Depends on which GT3 bars you have. From the factory, the 07-08 GT3 bars were set at full stiff rear, and I think second or middle from soft front. Setting front to full soft alleviates some of the push, but the geometry of the drop links is too acute so it's not really recommended. Swapping the rear GT3 bar to that from the 2010 GT3/GT2 is a better solution as it is much stiffer and brings the front/rear bar adjustment balance within better range. The GMG GT3 rear bar is essentially identical to the 2010 bars both in geometry and weight. They both have the same lever arm length, identical in external diameter, ~25.5 mm, with the Porsche bar weighting about 8.0 lbs and the GMG bar appx. 8.25 lbs. The GMG front bar though is noticeably larger and stiffer though, allowing a greater range of dialing in more understeer if you need.

 

There is a lot of good information and a lot of misleading info that is inconsistent so be carful with which you follow.

GT3 Chuck is one of the most accurate.

Stiffer in the front will reduce oversteer; opposite in the rear. I don't have a type 1 GT3 but I doubt that factory settings would start with full stiff in the rear.

Cation as to what you think is stiffer as the farther out on the bar you move the softer it is. Very easy to get this messed up. The engineering background types can probably figure this out without much previous experience.

 

Steve, you seem to know what you are talking about so this is probably a typo.

 

Sorry but that's incorrect. Stiffer in front reduces front traction transferring more of the traction to the rear wheels, increasing understeer.

Sorry that was a typo - I mean full soft, which while giving the front more grip and reduces understeer, puts the drop links at a bad angle relative to the strut mount. The extended drop links from Tarett address this.

 

Yea, sorry, i mention your typo and then do one myself in the process. I am sure will have everyone confused by the time were done.

I know what I'm thinking, just can't seem to get it correctly through this dam key board.

 

SteveW is correct. Other poster is backwards.

Stiffer front bar = more understeer
Stiffer rear bar = more oversteer

2010 RS will benefit from one hole stiffer in rear bar than OE. Helps to remove the steady state understeer (plowing).

Also critical but under appreciated- mind your hot tire pressures! Folks run WAY too high hot pressures which totally make everything greasy after 15 minutes.

Comments applicable to tracking on high performance tires such as Systems or MPSC or Trofeo.

I have no idea about .1 GT3 set up.

 

So then wouldn't moving the front one hole softer and leave the rear at the same setting do the same thing to mitigate understeer? Basically softening the bar increases the traction at that axle relative to the other axle?

 

That is part that gets me totally confused - I know now that in different years GT3 bars were different, what I have now is the (most ?) current set - front has GT3 stock bar suncoast sells for $252
http://www.suncoastparts.com/product...ry_Code=997sus

and rear bar is a correct match to it according to parts numbers, it is not an 'older' one which was softer. I do not think if it is a 2010 GT3 bar, not sure. What is an exact part number for 2010 bar? I do hope they changed it as if they did not it will add up even more confusion.

So I am not sure if I really need to install stiffer rear bar - like I said at camber I have now (-3f -2.5r) on second from softest front in front and middle one in rear car had quite some oversteer and moving front now 2 holes closer to stiff seems like it fixed that perfectly, well, as far as I can see it on a street on narrow street tires with no grip.

Tires I use for track/auto-x this season are 265/335 so essentially with that much rubber overall feel is different, i did not have a chance to push car anywhere close to the limit on a track at fast speed as i just started this season and as a green group driver my priorities are to learn the line and work on smooth transitions, not to brake speed records or push to 8/10 but at auto-x i do run this car quite aggressively and it did feel adequately balanced, car was turning in well and rear axle was pretty stable in corners and even some minor mistakes did not force car to spin, with previous suspension setup it was much more 'fragile'.

To swap rear sway bar is a very simple job but I really not sure what can it really give me, if anything, why do i need it to be stiffer? Plus what I started this thread from was - so, stock GT3 rear bar has 3 holes, GMG rear bar has 5 adjustment holes and is 1.5 times stiffer, right?
But where on a 'stiffness scale' would softest hole on GMG bar fit compared to stock GT3 bar? I just had a feel that is is wiser not to mix up different bars and if I go with stock GT3 bars their adjustments should cover my suspension fine, plus as I spoke to my mechanic and with other folks it is a common practice to 'compensate' softer springs with stiffer bars, in my case i have moderately stiff springs at 600/700lbs so I sort of hoped stock GT3 bars should work fine.

It is all fun to work with a complex suspension, it will definitely take some time to work out all the variables but it is truly a great fun. I just obviously need some 'RTFM' to do regarding tuning basics.

 

As others have stated already in this thread, I think you went wrong by changing the front bar. You should address the end that's not working (rear). Put the front bar back where it was and move the rear bar to soft.

Are you tuning with your shocks at the same time? You've got double adjustable JRZ's correct. You should have alot of tuning in the shocks as well.

I've always been told tune first with springs if possible, then shocks, then bars. Most street cars go the opposite direction because bars are the easiest, springs are soft and shocks are unadjustable. I think you've got all the equipment in place with your car to do it the right way.

 

interesting, i was told to choose proper springs, then adjust bars having shocks close to full soft, then fine tune shocks - i keep jrzs initially at 3rd click compression all around, 5th click on rebound and then dial it up as needed. but i do bars first, it is interesting to hear that it is considered to be wrong. i think wrong bar`s settings do have more significant effect than shocks, do they not?

problem with front bar is that it is not very easily accessible to adjust on a track - i need to drop both wheels off and put car on 2 jacks to undo those droplinks, so i want it to be set to position that I will not need to access/modify too often. still, i see what you are saying here and it makes sense.

 

Irony!

I think it ultimately got sorted out...

-td

 

all you have to do is turn the front wheels to opposite lock and you can reach in behind the wheel and adjust the drop-link

 

they were torqued quite tight and with regular wrench i simply could not undo them with rims on... and xenon light sensor on lca shim does not let bigger wrench to fit there. with wheels off it was way easier, but, well, it takes time to jack up car.

 

I went back and checked my reference material and your correct I mis-spoke on the order. Should be springs->bars->shocks. Sorry for even more confusion if I created any

If you previously liked the front I still would suggest putting it where it was and fixing the rear first. If you get it balanced and still feel you need more roll stiffness then go back and change both at that point