Re: BW4472 32 spline alloy input shafts
Re: BW4472 32 spline alloy input shafts
I found this page and have copied the content to help some guys understand torque and the limitations it puts on drivelines:
We now have enough information for 2 simplified equations. The first on is called "How Much Power is Available". (If you are a mechanical engineer, I apologize for the generalizations made here!) (U-Joint and Tube ratings use torque. NOT HP. Horsepower is simply an expression of torque in a given time. If you think you know the horsepower, but have no idea of torque, do this equation first; (T) = HP x 5252/RPM. Example: 400hp.@6000rpm., the equation would be 400 x 5252/6000 = 350 lb. ft. of Torque)
From the information you gave above, the power available at the back of the Trans. is;
(T) x (Tr)
The other equation is called "How Much Power Can Be Delivered To The Ground". This is the more important of the 2, and starts with this:
(VW)/(GR)
Now, take the answer, and multiply by a variable to adjust for traction and weight transfer.
For street tires, use: (VW)/(GR) x .6
For 8"-10.5" Slicks use: (VW)/(GR) x 1
For Really Big Slicks (example, 16.00x32), use : (VW)/(GR) x 1.5 (or even 2)
Play with these for awhile. You should figure out that the equation with the smaller answer is closest to what your needs are. If the available power is more than can be put to the ground, the result is either wheelspin or wheelies.
Below are torque ratings for the various U-Joints.
Ujoint series----------Cont. Torque-------------Short dur torque---------Min elastic limit
1310/7260--------------------------400-------------------------------------800-------------------------------1600
1330,3r/7290----------------------550------------------------------------1000-------------------------------1875
1350----------------------------------680-----------------------------------1240-------------------------------2260
Definitions; Continuous Torque is a reference only, used to determine life expectancy over a given time.
Short Duration Torque represents the u-joints ability to withstand momentary loading and still give long life.
Minimum Elastic Limit represents the maximum torque load the u-joint can transmit before failure.
Ok. This talks about U-joints so your asking what the hell did you put this up here for? It's to show you that anything can be broken in response to the gentleman's request for a "garantee". There are no garantee's in racing. The above should clearly explain why. You see those different ratings? Now, if your vehicle makes 1500 foot pounds of torque, look over at the 1350 "2260" rating. That does NOT mean that it will take 2260 foot pounds. That means it will FAIL at that point. It will DEFORM WELL before that. What does this mean for you guys? You HAVE to limit what you leave the line with. You cannot expect ANY driveline to hold up to 1000 foot pounds of torque sitting still twisting up and then being slammed. It is a mechanical CERTAINTY that you will break something. You must limit your takeoff and then build power with momentum. If you run a rev limiter and you smash it to the floor with a big torque setup and then do the bumble-bee high rev "frum frum frum" you are smacking MAXIMUM engine torque on your driveline, releasing it, and then doing it again. JACKHAMMER. You cannot do that and expect anything to live. BUT, once you are moving, you can ADD torque because you already have momentum. This is why people are shooting nitrous or adding two stage boost control. Get it? Look at Robert when he leaves the line. Looks like he took off from a stop sign. Very uneventful. But, he is CONSTANTLY building torque down the track. You cannot abuse the crap out of a 60 foot time to make up for a top end dog. I'm hoping this helps and explains why a guy can break the SAME components with an 11 second truck that another guy with SAME truck making MORE power with those SAME parts run 1000s of passes with high 8s. This is why NO ONE gives warranty's on parts used in racing. BUT, what we can do is use better materials and engineer the part a little different to open that "window" before deformation or failure. A guy that knows what he's doing with this setup WILL go less than 8s. A guy that wants to take off with 1000 foot pounds of torque from the line will break things. Could be this shaft, could be the transmission case, could be a rear axle, could be anything(this is why trans blankets are MANDITORY for a true strip car).
I hope this helps explain some stuff for you guys beyond this shaft. It's a whole "plan" when your setting your truck up. Want to have fun, do like Robert and Frank. Want to break stuff, run sideways into a wall when you shoot out an axle tube, run the jackhammer to it. In anything you decide, please be SAFE.
I've given guys like Adam a way to really push the limits of his autocross/hillclimbing truck setup. But it also takes him out of a relatively safe area and puts him into the limits. Ed Hess, Robert, Jeremy, all those guys PUSH the limit. Please keep that in mind when you start doing this.
I'm not trying to insult anyone's intelligence by putting up this info, so if your an old school guy that knew this already, please don't be upset. This is meant to be a tool for others to use to plan their project.
Also, I've given out more info about this than I've seen ANY OTHER vendor give on new product. Please don't insult me and ask for more. If you want more, buy one and measure the crap out of it, but I've left enough unturned, you'll still have to spend some money and do research to reproduce it.
