TD in DC

As most of you know, last year, I bought a n/a 944, and I am now racing with '44 cup. My car came with the following suspension:

o FRONT: Turbo shock mounts, strut tower brace, cut down 300 lb.springs, shocks. Heavy Porsche MO30 30MM front sway bar. High performance solid bushings. High strength boxed steel a-arms (This car is lowered approx 2 inches.)
o REAR: Porsche MO30 26 mm. sway bar, gas shocks.
o 30 mm. torsion bar. Solid bushings.

As a general matter, I tend to assume that any handling oddities are my fault rather than the car's fault.

I am, afterall, a relative newbie to all of this, and I am sure that I need to focus primarily on developing my own driving skills rather than on dumping $$$$ to fix a car that may not be broken.

I mean, I could dump $$$$$$$$ into 3 way adjustable motons and I still would not be Michael Schumacher

That said, I would like some advice on how one goes about "tuning" in a new to you car.

My car handles great in the dry.

However, in any traction compromised situation (e.g., rain, very cold, snow), it shows what I believe to be somewhat evil oversteer. Grip, grip, grip, snap and out comes the rear end fairly suddenly. I looped the car during my first race during a snowstorm, and I noticed that my car was breaking loose while other cars were going significantly faster than I was. I learned later that many had disconnected their sway bars, and that I should have done so as well. Lesson learned.

The jekyl and hyde nature of my car makes me wonder whether it truly is optimized for the dry, or whether I just haven't pushed the car hard enough in the dry to make the oversteering tendencies manifest themselves. In any event, oversteering tendencies are good because it is faster, right?

That said, can any of you provide me with advice on how to take a systematic approach to tuning the suspension on your race car? How and when do you do it? At a DE? How can I tell what is normal and what is abnormal? I mean, it is difficult as a newbie to know.

Thanks in advance for your advice. Rennlist has been a great resource for me.

Larry Herman

First bit of advice, let someone who is really good and who knows how 944s are supposed to handle drive your car. Not a "if you break it you bought it drive", rather a push it to the limit & try not to wreck it drive. That way the car can be separated from the driver. Who knows, you could have developed a style that pinches the turns a little, which will work in a low hp car in the dry, but nowhere else. That snap oversteer may be you, and not the car.

If it is the car, then you can start tuning. Maybe the car is too stiff in the back (as compared to the front) because properly setup 944s with their large polar moment don't tend to snap spin, it is more of a slow "here it goes". Also, beleive it or not, understeering cars can snap spin too. It is a condition the Nascar boys call "push/loose" and it happens when you are cornering in an understeering mode, with too much slip angle dialed into the wheel, and then for whatever reason, the front hooks up, and around you go.

TD in DC

Hey Larry,

I think that is a good idea, and I was even planning on having you or Dan drive my car at VIR, but . . .

I have been, and still am, assuming that this is driver error just as you mentioned. It is just hard to know when you should stop blaming yourself and start exploring the car.

APKhaos

Well, the first sentace just about says it all. If you car handles great in dry conditions, don't mess with it until you develop a more sensitive butt meter that will detect fine tuning issues that you can then correct.

Your rain tires were probably the most significant contributor to the wet handling issues. In a perfect world, you would dial up a softer setup for rain racing. Our cars don't lend them selves to changing spring and damper rates easily. Disconnecting the sways helps soften the car a little, but not a lot.
In fact, rain tires make more of a difference then any other single change between dry and wet racing. Driving style is another issue. As you spend more time racing in wet conditions, you will be smoother and far better as sensing the limits of your tires.

Saturday's race was a perfect storm of bad conditions: Snow/ freezing rain, very cold ambient air, very cold track after an overnight temp in the low 20s. Sounds like your tires reflected these conditions fairly accurately.

My full-tread RA-1's have been decent rain tires. They are now over three years old, and despite having had no more than ten sessions in that time, they are now hard as rocks [as I discovered in Saturday's snow race]. The Hoosier DOT wets performed very well in this race.

