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    Results 61 to 75 of 75
    1. #61
      Join Date
      Apr 2001
      Location
      La La Land, CA
      Posts
      2,240
      Country Flag: United States
      Quote Originally Posted by clinthart
      There is another benefit to not using the stock subframe... and that is typically weight. I got the Martz chassis, and I shaved about 200lbs off the nose of the car. Now,

      The problem with modifying your stock chassis is you really can't put in all the stuff these after market chassis have on them for the same price. Rack and pinion, tubular control arms, coil overs, disk brakes, etc. $1000 for the rack conversion, $600 a piece for tubular control arms, DSE kit is I don't know how much, and then the coil over shocks... ouch.
      You are on a roll here. Do you have the weight of the stock frame you removed? What is the weight of the Marts frame that replaced it? You really think you lost over 200 lbs with that frame? I don't think it could have been much more than 90-110 lbs, but I'm a skeptic.



      The second part of your statement is also a bit misleading. You need to realize that the parts you just mentioned are not needed to out handle a Martz or Fatman clip. You don't need tubular control arms to get the job done, and rack and pinion is such a waste of money with the new 670 power steering boxes on the market today. I'd be willing to bet you wouldn't be able to tell that we have a steering box in one of our stock frames, since it feels and responds exactly like a R&P. Coil over shocks also are not a requirement. Take a long look at CarlC's website to see how to make a landrum spring adjuster act like a coil over.
      I'll just say that we could outfit a stock frame with no tubular control arms, no rack and pinion, and no coil over shocks, and out handle a Martz/Fatman frame, for a fraction of the price.

      Tyler


    2. #62
      Join Date
      Aug 2004
      Location
      New Jersey
      Posts
      1,315
      Quote Originally Posted by ProdigyCustoms
      I think the Alston is a nice unit, but I would sure rather see you get creative and find some used Corvette stuff and do a Wayne Due. If not, no one will look down on you the the CW frame.
      To be frank, Frank I think a WD is probably overkill for what I'll be using the car for. Its mostly going to be street driven and won't be pushed that hard on a road course. I just want a new piece that will save alittle weight, and handle better then stock, bone stock. BTW your machinist Kevin is awsome, very nice guy and he is making a killer piece for me, thanks for the reference.
      Camaro Convertible Build Pics - http://s447.photobucket.com/albums/qq198/rob07002/

      www.musclerides.com

      Rob Stevens

    3. #63
      Join Date
      Aug 2003
      Location
      Orlando, FL
      Posts
      8,745
      Quote Originally Posted by TitoJones
      You are on a roll here. Do you have the weight of the stock frame you removed? What is the weight of the Marts frame that replaced it? You really think you lost over 200 lbs with that frame? I don't think it could have been much more than 90-110 lbs, but I'm a skeptic.

      Tyler
      Dude, he might have lost close to 200lbs. It's pretty damn light! Flexible as hell, but pretty damn light. Look at it, there is nothing there.

    4. #64
      Join Date
      Dec 2005
      Location
      Maryville, TN
      Posts
      839

      Geesh...

      Man, I'm glad I found this thread! I was having the same quandry... but was convinced I needed to buy the Martz chassis.

      So I've been reading in several difference places about this Gulstrand thing, and I've yet to hear someone actually say what it is or how you do it. I'm guessing there is a link somewhere?

      Also, what is it about the WD subframe that makes it so hot? I've lusted after those for a long time, even back when Rasmussen started selling them who knows how long ago... but have never actually talked to someone who had installed one.

      Do you guys know of anyone in the Tennessee area that can do these suspension mods you all are talking about to the stock frame?

    5. #65
      Join Date
      Dec 2004
      Location
      Bedford PA
      Posts
      27
      Frank,

      I was wondering if you could please provide me detailed information by email on the flex problem you had with our frame. Please email me at [email protected] I'd like to take care of this problem for future customers even if it's way too late to help you. I would also like to apoligize for Dad not addressing the situation properly and want you to know I am taking this very, very seriously. Any information you can provide for me will be beneficial. Let's call it a constructive criticism. If you have photos, illustrations, drawings, anything to help us take care of this.

