Dave Inc.

I tried searching but couldn't quite find the right thread. I've recently been running kind of a stock+ alignment with -0.5 and -0.8 camber front and rear, mixed with tires that are probably far too grippy for the suspension for HPDE, Hankook Ventus RS-4s. The result has been 1.2g cornering forces with a tremendous amount of body roll leading to critical tire wear on just the last inch of tire, to the point of badly overheating them and chunking them to the cords in one track day.

My question is, what would people suggest for a good combination of '82 stock suspension (bilstein sport shocks), euro ride height, alignment and tire for pushing it at HPDE? I tend to be pretty aggressive at track days and play at the limits, so tires that communicate well at the limit are appreciated.

Bill Verburg

The wear is due to unfavorable camber change induced by a large amount of chassis roll, You can add negative camber to a point to combat that but the real culprit is the suspension

Suspension is always a compromise, more so for a dual use car, so the first decision is how much street suitability are you willing to give up for more track suitability?

Start by deciding how stiff a suspension you can live w/
I've driven lots of 911 and find that 22/28 or 22/29 is about where I'd draw the line. Others feel that 23/30 or /31 or stiffere is fine. For street only I'd stay w/ 20/26 or 21/27

sways can be used to further reduce roll w/o too much ride compromise, adj is always nice ~22/22 would be a decent place to be

Have a digressive revalve done w/ rates to match springs and chassis weight

replace the bushes w/ new at a min, stiffer rubber or solid like the poly bronze is racier

lighten the car
lower the car to ~145/14

you'll have to play w/ camber to suit your setup and you may need camber plates to get there, stock all #S are (-) is 0/-1, real racy on a 911 is -1.5/-2.5, 0 toe in front ~10' in back

TargaPaul

Sorry for the hijack and newbie questions.....
#1 torsion bars?
#2 what is the stock sway bar sizes?
#3 what do those lowering numbers mean?
#4 how much camber can you get without using camber plates?

Bill Verburg

Stock t-bars for '72 thru 77 were 18.8mm f ,23mm r for '78 thru'85 18.8mm f, 24.1mm r, for '86 up 18.8, 25
stock s-bars for ''76-77 Carrera, SC & Carrera thru '85 20/18, , for '86 up 22/21


camber w/o plates depends probably ~-1.7

ride height
using factory method


RoW street 108+/-5mm f 16+/-5mm r
race 145+/- f14 +/-r to 160+/- f-5 +/-r


t-bar upgrades using 18.8/23 as base + is more rear(less understeer), - is more front(more understeer)

18.8/24 +20
18.8/25 +42

20/25 +7
20/26 +32
20/27 +60

21/27 +20
21/28 +52

22/28 +6
22/29 +41

23/29 -13
23/30 +26
23/31 +69

Dave Inc.

As far as the suspension goes, I've already redone all the bushings in the car but I stuck with the original rubber. Springs are stock rate as well with the bilstein sport shocks and even with that I think it's at the limit of what I'm okay with on the street. Heavy sways are a no-no as well. I guess what I'm saying is that I really like the suspension where it is for my mix of driving, I'm more curious what would be the limit of camber and tire that I could get away with on a street suspension. Clearly the Ventus RS-4 is too much for the stock suspension, I think even with a lot of camber, so I'd like to find a happy medium.

How much camber can you get on the stock adjustments? -1.5? Front seems pretty limited.

Bill Verburg

Normal street camber is 0° to -10' f/ -1° +/- 10' r
as you add more negative camber the tires ride more on the inner edge, this causes increasing wear in normal driving, On my own street car I run -.8°f / -1°r, this is a 3rd car and only sees fun driving, I almost always replace tires due to age not wear. On my track only car I run -3°f/-2.5°r, this gives excellent wear pattern for my style and speed. -.8°f / -1°r when used on track will still exhibit accelerated wear on the outer edges of the tire due to camber loss in the turns. W/o camber plates the amount of negative that can be used depends on the ride height and amount of tire wear you can tolerate

Amir@Avus Autosport

All of the street tires I have used and tested like a lot of camber. On my 911, M3, and NSX, I've run between -4 and -4.8 in the front, depending on the tire and what the pyrometer says, and around -3.5 in the rear, and zero toe. This has all been 200tw and from various manufacturers.