Oddjob

Couple questions for you:

1) your rear sway bar is not 26mm - there is no such thing. Probably the 968 M030 19mm? The 19mm bar is 3 way adjustable, so if it is not on the softest setting you could adjust it softer to reduce oversteer.

2) When you say "cut down 300 lbs springs", are they actually cut? Or just short springs? If you cut coils off a spring, it will increase the spring rate, so you may have an unknown front spring rate. But I dont know why anyone would cut down a 300 lb spring? Do you have a ride height adjustment / threaded lower spring perch kit on the front struts?

3) If the front rate is actually 300 lb/in, 30mm T-bar in back may be on the stiff side - balance wise. I would think that 28mm or maybe 29mm would be a better balance.

4) Gas shocks in the rear, what brand/model? What type of front struts?


I would not recommend going to the Motons on a 944 n/a, especially at this point. If you are going to upgrade the suspension, there are likely some "next step" setups that will give you some good results w/o damaging the back pocket nearly as much.

But as mentioned by others above, trying to dial in a car's handling in adverse conditions is probably not the way to go. If it handles well on dry pavement, drive it (practice) until you get to the point that you can get the car to its handling limits. If you can do that (some of us may never be able to do that), then look at upgrading the suspension.

As far as handling in the rain, that has a lot to do with the each track, the "rain line", tires, your experience driving in the rain, etc. Much more than just adjusting the car's spring rates.

RedlineMan

Todd;

Good stuff here. I'm going to pick on everything. I know this is what you bought, and it is not "your fault." You have a junk yard dog there. Who knows what anything really is, and that also means very hard to tune, to the extent that you can, which is very little. If it is a 968 rear bar, that means three settings, plus tire pressure. That's a bout it.

As I see it, you can live with it, or change, and that means most of it. The shocks are no help because they don't adjust. The front springs are too soft for the t-bars, as Oddjob mentioned. The front sway is WAY too stiff for a stripped NA. Lots of problems as I see it.

I think your instincts are correct (as yours usually are!). You are not driving it to a limit where you highlight deficiencies in the dry. The wet character is telling you there is something wrong.

As you know, suspensions are a system. I think you need one. You don't have one at the moment. I have a customer car like that. Ledas rear, Koni Yellow front, custom valved, but rebound only. So much rebound the front tires don't touch the ground. You have to be a madman to make this thing stick. It was a competitive car, but... Evil! She don't havta be dat way.

We should trade rides. I think you would be impressed! Till you get it figured, Tony is right on; drive what ya got till it feels like junk. Until it does, you won't have any better idea what you need.
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Reporting Live from Brockville, Ont.

M758

TD,
I will give you all the 944 suspension experience I can.

First my car.

Weight is 2615-2630 at the end of most races.
Tires 225/50 R15 RA-1's on 15x7 wheels.
Suspension

Front -
Weltmeister adjustable sway bar, 350 lbs 2 1/4" springs, paragon camber plates, stock steel arms, Delrin bushigns on the crossmember and red welts on the caster block. Koni yellows with stock valving.

Rear -
30 mm solid t-bar, weltmeister sway bar, black welt poly bushings, stock valved koni yellows

Non-limited slip diff.

What is critical can be the aligment on these cars
front 3.5 deg of negative camber 0 toe, caster is what it is.
Rear 2.5 deg of negative camber, 3/16" of toe in.

Ride height is approx level front to rear at about 4" to the rocker panel.

My car handles very well in my opinion. It leans torward oversteer, but in the dry is very easy to handle one you get familiar with how fast it reacts to things. In the wet... we I have have maybe 6 wet sessions in the car over its life so... any handling problems are more driver than car I'd guess.


I use the adjustability of welt sway bars to tune the balance. I have the attachment point measured for both front and rear bars. I can move it 10 milimeters and feel a difference in the balance. It my home track (Phoenix International) I have adjusted the car so that I have the best balance I can for the track. This means were I am flat out I don't want understeer as it scrubs speed. In some corners I can deal with some entry understeer by using trailbraking to pitch the back end of the car. Since I have an open diff I can't go too stiff with sway bars as they naturally cause less traction. So I have to balance one vs the other. In one corner I am force to traction drive the car (ie use a light foot to keep grip on the inside rear tire). It I have found is the best thing I can do given my lack of limited slip. I could adjust the car for more traction there, but that would cause understeer in the fast flat out corners thus costing me more overall.

