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Old 06-02-2015, 08:33 PM   #1
Jard
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Impreza WRX HKS Hipermax MAX IV GT Coilovers (2002 WRX)

HKS Hipermax MAX IV GT Coilovers

An everyday coilover?

I dismissed the whole idea of it a long time ago. I advised countless numbers of Subaru owners to just get a good strut and spring combo since all they really wanted was a car that looked better and sat a little lower.

Now, HKS is making a product that changes that.

Gone are the crazy spring rates of the JDM brands that came with the original 2.5RS the introduction of the WRX to the USA. The damping and super stiff springs were well suited to the glass-smooth roads of Japan but just didn’t work with our potholes and frost heaves.

HKS sent me the Hipermax MAX IV GTs to try on my 2002 Impreza WRX Sedan. The 106,000 mile stock struts were getting a little long in the tooth and were due for replacement, but, at the same time, I wanted to improve on the looks of the car with a drop in ride height.

I chose the GTs (over the stiffer SP models) because I have no ambitions of driving this car on the track. This is my (and my wife’s) daily driver through and through. It needs to be compliant enough to haul kids around and not rattle our teeth out on the suburban roads of Maryland just outside the DC Beltway.

So…let’s talk numbers.
Spring rates (in N/mm (kgf/mm)): F=59(6) R=29(3)
These convert to roughly 336 pounds / in in the front and 166 pounds / in in the rear. These will be an easier comparison to the numbers you usually see thrown around here on NASIOC for aftermarket springs.
Out of the box ride height change (in mm): F=-47 R=-16
These convert to drops of 1.85” in the front and 0.63” in the rear.

Even before the coilovers arrived I was surprised at how reasonable those numbers seemed. The front is stiffer to accommodate a lower ride height but not outrageous compared to the other offerings out there (stock springs are 163 pounds/in). The rear rates are bumped a bit, but again nothing crazy (stock springs are 119/132 progressive).

Many of the aftermarket springs available for the GD Impreza are either too low without being stiff enough or too stiff to work with stock struts. This means to get a good match you need to spend the extra money to upgrade your struts. Even then there aren’t a ton of great options available and you will not have the height adjustment offered by a coilover to dial in what you really want. Now there are a ton of coilover options out there but, in my opinion, most are either of subpar build quality or they are way too stiff for a street car, focused more on the weekend track warrior.

On to the Hipermax MAX IV GT as an option for a daily street driven coilover. Thanks to HKS for supplying them and a huge thanks to AJ711 for the help with the install!

What’s in the box?



The front coilovers were packed very well and came with instructions, a certificate of authenticity, washers for the ABS sensors (more on that later), some zip ties (I didn’t need them) and wrenches for adjusting the ride height.



The rears came with just the coilover units themselves.



I was impressed with the build quality. The coating looks durable and I like the way HKS integrated the dust boot. I also really like that everything is preassembled and pre-torqued. This helps my feeling that these could be a great plug-and-play replacement. The adjusters are actually on the bottom of the strut, so with the rears you don’t have to pull out the back seat just to stiffen or loosen them, if you desire. I like that too. For the purpose of this review we did not adjust anything. Ride height and strut stiffness was left as it came from HKS.

I’m not going to walk you through a full coilover install, there are plenty of threads for that. I am going to show you a few tips and tricks particular to installing these coilovers on a 2002 WRX Sedan.

Okay, what are we starting with?



It’s an almost bone stock 2002 WRX Sedan (yes, they still exist). Wheels are from a 2012 WRX: 17x8 and the tires are 235/45/17s. That wheel gap is hideous.

Family car!



No install write-up is complete without a picture of a cute kid helping (if you have one around).



I actually did the rear of the car first because "they" say do the harder part first. Taking out those seats and those top nuts is always a pain.

Using the correct tools helps a lot!



