Paseb

My kw3 are arriving tuesday
I have the front bump steer kit to install and front and rear camber plates.

How low can i go without rs uprights? Not looking to slam the car as the road are very bad in montreal but i really dont like the 4x4 oem look/stance!

What about camber? How much negative to have a good look and not wear tires too much.

Street car only

Thx

pp000830

The factory specifies the lowest setting using the standard uprights being the ROW lowered height or USA height minus 30.
I am sure you can go slightly lower than this but to retain the ability to hold the factory alignment and stay within what the factory intended during suspension travel I wouldn't go much lower. I am sure if you are willing to depart from the factory alignment specification you can go a bit lower and still retain good handling. Best to speak to a shop who has had success doing this.
Also, I would think tire rub during street driving would become an issue much below ROW Lowered height.
See attached:

rk-d

I have the ERP bump steer kit and my KWs are set to ~2mm above RS ride height. I’ve not seen any obvious issues with bump steer or weird handling and it aligned without issue or rubbing. I think it drives great, not to mention the fact that these cars look sooo much better lowered.

Obviously, the RS uprights are the ideal way to go - but there is a significant cost and there was a 2 month wait when I had looked into it. So far, I’m very happy with my set up.

il pirata

[QUOTE=pp000830;16018872
Also, I would think tire rub during street driving would become an issue much below ROW Lowered height.
See attached:[/QUOTE]

Why?

Mark in Baltimore

RS uprights are now in stock. www.carnewal.com

Steve Weiner-Rennsport Systems

If you stay 10mm above RS ride height, you will not have any issues.

rk-d

Too late now haha. My plan was to try the bump steer kit and go with the uprights if necessary.

I very well may end up doing it at some point but, as my car currently drives, it’s not a necessity. I have zero issues.

These cars are always a work in progress, regardless.

Paseb

So 10mm above rs without uprights?

Someone posted 2mm above and didnt have any issues ?

Ummm, what to do haha

OverBoosted28

What to do? Without fail, you should take Steve W’s advice on your car, more than just about anyone else chiming in! Although others may state, at said height below RS, they had/felt no neg input. Doesn’t mean there’s no induced bump steer. Just it’s not so obvious, it’s apparent. Reach levels of car, and some of these “non-issues” may rear their heads.

rk-d

If you are tracking the car and going 10/10 then go RS uprights. Otherwise I think you’ll be fine at just above RS with the bump steer kit. Below RS is probably a different story. That’s been my experience driving my car aggressively but legally on the street. If you’re concerned, take the more conservative route. Everyone is going to have an opinion.

Bill Verburg

here are the relevant curves for 993 front, pay attention to the toe(bump steer curve) and camber(grip) curves, ideal is a vertical line, the more horizontal the worse for handling,
the x axis is the reference datum for RoW non RS ride height
the dashed teal horizontal line is the reference datum for US ride height
a lowered car would have a reference datum as a horizontal line parallel to and above the x-axis
the curves are fixed and don't change unless you change the geometry of the front end, as w/ a change to RS wheel carriers, where you are on the curve depends on ride height
The curves represent static data and change dynamically ie the data moves up when the wheel is in compression and down when the wheel is in droop, total travel depends on the springs and forces involved


as you can see when the car is a static US ride height the toe curve is in it's sweet spot, almost vertical(this means as the wheel moves up or down there is little change in whatever the static toe setting was, as the car is lowered the the suspension moves to a more horizontal section, at RoW ride height The slope of the toe curve is ~-1, in droop the wheel toes in a little in compression it toes out a little. Notice that the slope stays preety constant as the car is lowered further. This means the bump curve doesn't get a lot worse as he car is lowered.

Th camber curve on the other hand gets better the lower the car is, You want the compressed wheel to get more negative camber(to a point) the further it is compressed. This increases grip at that important wheel. The other side is in droop and is contributing little to grip so not as important.

Holger3.2

Bill, thanks
very interesting but also confusing ...
Does this means that, if you get below RoW ride high, the conditions don't change but in case of chamber, getting even better? Honestly i'm a little confused right now ...

Bill Verburg

Lets try again
first assumption no change in geometry, ie stock uprights for all 3 cases
Horizontal Blue line is referenced for RS height, Black for RoW height red for US height


the camber curve is pretty much the same for all 3 cases,Though slightly less camber change at RoW or RS height
the toe curve is best(least change w/ wheel movement) at US but is pretty much the same at RoW or RS though the slope is gradually flattening the lower you go

RS wheel carriers moves the x-axis down by ~20mm, restoring the geometry seen at higher ride height w/ stock wheel carriers

pp000830

Keep in mind that it is only 20mm difference between RS height USA minus 50mm and ROW lowered height US minus 30mm so Steve's height suggestion is very close to RS height.
Also, my experience is the absolute height of a suspension can vary quite a bit between measurements and the idea that it is repeatable at a 2mm adjustment seems difficult to agree with. The factory specification for all ride heights are +/- 10mm probably for the same reason.
Andy

rk-d

It may be hard to agree with, but it is what it is.

My suspension measurement of RS +2mm is the actual measurement. Targeted suspension height was RS +5mm, but as the suspension settled, it ended up a bit lower. I've measured my suspension at the prescribed measuring points on 3 different driving days on a flat surface, and I've averaged at ~+2mm. I feel confident that the measurements are consistent within that envelope. I used a pretty precise caliper to do this.

I probably should have just said "RS" and be done with it. A lot of this is really moot/pedantic - Porsche specs call for +/-10mm variation so my ride height would otherwise be considered RS height.