Track set up HELP
 

I am thinking of taking my car to the track for the 1st time.

The car is equipped with ERP 935 style front and rear coilovers, Fox adj shocks and SRP anti roll bars.

The Foxes are set at 1 (softest level) both front and rear (1 knob no the Foxes controls both compression and rebound) and the swaus are also at the softest spot.

Obviously I know by hearth the 2 threads started on the matter by Ed (Lopresti) on shocks

http://forums.pelicanparts.com/showthread.php?t=380442


and anti roll bars

http://forums.pelicanparts.com/showthread.php?t=381348

The car weighs around 2,400 wet, has big tires (255 and 315) and has a lot of neg camber dialed in front and rear.

Also it has 6 degree of caster and some neg toe in front.

The springs are around 400/600 (need to come back to you on that).

The car right now feels extremely light up front. The steering wheel is incredibly delicate and every input is trasmitted to the wheels.

The car hunts the camber of the road and it is definitely a car you need to be alert in.

The roads here in the UK are crap, so I am not too worried abt the car hunting any imperfection but I would like for the front to feel more planted.

It is purely a matter of feel, as the grip after turn-in is sensetional up front.

Also I feel it a little understeering, especially in slow corners.

Here is how I am going to approach the day. Please do tell me if I am screwing up or if I should do things differently.....

1st session - learn the track, get familiar with the car on it and the current setup

2nd session - move both front and rear shocks to 3 (both go from 1 to 12) and go out

3rd session - stiffen both front and rear if need be. If car is all over the place stiffen rear to loose the mild understeering.

4th session - repeat above

5th session - when I cure the understeer... what do I do with the sways?

Thanks again

Matteo

You're going to have a blast with that car at the track, Matteo.

You'll be at the absolute best place to tune the handling of your car, too. But I'd suggest modifying your plan slightly. First off, if you don't have a lot of track experience, then most of what you're going to be doing on your first visit will be just getting used to what it's like to drive your car on a track. There's so much that comes into play your first few times out as you learn to navigate corners, and brake, and throttle, in totally new ways. You'll no doubt think there are immediate things to address in terms of the car's setup (I know I did when I first went to the track), but most of it isn't worth following up on. A newcomer's perceptions of how the car is behaving really have more to do with the newcomer trying to sort out this totally new way of driving.

At least, that's how it was for me. And I see it in students all the time.

Complaining about low-speed push in a 911 is like complaining that the car was made in Germany. There just isn't much you can, or should, do about it -- at least not if you plan on also driving it at higher speeds. (Autocross and street-only setup can be a different story.) Medium and high speed corners are where the important decisions will be made, and just about everybody gets it wrong when they try doing their own diagnosis, early on. And what I mean by that is that when the rear end steps out at 80-120 mph, it's scary -- and most people end up tuning their cars to the point where it has loads of high speed push, when what they really should be doing is going through the (very slow, sometimes scary) process of getting used to the rear end feeling a little loose at very high speeds in an environment that's much more controlled and predictable than public roads. Put another way, what 'loose' actually means will change as the driver gets more accustomed to handling the car at higher speeds.

My advice would be to get someone who's done a lot of track driving in air-cooled 911s to take your car out (with you in the passenger seat), and get their opinion on how the car handles. In a perfect world, you'd get two or three people to do this, preferably people with experience in tuning 911 suspensions. They won't be facing the same learning hurdles as you are with the track driving part, and they won't have already grown accustomed to whatever handling quirks your car already has. As the owner, you're used to those quirks in a way that'll make it harder to incorporate them into an objective analysis of how the car handles. (At least, again, that's how it was for me.)

I'd plan on a few different trips to the track to slowly dial in a car that's as unique as yours. The one downside to having a one-of-a-kind car is that you can't simply copy all the setup details of the other 911s at the track. Your car is going to require some slow and methodical work to figure out what spring rates, shock rates, swaybar sizes, swaybar settings, shock settings, tire sizes and tire pressures will all add up to the best-handling combination for your particular car.

