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#2462209 - 03/06/18 06:02 PM CM cage
cdwmotorsports Offline
super stock

Registered: 03/30/03
Posts: 997
Loc: Martinsville, IN
I currently have a MS cage in my Demon and am wanting to switch to a CM for smaller diameter bars. I have seen pics of cars with CM cages tied into the stock chassis and I am wondering how one does that. I can only presume the chassis is MS and that the CM cage is welded to it directly.
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#2462219 - 03/06/18 06:14 PM Re: CM cage [Re: cdwmotorsports]
6PKRTSE Offline
master

Registered: 01/29/04
Posts: 3346
Loc: Motor City
Look at my "Coming To A Strip Near You 25.5 Challenger post. Obviously,mine is an E Body but same principle for your car. My chassis and full cage is all c.m. and is ran through all the stock floors and firewall.


Edited by 6PKRTSE (03/06/18 06:14 PM)
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1970 Charger R/T S.E. 440 Six Pack
1970 CHALLENGER R/T, 25.5 Cert, Big Inch Alum 16 plug HEMI twin turbo.
1970 Charger 500 S.E. 440 4 BBL
1970 Plymouth Road Runner.
1996 2500 RAM 488 V-10 4X4.
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#2462225 - 03/06/18 06:23 PM Re: CM cage [Re: cdwmotorsports]
cdwmotorsports Offline
super stock

Registered: 03/30/03
Posts: 997
Loc: Martinsville, IN
Thanks I’ll check it out
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#2462274 - 03/06/18 07:21 PM Re: CM cage [Re: cdwmotorsports]
polyspheric Offline
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Registered: 10/10/07
Posts: 2615
Loc: New York
No one reads anything but their own post.
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#2462280 - 03/06/18 07:33 PM Re: CM cage [Re: cdwmotorsports]
CMcAllister Offline
top fuel

Registered: 12/30/05
Posts: 2311
Loc: Fulton County, PA
You may have MS frame ties or you may be looking at getting it welded to stock floors or frame rails. That is acceptable, the rule says any weld that affects CM needs to be TIG. MS to CM, CM to MS and CM to CM are all TIGed. Beyond that, rules for construction are pretty much the same until you get to an SFI certified situation. The rule book is pretty detailed in it's requirements.

Also, using ChromeMoly instead of Mild Steel doesn't allow you to use smaller diameter bars. Just reduced wall thickness. Doing a cage instead of a bar allows you to use 1.625 instead of 1.750 diameter.

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#2462523 - 03/07/18 10:08 AM Re: CM cage [Re: CMcAllister]
6PKRTSE Offline
master

Registered: 01/29/04
Posts: 3346
Loc: Motor City
Another thing is resale. A moly car will always be able to bring more $$$ over a M.S. car due it being able to cert or re-cert & usually less weight when compared to the amount of bars each car would have.
_________________________
1970 Charger R/T S.E. 440 Six Pack
1970 CHALLENGER R/T, 25.5 Cert, Big Inch Alum 16 plug HEMI twin turbo.
1970 Charger 500 S.E. 440 4 BBL
1970 Plymouth Road Runner.
1996 2500 RAM 488 V-10 4X4.
2012 Challenger R/T Classic.

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#2462619 - 03/07/18 12:54 PM Re: CM cage [Re: cdwmotorsports]
sgcuda Offline
master

Registered: 01/28/05
Posts: 3846
Loc: Charlotte, North Carolina
Cage specs from SFI/NHRA usually do not effect tubing diameter, but wall thickness. Before you decide to change out, make sure that if will work with what you have in mind.
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#2463548 - 03/08/18 11:35 PM Re: CM cage [Re: polyspheric]
cdwmotorsports Offline
super stock

Registered: 03/30/03
Posts: 997
Loc: Martinsville, IN
Originally Posted By polyspheric
No one reads anything but their own post.


Actually I did read your post, and regarding your statement about roll bar vs cage being the determining factor in bar size. I appreciate the correction. I however currently have a cage so in this instance it does allow for me to go to a smaller diameter bar.

Thanks for your original input
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#2463550 - 03/08/18 11:39 PM Re: CM cage [Re: cdwmotorsports]
cdwmotorsports Offline
super stock

Registered: 03/30/03
Posts: 997
Loc: Martinsville, IN
6PKRTSE, I have owned the car since 94, she ain’t going anywhere. Even if it only stays a street car. A lot of great people have helped me since I was a dumb 19 year old kid on this car and no less than two of them are no longer here.i have the trunk flooring and the windshield bars I want to change so now seems like the best time to change it all.
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#2463572 - 03/09/18 02:10 AM Re: CM cage [Re: cdwmotorsports]
FastmOp Offline
master

Registered: 01/20/03
Posts: 5115
Loc: Hot Rod Ridge
You know what you want. That's what matters. I agree with your plan.

A 6x6 plate is welded to the floor pan. If the plate is moly it's TIG welded. But most use MS and tig a moly pipe to that plate.

