New vs Old Frames - Perspective

Saro Marcarian · Posted: Wed Oct 24, 2001 6:23 am Post subject: New vs Old Frames - Perspective

Assuming that a frame DOES change over the course of it's life:

Can we start to design / tune / evaluate the chassis based on x number of minutes / hours / days / bumps / turns / Chocodiles by the trackside? Kinda like a break-in?

Does the new chassis 'work better' because all the data you have is from the factory teams who change frames more often than you change underwear?

My gray puddle of mush isn't much in the mood to communicate this properly but hopefully you get the idea...

-Saro

PS - The assumption at the top in NO WAY indicates what I believe one way or the other.

Chuck Bunnell · Posted: Wed Oct 24, 2001 6:47 am Post subject: New vs Old Frames - Perspective

Unfortunately predicting fatigue life or similar, like this, is a dreadfully inexact science. Even harder to actually keep track of everything occurence and its magnitude, direction and such. Probably going by the size of your wallet is a good guide.

Gary Kozuma2 · Joined: 03 Aug 2001 Posts: 446

Here's another perspective: If it works, don't change it. But....

After your frame breaks a seat mount or a column mount or a front axel, you may want to think about a new frame. I have a buddy who has welded his frame like 8 times, including the front axel twice.

Gary K.

lynn haddock · Posted: Wed Oct 24, 2001 3:54 pm Post subject: New vs Old Frames - Perspective

Are you sure that most chassis now in the market are 4130 ?

Paul Harraka · Joined: 28 Aug 2001 Posts: 1345

I know that Invader karts are made from 4130 tubing. My son Paulie's karts are from August 1998 and they still handle and scale out well. I'm sure that the reason they have lasted so long is due to not only the 4130 but they had to be welded properly and we run in 225-285 lb. weight classes. The biggest killer of a chassis is improper welding and weight. Thin wall 4130 tubing MUST be either pre-heated or post-heated. Otherwise it becomes brittle at the area around the weld.

Scott McFadden · Joined: 20 Jul 2001 Posts: 125

I think your now getting down to the supportable rational. Obviously there is more new chassis associated with the latest spec engines in the hands of the best drivers in the best most well funded teams complete with the most knowledgeable tuners doing the most testing.

Of course a new chassis is going to perform better in this environment.

My experience with 4130 is that failures are caused by corrosion, design flaws, manufacturing or repair deficiencies or a combination thereof i.e. rarely 100% attributable to fatigue. Lots of 50 and 60-year-old aircraft flying around quite happily with their original Chromoly parts some of them with hundreds of thousands of hours and cycles on them. And if you think this is not a severe environment, take close look at an operating 18 cylinder radial engine sometime.

The welds and quality of welds will have less impact on the handling of the kart than on its durability. It is the material and design itself that effects the handling. As previously mentioned Chromoly steel is, by design, a stable material. For it to become work hardened it has to be deformed (actually bent). "stiffening" or other fundamental characteristic changes, of a kart chassis made of 4130 due to normal use, I believe to be so small as to be imperceptible. Especially relative to the degradation of the related bolt-on components (many of which are made of relatively low-grade industrial alloys).

Someone also said that there does not seam to be much design difference between older chassis and new. I had the opportunity to compare my 99 CRG with a 2001 and the differences are certainly there, some obvious, some not so obvious. I took that information and made changes to my 99 chassis and the difference was positive and immediate.

My chassis was used when I bought it (evidently rode hard and put away wet). This year, my second season on the chassis, even I was surprised at the number of 2001 karts with much better funded operations that ended up behind me (and how quick can a 43 year old be?).

Would I like a new kart? Absolutely, but not because of the new 4130, rather all the new stuff that bolts to it and the little design changes that are included. In my world of a 63cent dollar however I believe the biggest bang for the buck is not necessarily a new chassis.