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.1 gt3- minimizing understeer- any feedback re: spacers to increase front track width

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Old 09-14-2014, 07:39 PM
  #46  
997gt3north
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Originally Posted by limitedslip
Hey guys,

I noticed some understeer with my car and just brushed it off thinking that I just don't know how to drive the thing yet; but upon closer inspection I found that my front bar is set on full stiff and rear bar on full soft.

A little background: I'm a fairly decent driver and can do pretty much whatever I want with a front engined RWD car. Now being new to the 911 world I'm taking it easy trying to learn the dynamics of the rear engined setup.

If I understand correctly though the current sway bar settings on my car are basically set for maximum understeer. The front is too stiff to allow it to bite and turn and opposite on the rear, too soft to turn (Correct me if I'm wrong!).

Thus I was wondering 1) what are the stock settings? And 2) what settings would you recommend I start with to shoot for a more neutral handling with a tendancy oversteer?

Thanks!
what car do you have? - mk1 or mk2

the mk1s came with the bars full soft front and full hard rear - thus some upgraded to the stiffer gt2 bar

as was noted above, many, very, very, very fast gt3 drivers can and will set up a car with a 'big' front bar so that the car will really resist rotation so that maximum aggression on the throttle is possible all the time and huge trail braking on entry is possible in race-type situations

all that said, on an mk1 car those settings, if you have them correct and not backwards, would be crazy settings tight settings - if the bars are in fact OE mk1 bars - if the rear bar has been swapped for the gt2 bar it would be less crazy and could just be a driver choice issue

on an mk2 - others will have to weight in - but my guess is they need some adjustment for a more neutral setup
Old 09-15-2014, 10:45 AM
  #47  
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Originally Posted by grrrmonster



it's got a little bit of aero going on
A Little?
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Old 09-15-2014, 11:49 AM
  #48  
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Originally Posted by 997gt3north
what car do you have? - mk1 or mk2

the mk1s came with the bars full soft front and full hard rear - thus some upgraded to the stiffer gt2 bar

as was noted above, many, very, very, very fast gt3 drivers can and will set up a car with a 'big' front bar so that the car will really resist rotation so that maximum aggression on the throttle is possible all the time and huge trail braking on entry is possible in race-type situations

all that said, on an mk1 car those settings, if you have them correct and not backwards, would be crazy settings tight settings - if the bars are in fact OE mk1 bars - if the rear bar has been swapped for the gt2 bar it would be less crazy and could just be a driver choice issue

on an mk2 - others will have to weight in - but my guess is they need some adjustment for a more neutral setup
big bar to a point... with the brake bias on the road cars being so far forward as it is you'll just wind up deep in ABS

correctly driven yes you're leaning on the stoppers almost to apex. otherwise it won't turn at any reasonable corner speed

rear needs a level of stiffness otherwise it will roll over
Old 09-15-2014, 01:29 PM
  #49  
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Originally Posted by 997gt3north
as was noted above, many, very, very, very fast gt3 drivers can and will set up a car with a 'big' front bar so that the car will really resist rotation so that maximum aggression on the throttle is possible all the time and huge trail braking on entry is possible in race-type situations

YES!!!!!

I run full soft rear bar and almost full stiff front bar, and my car doesn't push at all...in fact, it is loose on turn entry at times. If you trail brake this car, it handles wonderfully neutral. It really depends on how you drive it. On paper, my setup would be assumed to be really pushy.

That being said, when I first got the car I thought it pushed, so I just drove deeper into the turns.
Old 09-15-2014, 04:05 PM
  #50  
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Originally Posted by Spyerx
Agressive setup. I think if you drive the car very hard into corners to get it to rotate this setup can work (look at TPC Tom thread for example).

Are you in SoCal? Who is doing your setup/alignments?

Going off memory but with GT2 rear bar I have middle rear, 2 from soft front.

Originally Posted by 996FLT6
One off stiff rear one off stiff front and adjust front for softer as u go. Mike
Originally Posted by 997gt3north
what car do you have? - mk1 or mk2

the mk1s came with the bars full soft front and full hard rear - thus some upgraded to the stiffer gt2 bar

as was noted above, many, very, very, very fast gt3 drivers can and will set up a car with a 'big' front bar so that the car will really resist rotation so that maximum aggression on the throttle is possible all the time and huge trail braking on entry is possible in race-type situations

all that said, on an mk1 car those settings, if you have them correct and not backwards, would be crazy settings tight settings - if the bars are in fact OE mk1 bars - if the rear bar has been swapped for the gt2 bar it would be less crazy and could just be a driver choice issue

on an mk2 - others will have to weight in - but my guess is they need some adjustment for a more neutral setup

Originally Posted by BBMGT3
big bar to a point... with the brake bias on the road cars being so far forward as it is you'll just wind up deep in ABS

correctly driven yes you're leaning on the stoppers almost to apex. otherwise it won't turn at any reasonable corner speed

rear needs a level of stiffness otherwise it will roll over
Thanks for the replies guys, I very much appreciate it! It sure is fun learning!
I took the car for a nice long drive on empty back roads yesterday. What a blast!

I experimented a bit and to be honest I don't really have any complaints about how it drives. At my level anyways. Might be worth noting also that I don't have a frame of reference having not driven 'hard' any other 911 or rear engined car before.

I did notice though that driving at reasonable speeds the car didn't seem very willing to turn but coming in harder into the turns on the brakes the car turned just fine. Looks like it likes to be on the brakes to turn (what BBMGT3 said)? . I also tried experimenting with how early I could get on the throttle in a turn and when I did that too early the car pushed (never got any oversteer ever)...