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#2463582 - 03/09/18 02:44 AM Re: CM cage [Re: cdwmotorsports]
Cab_Burge Offline
I Win

Registered: 08/23/03
Posts: 30820
Loc: Bend,OR USA
I would try and get a copy of the current SFI specs on a NHRA legal cage, it will have the correct minimum tube diameters and wall thickness for both C.M and M.S. scope
The main hoop bar on a roll bar is 1 3/4, on a cage it is 1 5/8 is what I remember now work shruggy
If your thinking of having it certified later to faster than 7.50 ET in the 1/4 it has to have a all C.M. cage, not mild steel is what I remember a friend finding out the hard way later after having his new race car built with some M.S. bars in it tsk whiney
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#2463598 - 03/09/18 07:12 AM Re: CM cage [Re: cdwmotorsports]
dvw Offline
master

Registered: 03/16/06
Posts: 6958
Loc: MI, usa
I personally don't like installing a bar or cage on a 50 year old floor pan. Outriggers to a plated rocker make way more sense to me.
Doug


Attachments
0407091315.jpg



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#2463607 - 03/09/18 07:45 AM Re: CM cage [Re: dvw]
Jeremiah Offline
master

Registered: 03/03/03
Posts: 8099
Loc: Rogue River, OR
I also copied Doug's car and used 2x3 between the frame connectors (welded through floor) and rocker box. I had a really hard time welding to the rocker box due to contamination in the box itself. Not sure how to get in there and clean the backside of the box where the 2x3 is welded.

After I hole sawed through the top of the outrigger to locate the main hoop. This allowed me a solid fore-aft measurement for the roof halo, which works good in a 66-67 b body IMO. Once you have the roof halo leveled and tacked in you can raise the halo/main hoop up and slide a place under it to get the a-pillar bar measurements. I am 50/50 at this point between plates and outriggers on to land the forward bars after all of the trouble I had welding to the rocker box. At lease I can clean both sides of the floor pan for the plate.

That said if I was starting from scratch and not as a broke 19yo I'd have the car blasted before doing anything. The latest rendition of my red Charger has been the slowest going because the car is painted. If you google the NHRA rulebook 2017 is puplished and for what you are looking at it's the same as my 2018 book.

hth

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#2463773 - 03/09/18 12:15 PM Re: CM cage [Re: polyspheric]
jcc Offline
No politics

Registered: 12/21/03
Posts: 16974
Loc: Trumussia
Originally Posted By polyspheric
No one reads anything but their own post.


biggrin

Not always, especially when you have yourself on "ignore".
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#2463791 - 03/09/18 12:35 PM Re: CM cage [Re: cdwmotorsports]
Al_Alguire Offline


Registered: 01/20/03
Posts: 16723
Loc: Rockville MD & Las Vegas
As pointed out the only thing to consider is where welding of moly is concerned is the moly tube HAS to be tig welded in place. You will see a minor weight savings from MS to Moly n a simple cage. It wont be a ton of weight to be sure but some. I also prefer outriggers over plates on the floor
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#2463793 - 03/09/18 12:35 PM Re: CM cage [Re: dvw]
CMcAllister Offline
top fuel

Registered: 12/30/05
Posts: 2311
Loc: Fulton County, PA
Originally Posted By dvw
I personally don't like installing a bar or cage on a 50 year old floor pan. Outriggers to a plated rocker make way more sense to me.
Doug


I've always preferred to do it this way. I like to use 2x3 and section it up into the floor, sit the bars onto - or into - it above the floor, tying the chassis, cage and floorpan all together. This as opposed to the outrigger being under the floor with the floor trimmed around the bars. The 2x3 can be mitered and made to fit nice and clean. Most people think this is too much work, but it makes the car safer and stiffer.


Edited by CMcAllister (03/09/18 12:37 PM)

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#2463814 - 03/09/18 12:58 PM Re: CM cage [Re: cdwmotorsports]
polyspheric Offline
master

Registered: 10/10/07
Posts: 2615
Loc: New York
My point was that when people who weren't interested enough to post correct information assume that no one else has, they're just wasting my time.

My new rule: assume everyone already knows everything, and never makes mistakes.
Yup, that'll work.
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#2463831 - 03/09/18 01:19 PM Re: CM cage [Re: cdwmotorsports]
CMcAllister Offline
top fuel

Registered: 12/30/05
Posts: 2311
Loc: Fulton County, PA
And a note on Mild Steel, it's not all the same. ERW is a welded seam tube, typically made from 1010 steel. It's cheap and the wall thickness is hit or miss, which is why people have to use heavy .134 wall stuff to make sure it passes tech.

DOM is much more accurate and typically made with 1020. Usually you can use .120 wall with a .118 minimum spec safely.

ERW is really crap. Running a drill bit through both materials really shows the difference in them. Both are considered mild steel, costs are different.

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#2463918 - 03/09/18 04:32 PM Re: CM cage [Re: cdwmotorsports]
cudaman1969 Offline
master

Registered: 01/25/04
Posts: 4258
Loc: fredericksburg,va
I would go only one way if starting over. Build your cage, then attach your car to it. Front and rear frame rails attached with subframe connectors are your starting platform, build up from there. Sheet metal is just hanging there, but like my inspector said, you have two cages, body and roll cage.

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#2463952 - 03/09/18 05:15 PM Re: CM cage [Re: cudaman1969]
CMcAllister Offline
top fuel

Registered: 12/30/05
Posts: 2311
Loc: Fulton County, PA
Originally Posted By cudaman1969
Sheet metal is just hanging there, but like my inspector said, you have two cages, body and roll cage.


Exactly. The formed sheet metal body is also a stiff and substantial structure. Use it. With some planning, the body and the new chassis/cage can be made to support and reinforce each other, making the assembly stronger than if the body was just along for the ride. Tie them together, beyond the mounting points called for to get the cage in the car, to create one assembly

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