making the car turn!!
 

asking the experts here, what would you do to the setup if the driver complains that the car pushes too much in the slow corner like in the hairpins.


Our car is fast in the fast curves but we cant keep up with the other two fast cars in the serie in the slow corner.


My driver is coming from a FWD so he is used to get a car that rotates really well which doesnt seem to work with this one.


It seems like the nose is too heavy for the rear, all the weight that was removed was in the back and we added a supercharger in the front which makes thing worst.


we tried a lot of different alignment, tire pressure and shock adjustment but haven't been able to nail it yet so i taught i would ask here what you guys do. One opponent with a Genesis is much faster than us in the slow corner si it is not a fwd rwd thing.


By the way, we run on extremely cheap 300 threadwear tires, don' ask, that is how the serie is made.


thanks

My suggestion would be soften the front sway bar or stiffen the rear sway bar. It will probably affect your mid and high speed cornering as well, so you will need to adjust your aero again.

Videos?

Are you running a square or staggered tire setup?

Is the understeer on corner entry or corner exit?

maybe you should post the chronological order of things you did so that you wouldn't get a bunch of people telling you to try something you already tried.

right i agree, well we went from 500# springs to 400# because the last track we raced at is extremely bad and the tires have no grip what so ever. We are thinking about going stiffer in the rear but it seems counterintuive compared to what other people do on the forum.

swaybars are stock but we tried with and without a rear one and didn't help much. we tried every tire pressure from 30 to 40. We also tried to add toe out both in front and in the rear and didn't help much, i beleive in the end we were like 2mm toe out in front and 2mm toe in in the rear on each side.

We tried 2,5 deg camber up front and than 3,5 deg, a little better but still not as we want.

This is what i am thinking for now, we don't have an aftermarket LSD, i don't know if that would change something or make things worst

yeah we didn't try to unhook the front swaybar, it rides well in fast corners so was afraid to mess it up but it might be something we could try. Otherwise we would need to get some adjustable ones and play with those.

we are running square 245/40/17, with such low grip tires we try to use as much patch as we can, our only other option is 225/45/17.

I would say understeer is in the middle of the corner or maybe more towards exit. It only happens in hairpin or very sharp type of curves and the last track had a lot of those.

Can't help without videos or data, and specifics on your setup...

You definitely need adjustable ones. They are the easiest way to tune a car quickly at the track. Unhooking the rear bar should have only made it worse. In the series I run in the rear sway bar is basically the only adjustable piece we are allowed other than alignment adjustments.

You've mentioned front spring rates and camber, what about the rear?

What gear is the driver in, and what speed?

More caster. (#1 thought)
Stiffer rear compression damping.
Softer front rebound.
Raise the rear of the car slightly.

I would use a rear adjustable swaybar for sure.

A better rear LSD would help as well especially if your problems are from mid-corner to exit. But are a little bit of money.

Do 1 change at a time (especially if the car is good the rest of the time like you said).

Understeer in very tight slow corners with those low-grip tires isn't too surprising but is easily fixable with a little tuning.

- Andy

BTW if the driver is coming from a fast FWD racecar that I assume is extremely loose on entry (as those platforms should be), then there may be some driver adjustment as he adapts to a different RWD platform. It sounds like your results are still very good so I wouldn't get too drastic with changes.

- Andy

Give the car some toe out in the front and especially toe out in back and it will turn in AND rotate better. Maybe too well....

ok so let's try this again, here is the complete alignment setting after a call to the driver


Stock swaybars front and back, all 4 corners at 400lbs, rear is slightly higher than the front


front, 3,1 deg of camber, around 6 deg of caster and 2mm toe out on each side from front to back on a 17" Wheel


rear wheel is 2 deg camber and last time was 2mm toe in on each side, i beleive we were at 0 toe before and wasn't much better.


can't remember about shocks settings but i know they are soft since driver said the car didn't want to sit on the tire, seemed like the suspension was too stiff for the tires.


turns he has problem with are in third gear at low speed (hairpin) says he can't apply throttle early as car always understeer towards the exit

The shock settings are important. Give Myles in the office here a call or send us a PM and we can help there. Reducing front rebound is my off hand recommendation but it would be good to know where you are starting from.

Putting your rear 500s on and leaving the fronts at 400 is an idea, but I wouldn't go there just yet. Also with those crappy tires I'm afraid it would be too stiff especially for an actual race (as opposed to a time attack or HPDE).

EDIT: From looking at the pictures in your other thread, I would definitely add some front negative camber and reduce front rebound.

- Andy

well all those suggestions are giving me pointers, we are going to try a couple of those on our next practice, thanks everyone.

Are those two other cars you can't keep up with on the same cheap tires? Tires are probably the most important thing.

yes everyone in the serie is on the same tire

Keep us posted. :)

- Andy

I do think more toe out in the rear will help. 2mm is almost zero. I have run as much as 1/4 in total toe out in the rear of another car to get it to rotate. But stiffening the rear spring rates, rear shock rebound or stiffer rear bar also helps rotation (or soften front)

+1 on putting the 500# on the rear from an armchair quarterback, I seem to remember CSG (or maybe Racecomp) claiming that 20-25% stiffer rear spring is going to give a balanced dynamic which leads me to assume that an even spring rate Front/Rear would result in a softer rear (read: more planted rear) than front inducing some understeer, I'm drawing a blank on the specific post but here's what some quick googling came up with.

Here is CSG's Tein kit:
http://www.ft86club.com/forums/showthread.php?t=82796

And here's a discussion on the idea but it didn't seem to get very far:
http://www.ft86club.com/forums/showthread.php?t=56678

Rear toe out will definitely help rotation, looks like it's a track only car so definitely try it. Zero toe in the rear was rather darty and unstable feeling on the freeway to me so I've got some toe-in for DD purposes, I may be reducing it in the future...