But for starters, I'd set the shocks at a medium setting and forget about them. And assuming you're not bringing extra springs or swaybars to the track with you, I'd limit yourself to swaybar settings and tire pressure changes while you're there this first time. The swaybars will probably be the easiest way to make big adjustments to the front-rear balance of the car. I'd get someone who knows the track to drive the car, and get their opinion on whether the car needs more push or if it needs to be loosened up. Making the front softer than the rear will reduce understeer. Making the rear softer relative to the front will reduce oversteer.

I'd fine tune with tire pressures from there. You can also play with the shocks, at that point, but shocks are usually a fine-tuning adjustment for handling, in my experience. I don't think you'll be in a position to make those kinds of 1/100 or 1/10 second type of adjustments on your first visit. I know I wasn't.

I'm saying a lot, here, and it's important to note that I'm not a suspension expert. I hope some of the real experts on this board who helped me with my car will chime in and correct me where I'm wrong. But I think that 95% of your day is going to be spent getting used to driving your car in a totally new way. The other 5% might be adjusting settings, but you don't want to be adjusting suspension settings in order to address what might be rookie track driving habits in an unfamiliar setting. That's where tossing the keys to someone with broader perspective and more specific track experience will probably come in handy.

(One last important qualifier: I'm assuming that because you're taking the first trip to the track with this car means you haven't done a lot of track driving previously. If I'm wrong about that, then accept my apologies.)

Hi Matteo.

Some tips:

• Sways before shocks.
• Adjust tire PSI to correct tire temps throughout.
• As Jack says, forget about the low speed push.
• Since the car is green, I think you're planning on getting more tuning accomplished than you should.
• Write down what your settings are at the end of the day, the track conditions, your impressions of the car setup, and general weather condition including the temp. Having a log will really help you to tune the car over time.

Jack

thank you for the detailed response.

I should have mentioned my track experience to establish a starting point. Basically before moving to the UK I was certified solo with PCA and NASA HPDE (or whatever class they have) 3.

So I am planning on getting accustomed with the car but I hope it should be a quick process.

Recently I have mostly taken to the track a stock 993 and my Ford GT.

These 2 cars could not be more different. I found the 993 very easy and forgiving whilst the GT will punish you if you are not smooth.

The problem that I face now is that all the cars I have taken to the track had a "given" set up. And I had to adapt to it.

So the Ford GT has quite a bit of understeering dialed in (yes you can be a hooligan and flex your right ankle and the back comes out to play ala Jeremy Clarkson, but that is not the fastest way around a track) but there was nothing I could do apart from playing with the tire pressure.

Also I found that with the 993 I could be on the gas a tad earlier whilst the GT was much more tidy in corner entry.

The GT (with the 500 ft/lbs torque at 2k and no traction control) was a handful on exit whilst I could bury the throttle on the 883 and know the back end would stay there...

This car instead is fully adjustable and this is where I feel inadequate. I have never "played" with shocks, sways, wings, splitters etc...

I think (and I might sound a little bit of an arse here) I have a good sensitivity when it comes to the behaviour of the car (any car) on the track.

But this will be my 1st time with this particular one.

So what I am after is a sort of game plan. Whether this is going to take me 1-3-7 track days is not important. But one of the fun things about this car is that I can grow with it and tweak it to my liking...

If I understood you correctly then I should set the shocks to medium and then concentrate on the sways and tire pressure first, right?

For example with the Ford GT I would

- stiffen up the rear shocks a little
- add tire at the front (now 245 section)
- stiffen up the front to improve turn in
- set the new lap record... :D

But the Ford has a very decent base setup with just a hint of understeering. Also I drove the Ford only at a medium-slow track. I am sure I'd have different comments if I drove it at Spa or LeMans.

So What I am after is a solid base that I could then spend ages tweaking (isn't it the fun of it all since I am not racing?).

Matteo,

First - thanks for the nice complimentary reference to the DAMPER and anti-roll bar thread. I am very pleased that they were useful, and that so many others contributed.

Now, a compliment to you is in order on your well-thought-out and structured testing plan.

I shall take the assumption that you will become consistant on the track fairly quickly, and once your lap times show that, then start your program.

When almost any of the pro teams start with a new car, they set everything full soft (except the tires) - just like you have yours now. Aero devices are set to 0 or near 0 angle of incidence.

(1) They run some laps, and the car handles TERRIBLY, but this is a critical step!

(2) Is the car understeering or oversteering?

