full frame replacement for our unibody cars

Discussion in 'Classic Mustang Specific Tech' started by 65up2d8, Jun 22, 2005.


  1. Bullitt

    Bullitt Packin' Heat Founding Member

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    i've autocrossed a '69 camaro that was basically a tube car front and back, and am currently autocrossing a '79 camaro that's setup the same way.

    both cars are FAST and easily keep up with the Z06 corvettes that run in Solo 2 SS (these are CP cars, so not exactly a fair comparison, but it's something).

    if you're seriously considering this, look at doing the front suspension with circle track parts, or possibly even camaro components as they are cheap and very effective. the '69 camaro i drove had a corvette steering rack and circle track control arms (with coil over shocks), corvette spindles and was freaking sweet! the rear-end setup on both cars is a 3-link setup with a sprung 3rd link. both were easily the best behaved live-axle cars i've driven. far better than even a "modern" torque arm/panhard setup (3rd and 4th gen camaro) or the terrible 4 link on the pre '05 mustangs.

    anyways, that's my insight from a serious autocrossers standpoint...
  2. DukeGnarley

    DukeGnarley Member

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    i really think your best bet would be to build some custom sub frame connectors that also tie into the midsection of the car, reduce as much weight as possible, and get something like the griggs suspension installed.
    http://www.griggsracing.com/gallery.html

    if you built your sub frame connectors right, it would look just like a full length frame rail, and probably be stronger if it were welded to the floor.

    edit: missing word.... and it also appears that the griggs setup includes R&P steering.
  3. 65up2d8

    65up2d8 Member

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    The general consensus appears to be a loud he** no, which is cool if that opinion is built around factual observations. I guess the only thing that concerns me is that many of the members here, myself included, are mesmerized by the SN65 build, as well as reenmachine's build. If the best platform to begin with is truly the stock unibody with coil overs, a R&P steering system, springs, subframe connectors, a performance suspension rebuild, etc. (you get the idea; not enough room), why is there so much fascination on this forum with those two builds, which the builders of obviously feel the need for substantial upgrades from the factory style unibody/suspension setup? I realize reen is using the core unibody, but look at what he is using suspension wise. I am beginning to strongly suspect that if I had pretty progress photos to go along with the concept I am proposing, I would have many more supporters who would think this was the best idea since sliced bread. :bang: :) :shrug:
  4. 65up2d8

    65up2d8 Member

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    The Griggs setup appears to be totally friggin awesome!! I've checked it out prior to this thread, however, and the problem as I see it is two-fold. First, you could do what I'm talking about for the price of a full griggs setup (that ****nit must be made of 14K gold!). Second, and perhaps most importantly from a performance standpoint, you would still need an extremely rigid chassis to use the griggs setup on or you wouldn't reach its potential.

    I have fully welded M-Plus subframe connectors at this point. I have seen articles regarding integrated subframe connectors before, and I'm sure they'd be a big improvement over what I have, but my concern remains with the limitations regarding suspension setups you can run on the stock unibody, as well as the ultimate weight you would reach making a 40 year old unibody as rigid as a brand new full-frame in every respect. Just my $.02.

    Finally, maybe I am barking up the wrong tree with respect to the Art Morrison setup, but a couple of posters on this thread have agreed that a full, tube frame setup would be a major improvement over the stock unibody. What say ye others?
  5. 1320stang

    1320stang Founding Member

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    I think the MaxG chassis with a cage would be just fine. Matter of fact, I think that the MaxG chassis without a cage isn't going to be much more flexible than a stock chassis. You could have a full tube chassis done, but you'd be into it deeper than the MaxG chassis. You could build the chassis yourself, but as we've seen some do, your time will be close to a year and do you think you know what your doing better than a guy that's been doing it for years? Also, it's called the MaxG chassis, not the cobbeled up Street Rod chassis. Morrision's square tube bender does mandrel bends in both planes. This is way better than something your cutting and welding. Morrison has been building drag car chassis for years. I'm not saying you can't learn, but he probably knows more than 99% of us on this board do and he can probably do a chassis better than 99% of us do on our first one as well. I personally think that some sort of weld in chassis/floor for these cars that have need of floors and framerails isn't a bad idea at all. And if anyone tells you that the MII conversion without any sort of bracing is going to be less flexible and stronger than even the stock setup....

    I really don't know what the answer is, but I think the MaxG chassis is as viable of a solution as anything else. I don't think it's going to be as heavy as some people think either, it's not like it's 1/4" wall tubing.
  6. 65up2d8

    65up2d8 Member

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    It sounds like you may go this route quite some time before I think I'll be able to do so. If so, please let us know how it comes out. Art Morrison's website does not have a picture of the actual unibody replacement frame for 60's muscle cars. There is a rendering of it in the July 2005 Hot Rod, and it appears to be beefier than what you see on the website, which was designed for older cars.

