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Sorry guys - I've been out of town. I'll try and catch up on this thread as quickly as I can. The one thing that I can answer very quickly is the stano vs WL front bar. When the stano first came out I ran some calculations, and by my back of the napkin math I figured that the strano bar is about 15% stiffer than the WL bar set on 29mm.
 

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javid said:
Motion ratios ratio the motion of the strut / spring to the wheel. The impreza's strut moves at almost the same rate as the wheel (0.9). On a honda the wheel moves 1" for every 1/2" of strut movement. So with 1000# (per inch) springs on a honda the wheel will only need 500# of force to move 1 inch.

Spring rate * motion ratio = wheel rate
Ah, I see. Thanks for the basic explanation. I guess I need to read a book. :)
 

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Mykl said:
Ah, I see. Thanks for the basic explanation. I guess I need to read a book. :)
Well, only if your interested in the science. Else, ask trusted folks what to shoot for and then build it, drive it and adjust with your driving style, temp gauge and the old stop watch.
 

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Discussion Starter #64
Here's something new worth discussiong: Prodrive's forthcoming RB320 suspension package utilizes the factory stock front bar but replaces the rear sway with something beefier. This is completely contradictory to the typical tuning philosophy found here, but their research has found it to be the preferable setup. On the subject, Prodrive said:
In our testing we encountered a lot of understeer at high speeds with a larger front bar… Our current spec is a slightly larger rear with 2 settings and rubber bushes. We found this setup to be a perfect balance for the chassis.
As usual, Prodrive won't disclose the spring rates in said package. Also relevant is that this setup was designed for aggressive street tires, not r-compounds.

Nonetheless, even on street tires, this sounds very much like a "would lift a rear wheel easily" setup.
 

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wow, i must have spaced out big time for missing this thread. Now, I 've not read the entire thing, but i agree with Javid because of his practical applications of all this theory. BUT, I'd like to point out ICY/Pheonix Racing and their T2 Sti's, ALL of them lift a wheel, every one, and yet year after year they win the regionals and the run offs. Clearly its a fast setup, so if the best team in the nation is running cars that lift (on a restricted suspension setup) then it cant be all that bad.

Also, I'd like to point out that Sways and Spring rates are only a minor part of the suspension equation. You cant just single out one part and hope that theory works when you add it back into the equation. I don't have much in the ways of Javids on track applications, but i can tell you a few things about camber, and spring rates.
 

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IMO, rear wheel lifting is only bad if you still have the stock rear diff, or your driving gets you back on the gas early enough to expose the problem.

The lifting, in of itself, isn't a bad thing. It what happens as a result that is the problem. For me, I autocross and I left-foot-brake. When the wheel lifted, it was still up when I got back on the gas, making that wheel spin (the stock rear diff is junk), making bad things happen when it came back down.

Believe me, normally, I would have just enough front bar to equalize the front tire temps and then I'd stop. Unfortunately, I can't stop there.

For what it's worth, EVO's lift the inside rear all over the place.
 

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stretch said:
Here's something new worth discussiong: Prodrive's forthcoming RB320 suspension package utilizes the factory stock front bar but replaces the rear sway with something beefier. This is completely contradictory to the typical tuning philosophy found here, but their research has found it to be the preferable setup.
Don't forget that the RB320 package includes different shocks and springs -- and shorter bumpstops.

Looking at the totality of information on the topic, I really wonder if the early popularity of big front bars on STi's was due to the fact that they are into the bump stops so much of the time, and that a super stiff front bar would lessen the effect of same.

I have the Hotchkis "street" bars on my car, and while I love the flatter attitude of the body in corners I am not happy with how easily the front end loses traction. Then again I'm not running anything radical in terms of camber.
 

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All I know is, if I reduce the front bar size and leave everything else alone, I hike the inside rear up and it spins (with the associated loss of acceleration) until comes back down.

I am totally amazed at, given that its an AWD car with 3 diffs, that it won't accelerate with one wheel off the ground.

Since keeping all 4 on the ground and controlling enough lean to make -3 degrees of camber work are both required, I either have to have stiff front bars or much stiffer front springs.
 

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Discussion Starter #70 (Edited)
Splash said:
The lifting, in of itself, isn't a bad thing. It what happens as a result that is the problem. For me, I autocross and I left-foot-brake. When the wheel lifted, it was still up when I got back on the gas, making that wheel spin (the stock rear diff is junk), making bad things happen when it came back down.
Ah, you left foot brakers... I guess wheel lift would be a big problem in that situation. For a normal late-apex'er like me who get on the throttle more gradually, wheel spin is never an issue.

I wonder if your problem is more prevalent on 2004 STI's (I see that's the year you have). The car's power should never be going to just that one wheel- even if the rear LSD stinks, the center diff should lock up and allow the front tires to instead use that torque. The 2004 STI lacks a yaw or steering wheel sensor, so it needs to detect that wheel slip before it responds... and your slip is happening too suddenly for it to be handled gracefully. Only a little bit of torque needs to go to the front wheels because, once you've started accelerating, weight will then shift back onto your rear tires and alleviate the traction issue at the source.

Still, I would have expected even the 2004's meager default 35% front torque bias to be sufficient for this, so I wonder if it isn't a damper issue. I assume you have adjustable coilovers on your 2004? Do you run a lot of rebound in the rear? Reducing it may help.

2006+ STI's have a mechanical clutch in the center diff for ultra fast lock-up (not to mention a more even torque bias) so I would bet wheel lift is not an issue (or at least far less of one) in those cars even for left foot brakers.


wdb said:
Don't forget that the RB320 package includes different shocks and springs -- and shorter bumpstops.

Looking at the totality of information on the topic, I really wonder if the early popularity of big front bars on STi's was due to the fact that they are into the bump stops so much of the time, and that a super stiff front bar would lessen the effect of same.
Bingo. That's exactly what I think.
 

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Wow definately good information in this thread. Never thought about WDB's quote on the larger front bar. This makes more sense to me...:D Now I'll be going coilovers...I wondering if my 27/29 bar will be too much for the car...???



Anyway, good info indeed!



Kind Regards,
Ryan
 

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Actually, I have Ohlins (the ones I painted blue) and RCE springs. They are teamed with WL bars 29 front and 26 rear (that indicates their settings)

The car, as-is, is working wonderfully, though I do have the Ohlins set pretty high all around. Right now, I get no wheel lifting, no car upsetting over bumps in the lot, and very little of the infamous entry understeer.

I got the wheel lifting back when I had H&R coilovers with the WL bars (no droop travel out back), and with the stock struts and pink springs with only a 22mm rear bar.
 
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