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Steering rack swap?


Tronix

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The LGT rack is the same as the 05 STi rack.. doesn't get any better. For MOST corners the LGT rack is quicker than a EVO rack.

 

That said I think you are looking for more steering response which is completely different than the ratio of the rack.

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The Legacy steering rack is 15:1 ratio and the WRX was 16.5:1 ratio (unless you had one of the aftermarket racks) Why do you want to change?

 

Ted

 

 

I thought it was the other way around? hmm, weird, when driving a wrx the steering felt incredibly stiffer, quicker and more responsive.

 

Are there aftermarket racks that are tighter?

 

-T

for more pics and info... http://angevine.org/legacy/legacy.html
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Yep the LGT already has a tighter steering rack than a WRX, and better steering rack bushings. You should have seen the memory steer on my friend's FXT until he replaced some related bushings... And I think the WRX and the FXT share the same steering rack. Overall I really like the Legacy's steering feel and ratio. Try driving a Buick in comparison for a day.. bleh!

 

Crucial Racing makes a quicksteer for the WRX... but it's a really low ratio. I couldn't do that on a daily highway driver. lol

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I thought it was the other way around? hmm, weird, when driving a wrx the steering felt incredibly stiffer, quicker and more responsive.

 

Are there aftermarket racks that are tighter?

 

-T

 

Again, confusing the quickness (ratio) of the steering rack with steering response

 

 

EVO very quick steering response, quick on center, slower than a pickup past 1/2 turn. Why? Linear ratio steering rack.

 

The LGT with its varible ratio rack is slow near the center, and gets quicker at the ends of the travel. So somewhere around a 3/16 - 1/4 of a turn on the wheel the steering rack on the LGT starts to get FASTER than the EVO in degrees of steering input to degrees of tire angle change. A hairpin that both my full size truck and LGT take at 1/2 a turn of the steeringwheel, the EVO is at full steering lock and... er... needing more.... which is nice in one way atleast... teaches you to stay wide till turn in.

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Expand a little more on why my 13:1 ratio Evo is slower than my 15:1 LGT ratio? I think I understand what you are getting at on the surface, but not entirely. The Evo is 2.0 turns lock to lock, and the GT?
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actually, it's not A DIRECT BOLT ON for a 2002/03 WRX sedan rack to the GT.

 

I actually have a http://www.rev-lab.com steering rack (11.5:1 ratio, aka, 2 turns lock to lock, yes, you are reading this correctly, just 2 full turns, 720 degrees) that I had on my WRX.

 

The power steering hard lines and the steering coupling is not a direct bolt on. You would need to either bend the lines make some kind of coupling system to connect the lines to get power steering. You will then also need to either lengthen or shorten the steering column input shaft to make it mate up and work properly. The tie rods and the mounting points seem to be in a good spot for the car and you will probably have to just use rubber bushings to to make the steering rack brackets fit with the WRX steering rack.

 

Unless you are going to shorten your steering input as much as I did with my WRX (stock was 3 turns lock to lock and I shorten it by 33%), there is really no reason to shorten the steering input unless you race like I do on a normal basis (and even the SCCA rules prohibit such mods in the classes I race in). The GT and the WRX (aside from the TS) all have a 35.1' turning radius.. this is the critical point. The EVO has a shorter steering rack (2.2 turns lock to lock) but the turning radius is 38'.

 

The shorter steering rack is geared to do one thing: To let the driver do less hand work on the steering wheel. Unless you are a rally or race car driver, you really dont need to be turning the steering wheel much to begin with anyways. Even for my autocrossing, I understand more that I dont even need the shorter steering rack anymore.

 

The largest and most noticable thing that I dealt with when I switched the racks is that I was understeering more because I wasnt use to the shorten input that I need to turn the wheel.. basically I was turning the car too much, thus overloading the grip of the tires causing me to be understeering all the the time and chewing up tires.

 

Unless you are a true precision driver that DEMANDS quick steering response more than what I do on a regular basis, either you are eating up tires and beating the crap out of the car, or that you have just money to burn and want to have one kick ass responsive car.

 

If you want, send your rack to http://www.rev-lab.com and let them rebuild your rack for even a shorter response. I do not see the point of just shortening the steering just a tiny bit when/if you are going to spend the money, you better get a lot of performance out of it.

 

Keefe

Keefe
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Expand a little more on why my 13:1 ratio Evo is slower than my 15:1 LGT ratio? I think I understand what you are getting at on the surface, but not entirely. The Evo is 2.0 turns lock to lock, and the GT?

 

 

Evo = 2 turns lock to lock = 38' radius

WRX/GT = 3 turns lock to lock = 35' radius

 

In the Evo, the driver doesnt have to put that much input to make the car turn in general, but the car ITSELF doesnt have the turning radius to make it go where it needs to go

 

In the WRX/GT, it demands the driver a little bit more steering effort, but it also gives you a tighter turn when you need it.

 

The racks themselves can be fast or slow, it's up to the driver to make the car go fast or not ;)

 

If you are just talking about the racks, the Evo is faster than the WRX/GT due to the ratio, but, when it REALLY comes down to it, the driver can make up that difference in hand speed... so the real issue becomes "which car can turn tighter based on the suspension and steering angle?".. the winner here in this case is the WRX/GT.

