Elombard |
11-16-2009 01:06 PM |
Quote:
Originally Posted by TT Oversteer
(Post 5014560)
You might be able to get a ballpark setting by measuring outward from the hub centers but the objective here was to get as precise an alignment as possible using a home made setup. Most 911's have different track widths front and rear especially cars with wide rear tires compared to the front. A quarter inch difference will completely negate any accuracy you might be able to achieve with a toe measurement. Now if the center points are known, then you can add or subtract the difference in track width from front to back and adjust your measurements outward from the hub centers accordingly.
Another point to ponder is that you need to establish a thrust line so your car will go straight. Without the centerline reference to square the left string with the right, you could have a situation where the LF is parallel to the LR and the RF is parallel to the RR but L and R are not parallel to eachother.
I will concede that the set up of this project was time consuming but now I have the tools and knowledge to reset my alignment any time I want to experiment with different toe in/out or camber settings or when changing ride height, after corner balance, etc. Also, I have had a hard time finding a Porsche alignment specialist who really knows how these suspensions work andd how to set them up correctly. Sure, I can drive a long way and pay a lot of money to a known shop but then if I change the slightest thing I'm back off to the shop with checkbook in hand.............
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I should have added that the front and rear distance between the strings has to be the same. I think yo are suggesting that.
Let me throw out that a "pretty level floor" combined with a slightly tweaked chassis and even though you are measuring from the cars center you could be off more than even a 1/4" in manufacturing tolerance from the hubs.
Check my math here:
if your string is 20ft long or 240 inches.
and you are off by .25 inches
I think you are off by only .001 or .1%
I measure to the car hub not the wheel so trusting Porsche and their OEM suppliers where possible :-)
I got all of this out of Rays Scruggs book and some experience that I have, might save people time but be slightly less precise than what you are doing.
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