Why does a chassis wear out?

John Grinager · Posted: Thu Aug 02, 2001 6:26 am Post subject: Why does a chassis wear out?

Okay, I'm completely new to karting, so please excuse the neophyte question, but....

Why do serious karters seem to replace their chassis at least every two years, if not every year? The designs don't seem to significantly change (and before you beat me up, I mean I don't see totally revolutionary changes happening). Someone told me that they thought it was because the chassis don't flex the same over time. You mean to tell me that the material work-hardens and age-hardens THAT much? If that were the case, couldn't you just take your trusty, proven chassis and have it stress relieved every season, returning it to its original state? Please enlighten me.....

David Mayhew · Joined: 31 Jul 2001 Posts: 209

New chassis are cleaner and look better!!

Marc Miller · Advertiser Joined: 18 Jul 2001 Posts: 1834

John-

Let me put it in simple terms. Every 20K-30K miles you probably replace your springs and shocks on yoru street car. If you are in 99.9% of the population that has never pushed an automobile to even remotely close to its limits, that would be a fair assessment. The harder you push your car and the more you drive it, the faster you wear your suspension out.

Most karters drive the crap out of their karts and the chassis is the spring AND the shock. Many chassis you may be able to see a slight difference between new and used after just 3 or 4 races... some may take years, depending on usage and the level of the driver.

My reason? I've always liked that "new kart" smell *grin*

Good luck!

Marc Miller

Tim Blaney · Joined: 18 Jul 2001 Posts: 1127

quote:
Originally posted by Marc Miller:
99.9% of the population that has never pushed an automobile to even remotely close to its limits

Marc, so that is why your Jetta still drives like it just rolled off the assembly line!

John Grinager · Posted: Thu Aug 02, 2001 11:31 am Post subject: Why does a chassis wear out?

Thanks for the answers thus far everybody. But, this is the "Tech Hit Squad", so I'm gonna be a little more demanding!....

Has anybody ever done any controlled, quantitative tests on a chassis when it is new compared to when it is a year old, two years old, etc? I mean like measuring force required for a given deflection at a corner of the chassis, etc? Every material has a yield strength, and I would think that exceeding that yield strength is what it would take to alter the material, but that would leave it with a measurable permanent deflection. The only other situation that I can surmise is what I mentioned before, a combination of work-hardening and age-hardening the chassis material through usage and age. Of course, what would actually be happening is that the temper of the material would be being changed, so I would think that by now someone would have come up with a process to restore the original temper (heat treating, stress relieving) or would have incorporated a design that primarily stresses replaceable "gussets" or "struts" (torsion bars?).

With all of the high-techery and money that is generated by manufacturers, I would think that SOMEONE has done some exhaustive R&D on this subject.

C'mon, 'splain it to me, I dare ya!

(I like the "Because they're cleaner and prettier" answer the best so far....)

Tom Stephens · Posted: Thu Aug 02, 2001 11:42 am Post subject: Why does a chassis wear out?

And while answering John's last post, can anyone explain how stress-relieving is done and why it is supposedly a good thing? Arrow chassis are stress relieved...are any others, and if not, why?

Tom Stephens www.kartfinder.com

Marc Miller · Advertiser Joined: 18 Jul 2001 Posts: 1834

Dare taken... but my question is WHY would a manufacturer spend 100's of thousands of dollars to make a chassis that only costs $500 or less (just the frame itself) to make last longer??

What is in it for them to sell a chassis four times the price of their competitors even if they CAN prove it will last more than four times longer? It would only take one bonehead move for a racer to make that chassis that is four times more expensive worthless.

It comes down to R & D in making a good kart better. Like I said before, some chassis last longer than others based on their build materials, but when it is all said and done, those chassis are made for special high performance reasons.. they may be fast for one race, then slow down.... it may be great for a factory guy, but not for a club racer.

I have tested chassis (same make model) that I had raced all year versus a new one with as many variables removed as possible. In that case, it worked out that the fresh chassis worked better. I have known friends that had tested another make that said they could not find a worthwhile difference in their new kart at all, even citing that thier used kart was more "sorted" out than the new one and ultimately faster.

It all comes back to lack of return of investment for the manufacturer. I am sure I would want the chassis manufacturer developing a fast, easier chassis to work with than to find expensive treatments to make it last longer and add some $ to the price tag. Wouldn't you?

Darren has a valid point about the used kart market... and I have found that there are used karts out there that are not mistreated, never wrecked or have very few races on them for a fair price. A new karter will not be able to tell much of a difference between a 3 race old chassis compared to a brand new frame.... much less a 3 year old frame. When buying used, I would look more at the condition of the components and accessories rather than the frame itself (other than obvious mistreatment). You can tell if a kart has been abused more by looking at the componentry of the kart more anyway.

