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Jul 262010
 

Super Steer has been a product we have kept secret since the inception of the company. This simple little part is like nothing else offered for your Subaru STI. Like most car enthusiasts at one time or another you have driven a go cart and noticed the super quick steering they have. You hear from time to time, a car has “Go- Cart” Handling, well now you can make your car handle more like a go cart with the PERRIN Super Steer System!

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Its started years ago with the first WRX I had and the one thing it really lacked was quicker, sharper steering. First looking to things like aftermarket steering racks to solve this problem, I quickly found the issue is cost and installation. Subaru made quicker ratio racks as well as a few Rally companies, but at $2500-$5000 a pop plus a lot of work, this just wasn’t feasible for most people. This is what sparked the idea for the PERRIN Super Steer System.

The first prototype was built back in 2003 with intentions of it working on the WRX. Then shortly after the STI came out and it changed the whole project because of two things. One it needed redesign to fit this car, and two the STI craze made us focus our efforts on other parts shelving the Super Steer until a later date. Its now been 2 years into its testing lifecycle and its finally ready to release!

How Does the Super Steer Work?

So how can we make the STI steer quicker without the added cost of an entire steering rack, or extensive installation? Simply be relocating the Steering tie rod connection at the hub. Moving the linkage pivot closer to the center of the hub, requires less input from the steering rack to turn the hub a given amount. Normally when you turn the steering wheel say 90 degrees the wheels turn about 6 degrees. After installing the PERRIN Super Steer System, turn the steering wheel 90 degrees and now the wheels will turn about 8 degrees! Meaning you don’t have to turn the steering wheel quite as far as you did before in order to get around the corner. This, 2 degrees could mean the difference of keeping both hands on the wheel, or having to cross your arms for a turn.

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Here is another diagram showing how this change in leverage at the hub effects how much the wheels now turn. This diagram is exaggerated slightly to show the difference.

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The heart of the Super Steer is the tie rod bracket. This bracket is what relocates the steering tie rod closer to the middle of the hub. Mounting from the OEM tie rod mount and securing to one of the break shield mounting holes, you can be assured that this over built part will not fail and give you trouble free operation!

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Included with the Super Steer kit is new shorter tie rods. Instead of using some off the shelf tie rod we took it up a notch and made custom length tie rods using high quality Teflon lined spherical bearing rod ends. Besides providing superior strength and being lighter than an OEM type, these allow for a wide range of adjustments depending on the application.

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So with the wheels moving further with every turn of the wheel, the next problem we faced was limiting the wheels rotation. If left alone it makes for a great turning radius but it with wider tires, you get tons of rubbing! Our Steering rack collar locks control this problem. They fit between the steering rack next to the OEM rack stops. These simple devices create new stops for the steering rack and limit the travel of the rack to accommodate wider tires and even cars with wider tires and PERRIN PSRS installed.

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How Much Quicker Steering?

So how much quicker steering does this make your STI steer? Here are a couple graphs to help you understand how the Super Steer works.

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This is a comparison of a WRX and an STI and how steering wheel input effects the amount of turning occurring at the wheel. For instance if you turn the steering wheel 90 degrees in your stock STI, the wheels turn about 6 degrees. After you install our Super Steer System, turning the steering wheel 90 degrees now moves the wheels about 7 degrees. The extra 1 degree of steering translates to 23 degrees LESS steering wheel input to get the same movement! That is huge! When turning the wheel 135 degrees(right about where you start to cross your arms while turning) the change is almost 2 degrees which is about 45 degrees less steering input needed!

In simple terms think of a clock. After installing the Super Steer System, the corners where you would turn the steering wheel to the 3:00 position, you’ll now be turning the wheel to the 1:30 position.

Sometimes you here steering systems are rated lock to lock. That is a tough way to compare because sometimes this is affected by the ability for the car to turn a tight circle. So while lock to lock can be a way to describe the Super Steer System, its not an accurate way to describe how much quicker it is. The best way to compare is how much the steering wheel turns in relationship to the wheels turning. Below are some other cars to give you an idea how your STI will compare!

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I spent time going around from car to car gathering data from known quick steering cars. While the WRX is not slow steering relative to you normal grocery getter car, its something most STI owners can relate to since most of them had one at one time or another. The WRX steering is the slowest steering of the bunch as is the Lotus. Part of the reason why the lotus is slow steering is that it does not have power steering. But the Lotus makes up for it with Ackerman Angle. More on that later. In our world the EVO is known to have super quick steering compared to the STI. You can see in this example how the STI with Super Steer installed, steers quicker than an EVO! We threw in some steering data from an Ariel Atom to give you and example of how an extremely fast steering car compares to somewhat normal cars.

In these graphs we are showing just one side of the car and how much it turns compared to the steering wheel. What most people don’t know is that both wheels don’t turn the same amount! This angle difference between the left and right wheels while turning is called the Ackerman Angle. The Ackerman Angle is not something that is adjustable on a road going car, but it is something that greatly effects the handling of the car.

