boxed in my frame

Some of the gasser super stock trucks around here start with a 1/2 ton frame so it flexes.Another trucks rear solid suspension was to rigid,so he proceided to cut some bars out till it would hook better.
 
flexing

olegreen, there is a saying if you allways keep doing what your doing you'll allways get what you got. if you go out on a limb to try something new and your not scared to break and repair or return to step 1 then you haven't lost anything. but a little time welding gas and some scrape steel. in the few vechicels i've had drag racing and the couple cars road racing frame flex is the worst thing. you can not dial in a chassis for maxium traction when the body or frame is flexing throwing your set up off worse than when you started. i would think the same would go in sled pulling. its all about putting the power to the ground. if it would lift the front because the rigidity of the frame then the traction bars might need to be lenghtened to help rotate the front down with force from the rear and hanging weight will help with the front also. with your single cab truck you'll be able to hang a good bit of weight. WTD
 
BenM said:
olegreen, there is a saying if you allways keep doing what your doing you'll allways get what you got. if you go out on a limb to try something new and your not scared to break and repair or return to step 1 then you haven't lost anything. but a little time welding gas and some scrape steel. in the few vechicels i've had drag racing and the couple cars road racing frame flex is the worst thing. you can not dial in a chassis for maxium traction when the body or frame is flexing throwing your set up off worse than when you started. i would think the same would go in sled pulling. its all about putting the power to the ground. if it would lift the front because the rigidity of the frame then the traction bars might need to be lenghtened to help rotate the front down with force from the rear and hanging weight will help with the front also. with your single cab truck you'll be able to hang a good bit of weight. WTD
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:clap: I need more diesel pros like you, LOL :hehe:
 
looks great i had a 99 1ton dodge that the frame was bent right in the front of the rear spring pearch and cr frames are tubed from front to back
 
BenM said:
olegreen, there is a saying if you allways keep doing what your doing you'll allways get what you got. if you go out on a limb to try something new and your not scared to break and repair or return to step 1 then you haven't lost anything. but a little time welding gas and some scrape steel. in the few vechicels i've had drag racing and the couple cars road racing frame flex is the worst thing. you can not dial in a chassis for maxium traction when the body or frame is flexing throwing your set up off worse than when you started. i would think the same would go in sled pulling. its all about putting the power to the ground. if it would lift the front because the rigidity of the frame then the traction bars might need to be lenghtened to help rotate the front down with force from the rear and hanging weight will help with the front also. with your single cab truck you'll be able to hang a good bit of weight. WTD
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I agree. If I'd of listened to everyone else when I built my stroker, I'd have the same truck as everyone else. According to some my truck shouldn't even run, but its doing just fine:ft: And if it don't work for ya old green, I'll come down and help you put another frame under it, you've got a few to choose from.
 
XTrEmE9156 said:
i don't think we're missing anything.. mod trucks have a solid rear suspension with a tube chassis and coil-over control arm suspension in the front.. solid rear suspension doesn't move and the chassis doesn't flex..
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You wan't and need flex.
Keep in mind tube chassis trucks usually have one piece bodies, you might not see the flex but trust me they do flex...
 
to me all frame flex would ultimately do is lower your hitch height..
 
Yes sum, but it keeps the front end planted as well. IMO a solid ridgid frame would be great on a 2wd puller
Not the best picture, but kinda shows my thinking behind frame flex.
67mtgilead-1.jpg
 
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Exactly

The truck around here that was to rigid the front lifting even with the weights out front.
 
I understand your guys' point behind chassis flex being a good thing but explain to me why the mods (Ohio CAT, Scheid) that are running tube chassis don't have a front end lifting and tire unloading problem? Or do you think they've specifically built a tube chassis weaker to get frame flex? I don't see front end lift being a huge issue unless you can't hang enough weight, which maybe that's the problem. Thanks.
 
Persingerpulling said:
Yes sum, but it keeps the front end planted as well. IMO a solid ridgid frame would be great on a 2wd puller
Not the best picture, but kinda shows my thinking behind frame flex.
67mtgilead-1.jpg
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this picture is 100% true..

but..

