Okay leaving the mudpitt today I noticed it pulled to the right a little bit, but it has always did this. The 4wd drive works great just wondring if this was normal or what could it be, but like I said the 4WD works great no noises or anything like that.

 

does it only do it in 4wd? if yes, im not really sure, other than a bearing somwhere. if its all the time, id say either low tire pressure, bad wheel bearing, or a catching brake.

 

I would say normal and a bit of torque steering

 

were you actually in the pit? if it pulls it was prolly the truck following ruts. if it was on pavement it could have been mud and gunk caked up in the brakes causing it to stick

and yes also tire pressure would cause that as well

-cutts-

 

No it doesnt do it in 2WD. It pulls on pavment when I get speed I thought this was normal but just want to make sure before the snow hits. I dont deflate my tires in the pitt.

 

only 2 things that come to mind then are your brakes are sticking either from improper adjustment or mud caked in the drums, or your alignment is off.

when did it start pulling to one side?

-cutts-

 

Again a disagree, there is a lot of chassis torque on twist in 4wd in mud and under heavy throtle it cab cause the truck to want to good to the right a bit, The taller the gears and the bigger the tires, the more the effect can be, Algimnet does not stay static when the whole chassis is flex heavily under a high torque load. You are looking for "probems" that do not exist.

 

SnoMan, you'd need a hell of an engine to cause enough chassis twist for you to be feeling a pull to one side from it. He's also talking about feeling this at speed, not when he's mashing the throttle. There is no reason that even a built truck should be feeling this.

 

Not really, you should look at this link below and see how much force is being put on engine mounts at various drive shaft torque loads and the forces has to be disapated in the chassis. (for every action there is a equal and opposite reaction) It covers hill climbing pulling a trailer but it show the effect of torque on chassis.

Click Here

Also here you can see the effect of torque on wheel traction at link below. It is not transparent as some believe and it can effect vehicle guidance at times.

Click Here

 

snoman, sorry, but you cant use your own articles to back you up. to do that, were talkin serious hp and tq numbers here.

 

You miss the whole point. It is based on sound math and physics and just because you may not understand them it does not change the facts. You are welcome to review the formulas because they are quite valid. People just think that tire, axle ratio and such have no effect of vehicle and chassis performance and they are dead wrong because it does. Why do you think the left rear and right front tires alwalys breaks loose first on open diffes? It is from chassis and drive line torque and the change in whell loading in marginal traction conditions will change vehicle direction at times whether you choose to accept it or not does not changes the facts or physics here.

 

Interesting. The info may be somewhat proprietary, but for clarification, I would like to know what "variables" need adjusting, and what assumptions were made to produce the model. Some things that come instantly to mind are:
1. Was tire pressure and construction a consideration?
2. Does this model use stock motor mounts? The comressive strength properties of the mount material accounted for?
3. What is the generic assumption for x-member spacing? (i.e., reinforcement)
4. What frame cross section was used to build in the dissipative effect of frame twist?
5. You mention that the "twist" value is equal but opposite to the force placed on the driveshaft. Did the model account for losses through elements between the crank and the shaft? Did you apply it equally to both mounts?
6. Why is grade used as an axis of the model? Resistance to rolling motion does have an effect on engine torque, which is a function of airflow, friction losses, tangent resistant to the rotating mass and rpms. Wouldn't the grade variable make the model more likely to not approximate actual conditions because of pavement composition, coefficient of friction, smoothness, temperature, etc?
7. What engine family (generic) is this based on?
8. Was block shear of the frame or mount material a consideration in the higher resistance ranges?
9. Whose frame metal is this chart for?
10. Was any consideration given to the stiffeneing effect of other unrelated elements that are attached to the frame, such as the body, axles, etc?

Is there another model that relates the forces calculated here to overall frame flex or body roll? I have to agree with Ivan and fishmann here. Your argument may have some validity in theory, but the argument is purely academic. The kind of frame flex you ar indicating as commonplace is anything but. We all know there is a minor amount of flex associated with high revs on a powerful engine, but it is not sufficient to cause the problem at hand unless the frame is cracked near the crossmember.Ivan runs about 550 hp with 44s and 5.13 gears, I run about 500 hp with 42s and 4.88 gears. This twisting you mention has not been a problem for either of us, and my truck lives 80% of its life in the mud.

 

As an intelligent, deductive person, which you obviously are, you know that to use the word "always" in an argument is very dangerous. Especially when you consider that there must be countless varying circumstances that a 4wd with open diffs loses traction. Like substrate, temperature, tire tread pattern, moisture content both of the surface and substrate material, size of contact patch for each wheel, worn components, load dispersion per tire, contact angles, viscosity of mud, hardness or slickness of crusts, converter stall speed, blah, blah, blah, blah.

 

Assuming equal surface traction that is. Converter stall and tranny gears has nothing to do with it other than deeper tranny gears with taller axle ratio make it worse. If you have a posi rear axle and you are getting into it hard in mud, the drivers side rear will have more effective weight on it that the passenger side wheel due to drive line torque and it will tend to guide truck to the right. With open diffs the effect is less pronounced but still there.

 

you can disagree all you want but theres no way in hell that engine torque is the problem, and i'm not real sure where/how you did your math but if it doesnt take much to twist the whole chassis enough to allow the truck to drift to the right then why aren't all the diesels (even the pulling trucks) having a problem with this?!?!

-cutts-