I am giving the tarret rsr style bars some consideration. No real online info on smart racing/jwe from vendors.

A buddy has had issues with the tarett bars with the sliding style adjustments... They came lose on him on track and he now has to double bolt them to prevent slipping... Or tighten then to the point of badly scoring the bars. He said he would do rsr/smart racing style if he did it again.

In general, raising the spring rate (or the anti-roll rate) in the back will make the car tend to oversteer more. So going up with the torsion bars in back might not give you behavior that you want.

A more-balanced approach, with stiffer torsion bars in the front and in the rear, and very likely a softer front sway bar, might get you closer to where you want to be.

--DD

IMO if you go with 33s in the rear, you will have to up the size of the fronts. Probably a good idea if you are serious about autoX.

What sways are you running?

Here is my car. 22/30 torsions, 22/21 sways, Koni sports, raised spindles, and 2200 lbs.
http://forums.pelicanparts.com/uploa...1467135889.jpg

Steve Weiner has the Smart bars. They are in the neighborhood of $1500 for the full set.

Especially when he's running no rear sway bar and is running a front bar, basically amplifying the problem.

That makes no sense. The sliding design works great. It is used my more than just Tarett. I prefer the sliding design! I use them front and rear on my race car and have not had any sliding issues. Does he have the correct washers in place? Has he called Tarett?

Not to mention the understeering 22/29 torsion bar setup! Three factors pointing toward understeer. Get the sam size adjustable sways bars front and rear and to 22/31 torsion bars. Then he make the car oversteer a bit which is needed for autocrossing!

Here's my analysis - $.02, probably not worth that much:

You're too low for how soft your torsions are. On turn in, especially if you trail brake a bit, you're likely hitting the outside front bumpstop. That's making the front spring rate skyrocket, overloading the outside front, the causing push on entry.

Just like the front on entry, you're smacking the bumpstops in hard transitions. Spring rate goes virtually infinite, back end goes wonky.

Here's a frequency chart for my car (a fairly stock 84 3.2):

https://lh5.googleusercontent.com/-4...ide%2Bfreq.PNG

I'm assuming your car is quite a bit lighter than mine, but you can at least see what the wheel rates are - those don't change with weight. Your 29 rears actually have slightly less wheel rate than your 22 fronts - which would work great if you had a front engined car with 50:50 weight distribution.

Your rear torsions are too soft relative to the front. This is causing your mid corner push.

You car is (guessing) probably closer to 60:40 or even more, which makes the front more roll stiff than the rear, which causes push. Then you have no rear sway and a front sway on top of that is making it worse.

First things first, I would consider raising the car up. That'll get you off the bumpstops and make the car a lot more predictable. Next I would consider a rear torsion upsize over a big rear swaybar. To what I'm not sure, I'll defer to others, especially not knowing your corner weights. I can say 30s were very nice on my car, 33s were firm but sporty, the 36s are pretty brutal on broken pavement at neighborhood speeds but fine elsewhere.

To get my car where I wanted it, I had to go 23/36 torsions, 22.2mm oe style front bar, no rear bar, 245mm front tires / 255 rears. It's currently too loosey goosey for track, but great fun for AX. On power it'll push like most 911s, but it's dead neutral at steady state and a lift will induce nice controllable rotation. Challenging as hell to drive fast but very rewarding.

A nice addition to the Tarett bars, which i'm surprised aren't part of the usual hardware they come with, are the square nuts that fit into the lever arm slots. They do a great job of setting the link attachment point and don't come loose. It's the only thing good about the copycat TRG bars I suppose.

Rebel sells the nuts Suspension2

Those are slick. Surprised I haven't heard about them before. Great idea.

I mentioned something similar to Ira years ago but he was concerned with increasing the price of the bars. Nice to see you can buy them separately. Just ordered them.

We've been using the Tarett bars on several different cars and never had them loosen up. If you tighten them up correctly there is no issue.

I had the Smart bars and the shoulder bolt that connects the rear bar can be a challenge to line up. You need to readjust the droplinks to line up the holes and sometimes tap it into place with a mallet. It takes a bit longer and can be frustrating if you are laying on the hot asphalt trying to get it done between sessions. The bolts and heim joints are very small and can get beat up. I had to order extras from Smart racing and fortunately they were cheap.

If you are only concerned with performance I'd get the red Tarett bars. If you need the vintage look go for the RSR bars.

^ +1!

Yep those aluminum alloy slot-nuts are a nice little feature but a bit pricey at $64 for a set of four. That's the price you pay for convenience & custom! :D

