Cage diameter vs buggy weight in racing

[Ghetto Fab.]

I've been designing with keeping the passenger compartment main tubes 1.75 and everything in the front or the back is 1.5 tube. I'd like to try using 1.5 x .090 tubing for all the bracing that isn't going to see rock rash like the B-pillar X. I haven't actually looked much at weights, but yeah, in theory you'd be better off keeping the same diameter throughout, and just go lighter wall thickness where its warranted.

 

[Bebop]

I've been designing with keeping the passenger compartment main tubes 1.75 and everything in the front or the back is 1.5 tube. I'd like to try using 1.5 x .090 tubing for all the bracing that isn't going to see rock rash like the B-pillar X. I haven't actually looked much at weights, but yeah, in theory you'd be better off keeping the same diameter throughout, and just go lighter wall thickness where its warranted.

Gonna save .6 lbs/ft.

Hope the safety trade-off is worth it.

 

[Bebop]

Makes you wonder the weights of a 2" cage and 1.5" chassis?
Obviously most are gonna say not needed but if you already have the design it's easy to do the math.

.4 lbs/ft from 1.75x.120 to 2x.120

 

[Ghetto Fab.]

Gonna save .6 lbs/ft.

Hope the safety trade-off is worth it.

I wouldn't know since I have no idea what your comment was directed at?

 

[Bebop]

I wouldn't know since I have no idea what your comment was directed at?

I'm answering this portion:

I've been designing with keeping the passenger compartment main tubes 1.75 and everything in the front or the back is 1.5 tube. I'd like to try using 1.5 x .090 tubing for all the bracing that isn't going to see rock rash

Going from 1.75x.120 to 1.5x.095 is .6 lbs/ft of weight savings.
I don't think it's worth it.
That's my opinion, of course.

 

[cdemart2]

building a new car doesn't make sense not to use 2". TMR entire chassis is 2" no mix. I wonder what the shipping weight on that is.

those of us with existing 1.75 cars are kind of beat. I'm very fortunate i have enough local racing without U4.

 

[Ghetto Fab.]

I'm answering this portion:



Going from 1.75x.120 to 1.5x.095 is .6 lbs/ft of weight savings.
I don't think it's worth it.
That's my opinion, of course.

No problem with opinions, it's hard to discuss without more specifics though. One of the benefits to the forum is discussion to further the knowledge right?

So you don't think 1.5 x .095 for internal bracing is worth the weight savings? I get using something thicker in rock hit prone areas like the say roof bracing where you want to keep the tubes from deforming in a backflip rollover scenario. I would think interior bracing, that doesn't see rock hits and should only be in tension or compression would be fine going thinner. I do get that its not much weight loss in the grand scheme of things. I had considered going .060 wall also.

 

[Bebop]

No problem with opinions, it's hard to discuss without more specifics though.

True.

So you don't think 1.5 x .095 for internal bracing is worth the weight savings?

How many feet of tubing would you say you can switch from one size to the other ? Educated guess, on the high side to help the savings figure.

I would think interior bracing, that doesn't see rock hits and should only be in tension or compression would be fine going thinner.

How do you quantify this ?
In my mind you plan for worst case scenario. Imagine you take a hit from the top of Monsters Inc (the new trail at Sand Hollow), it's a loooong fucking way down.

I do get that its not much weight loss in the grand scheme of things.

That's exactly my point. I'd rather have the extra strength.

I had considered going .060 wall also.

If you feel comfortable with it, do it. Since it's a feeling and not hard #s, you have to use what you feel comfortable with. I just wouldn't.

 

[Sean]

I don't know if it's worth considering too much....but my DOM supplier often has 1026 over 1018 or 1020....so with a little more carbon, it's a little stronger. I wonder if that could be why the OP said what he did about 2" denting more easily....or for all we know the 2" was HREW and his 1.75 was DOM. Obviously, 4130 chromoly would be stronger as well (though in my area, markedly more expensive).

 

[dirtzuk]

I had debated using 1.5 vs 1.75 when building my portal buggy but in the end for me the weight savings were not worth the loss in strength .. Especially where I wheel we tend to have alot of hard roll overs .. The 1026 vs 1018 could be a good idea ? I wonder if thats why In the past Ive had good luck using sched 40 pipe is the carbon content ( .25 % vs .18% )

 

[chaplinfj60]

and the wall thickness i am sure helped some

 

[Bebop]

I had debated using 1.5 vs 1.75 when building my portal buggy but in the end for me the weight savings were not worth the loss in strength .. Especially where I wheel we tend to have alot of hard roll overs .. The 1026 vs 1018 could be a good idea ? I wonder if thats why In the past Ive had good luck using sched 40 pipe is the carbon content ( .25 % vs .18% )

Chromo out of the question ?

 

[Ghetto Fab.]

True.

How many feet of tubing would you say you can switch from one size to the other ? Educated guess, on the high side to help the savings figure.


How do you quantify this ?
In my mind you plan for worst case scenario. Imagine you take a hit from the top of Monsters Inc (the new trail at Sand Hollow), it's a loooong fucking way down.


That's exactly my point. I'd rather have the extra strength.








If you feel comfortable with it, do it. Since it's a feeling and not hard #s, you have to use what you feel comfortable with. I just wouldn't.

All good points.

These discussions often remind me of the tonka toy dumptruck strapped to a semi truck trailer with only one strap and someone saying its not strapped correctly. Why not 2.5 x .188 wall tubing, etc... In the end we have to draw the line somewhere and we're all just making the best guess we can. I think even the rulebook that is the OPs issue, we all know is setup on feels and intuition.

 

[gt1guy]

And motocross guys are pussies compared to the enduro and harescramble guys

None of them are pussies. The endurance that the Enduro and desert guys have is unbelievable. But I don't think they are running a heart rate of over 200bpm for hours on end.