So my point is I use my sways to fine tune the balance of the car. My camber & toe settings have been constant for a long time as they seems to provide even tire wear. With respec to toe in the front 0 should provide the least scrub down the straights while in the rear toe in is need to counter act the normal deflections of the rear. If I ran zero in the the stability under braking would severly compromised.

TD...
So what are your aligment settings? Ride height front to rear? (this does impact the car's balance)

Also you may want to get adjustable sway bars and use them to play around with the car. Move the attachments in 10 to 20 mm increments and feel what that does to the car. Then you can for realivlty little money learn what you can do to tune the the car to you liking.

In my view springs are the first tunning tool. 300 front and 30 rear is a bit off balance in my view, but probably not bad.

Aligment settings are next. These have the biggest impact on tire wear, but you want them to be solid first.

3rd adjustment is sway bars. If you have adjustable ones each session you can adjust them and tune the car. For a long time I ran 350lbs front springs and 28 mm t-bars and had great balance. In spite of the slightly "off spring rates" I could use the bars to compensate. No the down side was horrible traction in tight corners. my inside rear wheel gave me little grip. That was due to running the rear sway bar full stiff. When I went with more spring I soften the rear bar and the car got much better. However you can do alot with sways to change the car's feel very quickly.

Last thing to adjustis shocks. Shocks are the finest adjustment you can make. A huge shock change will have less impact on the balance than a moderate sway bar change. That said most racier looking for that last ounce of speed have their springs, aligment, and sway bars set right so all they have left is shocks.

Also you noted the car gripped gripped and then broke loose.

Well I am not sure where you are with respect to you driving skill, but the limit on a toyo tire 944 spec car is when it slips. You let the car slip a little the recover. I have noticed the new 944 spec drivers are 2-3 seconds slower until the being to get comfortable with the car sliding around corners. Really if the car still feels like it has grip you are not going fast enough. The fast guy drive the car while it is sliding and have learned how to control the car when it does that. There are places where force the car into an oversteer situtation on purpose to and simply manage that with a little counter steer and throttle.

It it very possibly that you felt the car slide a bit too late and could not react. The other folks may have felt the car slide early enough to correct it and simple keep driving.

jerome951

Hey TD,

Your rear setup does seem a little stiff compared to the front from what others typically run (especially in your lightened car), but if it handles well in the dry, I wouldn't change anything. What tires were you running and what were their condition?

The only time I've experienced snap oversteer in 7 years was during the same cold, wet race. I should have softened things as well, but got too lazy before the race.

RedlineMan

Joe's got some goood stuff there;

As a for instance, I run full coil, 500F/450R. Welt sways, Front is full soft because it is too big for this car to start with. I never touch it. I probably need a slightly stiffer front spring because I get some inside trail brake lock in bumpy areas. Similar to Joe's traction problem. i.e. too much roll stiffness.

Use the sways for coarse adjustment. I rarely touch mine, not once last year. When I've got them close, I use my shock damping for fine tuning. Gotta love those Ledas! Next year I am going a little stiffer on the rear bar because I know I have been a little wimpy in the oversteer department.

If I did anything with your car, I'd get a Welt rear bar. Fairly cheap, works well enough, and enough range to adjust away your problems. That is the one thing that every '44 should have, and an M030 just does not give the range you need. If you like higher quality stuff, Tarret is the way to go. After that, I'd get a set of real front springs so you know where you are at with rate.

A good alignment is a given.

M758

I do want to say the that once I dailed in my suspension I don't adjust the sway bars any more.

The car feels good and I don't touch them. However I did spend 2-3 day farting with them after I put in 30 mm t-bars. I was tweaking the car to get the balance I like.

