For the chassis guys out there:
I have put myself in a pretty good position. Wife and kiddies all have new or late model cars. Now it's my turn, but I am opting for an upgrade for the 'Cuda. I really want a new tube chassis for her. My questions are:
1) I know C/M is stronger than M/S, but since you are using thinner walls, which is stronger/safer when in use?
2) I know that either way, the final project will be lighter than my backhalved project, but how much weight will I really save using C/M over M/S for a full tube chassis?
3) Rough idea over cost difference?
At this point, I am putting together a high 8 sec project, but you never know what tomorrow brings, so getting it certified to 8.50 or 7.50 is also on the table as far as cost difference. I know that there are a ton of variables, but I want to consider apples to apples. IE; Control arms or struts, ladder bars or four link. I am just considering the chassis with body mounted. Whatever suspension I decide to use, I will install myself, just having all of the mounting tabs welded in place to start with. Thanks for everyone's consideration in advance.
Kenny

A CM chassis is stronger even with the lighter wall tubing..
its much stiffer... myself I wont even build a MS chassis.. I
quit building chassis's 2 years ago but when I was I wouldnt
even build a MS... every one wants a light chassis and CM is
a easy way to save weight.. it would be a CM chassis, strut front
and 4 link with a anti roll bar... you pay for tubing by weight,
there is a cost difference for CM vs MS but you are paying for a
.083 wall vs .135.. that extra wall thickness adds up quick... if
your building it yourself you will have about $1200 in tubing
EDIT
The biggest cost difference between the 2 is the welding... CM
has to be tig welded... that takes way more time.. time is money

Yeah, I know. Psyching myself up to bite the bullet. Wish I could just find someone's unfinished project...
Not sure if I want to attempt my own build. I remember Art Morrison made their Supergas kit years ago. I know there is another company making an Avenger kit, maybe Chris Alston?
I have had a lot of success with my ladder bar setup. I know four links add a lot more adjustability to the rear. Does tuning change from track to track a lot, or will I be able to find an acceptable setting for most local tracks?

On a 4 link you will find that once you find the happy point
that there will be about 4-6 settings that will work for about
any track... once I found mine I only changed it maybe twice
just to see if I could get it better.. but I always liked playing
with the chassis.. but in most cases you wont be changing the bars
but you would change the shock settings

Good to know. When I was in my 20's I lived for changes to make the car faster. Wife, 3 kids, 3 dogs, 2 houses later, just want one last hurrah!!!

I hear ya... I have already had my last hurrah .. due to no more
license ... but I was going 8.90s... now its 10.0 or slower

If you are thinking of high 8's or quicker , I think the four link decision is made for you.
Speaking metaphorically , when you are in the deep end of the pool , look to see what kind of suits everyone else is wearing.
I know people have gone that fast on leaf springs , but the vast majority do it with a four link car.

Raced at a bunch of tracks down here. Have never even been asked my name. Just pay and sign. NY and NJ were different. Pretty strict.

Good comparison. Ladder bars and coilovers are OK for a while, I guess. Hmmm, maybe it's time to look at a fresh roller.

RacerLex is selling Jimmy Bradshaw's old Dart chassis. May not be the best choice for pure race, but might be good enough for me. Better than what I have now. Price is right. Thoughts? Will it fit half way decent under 'Cuda sheetmetal?

Chromoly with a good 4 link with strut front end and real good double adjustable shocks on all four corners I traded my old Duster for a rolling 1970 Cuda with a tube chassis chromoly A arm front suspesion with 4 link rear with Koni double adjustables on all four corners, it had a blown B1 motor on Methanol that the former owner had gone 7.80s at 184 + MPH with that combination, I put a 505 C.I. bracket motor on E85 in it and throttle stop raced it most of last year to avoid renewing the Comp license and buying all new safety gear for the 9.99 license I did renew the license and bought all the required safety gear in August of last year so I could run it all out I have new(1965 Dart) rolling back half 4 link chomoly car that is ready to start plumbing, wiring, buy fibreglass parts, painting and so on. This one will be my last hurrah for drag racing Hopefully

Listed under Race cars for sale.
https://board.moparts.org/ubbthreads/ubbt...DartChasis7.jpg

Buy my car and put your engine and trans in it.. done.. and I'm
sure you'd run 8.50 or better... I'm selling pretty damn cheap
but its not a cuda

Thanks for the offer, Mike. And I know how meticulous you are with every project you take on, but I really want to stick with the whole E body thing.

Ah, yes, again we re-visit the MS vs. CM conversation.
A few facts:
The heavy wall MS has about the same yield strength (resistance to breakage) as the thin wall CM.

The weight saving is entirely due to: less metal used.

For a tube of given length, stiffness (resistance to bending or shape deformation) is almost entirely a function of its outside diameter. The relationship: R ~ OD^4.
Increasing a tube's OD by 25% (e.g., using 1-1/4" OD instead of 1") increases its stiffness to 244% - it's more than doubled.

Curved tube: avoid whenever possible, when stressed it will bend where it's already bent. Shorten the tube by running a strut as close to the center as possible.

The next factor is the wall thickness - pretty much linear (add 10%, get 10%).

Last is material, but CM and MS are almost identical, in fact almost every steel alloy (and all steels are alloys) has the same Young's Modulus of elasticity. Any steel is much, much stiffer than any aluminum alloy in terms of section thickness (not per pound), and stiffer than titanium.

The other big secret (meaning, no attention paid to it, although it's very important)? Minimal length of any unsupported (uninterrupted) span.
A tube 4 feet long is almost twice as stiff (+95%) as a tube 5 feet long. This is why triangles are used.
Unless the open area is necessary for something (driver exit, engine bay) all rectangular shapes should be shortened with a diagonal, even if it doesn't extend the entire height of width. Since these are generally not part of the required certification structure they don't have to be minimum diameter - they can be 7/8" OD and still help (saves weight and money).

Wow. Good to know. Thanks for the info.

Poly... I guess the NHRA thinks different.. if you build a
roll bar out of MS it has to be 1 3/4 X .135.. if CM it can
be 1 5/8 X .083... they must think CM is stronger or they
wouldnt ask for the larger dia... also why does it take more
pressure to bend CM over the MS.. I can see this on my gauge
when bending

Mike it has nothing to do if it is stronger or not. many articles have been out about this subject. NASCAR still uses mild steel.

Yes they do.. and they have a much heavier minimum weight also
but I still say that CM is a stiffer steel.. I can see that
when bending it(on the gauge) and it has a higher spring back rate

CM flexes, watch a top fuel car