    With respect to your GW coil over conversion, if you decide to go this route, try placing it in the classified section on this website to trade for something you need rather than for sale. I suspect you and the person you trade with would come out better as both of you would take a hit in reducing the price of your items for an outright sale. Just my $.02.
  7. 65up2d8

    65up2d8 Member

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    I totally agree with your point regarding the expertise of Art Morrison vis-a-vis myself, or for that matter, many people who have built custom, one-off tube frames. His company has been in this biz for quite some time and is probably the best known around. I know I don't possess the tools, machinery, or know-how to do better than AME.

    I do have one question after reading your post, however. Your statement that "I think that the MaxG chassis without a cage isn't going to be much more flexible than a stock chassis" really seems inconsistent with the rest of your post. Is that what you meant? Do you truly believe the MaxG chassis would be more prone to flex than a bone-stock Mustang unibody? No offense if that's what you meant, but if you look at the rendering of the MaxG chassis in the July 2005 Hot Rod, I would find that statement very, very hard to believe.
  8. 1320stang

    1320stang Founding Member

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    What I meant was, I think the MaxG chassis welded into the Mustang properly without a cage won't be anymore flexible than the stock chassis, matter of fact, I think it may be more rigid. But in this instance, I'm also precluding the fact that you would weld in steel floors that would tie into the rockers, quarter panels, taillight panel and firewall. The MaxG is made up of tubing where the stock chassis is made up from multiple layers of formed sheetmetal. If someone does go about doing this, it'd be interesting for them to weigh everything they cut out and everything they put back in as same for same though.

    People talk about ladder type frames twisting, this can be evidenced if you ever rode in the back of a 70's truck and was holding on to the front edge of the bed as your dad/granddad drove down a dirt road. These frames were true ladder frames in that there weren't hardly any changes in elevation up and down in the frame and they had a lot of flex. Someone mentioned street rods. What do rodders do? Box the frames? Why? To stiffen them up. Is a C channel frame boxed going to be stronger than a tube? I don't know, but I suspect not. The MaxG chassis has more severe kickups front and rear than an old truck or model A chassis. Will it twist? Sure. Will it twist more than the stock Mustang chassis? Again, I don't know, but I suspect not. I'm pretty sure that if you were to cut out the stock floor/chassis in a Mustang in one piece and compared it to the uninstalled MaxG chassis, the MaxG would kick the stock stuff's butt. You say, well, the Mustnag chassis is part of a system. If the MaxG stuff is tied in properly, would it not be as stiff? And the 4000# comment, I don't think installing the MaxG stuff will add 800-1000# to an early Mustang.

    All this is my own opinion and not based in any scientific fact, but then, neither is anyone else's that posted I believe. I've been around drag cars mainly, but race cars, street rods and custom rides pretty consistantly for around 15 years. I've seen a lot of cobbled together stuff and a lot of really nice stuff. I can look at stuff and get a pretty good idea of whether it works well or not, but I'm no expert either.
  9. a.vannoy

    a.vannoy New Member

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  10. 68rustang

    68rustang Active Member

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    Would your home grown, or drag strip derived chassis and suspension design have the proven on track performance the Grigg's system does? Where would you get replacement parts for your one off build?

    You seem to be stuck on the fact that there is nothing that can be done to significantly reinforce the factory unibody structure. Wouldn't adding a 6pt cage and through the floor subframe connectors essentially give you the "tube framed" "full frame" you seem to need so desperately. Ask the guys at Cobra Automtive how well they do with their unibody race cars. Ask Historic how well his car handles at the track, again a unibody car. Call Griggs and ask them how many guys run their suspesnion sytems on the street and at track days, then ask how many are "full framed" cars.

    If you are serious about pursuing this goal join over at www.corner-carvers.com and lurk for a while. Look for threads by "Preston", "BossBill", "Mean69", "Opentracker", to name a few.
  11. SN65

    SN65 New Member

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    Hi All,

    I have been watching this thread from the sidelines. I think it is time to throw my 2 cents in.

    I would much rather have a uni-body style design over the frame / body design. The car I am building is a uni-body design all though a rather unique uni-body, it is still a uni-body.

    If you want to learn more about how to reinforce your uni-body read the following thread. I found it VERY informative. This thread is the basis we used when evaluating different reinforcing concepts.

    http://corner-carvers.com/forums/showthread.php?t=13919)

    Good luck

    Bob
  12. 66P51GT

    66P51GT New Member

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    Take a closer look at the Griggs setup. They have two types of sub-frames. The first is the typical version that connects the front/rear of the chassis. The second style actually requries you to cut your floorboards in the rear passenger area. This is the in-floor frame kit ($229). Griggs measured a 1500% increase in chassis stiffness with this modification. Couple this with a cage and the chassis will be plenty stiff.