Agree with the guys above on the function of the Tarett style bars. We've used them, and a TRG copy or two, in our group of dudes for many years and no complaints from anybody. I 100% agree the Tarett's sliding adjustment function on the lever arms is really nice for quick adjustments compared to the SRP bars. I have the SRP bars on my racecar and they are very nice too. But like Cory said, the rear bar takes a bit of fiddling to get your drop link relocated into another hole location. That fiddling doesn't apply to the front SRP bar because it's a sliding clamp style. Here's the exploded diagrams of the SRP bar assemblies for reference

http://forums.pelicanparts.com/uploa...1467222108.jpg

By no means am I endorsing the TRG bars, as I understand it was a pretty blatant copy of the Tarett design. Just thought it worth mentioning that a feature on the TRG bars, which at first glance appears to be an improvement, is the lever arms have tick marks engraved on them like a ruler to help you set the location of your drop links generally the same on each side. But it's not super critical to get them absolutely exactly the same on each side. Plus over time the ruler marks can rub off from contact with the washersand that's the end of them providing you that measuring ability. Getting the links close enough to the same is close enough. But I will say the square nut feature is for sure a nice convenience too. All you need is one wrench to loosen the link location and slide it to a new one. Here's a picture of the ruler marks and you can see the square nut-serts on the end of the lower drop links

http://forums.pelicanparts.com/uploa...1415323076.jpg

However, using two wrenches is not a big hassle. You're already going to be under the car with a wrench and using one more is not an issue. The real issue is TRG's sway bars (the actual torsion bar that twists) are somewhat notorious for breaking. Apparently they don't do a good job of joining the hex "key" into the bar and it snaps off. A few guys in my local group have experienced the broken torsion bar firsthand.

So potential buyer who reads this, beware you've been warned. Just buy the Tarett stuff and know that you'll have a quality product and excellent technical & product support. Ira Ramin of Tarett is a top notch guy and takes care of those who buy his products.

Cory did a nice job years ago showing us the differences in the finer details

http://forums.pelicanparts.com/porsche-911-technical-forum/608587-rear-sway-bar-snapped-anyone-else-had.html

Understanding chart
 

Driven,
Help me to understand the chart better. I've got 21 and 27 on my SC. So, because the wheel rate are 231/197, all things being equal, I've induced understeer. If I go to 28 in the back, it is 2231/228. Neutral. 29's in back, 331 (I think) so oversteery.

Have I interpreted that correctly?

Note to others: I was at 24 in rear, 24.5 in front lowered, and I was on the bump stops a good deal of the time. Of course the car was skittery. I raised the car to 25 in front, 24.5 in rear. Much better.

At end of season will make some torsion bar changes. Most likely case is 21/29 and adjust balance with the Tarrett's. Car weighs 2550 without me in it emptied out for AX/track with 6 gallons of gas. http://forums.pelicanparts.com/uploa...1468087346.jpg

And another pic
 

http://forums.pelicanparts.com/uploa...1468087520.jpg

Looks OK to me. Car was just off braking and on to throttle if memory serves. Medium corner.

No, you have not. You are forgetting the weight distribution of the car and the dynamics of a moving vehicle with the motive force coming from the rear wheels.....

21/30 is relatively neutral.

My car came with 23/30 tb's and 22/21 sway bars. It is pretty neutral but I have yet to get it corner balanced again after 350-450lbs weight loss.

I will talk with the owner of the tarrett sliding style bars to see if i can better understand his failure issue, and solution. Nothing wrong with saving a few $$$ with the sliding style bars... Mind you I am not so keen on the color... Not that it matters much.

I think being able to easily switch between a softer street setting, and stiffer track setting at the start and end of each HPDE is key.

what do you guys think of the newer blade style bars?

Elephant Racing | QuickChange Blade Sway Bars | Porsche 911/912/930

Price aside.

edit: good read here: http://forums.pelicanparts.com/porsche-911-technical-forum/761952-elephant-quickchange-blade-style-sway-bars.html

The ability to soften things up quick for the (rough) drive home from the track is a big selling point for me. My car would not be a "set up and forget" for this reason, so easy adjust-ability would be key. Mind you, I swap tires at the track... so once I got it dialed in to my liking, I could just change things when I change my tires.

^Winders is correct, wheel rates only work for 50/50 weight distribution, ride frequency takes mass into account. Also of note: ride frequency is just a piece of the puzzle, far from the whole story.

There's a million factors at play. Weight balance, sway bars, static camber, camber curves, roll center heights, tire / wheel widths, track width, tire pressure, driving style, all the nuances of damping curves, bushing deflection and friction, etc. If this stuff was easy, top race engineers wouldn't be the highly paid individuals they are.

Frequencies ARE a good way to get into the ballpark though. I still think most of the "canned" setups on this site are too front stiff for anything but the most ham fisted drivers. They're very safe.

FWIW, my car has matching ride frequencies (2.79/2.79Hz) and way, way more front wheel and tire than OE (245s on 9" on all four corners.) Based on the chart that gets circulated on this site I should be so far past "oversteer" it's not even funny. Car drives awesome. Light push on power, light rotation on lift. Still have to be very ahead of what the car is doing like any TB 911, but super fun to drive. Now I did have to remove my rear swaybar completely to calm it down for my taste, but it was still drivable with it on. I'd probably like to tune in a little more understeer at HPDE speeds though, of course.

Getting back to this thread since I want move forward for '17 AX.
Refresher: 74 w/ stock 3.2L. corner balanced. torsion bars 22F/29R. Bilstein HD front and Sport rear, Front sway 22mm. Rear sway - none.
The Tarrett adjustable rear sway bar can be purchased for a "69-77" or "78-89" MY ranges.
Is there a way I can tell by looking at rear suspension, swing arm etc to identify which would be correct for my car?
I don't know what the difference could be and because the car is >40 years old, newer engine etc etc - possible that swing arms are not stock.
Like I've read more than a few times - settting up the car is a challenge. One that I am actually enjoying. Thanks for any input on the question.