On a 911, a square setup is only desirable when you don't have enough roll resistance at the rear. In other words, you are fixing an imbalance by making using the same size tires front and year. But clearly, for better performance, you want larger tires at the rear since most of the weight is back there. You adjust chassis balance with roll bars or torsion bars.

I love ya Paul, but Braid BZs look like they're out of my price range by like an order of magnitude of five. The 930 front 17x9 ET30 is pretty damn close to what I need though. Plus they look really pretty. When do the first 17s start coming off the presses?

And as always, I may not do things the right way, I do them my way. If some of you armchair quarterbacks don't like the way I'm doing things, you're welcome to come and try to beat me. I plan on being at SCCA Nationals this year, along with all the midwest Pro Solos, Match Tours, and Champ Tours. I'd love to not be the only 911 in the STR grid for a change. I stick out like a sore thumb. Hell, I'm usually the only guy with a roof. Until you beat me, I get to call myself the fastest STR 911 on the planet.

http://i57.tinypic.com/2ltn4o.jpg

"Wheel" see what we can do Matt. I still owe you something for those torsion bars anyway. We can offer variable offsets on the 17" BZ now without the extra charge it takes on the 15" and 16". Not only that we can make 964 and 993 compatible offsets too! Maybe even 996! Widths from 6" to 12".

I should get a sample prototype this week while four others are being tested in the lab. Assuming they pass I think we can start shipping wheels in about a month. Got to be better than welded up old wheels right?

I won't be joining you in the STR grid. As you know I'm way beyond STR and yet way too slow at the same time.

Just to update this, I've made some large changes to the car.

I did go nearly square - 245/255 Bridgestone RE-71R. I'm on class max 9" wheels all around.

Over the winter I went to chase down my front suspension noises and realized my front swaybar bushings were likely binding a little.

https://lh6.googleusercontent.com/-g...o/IMAG1135.jpg

All the grease was gone, but I also didn't notice that the bushing was quite a bit too large for it's mount. I sanded it down to actually have a slight clearance, and greased the hell out of it to boot.

Well, the thing had to be clamped rock hard, because doing that turned the car into a wild oversteering beast. Not even drivable. A friend calculated the spring rate of the fully bound swaybar at something like 12,000lb/in!! No wonder I couldn't get rid of understeer, my front suspension hasn't been working at all for the last two years.

So I hit the reset button quite a bit. Went back to something similar to my first guess setup:
23/33 t-bars
Big front bar
OE rear bar (with spacered to flat-based and sanded down poly rear bushings)

I was treated to a 911 that was actually balanced, with slight oversteer in sweepers, for the first time ever yesterday. I actually want to tighten the car up slightly now. Braking performance has improved 10x. The car is a completely different animal, drives like a real autocross car now. This project has a brand new lease on life.

I feel pretty stupid that I didn't notice the bind for years, but boy am I glad I've fixed it.

tl;dr GET RID OF THE BIND IN YOUR SUSPENSION

car @ work:
https://lh4.googleusercontent.com/-s...ac18ac3b_o.jpg

https://lh3.googleusercontent.com/-3...84837062_o.jpg

Well, I guess you can say I can generate some grip.

A few notes / things learned recently:

- The new crop of 200tw tires is insane. The RE71R is a longitudinal monster - even S2000s are nearly matching my 60ft times now, which eliminates my advantage at pros. The Rival S on my car is much easier to drive fast as it's more forgiving to slip angle overshoots.

- The KAAZ lsd works beautifully. At full steam my inside rear is barely touching the ground and I have no problems putting power down. The stability off throttle is lovely. It's holding up great to some hard work. I'm impressed.

- After driving a couple of "real" STR cars (Miatas) I'm fairly confident that my current shock valving is insufficient. The Miatas reacted right now where my car has a long lag time. I can hear the tenths of a second clicking onto my time every time I turn the wheel. The 911 is by far the narrowest car and should smoke the other cars in slaloms, but that feels like the weakest element in the car right now.

Digging a little deeper and I have virtually zero compression damping, where the fast cars run very high low speed compression with a heavy digressive cut. Wallet back open again. FWIW my 23/33 combo is on the low end, but supposedly within range of the spring rate per lb of the fast cars.