Added Features of the Super Steer System

Added Anti-Ackerman Angle

Imagine your car is turning in a small circle in a parking lot. The inside wheels are turning in a much tighter circle than the outer wheels. So naturally the outside wheel doesn’t need to turn in the same amount as the inner wheel to make the circle. Its this relationship from the inside to the outside wheel turn-in that the Ackerman Angle comes into play. A Pro-Ackerman setup is where the inside wheel turns in faster than the outside wheel. An Anti-Ackerman setup is where the outside wheel turns in faster than the inside wheel. Stock car guys and real race car guys will say a Pro-Ackerman setup is better for higher speeds, and an Anti-Ackerman setup is good for short tight courses. A simpler way to think of this is Anti-Ackerman creates some toe-in while turning. is when turning the wheel, the outside wheel is toeing in or toeing out compared to the inner wheel.

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In our testing of a bunch of cars and their relationship of steering wheel rotation to wheel rotation, we also gathered lots of data regarding OEM Ackerman Angles. 08 STI and most OEM cars are Pro Ackerman meaning the inside tire turns in further than the outside tire. The only car we tested to be Anti Ackerman is the lotus. Having driven Lotus many times before, you can feel how the steering ratio is slow at lower speeds, but as the car goes faster and faster it steers quicker and quicker. This is because of the Anti-Ackerman angles. One could use this info and determine that the closer you are going to get to an Anti-Ackerman setup the quicker the car is going to turn. The Super Steer system is removes some of the Pro Ackerman angle effects making the Ackerman Angle closer to that of some of the quicker/twitchier steering cars out there.

Ball Joint Extender

A feature that is built into the PERRIN Super Steer is a tie rod ball joint extender. When you lower your car, it changes some of the suspension geometry for the worse. So things like ball joint extenders and roll center kits bring these things back to where Subaru designed them. The Super Steer has a tie rod ball joint extender built into it! This saves you a couple hundred dollars if you ever plan to install a roll center kit. We made our offset such that it suites cars lowered around 1.5 – 2″.

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The idea behind the Super Steer is simple. Make your steering quicker by changing the geometry of your front suspension, but do so in a way that it doesn’t affect the geometry in a negative way. We feel we have done this with lots of testing over the last few years. There is one downfall of the PERRIN Super Steer System, when you get out of your STI you will have to settle for boring, slow steering normal cars! Who will want this? Any autocrosser, any racer, any casual track day participant, and pretty much anyone who has an STI and drives it!

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We have had a lot of questions come up regarding how strong this part is and also have questioned the Super Steers integrity. These below points are to help customers better understand those concerns. We really hope that this helps customers feel better about the part.

Tapered Bolt is Stronger??

This mentality of it being stronger is a concern for some, but the taper has nothing to do with being strong. Our body is being tightened between two surfaces, the bolt and the hub. Its not relying on the strength of a stud to work against like the OEM part or other ball joint extenders. In the OEM application, the stud is relocating the point of force 1.25″ or so form the hub. This puts a lot of force and deflection on the shaft of this part. This requires that is very strong. Which is why people who make extended versions of these parts have to make them really high quality as you are really starting to add stresses to the shaft as you make it longer. Our part is mounted right to the hub surface making the point of force very low. The deflection all goes into the billet body and carried by the both bolts. Again, very stiff.
The tapered part of ball joint extenders has nothing to do with making its stronger, it only has to do with keeping it tight with all that force trying to work that 1.25″ lever arm back and forth. But in the case of the PERRIN Super Steer, this isn’t an issue.

Will the Super Steer Come Loose??

The idea that it could come loose is valid concern. But if that was the case then what about all bolted connections on the car. Are all connections using bolt and holes loose and or moving within their mounts. Think of strut bolts, control arm bolts, trailing arm bolts, and others where they are under far more stress and all have holes larger than the bolts. They do not come loose because they are tightened properly.

For example, your front control arm forward bolt uses a 12mm bolt (11.08mm on the shank and 11.78mm on the threads), that is in a hole that measures 12.35mm on the arm and slightly larger on the subframe. That is .57-1.27mm of slop. But this bolt doesn’t come loose because its tightened properly (and has way more stress on it than our part does). Same goes for our part. In our case the head of bolt is locked into one side and only has a small amount of slop on the hub side. When its tight its not going to come loose.

But for that matter, there are many applications that use steering tie rod ends with ZERO TAPER to them (VW/Audi’s, Mercedes, Jag’s,Land Rover,..) They use a single sear setup, and are similar to how our OEM front endlinks connect. Some only have a chamfer to make sure its centered over the hole.

I think that with that, there is plenty of info out there for customers to make an educated guess if this is a product for them.

 

 Posted by on July 26, 2010 First Look, Suspension Part Design &Tech Tagged with: , , ,