      If ANYONE ELSE has issues PLEASE email me... Andy and I are doing our best to handle things correctly since Dad retired... it's a bit crazy here right now, but be patient with us and we'll help you as much as possible.

      And yes, we can shave 200 lbs off. The drag racers love us. lol.

      thanks,
      Jeri
      www.martzchassis.net
      founded in 1970

    6. #66
      Join Date
      May 2007
      Location
      Houston, Tx
      Posts
      2,200
      Country Flag: United States
      I have been trying to find an aswer to this very problem, im lucky i found this thread... I do have one question though, I have stumbled across a full chassis, and i was curious if anybody has used a Vennom pro touring chassis on one of their cars? Any insight into the full chassis idea is appreciated.
      Colin Russ

    7. #67
      Join Date
      Sep 2006
      Location
      Southern Indiana
      Posts
      4,699
      Country Flag: United States
      Cant say much for the other setups BUT i just finished setting up a fellas Camro with the Marts sub and as for it flexing I couldnt see as much as most stress BUT tthen the car was completely assembled and the fella wanted it to go on the Power Tour so I got my boss to let me set the front end up and I for one will say it is a very nice piece. As for being patterned after a Mustang II, if so that is one redsigned MII.
      We got herset up and went out for some fast blasts and it handled great. But then of course I believe that the air ride Technologies suspension helped a lot.
      i have set up hundreds of SCCA ACR Neons and many other cars since starting that so many years ago and I was very impressed with the construction and even with a tall deck BBC all iron it seemed to be a very nice piece.
      Lee Abel

    8. #68
      Join Date
      Dec 2004
      Location
      Bedford PA
      Posts
      27
      Thanks for the good feedback!
      www.martzchassis.net
      founded in 1970

    9. #69
      Join Date
      Apr 2001
      Location
      Central CA USA
      Posts
      6,108
      Country Flag: United States
      Jeri,
      I'm going to avoid any suspension lingo to make this understandable to more readers.

      A first gen subframe is near pathetic in torsion, so is a second gen sub. The fenders contribute nearly as much as the subframe to torsional rigidity.

      I read in Autoweek about the Aston Martin Vantage, it has something like 14,000 foot lbs per degree torsional rigidity. A first Gen Camaro is aprox 4000. Remove the front fenders and it's 2000, - Terrible. Add to that the factory rubber subframe to unibody mounts, and it's a wonder they went around corners at all! But remember, this sub was designed for a 4.5" wide tire and cornering G's of .6


      It was stated a Martz road race subframe is 200 lbs lighter, and the frame rails are smaller. I also see all the first gen Martz subs have large openings cut out just above the lower A arm bolts, also the main crossmember looks to be very open and not boxed in. It tells me that the designer was not concerned with torsional rigidity, - just light weight. It's quite likely your subframe has less torsional rigidity than a stock sub. While it may drive nicer on the street than a totally stock subframe, Pro-Touring is all about horsepower, sticky wide tires and a chassis/suspension that can make it all work together. A flexing subframe is an uncontrolled spring between you and the road. What you tell the car to do through the steering wheel and what it tells you through the seat of your pants goes through the chassis. It's the foundation of a responsive handling car.

      A Camaro front suspension usually handles 72 to 74 percent of roll torque created when cornering, but the front percent of total mass is less than that, it's 53% to 56%. When cornering the main mass of the car is twisting the front subframe by almost 20% of the total roll load. this twist is going through the subframe. In other words, when cornering hard 20% of the main mass of the unibody, all from firewall to the rear, - is trying to twist the subframe, because the subframe is doing more than it's share of resisting roll.

      I want to see a fully boxed crossmember, some triangulating braces, and frame rails that are large enough to resist twisting. Adding braces that cross in an X fasion from the firewall down would help more than you can imagine, but finding room for them is a challenge.