 

 

Keefe

Keefe
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Now that's the best advice yet (post #10)... less the 2.0 turns lock to lock on the Evo in my driveway.

 

Although the GT requires "more" input, I would not say it is "bad". Not as quick as I would like, but my Legacy is for a different purpose.

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The linear rate of the EVO is the reason the LGT takes less lock for some corners. The EVO you have to crank it to the end to get even the modest ammount of steering lock, while the LGT goes from slow to fast as you leave straight ahead.

 

However I am wondering if part of the issue with my EVO atleast is understeer even at low cornering speeds. IE the LSD, centerdiff, alignment, or something else was causing it to push out from where the front tires were trying to take it.

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change your tire pressures so that the car can bite more on the front end and send some power to the rear. Aside from that, that open diff in the front really needs to stay down and have some resistance so that the rear has some ability to swing for you.

 

 

Keefe

Keefe
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The linear rate of the EVO is the reason the LGT takes less lock for some corners. The EVO you have to crank it to the end to get even the modest ammount of steering lock, while the LGT goes from slow to fast as you leave straight ahead.

 

However I am wondering if part of the issue with my EVO atleast is understeer even at low cornering speeds. IE the LSD, centerdiff, alignment, or something else was causing it to push out from where the front tires were trying to take it.

 

You hit the nail on the head, but we'll need to move over to Evom to discuss that...

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Unless you are a true precision driver that DEMANDS quick steering response more than what I do on a regular basis, either you are eating up tires and beating the crap out of the car, or that you have just money to burn and want to have one kick ass responsive car.

 

 

 

I agree, if everything is going well on the track, you shouldn't need quick/big steering imputs. But for those times when things aren't going so great, the quicker steering ratio is nice to help straighten the car out. The only time I've felt I really needed a quicker steering ratio in my DSM was for rallycross. That is an exercise in flying elbows.

 

That said, I think the stock LGT ratio is perfect for the car.

 

Jason K.

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change your tire pressures so that the car can bite more on the front end and send some power to the rear. Aside from that, that open diff in the front really needs to stay down and have some resistance so that the rear has some ability to swing for you.

 

 

Keefe

 

Eh... Don't think I'm going to be playing with the tire pressures much.

 

 

http://www.ej255.net/EVO_1.JPG

It was a 2004 RS so it did have the front LSD, not that it seemed to do anything. HORRIBLE power on understeer, and unlike the STi pulling throttle doesn't tuck the nose it, doesn't scrub speed agressively, etc. That was the result of being off line by a couple inches, going a hair fast for said line, paying a bit too little attention, and not knowing the car quite well enough. Fix anyone of the three and it wouldn't have happened.

 

And BTW people go off that corner daily. I just missed the deep rut that keeps people out of the woods...

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Damn, sorry to see that! Hope nothing is broke that has to grow back!

 

I have much more of a problem with power on OVERSTEER with my Evo... The ass acts like a RWD if I don't keep an eye on it. I think ALOT of it has to do with setup, and people's line preference though.

 

BTW my Evo is in the 400hp range though...

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Came off not too bad. Bruised chest, welt on my arm from the edge of the steering wheel, concussion, and thats about it.

 

EVO wasn't happy after that.... Lol drivers door was the only one that worked right. The "angle" to the hit on the front of the car is because the back tire on that side dropped off the cliff right before I hit the tree. I was very lucky it didn't go off to the right of the tree... 30ft cliff.

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You could, theoretically, have a mack-truck slow steering ratio and incredible steering response, dependent on how the *rest* of the car is set up. Mid-engine cars like the NSX, or rear engine cars like Porsches, are known for their incredible steering response because of low-weight in the nose, not necessarily because of their steering racks. I think they had relatively slow racks, to boot.

 

The main reason for the numb feeling/turn-in problems is the heavier nose, thanks to the AWD system that hangs out a bit in front of the front wheels. You can alleviate that though, as in the STi, with stiffer bushings, quicker-responding suspension, stickier tires and other measures.

 

A car is not a block of wood with wheels attached, it is a large and relatively flexible organism that has lots of parts. When you turn, for instance, your front stabilizer bar reacts to keep the outside wheel down on the road. The independent front suspension does that as well, while absorbing any mid-corner bumps. The rubber bushings on the stabilizer bar and the suspension gives way a bit to absorb some of the NVH from the road. Bushings on your steering rack do the same. The wheels themselves flex as well, especially if they are RE92's.

 

The point I'm trying to make is this - imagine you are swinging a steel rod with your arm, back and forth. Fairly direct, and heavy. Now make that two steel rods, which are connected by a semi-soft thick piece of rubber. Note that when you start the movement, the rods start swinging independent of each other a bit, with the further away rod slower to react and bending away, especially when you reach the end of the swing and start the other direction. It's these flexible bits and inertia that you are fighting, and the heavier the nose of the car, the more flexible the bushings within, and the makeup of your suspension, the slower the response feels.

 

Cheers,

 

Paul Hansen

http://www.avoturboworld.com | http://www.sevenphotos.com | http://www.scoobymag.com

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