frame thickness

[CHEVMALI454]

have anyone tried using 1x1x1/16" thickness steel ? i know mostly using a 1/8th thickness, so i thoguht of using up all the left overs tubing i got in my garage and done building a bsr with those stteels, it came out good and strong ,using a raptor engine running alochol race around the block not a problem ...

[Woodchuckscustoms.com]

lets see some pics of that racer!!!:cheers:

[Mike Bean]

Hmmm...you could try the 1/16" steel. You might want to add a couple of additional inside frame braces if you get too much flex.

Just try it and see what happens... You might have some problems where you weld the rear axle hangers to the frame, unless you do some extra reinforcement.

Mike

[sniffles]

You probably want to make some braces with that steel. Better safe than sorry. I'm using .065" thickness and havent had a problem with it flexing while welding. I havnt ridden it yet though.

[RUBICON]

WELL....LET'S SEE....I worked on piper J-2's...and J-3's in the late 60's..( that's an airplane for all you young guys )...and it was designed with 1/2" , 3/4" , and 1" thinwall ( 1/16" ) carbon steel tubing....it had well designed gussets....and as you would expect ...good welds....gas welds...plain old gas welds.....on the engine mount...and every thing else.....was it strong enough?....yes.....if designed well....including the calculated deflections and stress loading....and welded "PROPERLY".........having "preached" all that...the 1/8" wall is a lot more forgiving on fabrication...and stiffer if you like.....if I sound pompous...mine is 1"x1"x 1/8"....it was easier for me to work at my age....good luck.....and remember....LIFE IS A JOURNEY!....ENJOY THE RIDE

[1100kaw]

I'm with Rubicon
1/16 will work, but will prob need to be over engineered to last.
Mine is 1/8 x1 1/4 round tube. My thoughts were, I wanted to build it plenty strong for anyone to ride, and not be nervous about something breaking. These things are all about the fun. I had mine out today, and everone that see's it wnats to ride it, rather they say so or not. So I push it on them, just to see them have fun, knowing they cant hurt it.
A buddie of mine, Large guy, rode it today, doing wheelie's and slamming it down hard, repeatadly.
I feel mine is pretty in-destructable, so, build it once, build it right.
I'd hate to see a 1/16" tube crack, right next to a great weld, and get you or someone else hurt
DD

[barstooldawg]

We have some of that 1/8" (3millimeters) thick stuff at school it looked abit to thick said my teacher and would just slow me down so i used
2 millimeter and 2.5 millimeter.....i dont know what the conversion is to inches.

[bm1]

1/16" is pretty thin and would require some gussets and extra bracing. I agree on the bearing hanger area. How much do you think the added 1/16" will slow you down

[CHEVMALI454]

i rode it again today , only problem im feeling is the back part of bsr wobbling when i go very fast, i dont know if its the tires or the frame is twisting.barely can steer too at high speed because it feel like the front tires are off the ground slightly ,maybe using 1/16 ' is a bad thing to do but a great experiment for me to do ..

[Mike Bean]

You could be getting some flex at speed or the frame might have some warpage from welding. You need to be careful on that thin stuff.

I know on the 1/8" you can also get warpage if you are not careful... It happened to me once when I was in a hurry.

Mike

[sniffles]

A good way to keep from warpage is to put a support piece between the main frame to keep it nice and straight. In addition to that you can take some gooseneck clamps or anything you have lying around and clamp the frame to the table. I have done this with .065" tubing with absolutely no flex. Hope this helps

[bm1]

Unless you have a fixyure to clamp everything in, you will undoubtedly have some warpage.
If you have a flat surface, try to clamp down you project, tack all pieces together and don't weld in one spot too long. Weld a joint at one end, then move to the opposite end and weld some, stop, let it settle(leaving it clamped) and alternate welding. This will keep "warpage" to a minimum. The best thing is to tack everything first.

[Mike Bean]

I am able to weld frames together without the use of a jig or clamps. You need to understand how the welds are going to pull the frame as they cool.