Anyways, after the drive I decided to take a second look at my sway bar settings.
I confirmed that the rear was on full soft and the front actually not on full stiff but one hole from there.

I decided to change those settings to stock (full stiff rear, full soft front, thanks 997gt3north). I haven't driven the car with those settings yet and I'm not quite sure what to expect but I figured I'd try stock and go from there.

Also noticed that both my front and rear tires are getting chewed up on the outside, begging for more camber. I'll hook up the camber gauge and see where I stand right now.

PS: the car is a bone stock MK1 (not RS) and I DIY so I very much appreciate everyone's advice in helping me setup my car!







Old 09-15-2014, 05:38 PM
  #51  
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Originally Posted by limitedslip
Might be worth noting also that I don't have a frame of reference having not driven 'hard' any other 911 or rear engined car before.

I did notice though that driving at reasonable speeds the car didn't seem very willing to turn but coming in harder into the turns on the brakes the car turned just fine. Looks like it likes to be on the brakes to turn (what BBMGT3 said)? . I also tried experimenting with how early I could get on the throttle in a turn and when I did that too early the car pushed (never got any oversteer ever)...]

This is more helpful information (i.e. your experience). Everyone that starts down the GT3 / track learning curve starts at this initial realization - i.e. weight transfer coming off the brakes and getting the nose set to avoid noise lift and throttle push - so fix your bars and then enjoy the learning curve of how to drive a GT3.

You will find amongst the many things you are about to learn, one of the most important is becoming a better braker of the car - and specifically how you are coming 'off' the brakes, managing the weight transfer into and out of a turn - ie. if you had a passenger in the car they should really not be able to feel when your braking is finished and when the initial throttle is applied - it is critical not to snap off the brakes and slam on the throttle as the nose will just lift and the car will push - as you get better with this, a light bulb will go on, and you will just 'get it'.

When you get it, and you then let this notion expand further in your brain, and if you are ever able to start doing track days, you will see how this is one of the key ways that GT3s are driven differently than cars with engines in different locations - and then more lightbulbs should start going on about using this heavy weight over the rear axle for added grip, added braking ability with the mass allowing the rear tires to work harder, etc. (but this stuff will become obvious when you start to see the areas on a track that you can gain distance versus the cars infront. If you can ever get a ride from a pro level driver in a GT3 on a track it will blow your mind in terms of what is possible.

have fun
Old 09-15-2014, 09:46 PM
  #52  
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Thanks for the great input!

I'm very excited about learning to drive this car!

Got any alignment/camber recommendations so that I don't waste my tires?
Old 09-22-2014, 01:16 AM
  #53  
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Thought I'd follow up since I finally got to take the car out on my favorite back roads with the sway bar reset to stock settings.

I found it to be a noticeable difference. The car turns at any speed (I no longer have to dive into the turns like a madman to make the car turn) and the rear end is definitely more lively which is more to my liking.

I think I'm going to keep it that way for a while and see how I like it after some more driving; but let says I want tone it back down gradually: Which is the recommend approach? Move the front one hole stiffer or move the rear one hole softer?
Old 09-22-2014, 09:15 AM
  #54  
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Originally Posted by limitedslip
Thought I'd follow up since I finally got to take the car out on my favorite back roads with the sway bar reset to stock settings.

I found it to be a noticeable difference. The car turns at any speed (I no longer have to dive into the turns like a madman to make the car turn) and the rear end is definitely more lively which is more to my liking.

I think I'm going to keep it that way for a while and see how I like it after some more driving; but let says I want tone it back down gradually: Which is the recommend approach? Move the front one hole stiffer or move the rear one hole softer?
Rear one hole softer. For a street car that's the approach for sure, and I'd recommend it for a track car as well. Softer bars increase the independence of the wheels, which is good for anything but totally smooth Tarmac.
Old 09-29-2014, 05:52 PM
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feedback from new setup (fresh off the alignment rack).

Understeer monster has been tamed. Specifically an improvement in steering responsiveness on initial turn in. Not sure of what the "as was" setting were, since we had a wheel bearing to replace and an inner bearing on the lower control arm in the rear.

Thus new set up highlights-
-stock springs & struts
- all monoballs through suspensions
- solid motor mounts
- -some aero going on (see pic in profile)
- 18 wheels 245s in front, 305s in rear
- front -3.5 camber and a little bit of toe out caster 8 degrees
- rear -2.0 camber stock toe

notes: while still not as crisp as I would like, the tires are now the primary suspect- these have had many heat cycles. Full assessment with a fresh set of rubber, but I suspect the new tires will cure my ills.

Had some great coaching over the weekend from Tommy Bryne and Brian Till. Spent an afternoon working on specific pointers with Brian-- and how to use the GT3's kinematic toe feature to the driver's advantage. Found out the timing of the throttle application was incredibly sensitive to how the car would respond (on the same corner, same line, as similar a set for the corner as I could consistently manager). A wee bit too much too soon and the nose would want to push out, a wee bit too late and the rear wouldn't take a nice, smooth set, but if you timed it oh so perfectly-- AHA! It works wonderfully.

We also increased the front track of the car about 25mm by shimming out the lower control arms.

Liking this set up, and have learned a great deal in the past few weeks with this
Old 09-29-2014, 06:15 PM
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Is 245/35ZR19 and 325/30ZR19 the plus size everyone gets for Pilot Super Sports?
Old 09-29-2014, 06:58 PM
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You were going pretty darn good out there this weekend. Very nice to meet you and chat for a bit. Wish we would have found more track time together. I'm sure we will in the future.



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