I know there's a lot of suspension information out there for a track setup, but my goal is to have a good street setup on a reasonable budget.

Let me start by giving a little information about myself. Things like tires and suspension setups are very subjective, so I believe this is important to understand the experience level and speed of the reviewer.

-I have been either autocrossing or doing HPDE events for the past 28 years.
-I won a AS state autocross championship in 1993 with my Twin Turbo RX7
-I was an instructor candidate for BMW CCA, before deciding not to attend anymore BMW CCA HPE events (due to one event being on my son's Birthday and the number of cars per run group)
-I currently instruct for Chin Motorsports
-During driver training, I'm less than one second off the professional drivers time.

When I first drove 911TT's, I really didn't care how they handled stock, as I knew they could be setup to handle well. I've also never found a stock suspension car that really handled well (except for a 997 GT3RS, but more on that later).

I was very happy to see that the car I ended up buying had PSS10's and a GT3 rear swaybar. I figured that this setup would be sufficient as my intent was for this to be a street car and not a track car.

Boy was I wrong. The first thing I did, was install new tires, so I could remove this as a negative factor. I installed Michelin Pilot Super Sport tires (245/35R19 front and 295/30R19 rear). I run these tires on both my M5 and M3 and love them. After the new tires were installed, I had five issues with the handling.

1. Definitely "floaty", which I thought I could live with because I didn't want a super stiff setup for the street.
2. The car had a tendency to "pogo" over bumps mid-turn. Probably due to issue #1 and though I could deal with issue #1, I couldn't deal with this issue.
3. The car felt waaayyyyy rear heavy. Given that the car has 62% of the weight in the rear, this didn't surprise me, but definitely not what I wanted.
4. The car would turn-in nicely, but then understeer mid-turn while only maintaining throttle.
5. The car would go initially into understeer, but if pushed, the front end would occasionally set and cause the rear to try to snap to over-steer (similar tendency I saw while driving my friends stock 996 GT2). Keep in mind that I'm talking about steady state corning and not trail braking, drop throttle (to initiate rotation) or throttle induced over-steer.

I drove the car this way for approximately 18 months, before getting a new point of reference. I had the chance to drive a 997 GT3RS. What really hit me, was how the rear of the car felt 400lbs. lighter than my car. The car just felt much more neutral and definitely not like the rear engine feel of my car. After this drive, I knew my car did not have to feel so rear heavy, so I started to do some research to understand why the cars felt so different.

I knew the 997 had a wider track and different suspension links, but surely there was something I could learn that could be applied to my 996 turbo. The first thing I did was look at the weight and weight distribution.

996 Turbo 3,543lbs. 38% front and 62% rear
997 GT3RS 3,245lbs. 37% front and 63% rear
My Turbo 3,445lbs. 38.4% front and 61.6% rear

Given this information, it was apparent that this wasn't the difference. As you can see, my rear weight bias was within 1.4% of the GT3RS and my car was actually less rear biased. I was also only carrying 78 more pounds in the rear versus the GT3RS.

After this, I decided to look at my wheel rate percent relative the the my weight distribution.

996 Turbo rear bias 62% weight and 45.5% wheel rate
997 GT3RS rear bias 63% weight and 62% wheel rate (more like I would expect)
My Turbo rear bias 61.6% weight and 46.4% wheel rate (with PSS10's and GT3 swaybar set to the next to softest setting)

Since the GT3 rear swaybar was adjustable, I thought I would first move it to its stiffest setting. Unfortunately the previous owner had installed the bar without changing the drop links, so I first needed to change to longer drop links. With the drop links changed and the swaybar set to its stiffest setting, my rear wheel rate percent went to 48.4%

The change was noticeable, but only slightly. It definitely felt like I was going in the right direction, but just didn't take a big enough swing. At this point I began looking for something to get my wheel rate percent in the high 50's to low 60's. This could have been done with new springs, but the PSS10's already felt on the edge (given the pogo effect over bumps), so this would force me to change coil-overs or revalve my PSS10's.

After getting some information and doing the calculations, it appeared the H&R rear swaybar was going to get me the closest. It's a little larger in diameter, but the huge stiffness increase came from it being solid versus the hollow GT3 bar. Adding the H&R rear swaybar (at its stiffest setting) would move my rear wheel rate percent to 55.3% with no other changes.