      Drag racing does not require as much torsional rigidity since they use skinny front tires. I suggest you look into the importance of torsional rigidity and it's effect on handling. Also look at the Detroit Speed subframe with it's hydroformed frame rails, or the Morrison sub. These are two good examples of the strength needed to form a good foundation for a car that will be driven hard on the street, autocrosed or open tracked.

      Buy this book and read about how to test for torsional rigidity.
      http://www.amazon.com/Chassis-Engine.../dp/1557880557

      I commend you for asking questions and not getting defensive. It gives me hope that you have what it takes to improve your product so it will better suit your customers needs. They don't know the difference it can make, the car will go where it's pointed more responsively and stay on track better.

      It's interesting to note that my Lola Vintage racer has about 6000 ft lbs per degree torsional rigidity.

      David
      Last edited by David Pozzi; 06-11-2007 at 12:13 PM.
      67 Camaro RS that will be faster than anything Mary owns.

    10. #70
      Join Date
      Dec 2004
      Location
      Bedford PA
      Posts
      27
      I will be sure to pass this on to Andy. Thank you for taking the time to mention your concerns.

      Though I cannot get technical, I do know that the original design of our frame came from my father's dirt track racing days. Some of the design also came from his NASCAR experience. This is extremely general, I know, but further info will be needed from Andy before I can post anymore.

      Also, the frames only lose that 200lb with lightweight disc brakes. The unit with standard GM brakes only loses approx. 150 lbs.

      thanks.
      Jeri
      www.martzchassis.net
      founded in 1970

    11. #71
      Join Date
      Aug 2003
      Location
      Orlando, FL
      Posts
      8,745
      Sorry for the delayed answer Jeri. I was not following this post. Here is a link to the build we did using your chassis.

      http://prodigycustoms.com/petes-camaro.asp

      You can see in the pictures the lengths we went to try to firm it up welding in frame connectors, hard moubting it to the body, the pie cuts under the riser area, the braces along the rocker. Still when the dust settled and the car on jack stands. It was still very bouncy.

      I am no engineer, but feel pretty confident the use of 2 X 4, or even 2 X 5 rails would help tremendously. Again, I am not engineer, but I know bouncy when I see it. And I know other frames we have used are not as flexy. David is much more of a suspension scientist then I, and his suggestions to beef up the supports, particularly in the crossmember area, seem quite logical also.

      As for dad not helping me. It may have been a bad day, but it seemed like I was bothering him and by the end of the conversation I still did not under stand how using the firewall braces would help with a convertible. In the end I made the executive decision to not use the firewall braces in fear it would damage my paint job if the doors were forced into the quarter panels, or the fenders jambed into the doors on wicked bumps.

      Like David, I appreciate your desire to make things stronger. I believe it could only benefit you.

    12. #72
      Join Date
      Apr 2001
      Location
      Central CA USA
      Posts
      6,108
      Country Flag: United States
      A circle track car would have a roll cage and the cage would tie in to the front suspension with braces, lots of braces on a good chassis.

      Go find an old shoe box, the kind with the separate lid, with lid off grab each end and twist the box, then put on the lid and twist, - quite a difference. The crossmember underneath the engine is very important to rigidity, also the frame rail size and thickness. For a drag car you want light weight and you just go straight, very little twist load on the suspension, but what we need is strength for good handling.
      David
      67 Camaro RS that will be faster than anything Mary owns.

    13. #73
      Join Date
      Dec 2004
      Location
      Bedford PA
      Posts
      27
      Thanks for posting Frank, I'll let Andy know.
      www.martzchassis.net
      founded in 1970

    14. #74
      Join Date
      Oct 2004
      Location
      NJ
      Posts
      765
      Country Flag: United States
      now you care about the issues I stated, where's my compensation.

    15. #75
      Join Date
      Dec 2004
      Location
      Bedford PA
      Posts
      27
      So far on our in house fittings on Chevy II's and all Camaro's we offer, we are only experiencing less than 1/8" inch flex. This is why we are so concerned. We are simply not seeing the flex issue here in our shop. That is why I've been asking for info on this. Our guys are simply stumped. We are just not seeing it here.
      www.martzchassis.net
      founded in 1970

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