(3) Evaluate the tires: scrub across the entire "tread" of each? Are any rolling over on the sidewall? This will also tell you about camber and toe.

(4) Adjust tire pressures, and attempt to improve under/over steer JUST WITH TIRE PRESSURES.

(5) Run more laps:
A) After tire pressure change(s), car is balanced - then stiffen front and rear anti-roll bars perhaps one-quarter.
B) After tire pressure adjustments, car still UNDERSTEERS - then stiffen the rear anti-roll bar one-quarter.
C) After tire pressure changes, car still OVERSTEERS - then stiffen the front anti-roll bar one-quarter distance.
(6) More laps.

As Jack says, leave those Foxes alone for now, and work those anti-roll bars, increasing from compliant to very stiff. If the car starts to dart sideways over bumps, or you get wheel-hop on acceleration or braking, soften anti-roll at THAT END of the car by perhaps 10%.

And as the Captain so rightly recommends, make detailed notes at each change.

And as I have asserted countless times, the car will tell you exactly what it needs.

Experienced or not, that should keep you plenty busy for the first day! Is it Brands Hatch? Silverstone? Enjoy, and report back!

Ed

Ed

Thank you very much for the detailed game plan.

I am going to Donington Park

http://bookatrack.com/-p2?779&5

It is a pretty good track with fast and slow turns, the ideal to set up a car.

I booked Brands Hatch GP for 4/23 and Silverstone for 5/13. Looking to squeeze a march date in there too.... most probably Brands Indy (without the forest bit).

Thanks again for the tips!

I also print this www.wtrscca.org/tech.htm taken from Taken from the book "Performance Handling" by Don Alexander as a quick reference guide....

What do you think?

Something implied in Jack's and Ed's posts and I only raise this because your initial post was to the contrary - change only one thing at a time on one end at a time and have a reason for changing it.

Also, try big (not the same as stupid) changes first, then dial back if too much of a good thing. Sometimes small changes will not be noticeable, except at 10/10ths.

Finally, a tire (tyre) pyrometer can be very helpful with setting camber and tire pressures, eapcially if you have access to a skidpad. But, the clock is the final arbiter.

Most of all, have fun and please do not put that beautiful car into a guard rail.

Oh yeah, send some pictures with your post-setup report.:)

Matteo,

Chè successo? How did someone named Matteo end up in Great Britian?

Anyway, I took a look at that SCCA link, and it seems like a very nice guide. I was particularly glad to see the Tire Temperatures section, although "Inadequate load on front tires." as a REASON, is not very helpful. We use a very similar grid in our Prep Your 911 for the Track seminars when we are discussing the pyrometer.

A point of interest to show how very important the tire dynamics are: Many teams running late-model Van Diemen F-2000 cars have software which tells them what suspension changes to make.

Once one has entered tire width, diameter, the ride height, caster, camber, toe, and corner weight basic info, which can be done in the garage before ever getting to the track, THE ONLY INPUTS are pyrometer temps! From those varying readings, the "computer tells them" the adjustments to make for more optimum handling!

We could be out of business!

Naturally Donington Park is very well known. I believe many, many Formula One drivers "cut their teeth" there in FF.

Ed

Ed

my story is a long one... Born and raised in Milan I started working in London after Uni... then Germany, back to London, Charlotte NC and now green Surrey...

I am going to take the car for an alignment early next week. The only complaint that I have so far is that the steering lacks weight.

It's way to easy to turn in, and it feels as the steering is hypersensitive.

Obviously a lot depends on the brand new suspensions. But i was wondering if I should change the toe to toe in vs my current toe out set up before going to the track.

Bob yes... change one thing at a time, otherwise you cannot tell what effect came from which input...

And yes, the ONLY important thing for me is fun. I am not racing nor trying to set up the fastest lap.

It took 26 months to get the car built.... Believe me I am taking a slow and humble approach.

Still I like to have a game plan. And set goals (with no time constraint) to monitor progress....

Matteo,

You spoke of this super-light steering before. Is it just at high speed, or all the time?

You are absolutely on the right track (pun intented) with toe - maybe too much OUT? The other factors (beside tires) coming into play are (1) caster - not enough (2) front ride height (rake) (front too high), and (3) if there is severe pre-load on those front springs (the perches have them compressed, even in full droop).

