RedFive

Hi,

I'm trying to convince my parents to let me buy a 944 to replace my old Cherokee (it's a great truck, but after 210,000 miles of hard driving it just needs a rest)...so I thought I'd write a physics paper comparing the two cars to (a) show my parents why the porsche is safer and (b) maybe also show them that I am actually learning things in college.

Anyways, my question is how high is the center of gravity in the 944? If nobody knows, is there someplace I can write to to find out?

Then I just have a quick second question...how much would it cost me in parts to replace the clutch in a 944...and would I be crazy to do it in the parking lot (that's where I work on the Jeep, so why not?!)?

Thanks!

Cyrus951

Wow, you got a weird way of convincing people to do things..
Don't know about the center of gravity, but a clutch job will run you at least $1k with a pro. If you do it yourself, you'll spend half as much.

TaylorSea4

Dunno 'bout no center of gravity, they ARE amazing handling cars; even by today's standards. Do a search on wrecked ones and you'll see that they hold up to a beating as well.

I know that a lot of the tire manufacturers used 944's as test mules because its perfect 50-50 balance made for good tire evaluations. Rotsa ruck, dude...

RedFive

Well it doubles as physics homework too

Yabo

dont worry, your not going to flip teh 944 unless you hit something. or do something extremely dumb.

RedFive

I'm not worried about it. Hell, I pull 180s in my Jeep and don't flip it...but for the purposes of my physics paper...does anybody know??

Jim 944S

Red,

I wouldn't want to do a clutch in a parking lot. Not that it's all that technical, it's just an involved PITA. If you had a friend who had done it before, and if you had all your parts before hand, and if nothing at all went wrong (stripped threads, etc.), and if you had all the right tools readily at hand, it might be something to do. I much prefer the security of a garage, myself.

Anyone else, please chime in... maybe someone up there could walk him through it!

Oh... don't sell the jeep until the 944 is running...well!

Jim 1987 944S (so proud of my solo clutch/torque tube replacement, I bought a Porsche cap to celebrate... it was all I could afford after that!)

DerSchlechtSpecht

AHHHHHH, physics paper!!!!!!!!! You are bringing back some absolutly horrible memories!!!!

-Christian

FSAEracer03

...yeah me too, like two in particular from last week saying I have dynamics AND mechanics of materials homework to do tonight... oh ****...

anyways, finding the centroid axis and/or c.g. of a car is nearly impossible for the average joe. The equations involved take some working on, and the calculations could easily take you a full semester's worth of work to be accurate. However, if someone randomly has a Pro/E or Autodesk Inventor assembly of the whole car, it could be done in a few days LOL

Porsche might know, and someone on the forum might know... but I don't have a single clue of how you'd track it down. If you happen to, I could help you out with the equations on cornering loads, handling capabilities, and other great points to argue how much safer the 944 is to a Jeep (unlike America's general misconception of the opposite!).

now... about that homework....

RedFive

Well I got the CG for the Jeep from a paper published by the NHTSA...but that was all about SUV rollover...so there weren't any cars there. I already figured out that the rollover angle is 46 degrees for a jeep...and if you hit a curb sliding sideways at a speed greater than 5.5 mph you'll roll. Hmmm...I also calculated that if you corner a turn that has a radius of 25 feet at 20 mph the cetrifugal force provides 3600 pounds of lifting force...and since the Jeep only weighs 3100 pounds, that means rollover.

So I was going to do all these same calculations for the 944 and show how much safer it is....but I need the CG height!!!

Give me some more ideas though!

ljd-924SE

ever seen those profiles in all the car & driver test articles? they show the engine/tranny layout within the car. i'd look for one of those to use as a schematic. Then i'd approximate the weights of all the major components using the overall weight of the car and determining what contributes based on a percentage. This can be a simple or as rigorous as you like. From there, you just estimate an approximate center of gravity for each major component based on that layout, and then measure the distance of each of those components to the ground. input those numbers into the overally expression and you have it. that's a very rough approximation, but i'd bet everything would average out to be pretty close to the actual center of gravity.