Question for those with the 22/29 T-Bar Set Up

arbita1 · arbita1's Garage

On Sunday, I autocrossed with my new suspension set up. And I found that it was a bit more tail happy (oversteer) than I expected. I'm wondering now if I should have gone with 28's in the rear instead of 29's.

It didn't help that I haven't aligned and corner balanced it yet...so that may have been a factor. I know I had 0 deg. camber on the passenger side rear wheel and -3 degs at the other wheel. So I'm sure handling was affected.

Also, I'm running on agressive street tires instead of R compounds. So that could be a factor too.

But I was wondering what the consensus was from others with this set up. Is this something I need to get used to and will learn to use? I also have 21mm rear sways...maybe I should drop down to 20mm or even back to the stock 18mm's.

At any rate, other than that I definitely loved the stiffer feel and major reduction of body roll.

Here is the before:

And after:

VFR750 · 10-23-2007, 05:54 PM

I went from 22/28 to 22/29. And yes the car is more willing to rotate. But, I got used to it. I only ran a couple of track days with the 22/28 and it was more tolerant of tossing the car into a turn. With the 22/29, I had to learn a smoother entry technique. Now, I see no need to go back to the 28s.

Before you change anything, get the other stuff fixed. Tires are not the problem right now.

gunlover05 · 10-23-2007, 07:02 PM

going to do the same exact upgrade this winter for my AX'ing (22/29s)...do you think you ran "faster" than with your old setup? if so, curious to know if you can guess how much...

VFR750 · 10-23-2007, 07:10 PM

Not sure which of us you are asking, but for me, I couldn't tell.

I'm faster now because I have more experience, and drive smoother.

dd74 · 10-23-2007, 11:55 PM

Subscribing...
I was thinking of the same change from 28s to 29s, maybe even 30s. I'd like to hear more insight.

IROC · IROC's Garage

I've had 22s/29s for about ten years in my car. I actually find it very neutral. I have factory Carrera sway bars (22/21) and run about -1.5 degrees of negative camber all around. I even have zero toe-in front and rear (gasp!). I am running 245/275s for tires, though, so that helps keep the rear planted.

The only time my car seems tail happy is right after turn-in. I have to get back into the throttle pretty quickly to catch the rear end at that point, but overall I am very happy with the set-up. It is neutral through fast sweepers which was my goal.

Edit - I just noticed my avatar....that's coming through turn 12 at Road Atlanta. Definitely a place where you want to avoid an oversteering tendency... :>)

911 tweaks · 10-24-2007, 05:51 AM

from what I have been told, all of the above is true more or less i.e get proper alignment, get corner balanced, get proper tires for intended use.
However, what I am not hearing here is what shocks you are using. If using Bilstein Sports or what ever shock, you really need to have the shock set up to have proper compression and rebound settings THAT MATCH the torrsion bars being used.

Good luck here!
Bob

arbita1 · arbita1's Garage

Quote:

Originally Posted by 911 tweaks

from what I have been told, all of the above is true more or less i.e get proper alignment, get corner balanced, get proper tires for intended use.
However, what I am not hearing here is what shocks you are using. If using Bilstein Sports or what ever shock, you really need to have the shock set up to have proper compression and rebound settings THAT MATCH the torrsion bars being used.

Good luck here!
Bob

Bob, I have Bilstein Sport shocks that have been revalved by Smart Racing to match my T-bars.

KTL · 08:52 AM

Get the car aligned before passing too much judgment on the setup. Alignment makes a BIG difference in how the car handles.

Corner weights are pretty important too. I had mine checked by a friend with scales which told me what I thought- light right rear. Without the aid of the scales to actually balance it, I just did a minor adjustment to the car to help with the wheelspin i'd have on high speed corner exits. I had a light right rear corner, so I lowered the left front a bit and it did make a noticeable difference.

BTW, I have the 22/29 on my car and they're decent. The street attitude is nice since it feels tighter than the original 19/25 bars. Although i'm a bit disappointed by the presence of basically the same amount of body roll- I thought some of that would be arrested by the stiffer bars.

After talking with same scale friend (cstreit) he pointed out to me that the stiffer bars are not a huge increase in spring rate. Hence the reason for body roll still existing. The upside is that I have a rear adjustable sway bar (Weltmeister 22mm) which made a BIG difference in how the car handles. I can now get the car to turn in much better than before. Increasing the rear roll stiffness removed the tendency for the car to understeer/push on turn in, exit. The car now has a bit of turn exit oversteer, but it's completely controllable and much more confidence-inspiring than the former understeer characteristics.