Who knows what their car's weight distribution is? It'd be interesting to see what sort of front/rear weight distribution results from different engine/frame/body/setback/wheelbase/etc. combinations.
On alot of these early hot rods the weight distribution is pretty good due to the engine being mounted completely behind the front axle.
I sort of figured that, but it'd be cool to know the actual figures. I'd expect a tight range either side of 50/50 for "thin-fendered" cars.
The dynamics of WD change as the car accelerates off the starting line and down the track. A lot of it has to do with hook up at the line. So are you talking static WD or accelerated?
Static. That's the baseline. Once you know that the suspension geometry will tell you what kinds of transfer dynamics to expect.
I don't think i've scaled a model a or similar, but the race cars with suspension i like 55% rear (other builders prefer 50%); for comparison a modern mustang is about 55% and greater on the front. I think suspended race cars are limited to 60%max on the rear; many race cars (prostock etal) can't get there due to engine set-back rules. You have an inquisitive mind there Ned, what are you fishing for?
seems like all the weight is up front on mine... You can estimate it using statics. Sum of the moments about any point equals zero.
Theoretically, 50/50 is desirable. However, the number of variables is staggering. Relative tire size, spring rate, center of gravity, roll center, suspension design and compatibility front to rear, are just a few that come to mind. It is my opinion, from years of observation, that most, certainly not all, rods and customs get whatever the builder either a) has available....b) is the current fad......c) the 'traditional way'............d) what looks good to him..........e) no concept of any geometry or physics whatsoever....... And, for the most part, it works, anywhere from just adequate to quite well. Mostly because it (the vehicle) isn't being tested to it's handling limits as might be the case with a race car on either a circle track or road course, unless an emergency maneuver for accident avoidance comes along. Ray
I scaled my Willys coupe on a public weighscale at 1680 lbs front and 1680 lbs rear with a full tank of gas and no occupants. However I would have to agree with Hnstray that option e) is by far the most common...
As the '31 design develops it's getting to actually sizing the hydraulics for the suspension interlinks, and that's got to do with the weight distribution, as I'd want to place "effective fulcrums" (two interlinked wheels act - under certain cir***stances - like one wheel somewhere between the two) fairly accurately. I'd thought in terms of making the system tunable from 100/0 to 0/100, but that's becoming complex and probably much heavier than I'd need. So my thinking goes, leave a 10% window for fine-tuning; but then the basics have to be sized roughly for the weight distribution I want. And that'd be somewhere between 50/50 and 45/55. And I'm wondering if that's where I'm going to end up. And then I'm thinking, be that as it may; which comes back to my first post: It'd be interesting to see what sort of front/rear weight distribution results from different engine/frame/body/setback/wheelbase/etc. combinations.
Well Ned, the only real variable is the drive train. All the other stuff is pretty well situated. I recall at one time we worked out that a sbc (alum head, rods etc w/hi-nickel block) equalled 40lbs an inch, so that if the engine moved rearward 1" 40lbs would go off the front and 40lbs would add to the rear. That was a rough or rule of thumb, the weight would actually change in a percentage and all 4 corners would be affected proportionately. One thing to ponder in your calculations, is that there are two different static weights, the first is the actual weight and percentages of the vehicle as it sits on the scales; the second is what it wants to weight, i am speaking of all 4 corners here. If you know the corner weights, percentages then you can calculate what the car actually wants to weight.
I had a 32 chevy coupe, that was weighed by UPS at a nsra event. I t was full fendered, a small block chevy, automatic, with me in the car. And it weighed just a little over 700lbs per corner. It was almost dead even...
My 32 sedan highboy with blown sbc was 1440 front 1600 rear with me (circa 250) and not much gas in the tank.
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