Project Gen 3 STi: Suspension upgrade with M7

Project Gen3 STi GR suspension M7 coilovers SUbaru

Project Gen 3 STi: Suspension upgrade with M7

by Wes Dumalski

When last we left off with Project Gen 3 STi we were enjoying the power and up to this point the only modifications we had done so far were to make the car go faster. It's was time to change that as the GR STi is a bit soft around the middle. Our friends at M7 came to our rescue with their Super Street Performance Coilover setup. 

We were eager to put this new suspension through its paces to see what type of performance it really offered. The M7 coil overs have a retail price of just $1,595 making them quite affordable and us slightly skeptical. We knew going in that the real answers would come with time spent with the suspension and as such we offer this disclaimer. This review will be ongoing. One cannot simply bolt on a suspension and comment on ALL of its attributes or deficiencies in a single weekend. This certainly is a dual purpose suspension that will see the street as well as track and autocross time and as such we want to comment on our experiences as our build progresses. With that out of the way let's talk about what we noticed upon receipt!

While out covering the Modified Streetcar Shootout I came home to find a large parcel clogging up my hallway. While out of town my family members who were kind enough to care for my cats were also kind enough to move the M7 box in to my house. I mention this because if it were not for them we very well might not be reviewing this suspension right now and you very well may have bought it off of the electronic Bay for pennies on the dollar. Thanks to their assistance I quickly dropped my bags on the floor and wasted no time in opening the box. 

The first thing I looked at was the packaging and how it protected the product. M7 used double boxes and individual bags of packing peanuts to protect all 4 coil over assemblies. As I pulled out all 4 and unwrapped them I also found the tool bag inside. The kit comes with two spanner wrenches for perch adjustment as well as the proper allen head for the camber plate bolts. As I set up my station for a photo shoot with the M7 goodies I took in their fit and finish as well as design features. Frankly for their modest price point they have no business being this nice right out of the box. The anodizing on the top hats and perches is perfect as is the coating on the damper bodies. The adjustment knobs are knurled for easy adjustment and etched with arrows and the M7 logo. All of these nice little details make for a good initial impression.

M7 coilovers Subaru STi Gen 3 GR
The knurls on the adjustment knobs make for easy changes even with wet or slippery hands in the pits. The S and H marks along with the arrows make them virtually idiot (Wes) proof. 

I turned my attention to the front setup first and deduced what I could. The adjustment knob is on the top of the damper shaft and is labeled as a 35 way single adjustable damper. They use an adjustable camber plate that has reference markings on top and a sealed bearing design on the bottom. As you move down the damper you will notice the dust boot assembly as well as the plastic sleeve on the spring perch that isolates the spring from metal to metal contact.

M7 coilover camber plate sealed bearing subaru STi
Here you can see the sealed bearing design under the top hat as well as the spring isolators and dust boots. This setup comes fully assembled and ready to go out of the box. They also label the Left and Right side for ease of installation. 

The dampers use threaded bodies that screw in to the bottom housing and these housings have the tabs that mount to the control arm. They also have the appropriate mounting provisions for the ABS sensor as well as the brake line fitting. They use 2 collars in a jam nut configuration to secure the perch and adjust spring pre-load while a third collar on the bottom holds the damper within the bottom housing.

M7 coilover spring perch body jam nut STi suspension damper
Here you can see all 3 jam nuts that are turned with the included spanner wrenches. The lower nut unscrews to allow the body to thread in or out of the lower housing. This allows ride height adjustment without affecting spring pre-load. The upper perches adjust spring load. Our observations lead us to believe this is a monotube design with a single adjustment that controls mostly rebound with some compression. Unless we have the occasion to disassemble them or get them on a shock dyno our speculations will remain exactly that.

The front springs are labeled with the numbers 62 200 008. These numbers tell us the spring diameter and length in mm as well as the spring rate and in this case we have a spring that is 62 mm in diameter, 200mm long, with an 8kg/mm spring rate. If you convert that to standard measurements they are 2.5″ diameter springs, 8″ in length, with a rate of 448 lbs/in. For those of you who are curious you can convert kg/mm with the following formula: 

Formula = 1kg/mm = 55.9974146

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