The high speed only problem has more to do with ride height / rake.

Spero chè questa informazione è utile.

Ed

OK... It happens all the time....

- I have 6 degree caster
- tires top is higher than the fender, i.e. there is no way I can lower it
- it might be the toe

I spoke with Zuffehaus (they built the car) and they suggested keeping the caster and going for 1/8 toe in...


Ed grazie per le informazioni. Sono fortunato ad averti come interlocutore!!!!!

Most likely it's the toe. how much toe-out are you running?

I don't know. I am going to take it for an alignment tomorrow.

But all this is becoming a bit of a mute point because I am not going to be able to go to the track anymore.

Basically I fried the second igniter (the ICU uder the seat) in 3 days and I am running on 6 plugs only.

The coil is not getting any current.

I had the same problem 3 days ago and ordered an ICU from Porsche just to have it fail again sometimes today...

I am really upset. I have run out of ideas apart from being an ECU fault.

It was a wiring problem. I am all set to go tomorrow. I also changed the toe.

These are details

Front camber: -2.5
Front caster: 7.5
Toe in: 1/64

Rear camber:-3

Front shock rate: 425
Rear shock rate: 550

I will report on Tursday. Thank you everybody for your help!!!

425 and 550 would be spring rates.
When you start to adjust your shocks you might be working with compression and rebound settings.

If you are not a seasoned track driver it might help to get one to test drive and suggest changes to get your car near its potential.
Carrol Smith's, Drive to Win is a helpful book.

When I dialed in my car 2 suspension experts came along and made changes between test laps.
It went something like this........

First we did a spring scan.
We started with 450 front and 500 rear.
We disconnected the sway bars and proceeded to do a spring scan.
Did 5 laps got the air pressures right and did another couple laps.
Car pushed, installed 600lbs rear springs, test it pushed again so went to 700lb rears, tested it and it was getting better but not there yet so went to 850lb rear springs. Car was neutral but skatey. (Later after lunch consensus was my used slicks were dead)(We found a set of good Hoosiers)
We eneded going with 400/600.

Next we did a shock scan with rebound, compression and can N2O pressure adjustments. After several laps and an hour or so we felt in the ball park with the shocks.

Then we reconnected the front and rear sway bars adjusted to the full soft position. Car pushed a bit and we tighten the rear bar a little.

Cary the owner of ERP arrived. Cary is a bit of a genius with JRZs and car set up. Besides his business of producing 935 style 911 suspension components he spends his free weekends as a race team engineer for Grand Am and Speed Channel sports car teams.

Jae and Cary called the shots I just drove and gave feedback. Every time Jae and Cary adjusted the shocks that is the rebound, compression and can pressures performance improved till the end of day where it felt like it was on rails.

We never got a chance to improve the aero, the car was loose through T9 killing our T8 momentum and costing us a second or so. Maybe a 1/2 inch wickerbill on the wing would be nice.

Mike thanks for the extensive write up. I will dig up yuor thread on the building of your car...

Anyway I went to the trackyesterday...

And as all of you said I didn't have much time to even start playing with the sways!

I had never been to that particular track and it was the 1st time for me driving the car.

So it took me all day to get consistent and most of all confident with the car's reaction/behaviour.

I must say the car shows huge potential, it is that thing behind the wheel that needs to improve dramatically.

Anyway I established a good base to work from on this track.

I printed this thread as I will revert to it often.

Next stop is Silverstone. I need to do something to the exhaust as it is very loud (115db) and most of the tracks here have noise limits....

So did the car feel better with more toe in? Or the same?

Matteo,

Sounds like a rewarding first outing for the "two of you". We NEVER get in all the testing on our list for a particular day, so get used to that.

Take your time in figuring out the exhaust muffling. As you probably know, these older air cooled motors live and die by their ability to breathe! We tried Supertrap difussers on our SC racer, spent a lot of time testing different stack arrangements, and contrary to published propaganda, it was like disconnecting one of the spark plug wires!

Stating the obvious, a key for going quick on the track is throttle response. Everything we have seen which limits noise, creates backpressure, and disturbs flow in the headers. That backpressure kills throttle response, especially "decay". We simply stopped running tracks where we could not run unrestricted exhaust.

Ed