My vote is driver training with this platform. I find understeering at corner entry into a hairpin is always my error, usually not enought trailbraking. Otherwise, what brake pads are you running front/rear?

we are currently running DTC60 but entry isn't the problem he says it is on exit that the car understeer, he has to wait too long to apply the throttle.

Is the corner slow enough he can drop to 2nd and use the extra torque to rotate the car on exit?

If not, I'd try a bit less rear camber or stiffer rear spring rates. In the other thread there's a shot of it lifting the inside front tire on exit, that can't be helping front grip.

Sorry if you've already addressed this, but how do your cross weights look? I didn't see any mention of them, or pictures of scales anywhere.

This was my first thought as well. Probably needs to use more trailbraking, especially coming from a FWD, which is typically set up so that you don't use much trailbraking.

i thought i took a picture of it but it seems like it is before the supercharger install, i'll try to take one after the next race.

A few things.

- Enter the corner slower
- Get the weight transfer performed in a matter that takes you into the corner with more yaw
- change your spring balance
- add rear camber
- add front toe out
- Add rear sway
- Add rear tire pressure or subtract front pressure

You've giving me ZERO details about your setup so I'm stabbing at the dark.

To the OP..

Start with RaceComp's advice here.

A fellow racer who's "one of the fast guys" runs a 944 and him and I will rent each other's cars on occasion (I have a CRX that's setup fast/loose). I have RWD and FWD experience so I can hop in his car, I adapt my driving habits immediately and can match his fastest times but when he drives my car it's been difficult for him to adapt to this very unforgiving type of setup, in fact he just had to rebuild my splitter because of this.

Show him what it's like to do a slower corner quickly from a RWD driving style and he will may see the error of his ways and adapt. I suspect he's struggling to adjust to a car that has more rear grip than front grip as he's coming from a car that's probably setup with more front grip than rear grip.

Doesn't help you with details, but this might give you more clues:

http://img.photobucket.com/albums/v3...pspq6mkg0j.jpg

I'm going to say less front sway or more rear roll stiffness.

well check post #15, what else do you want to know?

We were running pretty equl pressure font to back, maybe a little higher in the rear could help.

i would also like to remind everyone that he is the driver out of a field of 30 cars that won the championship in 2013, came in 2nd in 2014 and is currently leading in 2015 so he is no rookie either. Of course he has an adaptation period but he is no newbie to racing.

About the lifted wheel, what can we do other than going to a smaller swaybar? Is there such a thing as a smaller swaybar than OEM? Are the adjustable one on the softer holes softer than stock?

About the rear camber, at which point would it becomes kind of a negative effect on braking or power delivery? What would you guys run in terms of rear camber with those shitty tires?

We are going to practice maybe next monday or in two weeks, we will try a lot of the things that were suggested here.

If I had to drive around that issue I would try trail braking a bunch more in those turns right down to the apex.

I would start with zero rear toe with the expectation of increasing rear roll resistance. However, for an easy test of roll resistance you can unbolt your front sway and do a couple laps and see if that provides enough additional droop too keep the inside front tire on the ground.

Considering I run 600 and 750lb springs on a 2100lb car it stands to reason that you're way under sprung especially if you're on R-Comps or slicks. The lack of rear roll resistance could be reason of front tire lift and understeer and/or lack of front roll resistance means you're losing too much camber under compression (mac struts)... However I'd start by going around the corner with all 4 tires on the ground. :)

we are far from being on slicks, we are runing Falken FK453, those are pretty much all season tire, like 300 threadwear.

i agree i didn't really see it that way and thought a wheel in the air made a good picture but yeah it would turn better if the wheel was touching the ground... I'll try to take the swaybar off, it doesn't cost anything and will probably tell us if we are going in the right direction.

This sounds really likely. Need to rely a bit more on weight transfer, and that takes adjusting.

Oh wow, this tells a story. Only 1 tire is doing work in the front. Front swaybar definitely needs a softer setting. I've never lifted a front wheel like that.

Yeah that's the picture I was referring to as well. Needs less front rebound for sure. That's a surprising amount of grip honestly for crappy 300 treadwear tires. A little more rear roll resistance would help and I'd add a little more front camber.

- Andy

I'm running 0 toe around and experience exactly that on highway. I commute on highway to work, and it kind of bugs me especially in the rain. What did you change your toe to? And is it much better once you changed it?

I want to say it was ~1/32" (~0.8mm) toe in on the rear and it was stable like it was from the factory, there is still a little bit of wandering as it follows the pavement which I think is just in the nature of the car. It may be as high as ~1/16" (~1.6mm) but I'm not sure, definitely less than 1/8" (3.2mm).

well folks we just came back from a new day of practice and we did a whole bunch of things and the car now runs better, we gain 0,5 seconds on a 10 degC hotter day.


we started by trying some toe out in the rear and immediatly the driver said the car felt better. We than tried to put the stiffer springs in the back and it helped also a little bit but the best mod ended up being the the toe out. We lacked some time at the end of the day but we might reduce the toe out a little next time to see how much it slows us in the sraight lines but at least now the car turns better.


About the lifted wheel, we finally realised that the picture was taken at a place on track where there is literally a jump, we don't see it much with our low grip tires but the CTCC which runs in Continental slicks, the Minis completly lift off all 4 wheels at this place so this was the reason of the lifted wheel.


We also used some really old tires with lots of heat cycle (wanted to finish them during a practice) so we are confident the car is going to be faster for our next event on a track that also has a lot of thight curves and hairpins.


thanks everyone for your feedback.