If you're happy with the suspension, I'd max out the front camber, set the rear accordingly, leave the rest of the set up as is. It'll be a major compromise in terms of keeping the tires happy, but will keep you happy on the street.

Dave Inc.

I ended up using -1/-1.5 camber and...pretty well chewed up the shoulders of my conti extremecontact sports. I'm ready to throw in some stiffer springs if it means I can keep my tires alive for more than one day. The car has felt overdamped using the bilstein sports and stock springs, so I think I'd like to get the springs lined up with the dampers and maybe a scooch on the stiffer side for some more body roll resistance. Would the 21/27 be a "best fit" for the Bilsteins, with the 22/28 being that extra scooch more?

I'll also add some camber plates up front because I'm at the limit of adjustability. I think -1.75/-2.5 would be my target but I'd talk that through with the shop (Porsche race car specialists).

I'm still on the fence about the sway bars though. I'm at the stock 20/18 but I'd just much rather reduce roll through spring than sway. Am I being silly on this one? Just caught in the street, track, street, track, indecision I suppose.

Mark Salvetti

I don't expect to do much track time with my Targa, but I'll have the suspension apart and wanted an upgrade that would be a good street compromise. Working with Steve Weiner's recommendations, I'm going with 21/27 torsions, and the later Carrera 22/21 sways. Already sourced those items used.

Soon I hope to be ready to order the Elephant rubber bushings for front and rear and custom valved Bilstein struts from Steve (HD in front, Sport in rear) to match the rest of the suspension. I understand that the custom-valving will make the car a lot more comfortable to drive with the stiffer suspension, but I don't have a feel for how much that really is.

I think you want to work with Steve or Chuck at Elephant to put together a package. If I can live with 21/27 torsions on a Targa, I would think that is a no-brainer upgrade for you, and maybe even another notch bigger. You might find that the custom shocks will make a big difference to how even your current suspension feels, I just can't say how much.

Mark

Bill Verburg

I assume that the outer edges were what was worn. If so what's happening is that the body roll and wheel travel is inducing positive camber gain.
You've correctly identified the cure => lower the car, stiffer springs and sway bars more static camber. You might want to investigate some more track oriented tires too.
You want to set the car up w/ springs and then use sways only as a tweek. Additional tweeks would be from bushes, wheels and tires
here's an old but still relevant factory setup guide


a summary of some setups


and a survey of common t-bars and their effects on the cars handling

wildcat077

Dave ,
First of all ,the Continental DW's are not a good track tire as the sidewalls are really soft and if you like to push your car you would be better
off with something stiffer and more track friendlier ... i won't elaborate on tire choices but there is more selection in the 17 inch range !
There is also the option of Elephant decambered ball joints which will help get you into the desired camber range.

Don't get me wrong though , i used the Conti DW's as rain tires and they were awesome , i even use them on one of
my daily driver street cars.

Dave Inc.

These are the extremecontact sports, which are more in line with a Michelin PSS. Still not an ideal tire for track duty, but I was hoping that a little less ultimate grip would reduce overall body roll.

Dave Inc.

Well I finally have all the new springs in with de-cambered ball joints. What surprised me most with the 22/28 springs and the bilstein sports is just how much better it rides. I guess the sport shocks were simply way too much for the stock springs, and these are such a better match that it handles bumps so much more smoothly than before. Not to mention that it doesn't roll nearly as much and settles into corners immediately where before it would wallow against the shocks.

I should have done this right when I changed the shocks from HD to sport.

Now of course my alignment is eye-balled and terrible, but I'm taking it in for an alignment and corner balance tomorrow.

Dave Inc.

Oh, as a followup for anyone searching in the future. The 22/28 springs gave much better ride control and quality with the Bilstein sports, and with 1.7/2.5 camber I used the full width of the tire instead of just the shoulders. I think I ended up being about a second faster than last time, and considering track temps were likely 60-80F higher I'd say not bad!

Here's some video even! Now sure I did spin but I guess that's how you find out how much speed you can carry through an apex.

raspritz

I'm guessing you really mean track temps were 60-80 degrees, rather than 60-80 degrees higher? There is a complex relationship between ambient temperature and lap time, having to do with track temperature, tire temperature, tire compound, tire pressure, ambient air pressure, air humidity, and air density, but in general lap times tend to be faster with higher ambient temperatures.

Rich