Right now a PIR I wont touch them. I feel I have them set for the right balance between not too much understeer and mainting rear traction with my open dif.

Of course going to a new track might mean I need to adjust these settings. However the first thing I try to do is fix the driver first. Once I feel I am getting all I can from the car I can then think about tweaking the setup.

Interstingly in my last DE day. Since it was a DE day and I was instructing in a track we don't race on I figure it was "skill building" day. I had corded on tire at an autocross and was down to my "race" set, and old set for storing the car and 3 ok tires. I got a new full set as I always like to have two sets in good condiition. I took a risk and grabbed my best of the old storage tires. I had no idea how old it was. I could see visually it was sound, but I know put it to storage duty after it had "cycled out" long ago. So I put the 3 decient tires on and my old "mystery" tire. I stragicly placed it on the left front. Given the track I figured it would be safest just incase the was really crappy.

So upon driving the car I found that yep it was old and it sucked. Noticealbly less grip than the others and caused a nasty push in 2 corners on the track. I had my new spare set, but figured it would great practice for learnign to "drive around" problems. So I spent the day adjusting and tweaking my technique in those 2 corners to "minmize" my loses. Turned out to be fun. I also learned that I could feel the tire change during a run session and also it took a beating on my right front too. By the end of the day both fronts were acting wierd displaying poor, but ok grip early and then the grip going to dumps by the end of the seesion. Tire pressure seemed to rather normal, but I can only guess that behavior was a result of the old compound and the extra abuse I was giving the front tires. Neither tire corded however. Don't worry I checked each session.


I think I learned a few things about how to induce oversteer and deal with problem car. For a racer it is an important skill to be able to nurse a car that is suboptimal and to learn what is a tire problem vs a chassis issue. Plus I got one more day out of set of old tires so saved a little green in the process.

Premier Motorsp

TD,

The first thing you need to do it say whether the oversteer is on entry (that is during decel) or on exit (during accel). This will give you a direction to go.

The other thing you need to consider is that maybe this new data isn't valid. If it was snowing (??) during the race then I'll bet you tires were ice cold. Tuning on cold tires is dumb.

I think what you have is what I call a 944 spec car. Cheap suspension, stock engine, small and hard tires. If this is what you have the following is good advice:

Soft front springs (I like 250) and 30mm torsion bars. Yes it is going to oversteer on entry. Once you learn to deal with that you will be sailing right past your friends who have stiff springs on the front and are understeering. If you take this advice and run 250's get the Weltmeister street type coils and not 8 inch Eibach race springs.

968 M030 front bar. Use only the stock rubber bushings and don't run those braces that connect to the front subframe bolt on each side. You want this bar to be pretty floppy, and it is when it is stock. Joe P notwithstanding (he's fast somehow) the Welt bar is major overkill, and when it is set up correctly, it is very sensitive because it has no rubber in the whole system. Plus it weighs a TON.

Your 30mm T-bars are going to allow you to put power down quicker then the guys who are afraid to run stiff bars. You will need a moderate rear sway bar, especially if you do not have LSD. The 968 19mm is maybe a little big. This is an easy part to swap and experiment with, and they are very cheap.

I think you need power steering to make this work.

Your goal with these cars is to get the rear tire temps a little higher than the fronts. If you achieve this, you will be fast.

Chris Cervelli
Premier Motorsports

M758

While I perfer a different set-up (I like manual steering too) to what Chris suggested I will say the following.

Chris aligned and conrer balance my car after I put the 30 mm t-bars in it. I still use those settings. Nice job Chris.

Second there are others in my class that run exactly what Chris describes. In fact he set-up some of them. They are just as fast as my car. The small differences in speed I attribute to driver skill level.

What does this all mean.... Suspension set-up is darn complicated.

TD in DC

Thanks all. Very interesting!

Chris, why do you say this?

You are probably right about the fact that I should ignore the handling situation during Saturday's race. It was a snow/sleet storm, and several people were going off track.