Here’s your first tip: leave the nuts on the top studs very loosely. It will keep the strut assembly in place after you remove the bottom bolts. You can reach up and undo these with 1 hand while holding the strut assembly when it’s ready to come out (if you don’t have a helper).



We actually pulled the brake calipers off in the rear to get better access to the bolts at the spindle. An electric impact wrench made quick work of them and we pulled out the stock stuff (don’t forget about the clip holding the brake line to the strut!).

Let’s look at the rears side-by-side.



They are certainly prettier than the stock struts. The overall length is just a little shorter for that mild ride height drop in the rear.
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Last edited by Jard; 06-03-2015 at 10:23 AM.
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Old 06-02-2015, 08:33 PM   #2
Jard
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Here’s your next tip: The metal plates that are over the tops in the rear won’t fit. The nut sticks up too far on the Hipermax coilovers so you can just discard this plate (call it weight savings).



Fitment was A+ and the rears went in without any issue. Don’t forget to reconnect that brake line with the stock clip!







Again, the proper tools make this much much easier.



On to the fronts.





Okay, now we are starting to see a big difference. At this point I started to get a little concerned: are these going to be too low?

Build quality is excellent and the connectors for the stock brake lines and ABS sensor are present.

Here’s where we hit our first minor issue.



After snugging the top bolts the hub was nowhere close.

Time to improvise.



Ah yes, the old jack trick! Be careful when lifting the hub with the jack that the hub assembly doesn’t slip off as you are going up. We got this side bolted in without much trouble and moved on. The other side was actually a bit easier as the sway bar pulled some slack up and moved the hub closer to the mounted coilover.

All done!



Yes, I should replace that rotor…

The only minor difference with installing these versus stock struts is the washer used on the ABS sensor line. The washer will prevent the bolt from coming in contact with the body of the coilover, so make sure you use it. The instructions were clear but I wasn’t sure why it was needed until I actually bolted them up.

Fitment again was A+ and everything bolted into place without much hassle.

Last edited by Jard; 06-03-2015 at 10:23 AM.
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Old 06-03-2015, 10:23 AM   #3
Jard
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First impressions.


LOW

That dreaded wheel gap is now gone.

We took it for a ride and it was immediately apparent that things were stiffer than stock. My street isn’t very rough so there wasn’t a huge basis for comparison there, but I did not think the ride was either jarring (oversprung) or bouncy (underdamped). Once we got up to speed on a main residential artery the HKS Hipermax MAX IV GT really started to shine. As soon as we cleared 35 MPH the ride smoothed out tremendously. I really feel like HKS nailed it here in terms of spring rates and strut valving and I wouldn’t change a thing.



It’s now been about two weeks and I’ll add some additional driving impressions:
The settings from HKS are low enough to look good and also stiff enough to keep from rubbing or bottoming out even with wider tires like my Bugeye WRX. I continue to be very impressed with the ride once up to speed but I do feel the low speed (under 35 MPH) ride is somewhat of a tradeoff. Unfortunately that’s where we do a lot of our driving since we use the car as a commuter and we have a lot of stop and go between lights. I understand some of this is just a byproduct of stiffer springs and our driving habits and we would have the same issue with conventional lowering springs.

With all that said, I would not hesitate to recommend these HKS Hipermax MAX IV GTs for anyone interested in lowering their car without sacrificing complete comfort on a day to day basis. My wife reports that the car is more fun to drive and she feels like it is much flatter in corners (so they pass the wife test!). I plan to contact HKS to see if raising the car a little and adjusting the struts could help the low speed ride, and I will report back after some testing. The beauty of coilovers is I will be able to do that!

CN: Installed some nice new coilovers from HKS, they fit great, I love the way the car looks, I like (almost love) the way it rides
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Old 06-03-2015, 10:25 AM   #4
HKSUSA
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Thank you for the excellent write-up & review!
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Old 06-05-2015, 01:53 PM   #5
wrxhard
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Very helpful write up (especially for someone in the market) and a great looking product. Thanks Jard and HKS.
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