Bent frame, possible problems

Gerry Harris · Joined: 08 Aug 2001 Posts: 7 Location: Canada, Toronto

This was my son's first year in sprint racing, at the beginning of the year he was running ok however as the year went on and he got faster we chased a loose condition that we could not get a handle on.
At the end of the season I totally dismantled the kart and started checking the frame for square and flatness, to my amazement the left frame rail was bent upwards. ( at the centre of the bearing mounting position the gap from frame rail to flat surface was 1\8" )
Would the bent frame cause the persistent loose condition?

Thanks

Gerry Harris

Pete Ryan · Posted: Tue Dec 04, 2001 12:57 pm Post subject: Bent frame, possible problems

if it was fast with it bent you could leave it like that. if not you could get some large people and stick a pole in the frame and try to bend it back. the one person i used to know bent all of the chassises his son ran so he could get them to scale right.
But like Keith said scale it and see how the numbers are

Gerry Harris · Joined: 08 Aug 2001 Posts: 7 Location: Canada, Toronto

Thanks Keith and Pete for the feedback-

Keith, we were always loose on the exit of the corner. Looks like bathroom scales are on my Christmas list!

Gerry Harris

Gerry Harris · Joined: 08 Aug 2001 Posts: 7 Location: Canada, Toronto

Thanks Keith and Pete for the feedback-

Keith, we were always loose on the exit of the corner. Looks like bathroom scales are on my Christmas list!

Gerry Harris

Jimmy Moore · Joined: 26 Jul 2001 Posts: 664

Sounds like someone popped him in the back bumper or he backed into something. The frame is easy to straighten right there. I use a large piece of square tubing (3"x5") and a heavy chain to hang it from the frame. Put a 5 ton bottle jack in between the two and pump. Don't forget a 3"x3" aluminum pad to protect the frame rail. You'll be suprized how much you have to bend chromalloy to get it to move.

Keith Archambeau · Posted: Tue Dec 04, 2001 11:23 pm Post subject: Bent frame, possible problems

Gerry, seen many chassis with this amount of twist. Scaling the kart will tell if it is bad enough for a handeling problem. Normaly this will show up as the kart turning better in one direction L or R. As your speed increases (lower lap times) All kinds of different handeling problems appear. First your loose then you fix that and go faster then your tight and then your loose again. All in the same day!
WE found that our first loose condition was due to the pendulium effect. In short to much rear weight. Try moving the weight or seat forward. Another thing, if your confident the weight is correct, a stiffer axel or longer hubs will help.
Where in the corner are you loose? Entry, Exit? A different story. Hope this helps.
RACE!

John Learmonth · Posted: Wed Dec 05, 2001 2:47 am Post subject: Bent frame, possible problems

quote:
Originally posted by Gerry Harris:
Thanks Keith and Pete for the feedback-

Keith, we were always loose on the exit of the corner. Looks like bathroom scales are on my Christmas list!

Gerry Harris

In one direction, or both?? If the problem is in both directions then its probably not caused by the chassis twist (some chassis seem to be more sensitive than others). Having said that, in most conditions (ie on most tracks) you do want the chassis to be 'flat'.

Keith Archambeau · Posted: Thu Dec 06, 2001 1:47 pm Post subject: Bent frame, possible problems

Gerry, loose on corner exit can be the inside tire is not coming down to contact the ground. Two tires with a given amount of weight will have more traction than one. Also both tires in contact will cause a push at a given stearing angle & speed. Taking caster out, narrowing front, harder axel, longer hubs, lower weight (CG) will help, try one thing at a time.
RACE

Graham Macleod · Posted: Fri Dec 07, 2001 3:07 am Post subject: Bent frame, possible problems

Gerry, get the frame only with spindles to Bob Morphy in St Thomas, Ontario (519) 633-0999, Best $50 Canadian you can spend.
regards, Graham

Rodney Ebersole · Posted: Fri Dec 07, 2001 5:45 am Post subject: Bent frame, possible problems

Gerry Harris, You may want to check that axle out with a dial indicator as it is most likely bent as well.

Steve Clark · Posted: Fri Dec 07, 2001 9:53 am Post subject: Bent frame, possible problems

Gerry

I agree with Graham. Bob does a great job with the chassis. Although since I have a shifter now Bob joked that if I need his services to straighten that I probably went home in an ambulance. It's amazing how much damage some folks can do to a chassis. Race on Sunday . . send to Bob on Monday.