

If they do I hope to hell they dont build it like that again. That was a crappo idea...

[DraVen]

speaking of cages(still havnt got the damn rule book in the mail yet) does the cage HAVE TO tie into the front and rear shock towers? and how is the SCORE LEGAL way to tie my cage to my frame i have about 13in. for the frame rail to the out side edge of my intirior floor board. do i have to put 3x3 tubing from my frame to the cage point? (if this doesnt make since i will take some pics)

[Dave G]

...does the cage HAVE TO tie into the front and rear shock towers?

No.


... how is the SCORE LEGAL way to tie my cage to my frame...

IIRC, in the SCORE rule book, there is a drawing that shows a piece of tubing with a 90* bend that attaches the bottom of the cage pillar through the sheet metal (using doubler plates) to the frame. However, it would seem wiser to have your front and rear hoops bend together about 12" or so above the frame at a 45* angle so that they terminate closer to your frame. You can then add additional structure to protect your feet and legs as needed. Does that make sense, or should I try to post a drawing?

[DraVen]

yea im not getting that...

[Dave G]

Sorry, it's not an exact example of what I'm trying to show, but it should get the point across.

I'm referring to how the hoop (the rear in this shot) bends inward so that it terminates closer to the frame. (this truck has something else going on where the cage exits the cab through the back wall.)

Does that help?

[DraVen]

yea that makes since. now i need to find a place that can and will do a cage...there isnt crap for that type of fab shops here in Sac.

[straightaxle]

River City Differential does a bunch of cage work for rock buggies, but I don't know if they are set up for the 2" stuff that SCORE requires. That takes a serious bender, and Dave and I don't even have the stuff to do that big right now.

[gunit]

Sorry, it's not an exact example of what I'm trying to show, but it should get the point across.

I'm referring to how the hoop (the rear in this shot) bends inward so that it terminates closer to the frame. (this truck has something else going on where the cage exits the cab through the back wall.)

Does that help?

Here is a pic where the cage has been brought in to meet the frame.

http://www.supermotors.net/getfile/541785/fullsize/picture-001.jpg