track alignment

jsmithcds · 09-09-2009, 05:14 AM

79 sc with a 3.2ss conversion flared for turbo look.

Looking for some advise for a track alignment.

Car is lowered and corner balance is good.
Bilstien Sports all 4 corners.
Fronts are 255's and rears are 315's 17 Inch Kuhmo Ecsta xs all new
Rennline 3 point tower brace installed.
turbo tie rods
Stock brakes which I am happy with.

Car will see 4 or five track days a year. I run Road America mostly and plan to visit Black Hawk occasionally. Road america is a 4 mile track with a pretty good mixture of high speed and low speed corners.

I recently changed the tires to the Kuhmos and am pretty happy with them. I am still experiencing push.

I do not want to take this car much further than the current set up as far as the track readiness than it already is.

Any suggestions on allignment values and use of the strut to aid in the process. For example Tightening or loosening it for track day applications? I plan on taking it in and having an allignment done this week.

Thanks
Justin

IROC · IROC's Garage

I'm sure you'll get a lot of responses on this, but IMHO your actual alignment specs will end up being whatever you need to do to result in even tire wear (on the track). For me, I have max'd out the negative camber in the front (only about -1.5 degrees) and have slightly less in the rear. I have essentially zero toe front and rear and that works for me.

As for the "push", is it at turn-in? Low speed corners? High speed corners? For me (again, YMMV), turn-in can be helped with the zero toe in the front and it seems low-speed understeer is the compromise I've made for high-speed neutrality. Getting the nose of the car to the apex in a hairpin is a little frustrating sometimes, but coming through turn 12 at Road Atlanta in a nice 4-wheel drift (rather than on the ragged edge of oversteer) is nice.

Just rambling. Hopefully you'll get some good advice.

jsmithcds · 09-09-2009, 05:35 AM

The push seems to happen most slower corners, most noticable at turn in but I feel it pushing evenly thru the corner. It seems to handle the high speed corners pretty well. Not sure if that made sense?

Turbo Werks · 09-09-2009, 06:10 AM

you need adjustable sway bars to be able to adjust for push or loose conditions

tobluforu · tobluforu's Garage

What sway bars do you have?

911st · 09-09-2009, 07:15 AM

Are you stock or have you stiffened up your suspension? That is what are your sways and springs?

Is the car daily driven? Are you willing to live with accelerated tire ware for the best handling?

The front of a 911 is neg camber challenged to a significant degree and the rear to a limited degree in my opinion.

Running max caster helps some but it is worth looking into a Smart Racing Camber-King or ER/Tarret adjustable spring plate. With one of those and a the shock hats removed one can get up to -3 deg on a good day. If not a full race suspension you can probably benefit from all the camber you can find front and rear.

If I could get -3 front and rear I would. I would then experiment with reducing front Caster from max to reduce steering effort some and reduce camber change with steering angle change.

Front Toe of zero "pressed" is good to ok. Rear needs a little toe for stability.

Again, camber, camber, camber...

ljowdy · 09-09-2009, 07:39 AM

Try a softer front sway bar or a stiffer rear sway bar..

If you soften up the front, it will grip better and help with turning.

If you stiffen up the rear bar, it will decrease grip and make the back rotate into the turn

jsmithcds · 09-09-2009, 07:58 AM

suspension other than the shock is stock as far as I know. The car was definatley raced or tracked at one time by someone. I really have no idea if the sways and torsions are stock or not. I suspect they are but do not know for sure.

It is not a daily driver but not a dedicated track whore either.
The key with my question is I don't want to dump more cash into the suspension on this car.

Just curious on what to do with the allignment to get as much out of it as possible.

In a previous resonse From KTL he rcomended
Front: Max equal camber on both sides, max castor and 1/8" total toe out.
Rear: 1 deg. more neg. camber than the front, 1/8" toe in.

This is what I was planning on starting with. Sound about right?

Also as far as using the strut brace to help. Should I be doing the alignment using no strut brace assist, do the allignment and then just snug it up? Would the brace allow me to make any adjustments to help at the track? Or is it strictly bling?

ljowdy · 09-09-2009, 08:03 AM

Are the anti-sway bars adjustable??? If so, you can move the vertical bar forward or back on the anti-sway bar. Moving it towards the bend in the bar makes it tighter, moving it away from the bend softens up the bar.

jsmithcds · 09-09-2009, 08:06 AM

Sways are the non adustable type.

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by jsmithcds

The push seems to happen most slower corners, most noticable at turn in but I feel it pushing evenly thru the corner. It seems to handle the high speed corners pretty well. Not sure if that made sense?

As handling characteristics change w. speed it's very normal for a car to behave well at speed and push at low speeds, very normal.

I wouldn't want toe out except for a/x use, 0* pressed is the usual, camber depends on the tires and driver, usually max neg(~-1 to -2) on a stockish 911 suspension w/o camber plates

911st · 09-09-2009, 11:34 AM

Quote:

Originally Posted by Bill Verburg

usually max neg(~-1 to -2) on a stockish 911 suspension w/o camber plates

Is this all that is needed or all one can get?

JB36 · 09-09-2009, 04:02 PM

Quote:

Originally Posted by 911st

Is this all that is needed or all one can get?

It was explained to me that as these cars age, the shock tend to move in the wrong direction. I was only able to get -.5 and 0 on the other side. This was my case. I'm sure some cars can get up 2 degrees. I use a Wevo Camber King which is a strut bar with integrated plates and mono-balls. 1.8 on both sides and could easily get another degree.