Power? This seems crazy to me. Why a power rack on such a light car?

Thanks again for the blueprints.

The aspect ratios needed to be adjusted just a little before all of the written dimensions would actually match correctly in Solidworks. At this point, I can draw construction lines at points on the car, measure the distances between and they'll match the drawing! YES

Well... here goes my first vehicle model attempt! Hopefully the +/- error wont be too bad - if its under 5cm, I'll be happy. This is only to experiment with possible engine/axle swaps, and to play with the visual appearance, etc.

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Does anyone have a chassis blueprint image??!! Or anything else for that matter.

Make one then, so I dont have to!

thanks ddgonzal!

I've found drawings like these, but sadly none of them are quite the resolution I'm hoping are available somewhere.

Has anyone seen these diagrams in resolutions up to 1000+ pixels width? Also, apparently there are chassis blueprints also, which may prove to be more useful for me initially.

Anyone? thanks!

Hi all,

I'm tryin to get started on a project 1200 sedan - first thing: vehicle model.

I'll be buying a roller asap, and from that I'll make the measurements to input into SolidWorks for the parts I'll design for manufacture. In the mean time however, I'd also like to have a reasonably accurate modeling of the rest of the vehicle - the bodywork essentially.

If there are any blueprints, or most preferably (but probably unlikely) an accurate 3d model of the 1200 saloon somewhere that one of you know of... that'd be fantastic. I'll gladly take blueprints however, due to how boxy the car is.

Thanks

Quote:
datsik gets me.

I guess my understanding is slightly swayed then from this discussion. I suppose horsepower alone may be misleading, depending on what sort of an engine we're talking about - diesel truck engine, 4cyl motorcycle engine, etc. However I do believe that torque ALONE is just as misleading as horsepower; in literature you'll find the terminology is intermixed when describing the need for a beefier diff because you have "more power".

I think the Tech Wiki might need to be updated to at least include a reference to gear ratio alongside the engine peak torque, if its agreeable that engine torque alone does not dictate the torque found in the driveshaft.

I like that we've also discussed "tramping" (although I've never heard it described with that term) - I race shifter karts and here we have a similar problem... however since there is nothing but wheels, a hollow axle, chain, and transmission, this instant torque caused by an engine spool when the drivetrain bounces can cause CRANKSHAFT shearing!

Thanks for the discussion!

Are you saying that engines reving to 14k is out of this world?

Hello all,

Firstly, I've come across the Datsun B110 because I'm interested in planning a "hot-rod" project for myself, and this car is about the lightest base frame I can find for that purpose.

I was delighted to find this great site and immediately started looking around at technical stuff. One particular area I am concerned about in my initial concepts for this project is the rear-end of the Datsun. However I found the Tech Wiki, and in that there is a section on rear axles with lots of useful information. In that section there is literature stating that horsepower is not a relevant concern when selecting a differential for a car, but instead crank torque is all that matters.

This does not make sense to me, and I hope to verify my understanding of this with the forum's help. Hopefully I am sufficiently clear.

Here is an example to aid my discussion:

Take two drastically different engines:
1) A X horsepower motor which makes 100 ft lb @ 14,000 rpm.
2) A Y horsepower motor which makes 400 ft lb @ 3,500 rpm.

Both of these engines are coupled to a transmission which is essentially a torque multiplier.

The resulting torque fed to the differential is a multiple of the rpm at the motor. Torque is increased, and rpm is reduced to make it reasonable for driving the wheels of a motor vehicle which typically operate at a lower angular velocities.

If rpm is the variable that affects the multiplication, and horsepower is a product of rpm, torque, and known constants, how is horsepower an irrelevant term when determining the ultimate turning force at a differential?

To further illustrate, realize that the turning force at a differential in a high power drivetrain is in the upper 6,000-12,000 ft lbs. Clearly there is a multiplication of the engine torque.

Some seasoned people may know of this formula:
Torque at
rear axles = Torque x First gear
ratio x Rear gear
ratio x 0.90

Notice that torque is an essential variable in determining the torque at the axle, however this figure is meaningless without factoring the first gear ratio. The first gear ratio effectively cuts horsepower out of the equation, but this ratio is determined by many factors, one of which is the engine rpm, and engine rpm dictates power.

Return to the original example of two engines with X & Y horsepower. Set X=Y=400. Would it be advised to hook a differential sized for a 100 (crank) ft lbs engine to the first, and a differential sized for 400 (crank) ft lbs engine to the second?

It seems that horsepower should be used as a rule of thumb, and formula based on maximum torque and first gear ratio (based on a launch scenario) should be used for a more accurate verdict.