During the storm, I looped the car right at/slightly after turn in. I probably turned in too much, and, IIRC, it looped right when I started to gently roll on throttle at T17 at VIR when I hit that spot where the water goes across the track. May have been an anomoly.

The only other time I had "issues" was during a cold/wet day at Summit Point when I was using Michelin Pilot Sport Cups. There, the car would snap out 4-5 times each corner, typically right after turn in throught the apex when I was applying gas.

I have an LSD, but I do not have power steering.

Thanks,

TD

Premier Motorsp

I like power steering because in order to go fast in a 944 (and really almost any car), you need to get 100% out of the rear tires. When the rear tires are really at the limit, it is going to take a great deal of steering to keep the car going where you want it to go. If you are steering a great deal, you are going to get tired. When you get tired, you are not as precise.

Also, when you trail brake correctly, the front end is really loaded hard, and the steering is going to get very heavy. Once you are tired, you are going to conciously or subconciously avoid that situation and then you will be slower.

The other thing is that the manual rack has a slower ratio, and that means you can't keep your hands on the wheel as much due to shuffling. Also, all your steering corrections are slower.

I ran a 944 spec w/o p/s at least some of the time, and while it is not really very physically difficult, I know I would have been faster with p/s.

Chris Cervelli
Premier Motorsports

Geo

Well, I just skimmed the responses, but I would start by getting front springs that are not cut so you know what you are working with. I'm assuming they are coilovers. If they are not, get them.

Then I think the first thing to do is to set your ride height to the target you're shooting for. Since 944 Cup allows ITS cars, I would shoot for the ITS legal height of 5" to the bottom of the rocker (not the pinch welds) all around. Then I would corner balance the car.

Once you do that, if there is a track near you with a skid pad (I think Summit has one doesn't it?) and spend some time on the skid pad. Now, before I go on, there is certainly debate about the value of this, but I think it's worthwhile. If your car has a basic set-up/balance problem it's likely to show up there. It will give you a change to adjust tire pressure and swaybars to acheive a steady state cornering attitude that you are comfortable with.

Now, of course much of your time on the race track is not spent in steady state cornering. Mark (Sunday Driver) and I had a good conversation about this a year or so ago. So, you are going to want to adjust your set-up for corner entry and exit, most likely having to make some compromises along the way. But that's OK. You said you want to do this systematically. I think the skid pad will give you good base settings you can always come back to if you get your set-up all goofed up.

Something else I didn't see mentioned (but again, I only scanned) is your alignment can have a significant impact on handling. It can also affect corner balancing, so get that done before corner balancing as well. Remember, you want to start out with a good base set-up you can always come back to. Sometimes when we dink around with things we can get ourselves all screwed up and can't unscrew ourselves very easily from where we end up. This is why a good base is necessary.

Mark (and others) can probably give you better insight into damper tuning (even though yours are not currently adjustable). I think this would be a good place to work on once your base settings are established. Pro teams are spending incredible amounts of money on dampers. There is only one reason for this.... they are finding advantages there. Dampers are probably the most under-apreciated component in a amateur car. There are lots of good choices for 944 Cup and ITS legal dampers.

Leda, Koni, Bilstein, and others make them. I don't think you can get DA Ledas w/o the remote reservoir (to remain legal), but I know you can get SAs. Koni has several choices of SA and DA. You can get the street performance SAs from Koni that are quite common. You can get 8611 DAs for the front and a couple of different DA race dampers for the rear. The 8610 SAs can be used up front and again, at least a couple of SA race dampers for the rear. Then of course you can get the super duper, extra cool 2817/2811 DA gas dampers from Koni (about $4,500) that use F1 technology. Bilstein has non-adjustable street performance gas dampers and SA race dampers.

If you get adjustable dampers the most important adjustment is rebound, so virtually all non-custom SA dampers are rebound adjustable (although most have some minor impact on compression).

Anyway, I'd mess with dampers after you get good base settings and then fine tune with tire pressures. If you get to that point and do it systematically, you'll be ahead of most amateur racers in knowing how to work your set-up.