Porsche special tool 9243

[c2 rower]

Has anyone ever come across this bugger? It is used for checking the balance between the two rear torsion bars which supposedly influences the corner balance to a large degree (perhaps because the spring rates are higher in the rear. You disconnect the rear sway bar, jack the front up and put this under the front cross member and lower it down onto this thing which basically acts like a pivot. This enables the rear springs to reach equilibrium. You measure the left and right and adjust the spring plates. Thats how it was described in the Oct 94 Excellence tech notes. Anyways, does anyone have a picture of the tool; I want to make one. And if anyone has actually tried this procedure I'd be interested in knowing how it went.

[diy83sc]

c2,

I just read the article (tech note). Based on the description, it sounds like a plate to extend the width of the cross-member with a thick pipe welded to it. The other piece could be a similar plate that sits inside the cavity of a floor jack with two vertical plates on each end drilled to allow a bolt to pass through each end and through the center of the pipe on the other piece. Like a hinge? I architect software better than I do tools Great find! I may build one myself.



Tony

[RoninLB]

I couldn't find the article

[ChrisBennet]

Doesn't everyone just use corner weighting scales instead?
-Chris

[ubiquity0]

It looks like that would be alot cheaper to fabricate than corner balance scales

[diy83sc]

Yeah! I would think that if the rear is set by balance and the rake is correct and as well the a-arm angle, the front would not be off by too much.

Tony

[greglepore]

Man, that looks like a great idea, but how do you ensure that the pivot is directly aligned under the center of the car?

[diy83sc]

The diagram/drawing in Excellence shows a dimple of some sort. You could also use the two drain holes of the crossmember to center...

Tony

[c2 rower]

Thanks for the pictures and comments. Four scales of sufficient capacity would not be trivial. The intent is to come up with something a do it yourselfer could do to achieve resonable corner balance on a 911.

[billwagnon]

Four scales of sufficient capacity would not be trivial.

But four bathroom scales, four 2x12s, and four short 2x4s would be.

[greglepore]

How would the bathroom scales work? The car weighs over 2300 lbs, so that's more than 500lbs a corner. Am I missing something?

[djmcmath]

To second Greg, many of us have cars that weigh nearly 3000lbs (wet). From an engineering standpoint, I won't feel good about stuffing a scale under a tire unless I'm pretty sure it can support more than half of the car's weight, ie 1500lbs. I've honestly been keeping my eyes open, and haven't yet found a bathroom scale that'll do me for 1500lbs. If you have a lead on these, please let me know!

Dan

[c2 rower]

You could set up lever arms to make the bathrooom scales but the tough part is all surfaces need to be on the same level.

[billwagnon]

end of 2x12 goes on the scale

other end is suspended by short 2x4

car wheel goes in the middle of the 2x12, towards the 2x4. the closer to the 2x4, the less weight is on the scale

put the wheel in the same place on every 2x12 and you can determine the proportional weight imbalance

if you know the weight of the car, sum the scale readings to determine the reduction factor

on my car the reduced amount was from 140 to 195 lbs on each wheel

having said all that, corner balancing is still the proverbial b!tch