EVOlutionary

iTrader: (38)

In my ongoing quest for better and better handling from my 2-time National Championship winning Street Modified class autocross EVO, one thing we are always searching for is better turn-in and cornering. The car has always been great in the slaloms and hellacious at rocketing from one corner to the next - but we have always wished the car would turn like those dang Bimmers!! Short of dropping a few hundred pounds and finding a way to even out the 62/38 F/R weight distribution - the next best option may just be the Perrin Performance PSRS Bushings!

Perrin Performance has been a member of the EVO tuning community amost since they first hit American shores. I have been using their rear sway bar end links for nearly 6 years. Yes, that's right - 6 years on the SAME set of end links!! They just work, so I kept on using them. Even swapped them over from my '04 EVO to my '06 EVO when I set out to build the ultimate autocross car. Despite the absolutely superb suspension Mitsubish has graced us EVO owners with from the factory - one thing that it does not have is adjustable caster. The factory caster setting is pretty low. That gives us the awesome twitchy, darty handling and great steering feedback through the steering wheel, but it does not necessarily give us the most amount of grip in a corner.

Enter the Perrin Performace PSRS (Positive Steering Response System). This is a replacement for the jumbo rear bushing in the lower front control arm. Even when replaced by a polyurethane unit - this jumbo bushing has so much flex that it allows caster and toe changes under hard acceleration, braking, and cornering. This does not yield the most stable feeling front end in the world. The Perrin PSRS replaces this bushing with an aluminum housing holding a spherical bearing. That means NO flexing of this suspension mount and therefore no changes in toe or caster under any sort of pressures. . .

The PSRS is available in two versions. The "stock" version which is a direct replacement of the stock bushing that does not change the static suspension geometry - just keeps it from flexing and changing under load. The second version uses an offset bushing that adds more caster to the front end for better turn-in response. This is the unit I chose to test. . .

For the installation you need to remove the front control arms. To do this you need to first detach the front ball joint from the upright, as well as detach the front sway bar endlink . . .



Then remove the bolt that goes up from the bottom through the rear bushing. . .



Then remove the front bolt that goes horizontally through the bushing . . .



This should allow you to take out the control arm. You will then need to press out the old bushing and press in the new PSRS. Be sure to align it properly when pressing in or your control arm will not go back in the car. . .

After reinstalling - the PSRS looks like this . . .





As you can see, the offset bushing moves the rear of the front control arm "out". This causes it to pivot about the front bushing and thus pushes the front wheel forward. This adds caster angle to the front suspension geometry. You could also achieve this by moving the top of the front strut back - same effect. (One thing to note here - as mentioned above this kit will move your front wheels forward. Looks like about 3/4" forward. If you are running very wide wheels/tires you may have to trim your front bumper. I am running 18x10" wheels with a +17 effective offset and I had to trim my Voltex front bumper. I will get pics of this soon)

You can also adjust the anti-dive/anti-lift geometry of the front end by changing the orientation of the spacers in the rear mount to raise or lower this pivot point. I have not played with this feature yet - but I look forward to tweaking it in the near future. Dialing in a lot of antidive should cause the nose to dive less under braking, but at the same time it may give the suspension less compliance and cause skipping under braking. We'll have to see what happens when I start playing with it. . .



HANDLING

So far I've had the car out for a few autocrosses and a test n tune day. The first thing I noticed just driving around town was that the car seemed less "twitchy". Before the car would tramline and want to follow every little groove in the road. With the added caster it does not seem to do that as much. It feels like there is a little more "dead" area right at the center of the steering, but as soon as you crank the wheel the tires bite HARD. Also seems to be a little less force needed to turn the steering wheel, almost like the power steering is amplified. This definitely helps in fast slaloms where you are cranking the wheel back and forth about as fast as you can. This should translate into less driver fatigue during a long stint on the road course. I should get a good feel for that this weekend as I'm running the NASA HPDE at Blackhawk Farms in Illinois.

I will add more feedback as the season progresses and I get more seat time behind the Perrin PSRS.

EVOlutionary

PERRIN_JOHN

iTrader: (4)

Thanks for the review and post.

Click HERE For The PERRIN Instructions On Line

EVOlutionary

iTrader: (38)

Thanks for the added pics John. I updated the original post with some handling feedback.

antilag_200

iTrader: (49)

Nice write up. I have the zero offset bushings. It would be nice if the zero lift and anti lift feature is explained for a suspension novice such as myself.

FJF

iTrader: (18)

Very interested in your impressions throughout the season. Subscribed.

EvoIXMR

iTrader: (66)

did you have to grind the subframe at all. I had to grind on my Evo VIII with the offset bushing and I believe you have to on the X as well.

Any info on your front tie rod end (balljoint?) Seems custom and not the whiteline version.

MJ23FE

iTrader: (3)

+1

Very nice review, Evolutionary!

Perrin John,
Can you provide any recommendations for those running your PSRS in regards to the spacers? Whether it be a car that is DD, or autox or road raced. I'm sure each one of us could tailor it to how we want our car to handle and/or react, but have you seen any combo working better than the other?

-Jalal

McLaren F1 2003

iTrader: (8)

+1 for more info on what the spacers are for

EvoLutionized8

iTrader: (62)

very nice write up. I am going to have to try these out. Cant wait to hear the rest..

Caesar

iTrader: (13)

I put these on my ride a few months back and was able to test them on a few track days, huge improvement in the response!!!

revvin9k

iTrader: (23)

Ditto.

Best review on these thus far. Heard of them through my tuner, now i'm sold.

CBRE

iTrader: (77)

Looks like a must have, ordering right away.

EVOlutionary

iTrader: (38)

I don't believe we had to do any grinding when we installed these. The instructions for the X did show a little bit of material that needs to be removed from the subframe. . .

The tie rod ends are Unlimited Works from Japan.

rawkus

iTrader: (16)

We are running these on our car and had to notch the frame... but we are on a VII.
Dan

PERRIN_JOHN

iTrader: (4)

Having the spacers like the OP does is stock like. Moving the extra spacer to the top, ultimately lowering the control arm mounting point gives it some Anti-Lift characteristics. Hope that helps.

JL