The first thing I do it tack weld the whole frame together. I usually will tack weld the outside and insides on the corners of the frame first.

When I start to finish weld, I start by welding the 4 inside corners and let them cool down. I then weld the four outside corners and let them cool. Once I have all the inside and outside welds I start on the top and bottom welds.

You just need to be sure you have your welder setup correct and don't spend too much time in one place. If you goof up, let the weld cool and grind it out and make a new weld.

A tip for welding the foot rests if you have them... As I mentioned above weld the insides and then out sides first. When the welds are cool to touch then only weld one top or bottom at a time and let them cool. I have found out if I weld both the tops or bottoms that connect to the frame the welds will pull the foot rest. If I do only one at a time there is not enough strength in the cooling weld to pull it.


Mike Bean
:hot:

[CHEVMALI454]

I Think I Have Figured Out The Problem , Front End Is Not Aglined, How Do I Get Front Wheels Aglined?,everything Looks Solid And Added Few Braces And Gussets So I Beleive Its The Front Wheels ....

[Mike Bean]

Chevmali,

Can you post a photo of the front of your BSR so we can see how the tires are and spindle brackets are positioned?

Thanks,
Mike

[bm1]

Are you sure you have the rear axle square in the chassis?
To check the front end alignment:
1- Mark the center of the front tires. You can do this by rolling the tire and using an ink pen or sharpie to mark the center of the tire.

2- Take a straight edge long enough to reach from the rear to the front,(maybe a piece of sq tube) and lay it against the right rear tire. Make sure it is flat against the wheel. You might need an extra set of hands to do this.

3- Make sure the front wheels are straight and the steering wheel is centered.

4- Measure the difference from the rear outside edge of the front tire and the front edge of the front tire.

5- Adjust the tire rod until both front and rear of the front tire are the same distance.
Now the right front is square with the rear.

5- Lock the steering in place to keep the right front from moving.

7- Now, adjust the left front to the right front by measuring the centerline you scribed on the center of the front tires from front to back. Measure the distance from the front of the tires on the centerline, then measure the back of the tires on the centerline. What you want is about a 1/16" toe in. That means you want the front of the tires to be pointed in 1/16" more than the rear.
Hope I didn't confuse you but actually it's pretty easy. Hope this helps.
bm1

[Speedycheater]

You probably want to make some braces with that steel. Better safe than sorry. I'm using .065" thickness and havent had a problem with it flexing while welding. I havnt ridden it yet though.

1/16" is the same as 0.065"....

16g. = 0.065" = 1/16"

Also, you want some flex in your frame. Without flex in your frame it would be nearly impossible to steer, since most barstool racers do not have diffs. The outer rear wheel must break traction to allow the BSR to turn. Flex in the frame allows this wheel to come off the ground or at least break traction. In theory, if you has no flex in your frame and both rear tires had 100% traction with the ground, it would not be possible to turn. Racing karts work on the same principal. That is one reason most racing kart frames are made from very light guage (usually 16g) tubing with little bracing.

[RUBICON]

Speedycheater...Your explaination is close but think of this....Karts need frame flex to keep all 4 tires on the ground..and they adjust the flex to control the loading of each tire. When they corner they want the inside tires to grip also. The radial slip ( difference in turning radius with a solid axle ) of the "inside rear" tire is accomplished as the tire drifts in the turn. On a barstool with a solid axle you actually benefit from a rigid frame. The reason is that you need to transfer weight to the outside front tire in a turn and allow the inside rear ( not outside rear as you stated ) to slip. If the frame flexes too much it is harder to break the inside rear tire loose in a turn.....just my thoughts

[voodoo_stepchild]

I used 14 ga on mine however I went with 1"x2" rectangular tubing. Lot different animal than you have. But we race every other weekend W.F.O. and have had no problems whatsoever. The chassis flex's just like its supposed to and the steering geometry is dead on but no crack, no broken joints, no bends nothing.
Im with you trying to use your old stuff laying around though. I hate seeing perfectly good steel just laying in the pile doing nothing

Voodoo