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Author Topic:   Cracks in chassis?
dirtracer14
Dirt Forum Champ
Total posts: 1261
posted August 04, 2005 08:55 PM  
Looking at a new car for next year and would like to hear how long till you had a crack in your new chassis and what brand was it? About how many races till you found some or how long have you had it without cracks? Im not looking for sales pitches im looking to get a honest idea how other chassis hold up. I race on tacky and sometimes rough tracks and have gotten cracks in the first 6 races on some cars. Thanks, Craig Moore

chickenlittle
Dirt Full Roller

Total posts: 63
posted August 04, 2005 09:10 PM  
I run a 98 Ellis and it had some stress cracks at the welds where the front A-arms mount and at the shock mounts on the frame. I think if you set up a car so it twists you will get cracks after a dozen or so races.

CUSTOMPERFORMANCE
Dirt Forum Champ
Total posts: 1172
posted August 04, 2005 10:57 PM  
Only place I have had any welds stress crack on my latest ones have been around the motor mounts after being raced on some rough tracks. Normal racing 2-3 nites might see some in other areas after a year or two. The test car I built last year didnt have any welds crack when it rolled end over end about 3 times and after being pulled straight and 2 bars replaced it went on to win a few heats and 2 features afterwards.

What really makes a difference in if a chassis is gonna stress crack alot or not is the ammount of flex it is built to have and the size and thickness most of the tubing is made out of. last but not least is how good of welder the chassis man is too. Most times a weld joint on tubing depending on thickness is gonna stress crack near the weld do to too much heat.

[This message has been edited by CUSTOMPERFORMANCE (edited August 04, 2005).]

happy
Dirt Full Roller

Total posts: 73
posted August 05, 2005 06:14 AM  
I used to work at a place that made "high $$$" machinery for the wood working business, on all of the fixtures they had a Ultra Sonic type machine hooked to them that more or less vibrated the the jig with sound waves. When I asked them about this they said it relieved the welds and helped keeping them from craking, has any welders or chassis builders ever heard of this and do you think it would be good or bad for a race car chassis?

2nd2none
Dirt Forum Champ
Total posts: 755
posted August 05, 2005 08:11 AM  
dirtworks has a shaker. Most of the time they're production cars will never see it but the house built cars are put on it. We've got 2 of the last cars Monty built in our shop and both of them where put on the shaker.

JT54
Dirt Maniac

Total posts: 170
posted August 08, 2005 09:27 PM  
What wall thickness are chassis guys using in the front of the car to keep weight down and still be strong?....I am thinking of building my next one with 1 1/4 .083 for the front hoop tubes with 1 inch .083 bracing .....will this be strong enough ?.....my car right now has 1 1/2 .090 throughout and it is a tank ....a fast tank but would like to loose a couple hundred pounds and mostly off the front end .....custom ,any sugestions on wall thickness and tubing diamiter? for a good light reliable chassis?....thanks...JT

CUSTOMPERFORMANCE
Dirt Forum Champ
Total posts: 1172
posted August 09, 2005 01:19 AM  
1 1/2 .065 for main nose bars and 1 1/4 .065 for bracing or use the 1 1/4 for all of front bars.

JT54
Dirt Maniac

Total posts: 170
posted August 09, 2005 09:07 AM  
thanks custom ....this explains why my car needs so much weght in the back to have good %....abolutely no cracks for two seasons and very ruged but I cant help but wonder how fast it would be if I could make minimum weight and still have good %....thanks again..JT

CUSTOMPERFORMANCE
Dirt Forum Champ
Total posts: 1172
posted August 09, 2005 03:51 PM  
In the rear I would use 1 1/2 .065 or .083 with 1 1/4 .065 for bracing.

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