AND Tim... the $3000 suspension helps my car... although... like you experienced, that suspension doesn't mean squat without decent tires *grin*

Regards-

Marc Miller

[ August 02, 2001: Message edited by: Marc Miller ]

Doug Welch · Posted: Thu Aug 02, 2001 1:46 pm Post subject: Why does a chassis wear out?

The question was asked about stress relieve. You take the frame(chassis), put it in a furnace and heat it to around 1200 deg f (more or less depending on material type), soak at temp for 1 hour and cool in the furnace. The reason for doing it has to do with the welding. When you weld chrome moly steel (4130) you form hard noduals where the carbon precipitates. Hard spots. Stress relieve removes these hard spots.

This problem is more pronounced with a frame that has been mig welded. A quality tig welder who purges the inside of the tube with argon will have almost no problems. Most frames I have seen are mig welded. It's fast, cheap and can be done with a robot. Tig welded frames require a very good welder and must be done by hand to be done right. DFM tig welds their frame as do some others. I think Trackmagic tig welds them also. A mig welded frame should be stress relieved where a tig welded frame properly done does not.

Doug

John Bosanek · Posted: Thu Aug 02, 2001 2:27 pm Post subject: Why does a chassis wear out?

quote:
Originally posted by Doug Welch:
. Stress relieve removes these hard spots.

DFM tig welds their frame as do some others. I think Trackmagic tig welds them also. A mig welded frame should be stress relieved where a tig welded frame properly done does not.

Doug

Anyone know who else TIG welds thier frames?

Keith Archambeau · Posted: Thu Aug 02, 2001 2:27 pm Post subject: Why does a chassis wear out?

Now all we need is the manufactures to devuldge the alloy!

John Grinager · Posted: Thu Aug 02, 2001 2:47 pm Post subject: Why does a chassis wear out?

Thanks Marc, although your second post did not answer the technical aspect of my question, you make an excellent business point that is so obvious that I'm surprised that I hadn't thought about it. I guess I was so caught up in the technical side that I hadn't stopped to realize how silly it would be to make a chassis that lasted so much longer. Oh well, I guess I'd better contemplate a couple grand per year for a new setup!

Brant Williams · Posted: Thu Aug 02, 2001 3:51 pm Post subject: Why does a chassis wear out?

The "throwaway (Euro) chassis" syndrome has been around for a long time.

I think that for a long time many European Kart mfgs used milder steels in chassis construction. These chssis' were known to be often good for only 2-4 races as noted above. I could always imagine the Italian factory driver coming with a chassi two weeks old and tossing it away...sheeza noa good...

Perhaps someone with better knowledge of the European Kart market could confirm this, but I believe Tony really upped the game...going to CNC machinery and higher alloys. Haase was actually built by Tony before they did their new plant (compare a Haase Skorpion and Tony Espirit circa 1996) , and CRG upped their game soon after. I don't know about the grand daddy of em all...Birel, etc. There are many other "2nd Tier" brands like Energy, Fullerton, KGB, MBA etc etc etc. Many of these guys are design firms only. The actual fabrication is done by people like Parolin which is a BIG BIG mfg. I think there are still quite a few 2nd tier kart mfgs that use standard steels, as opposed to 4130's, etc. So you can still get stuck with a blown out chassis.

I also think this is the reason Tony's have such good resale, where as a Brand X might not....

Mark Dismore Jr · Advertiser Joined: 21 Jul 2001 Posts: 1098

quote:
Originally posted by John Bosanek:

Anyone know who else TIG welds thier frames?

All of our karts are tig welded. It looks a helluva lot better than mig.

Mark Comet Kart

Greg Cavouras · Posted: Thu Aug 02, 2001 6:57 pm Post subject: Why does a chassis wear out?

quote:
Originally posted by Brant Williams:
The "throwaway (Euro) chassis" syndrome has been around for a long time.

.

It's funny you should mention the "throwaway european chassis syndrome". That's what they told me about my 1997 Gillard 05. This chassis is a prototype built specially for Mrs. Lotta Hellberg to run at Charlotte. I bought it after that one race on it, and now, four years later, it's still winning. Now I know my "exceptional" skill

has something to do with it. J/K!!! but it seems to me the "one race euro chassis" was a mythological creature!

John Grinager · Posted: Thu Aug 02, 2001 6:58 pm Post subject: Why does a chassis wear out?

Be careful about assuming that TIG welding is inherently better than MIG. I have been in the metal fabrication business my entire career, most recently having erected an ultra tech, robotic manufacturing facility from the ground up. True, TIG welding will almost always LOOK better than MIG, but they are both only as good as the operator when done by hand. Welding is an art in itself, and the integrity of the weld is affected by a multitude of factors such as shield, sacrificial substrate, current amount and type, operator technique, and many others. To be perfectly honest, in a production environment, I would feel that I was at least getting a CONSISTENT weld quality if it were done by robotic MIG. Again, this is a generalization at best, so it is merely a point to consider....