I contacted H&R's technical department to discuss the setup and they gave me the green light, but other experienced 6SPO members warned of excessive over-steer.

After installing the bar, here are my impressions.

1. Still "floaty", but it now feels like I don't need such a large spring rate increase. I'm currently working with BMP Performance and Bilstein to see what we can do with my current PSS10's.
2. The tendency to "pogo" is significantly improved. I actually haven't felt the car do this anymore, but that doesn't mean it won't, given the right road. Either way, it's a significant improvement.
3. The rear heavy feel has almost completely gone away in steady state corners. The car does tend to get more unsettled than normal as the rear unloads, such as with trail braking or mid corner bumps. I'm not sure a novice driver would need or want this. Definitely manageable, but not what you would want to go fast on a roadcourse.
4. The car still turns-in nicely, though not any better than before, but the mid corner under-steer has improved significantly.
5. The tendency to push and then snap over-steer (not really as excessive as over-steer as much as the rate of rotation increasing) appears to have went way. This of course could return and be worse when it does, but I have yet to feel it since installing the rear bar.

I would conclude that this is definitely worth doing if you are using the car as a street car and have PSS10's, but it's still going to need some more spring to truly be a great street setup. I would not recommend this as a track setup as you would spend too much time easing the car into a corner where you need to trail-brake, or where there are mid-corner bumps.

Hopefully I will get some recommendations from Bilstein shortly and will give more information as I make more changes.

Below is a link to some good information on this and other setups. Suspension setups are very personal and very relative to how you are going to use the proposed setup.

https://www.6speedonline.com/forums/...996tt-rwd.html

Later, Steve

 

 

 

Get the GMG WC hollow bars.

I have them on my turbo.

They are superior in every way.

Good Luck

 

I haven't spent much time here recently, but thought it was important to give an updated to this old post. When I added the H&R rear bar to may car, it was much more balanced and felt much better. At this point the wheel rate was 48% front and 52% rear. For reference, stock is around 59% front and 41% Rear. Pwdrhound had mentioned that this was going to be an issue (since he had an issue with a similar setup on the track). I disagreed, but was confused because I do respect his knowledge of the subject. Either way it felt great as was very balanced in steady state cornering.

Recently my son (19 years old) decided he wanted to go to the track, so I suggested a couple seasons of auto-crossing first. I had only been to one auto-cross since 1993, since I was spending my time at HPDE events. Since it was a good chance to spend some time with my son and an excuse to drive my 911 (not used for the HPDE events), I decided to join him. I now discovered how Pwdrhound was correct and why I had not experienced the issue. During steady state cornering, the balance is great. Under heavy trail-braking, it immediately wants to swap ends. Most of the time on the street, you just roll into corners so you don't spend time with heavy trail-braking. So, be careful if you have PSS10's with a solid rear H&R bar.

Given this, the fact that the car "pogo's" and the front end gets too light under acceleration I decided there was more work to be done. This is still meant to be a street, so I wanted to maintain a reasonably comfortable ride while improving the stability. I also believed a lot of the issues were being caused by the weight transfer under acceleration (my car makes over 500whp). I decided the best plan of attack would be to change the rear springs on the PSS10's from 515 lbs/in to 672 lbs/in (12K). Bilstein states the stock valving is good for up to 700 lbs/in. This changed the wheel rate percent to 44% front and 56% rear. This made a huge difference and I love this setup for the street. Still too soft for heavy track work with sticky tires, but great with street tires. For comparison, my wife couldn't tell the ride quality changed at all.

Good luck out there!

 

Semi solid motor mounts and transmission mounts. World of difference makes the car more edgy in the turns no swag.

Running sport, springs and sport shocks struts.

 

Until you get rid of the stock 59% front and 41% rear wheel rate distribution, the car is never going to be or feel balanced at the limit. Basically it will continue to push excessively at the limit.

 

Do tell. What's the diameter and wall thickness of these bars. I would love to ditch the solid rear bar, if I can get the same rigidity.

 

Don't have that issue with my car. Stock front bar, rear H&R, Bilstein PSS9's. Car is very neutral on track, going into oversteer and would easily oversteer at the auto-x