When using the "level-type" KT tool, which has a range from -5 to +5, what should the KT be set to for a track alignment - this is for a car that does not see street, track only. I have heard +2, but thought I would check before I end up on the track with an undriveable car.

 

interesting question,
paragon products sell a kinematic tool and has a link to the instructions.
https://www.paragon-products.com/v/v...toe%20reva.pdf
I have the tool as pictured in the instructions, what is the level type you have?
the basic part of the instructions that I've followed are making sure the measurements are the same for each side.

the instructions also state that on factory race cars kinematic was maxed out, 'max rear castor.'
but what the hey does that mean? the K tool I have goes up to +8.5 and while it doesn't fit well on my track car, when I do shove it in place the bubble disappears past 8.5.
this is with rear camber at -3.3 and the difference between #2 and #5 arm angles as close as possible side to side(garth s method).
so maybe that is max rear castor?

 

@ 93mm rear ride height
The factory recommended 3° of rear caster, 15' toe/side, 3°40' camber

the question is how are they measuring it. You want a small amount of rear caster and you want it equal on both sides. This does not mean that the eccentric is the same on both sides but that the actual caster is the same small amount on both sides, if you go to zero that's too small

 

THE most important part is having them equal on both sides, For my car at 100mm rear ride height (and using the Motorsport style gauge) Mine sits at +2ish...

I have always wondered how the factory measured the rear castor, unless the markings on the Motorsport gauge are actually "their" measure of castor then a +3 would be 3° of castor, of course this is pure speculation.

The only way I could think of measuring castor would be to do a process similar to doing the front and instead of turning the wheel through 20° disconnect the toe links and then max out toe in, measure camber, then max out toe out and measure camber, then calculate the castor from there.

Of course it will be impossible to get 20° of wheel turning in the rear, however could edit the calculation to take the small swing into account.... Again random thoughts with no idea if it is even plausible...

 

Thank you very much for your input. I should have known, that as usual, setting up the 993 is not in the least bit simple and if you get it wrong the car can be a nightmare. When I first got my car the KT was setup wrong and the rear felt completely disconnected from the car in medium to high speed corners - it was very unnerving.

Thinking about this more, I believe Chris Walrod may have commented on 993 setup years ago - I will try to find that post. Thanks again

 

Keep in mind the fact there is a lot of confusion wrt what is maxed or minimized

If you play w/ the eccentrics, if the KT arm eccentric is maxed, ie the arm is lengthened to it's max, the effect is to minimize both castor and camber, the caster goes toward vertical(0 caster) as the hub rotates forward and down at the same time, when the KT arm eccentric is at it's min, ie the length of the KT arm is minimized it maximizes caster and camber and rotates the hub up and backwards at the same time

The guys w/ all the rear parts on display can see and play w/ this easily, it's harder on the car.

 

I agree completely Bill..... I was just theorizing, and not very well

This is one of those times it would be great to get the insider info from the factory...