The front end of the given vehicle will lift because there is a downward force on the frame, aft of the rear axle. If the frame flexes, the front tires will not lift off the ground. This is due to the absence of the sufficient downward force aft of the rear axle to cause the front end of the vehicle to lift.. If the hitch height is too low there will not be sufficient downward force on the rear of the frame, aft of the rear axle to cause the front end of the vehicle to lift.. The reason that the front tires are not lifting any more is because the frame doesn't provide enough strength to support the entire weight of the vehicle.. Henceforth this is why weight is required on the front of the frame ahead of the front axle to counteract the downward force aft of the rear axle, causing the front end of the vehicle to lift..

Crude drawing...
frameflex.jpg
 
Of course your picture shows and you are making an assumptions that may or may not be valid.

Your having the vehicle flex at the rear axle, most of them appear to flex at the bed/cab joint.

If the frame is not flexing something it happening, your either pushing the rear tires deeper in the ground or your lifting the front of the vechicle. I am guessing you do some of both.
So is loosing an inch of hitch height worth the resultant less force lifting ont he front? Until you quantify how much your lifting on the front, the coefficient of friction on the front tires this all will be speculation.
 
One thing you guys have to remember is that with the mod trucks. Diesel or gassers with there tube frame and totally gutted steel bodys or glass bodys is that they are so light in the rear end that the weight in the weight bar can be way more than you will see in any normal street truck pulling. Im not 100% sure on the diesel mod truck but I know up here that the Gasser Super Mods (blower trucks) are light enough than 2 average sized guys can pick up the back end and turn the truck (this is with a 6200lbs truck)

I took structural engineering years ago and if I could fully remember the stuff I learned I would explain to you in detail about my theory with the "fulcrum and moments and angles" which all deal with one major equation that will show you exactly how much weight possibly can be planted to the ground. Im going to have to find my notes from 10 years ago and try to give you guys and example.

Ryan

PS: this would probably be a good post to move over to the sled pulling forum.
 
zstroken said:
Of course your picture shows and you are making an assumptions that may or may not be valid.

Your having the vehicle flex at the rear axle, most of them appear to flex at the bed/cab joint.
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The frame will flex wherever you have your suspension stops installed.. The stops will act as a fulcrum.. I'm assuming it looks like the frame flexes at the cab/ box joint, because four of the six bed bolts are behind where the stops go, if I'm not mistaken..
 
A rigid frame is a great idea. It will point out how bad the suspension setup is.

A flexible frame is also a good idea...it will hide how bad the suspension setup is.

so, if you box the frame, get some decent suspension.

Oh, and go down to the locak Junior College and pick up a used Statics Text.

Also Shigley's Mechanical Engineering Design text is a great reference.
 
XTrEmE9156 said:
The frame will flex wherever you have your suspension stops installed.. The stops will act as a fulcrum.. I'm assuming it looks like the frame flexes at the cab/ box joint, because four of the six bed bolts are behind where the stops go, if I'm not mistaken..
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I don't believe that is correct, yes I understand the fulcrum, but the guys who weaken the frames are pushing for the frame to flex well in front of the suspension stops. Most of the time the hitches are moved forward, so there isn't much lever arm on the frame behind the suspension stops. You then have a triangle formed consisting of the frame, the suspension stops, and the ladder bars. The frame will then flex in front of the ladder bars. You see this more on trucks that run short ladder bars.
 
XTrEmE9156 said:
:clap: I need more diesel pros like you, LOL :hehe:
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wow some people just live to put others down in any way they can without any regards for the fact of how childish it makes them look.

feel free to jab away.
 
RyanB said:
One thing you guys have to remember is that with the mod trucks. Diesel or gassers with there tube frame and totally gutted steel bodys or glass bodys is that they are so light in the rear end that the weight in the weight bar can be way more than you will see in any normal street truck pulling. Im not 100% sure on the diesel mod truck but I know up here that the Gasser Super Mods (blower trucks) are light enough than 2 average sized guys can pick up the back end and turn the truck (this is with a 6200lbs truck)
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Pull I watched a week ago the tube chassis gassers, the rear end would bounce up in the air about 6-12" just driving away from their holes they dug at the end of the pull...
 
look at the body line in this pull imagine if a lot of weight is on the front it would be alot worse thats with 120psi of air in each of my air bags i understand it needs to flex some but i think this is excessive either way at least i will know if it helps btw that truck pulled 314ft at the wilmington ffa pulls in the 2.6 class still had the stock charger on it next year it be around 800hp gotta get something figured out
tblair3.jpg

tblair2.jpg
 
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