    Taking into consideration the total price of the GR-350 suspension kit ($9,500) it is a deal; especially considering the quality of parts (Koni Adjustables, Watts link, etc.) and engineering that goes into each part and that all of it is proven and tested on the track. There is still a considerable amount of fabrication required to install the Griggs setup, but it is much less than retrofitting your body on a frame.

    The cost of engineering a frame with SLA or twin wishbone front suspension and rear multi-link that will incorporate the footprint and dimensions of a 196# Mustang would cost more than $9,500. An experienced engineer at $200/hour would have to design it in about a week. Then you have to build it and buy the parts and hope it works.

    My persional favorites in kits in order of proven track performance:

    1. Griggs
    2. Cobra Automotive
    3. Global West
    4. TCP
    5. Shelby Specs (take your pick)

    Now, to make things even... take the same driver and place them each in prepped cars by the afformentioned companies using the same year car, same engine prep, same brakes, etc. I bet lap times at either Sears Point, Watkins Glen, Laguna Seca, you name it... will be within seconds of each other.

    Oh, and if you haven't seen the in-car video of the Cobra Automotive fastback... it may change your mind about the direction you are going: http://www.cobraautomotive.com/wg_movies/wg_lap_320x240.mov
  13. krash kendall

    krash kendall Active Member

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    You're building a car? Hadn't heard about that! What's so unique about it? You should start a thread so we can check in everyday!
  14. a.vannoy

    a.vannoy New Member

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    Yeah i second that :rlaugh: :D :banana:
  15. 66P51GT

    66P51GT New Member

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  16. 68rustang

    68rustang Active Member

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    those parts are listed here on stangnet and corner-carvers as well.
  17. PickupMan

    PickupMan Founding Member

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    I like the idea of the full frame. If I were to do it again I would make up a full frame to get rid of those damn shock towers and set up a four or three link in the rear. Hell I want a damn race car with a 66 coupe body....the all around car...go fast, corner,stop and accelerate like a SOB! :nice: Personally I love the SN65 project but it would have been better with an 05 model.
    Personally it's a pretty simple thing to do for not alot of money. Get yoursely some 2x4 box tubing and go to town. Use the car as a template and go from there. Sure it's easy to say but I still think it's not that bad of an Idea..why it's a damn good idea......... :cheers:
  18. 65up2d8

    65up2d8 Member

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    Although I was actually talking about using the MaxG chassis from Art Morrison rather than using a hand-built frame, I have to give you kudos for giving some thought to the idea and seeing the advantages of it. C5 Corvette brakes on the front, a 3 link rear suspension set-up, and loads of room for rolling stock seem like some pretty good advantages to me, in addition to possibly more torsional rigidity. I frankly don't understand why it seems to be such a sore topic with many individuals on this site, but at the same time, I respect everyone's opinion. After all, opinions are what I asked for in the beginning.
  19. PickupMan

    PickupMan Founding Member

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    I think they are sore cuz it's a new idea. No one really likes change but I've been around mustang for not that long but have seen the hobby go from one extreme to another. Just look at the restomod thing....no one wanted a modified mustang years aga but now that seems to be the thing people will pay money for. So in due time there will be all kinds of crazy mods for the mustang....wait there already is now! All we need is the cash!
  20. Hack

    Hack Active Member

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    I don't think people are generally "sore" about it. It just isn't a good idea from a money or performance standpoint. My opinion is that if you want to pay someone to hack up your car that's your business. I plan on hacking up my car at some point in the future, so I'm not going to tell you I think there's anything wrong with making changes.

    But realize that your modifications will cost a lot of money to put back stock, and unless you are willing to spend a lot of time designing or adjusting the front and rear to work well together it will never work that well. You know the 80/20 rule - you can have a well-handling car with inexpensive and subtle modifications, or you can spend a mint for a slight additional improvement. The last bit of improvement costs a lot.

    Your car will also be worth less money if you decide to sell in the future. So far from getting money back out, you will spend money to lose money (if that makes sense) :)

    It would be cheaper to keep your classic as a fun car for nice days and buy a separate car for track days. You could pick up an 80s Fox Mustang set up for racing for less than a tube chassis would cost installed.

    Again, there's nothing wrong with spending 2, 3 or even 10 times as much money to do what you want - but since you asked I figure it's my duty to at least make sure you're aware that that's what you are planning. Good luck!

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