boxed in my frame

Diesel Freak said:
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.
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Pretty close to what I was thinking.
 
question

olegreen95 said:
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who's red dually is that? looks like bob holmes??? that rust bucket still running?
 
I fought a bounce issue for two years and tried just about everything. While Ford claims the toughest frame it is also the most flexible. Ask a frame shop about frames. I also thought the flex was at the pivot point, or travel stops. Plating the frame over the rear axle did nothing. After seeing a video shot from the side it was easy to see the flex was ahead of the (front) rear spring hanger. I put bars (truss) from the (rear) front spring hanger and over the rear axle to a point 6" below the frame under the cab. Flex was gone and bounce was for the most part also.

Same truck and combination with the Cummins and more power now I have traction issues. LOL I get my ass handed to me by street trucks. Flex plants the rear tires and keeps the front on the ground. It's a balance between frame and suspension. The flex in the frame stores energy. If it holds it through your doing good. If it unloads that energy it can cause bounce.
 
yea its bobs it was runnin till i broke the posi unit the other day at kill-kare lookn for a used one want to get it into the 11's before the end of the year i guess the posi didnt like the slicks runs pretty good for a old wore out 12v
 
Not to stir the pot or anything, but if boxing the frame in for sled pulling is that bad of an idea, then how come most of the CR trucks (Factory boxed chassis) do so well?
 
?????????

olegreen95 said:
yea its bobs it was runnin till i broke the posi unit the other day at kill-kare lookn for a used one want to get it into the 11's before the end of the year i guess the posi didnt like the slicks runs pretty good for a old wore out 12v
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alot of trucks has had his hands or knowledge in to them. that man has forgotten more about sledpulling and diesels than most will ever know. great guy to talk to and listen to all the testing and parts he has tried over the years.
what does he think about strenghting the frame like you've done?
 
kino_fab said:
Not to stir the pot or anything, but if boxing the frame in for sled pulling is that bad of an idea, then how come most of the CR trucks (Factory boxed chassis) do so well?
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Frame design, its boxed but the steel is half as thick. The full box design does flex less, however, its not solid.

Tube chassis flex, dont think so? Watch a top fuel car launch.

Flex is good, its a matter of flexing the right places.
 
8,000hp will make it flex but do you think the teams build flex into the car? Or do you think that is just a side effect of running that much power?
 
Both, flex is there to help the front tires contact the ground. Also make the car launch harder.

IIRC the point just before you lift the front tires is ideal. After that its wasted energy that could be used to make the car faster. Been awhile since Ive heard that could be wrong.

Look at it like this, you will never have a frame that doesnt flex. Just frames that flex less than others.
 
roachie said:
Both, flex is there to help the front tires contact the ground. Also make the car launch harder.

IIRC the point just before you lift the front tires is ideal. After that its wasted energy that could be used to make the car faster. Been awhile since Ive heard that could be wrong.

Look at it like this, you will never have a frame that doesnt flex. Just frames that flex less than others.
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I agree but I think minimizing flex is the idea.
 
hmmm interesting...lots of supposition.

has anyone here ever tuned suspension??? My small experience in the offroad racing world (XC and some MX) frame flex is never good. Frame rigidity helps make the suspension actually easier to tune.

I actually can't believe someone would drill a frame to make it flex more...that is just idiotic
 
roachie said:
Frame design, its boxed but the steel is half as thick. The full box design does flex less, however, its not solid.

Tube chassis flex, dont think so? Watch a top fuel car launch.

Flex is good, its a matter of flexing the right places.
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What is the thickness of a 3rd gen chassis?

Also, irrelevant but a top fuel chassis will flex as they are designed to do.
 
Ill have to get a gauge out, I cant remember off hand.

I know an F350 is around 0.25", I think a 2nd gen dodge is 0.18-0.20?

Soon as one gets handy I will measure one.
 
Well just a simple explanation is a rail car or a funny car or any other tube chassis type car you can literally get the car bouncing due to the flex in the chassis by just pushing down on the engine while the car is sitting still. Another example is tube chassis flex so much that alot of people keep boards or jacks or whatever between the frame and bottom of there trailer so that while in transport the car doesnt sit in the trailer and flex and put all of that strain on the car. Because after thousands of miles of the car flexing in the trailer with every little bump cracks start showing up everywhere. Dont get me wrong the frame of a pickup truck flex's also it just takes a ALOT more force to get it too.
 
grncummins said:
Well just a simple explanation is a rail car or a funny car or any other tube chassis type car you can literally get the car bouncing due to the flex in the chassis by just pushing down on the engine while the car is sitting still. Another example is tube chassis flex so much that alot of people keep boards or jacks or whatever between the frame and bottom of there trailer so that while in transport the car doesnt sit in the trailer and flex and put all of that strain on the car. Because after thousands of miles of the car flexing in the trailer with every little bump cracks start showing up everywhere. Dont get me wrong the frame of a pickup truck flex's also it just takes a ALOT more force to get it too.
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So in your opinion, if top fuel dragsters were constructed the same way a pickup chassis is, it would flex less than the tube chassis design they use now? :confused:
 
BenM said:
alot of trucks has had his hands or knowledge in to them. that man has forgotten more about sledpulling and diesels than most will ever know. great guy to talk to and listen to all the testing and parts he has tried over the years.
what does he think about strenghting the frame like you've done?
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Thats true! I'm pretty sure I saw that green truck with stacks at kilcare runnin 12.xx....not bad for a 5spd!
 
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