Still off the pace of the NC / S2k but right now I really love driving the car. It's difficult as hell compared to modern cars, but super satisfying when you get things right. I'm registered for Nationals so we'll see just how close to DFL I get against the best in the country.

What I see in that pic at the rear is typical for a 911 with good tires. What I see at the front tells me the car is much more roll stiff at the front than the rear. Think about it, you only have one on the ground up front. You are giving up grip because of the other choices you have made. If you want to be as fast as possible, you want that front tire on the ground. That means stiffening the rear or softening up the front. But, to keep reasonable chassis balance, that means you need more differential in tire size front to rear. Why would you want to run a near square setup in a car with so much weight at the rear??

I'm limited to 255 on 9" max per rules. I can reduce the front, but not increase the rear. Would the car be faster reducing front tire?

Good to hear things are working out well in this update.

911s are going to lift the inside front tire at times.

The big question is; how is the car on corner exit? If it isn't pushing to bad you are well set up IMO. Getting the power down ASAP is key. Looks like you are good in that respect.

If you are running Bilsteins, custom valving is what most have success with. Adjustable Konis may be something to consider, if rules allow. But that is just another thing to fiddle with...

I autox my NC Miata and it seem sooo easy. I'm not a good driver at all, but your thread gives me hope! I might take out the 911.

But I am filled with worry. I'm worried something might happen to my 2.7 headstud puller. You have a nice solid 3.2, should I be worried, or just rip on it?

Anything you've done to protect the engine?

Edit; Also, how exactly did you figure out the front end was binding? Just from removing the mount? (Sorry I'm a newbie). That's why I like the NC, it's already 'set up', it's pretty hard to screw up. I don't want to start messing with my 911 and make it worse.

What's the first few things you would do to a stock 911? :)

You are absolutely right about the Bridgestone RE71R. They are hilariously grippy. They feel like a Hoosier A6. I have them on my Mini Cooper S that is prepared for STX and whipped up on people I was previously a second behind. No WAY are they legal next season.


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Balance on exit is very dependant on how I got there. Rolling onto the gas from a sweeper, it will push lightly. Romping the gas upsets the front and induces big push. On throttle in transition exits the car is a raped ape - plant the foot and be ready with a little counter if needed. A few people commented how strong my car looked on exit, so I guess I'm pretty good there.

Rear shocks are ordered - I'm trying some Hotbits from a fellow Pelican. I asked Chuck if he'd be willing to try revalving my Bilstein fronts with more compression, and I apparently offended him as he said he's not interested in being involved with the type of valving I was requesting. Maybe I'll send them to Bilstein themselves in the offseason.

I know nothing about the 2.7, sorry. I've done nothing special to my motor.

As far as the front bar, it was squeaking pretty bad since not long after the install. I intended just to regrease the bushings last winter, but remember seeing an article about binding with oversized poly bushings somewhere online. I did NOT expect sanding down 2mm of poly could have so huge of an effect. It was massive, like hitting the reset button on the whole car.

Yeah, they're real monsters. But since they fit the 200tw rules, and seem to work very well all the way down to the cords I don't see much of a case to ban them. Looks like I'll get a full season out of my rears, exactly what I got out of the Z2s I ran last year. Honestly, I think the Rival S is just as fast on certain types of cars as well.

You are effectively doing this on your own by having the front so stiff compared to the rear. This means you are losing compliance in the front which can have a dramatic effect on how the car performs unless all the courses are glass smooth.

I think you would be faster with 225's on the front and the front end would be more compliant because you would have to soften it up to maintain the chassis balance you have. You will still lift the front tire, but not as often and not for as long.

Interesting - so if I were to go narrow and soften, would I soften spring or soften bar? Or both?

I would start with the sway bar....also, if you add compression damping like you are talking about doing, you would need to soften the bar more yet.

How much room do you have to soften the front bar?

My favourite pelican thread- just sayin.

I have to stay underbody, so I have a 22.2mm bar on. I do still have the OE 20mm bar.

Is the rear bar adjustable?

No, but I have two of those as well. OE 18mm and a 22mm.

You can borrow my 225 Rivals.

I have 225 Rival S. I was slower on those than the Bridgestones.