My apologies on this review has been long overdue. But the opportunity to take my car to the track has been challenging this year and has delayed this review. But enough with the excuses, and onto the good stuff.
This is a review for HKS Hipermax IV SP for 370Z. SP model has been released this year for 370Z finally. Until this year, only Hipermax IV GT was available for 370Z from HKS. On my 2013 370Z Nismo, I was running the GT model through last year. I was running the GT coils in conjunction with Eibach sway bars. GT coils are aimed to be for street focused application. Even at the stiffest settings on the sway bars as well as the coilovers, the set up was too soft for the track driving. It rode very smoothly but the 10k/8k spring rate just wasn’t strong enough for the track driving in my opinion.
Current suspension setup:
• HKS Hipermax IV SP
• Eibach swaybars
• SPL front control arms
• SPL rear camber arms
• SPL toe bolts
• SPL endlinks (front/rear)
Current tire setup:
Street: Bridgestone Potenza S-04 Pole Position 265/35-19, 305/30-19
Track: Toyo Proxes R888 265/35-19, 295/30-19
When I received the Hipermax IV SP coilovers and read the spec, I was shocked to find out how stiff the spring rates were. Front came in at 14k, while the rear springs are whopping 16k! Moving from 10k springs to 14k springs is a good upgrade considering how soft the car was running on 10k. But I was curious how stiff the car would ride in the rear, going from 8k to 16k, basically doubling the spring rate.
Wanting the coilovers to perform at is full capacity, I read the instructions HKS has sent me carefully, and settled on a lowest recommended ride height to start. Also, I did not add any preloads to the springs. As these coilovers come with 1-way adjustment, I initially set both the front and the rear at 10clicks from the stiffest. (30clicks total available). Upon my first drive, I immediately noticed how loose the car was, especially on the rear end. I assumed it’s due to the stiff springs, and I started lowering the compression on the coils. The front end also would understeer on turn in. And I started taking out the compression in the front also.
What I first noticed, was how smooth the ride was even though the springs were very stiff. The car felt stiff, but very well dampened. As low as my car rides, often, my front end will scrape on highways when I hit dips. But with the SP coilovers, I was not scraping anywhere as much as I was with the GT coils.
My first opportunity to drive on the track was supposed to be in April at National Corvette Museum in Bowling Green, KY. However, due to the forecast calling for 100% rain, I cancelled the track day, as it would have not been a good test at all to go out in the wet as the first test.
Instead, my first chance to drive aggressively came at Zdayz 2017, at the tail of the dragon and other twisty roads. This is when I fell in love with these coilovers. Not only these coilovers handle the rather heavy weight of 370Z way better than previous set of coils I had, these rode more plus than stock NISMO. Best of both world!
However, I was starting to feel the car wiggle more as the trip went on. I suspected that the alignment may be off in the rear. I took a wild guess, and ordered the SPL lockout bolts for the rear. Upon taking the car to the alignment shop, we discovered that the rear was not holding the alignment, and we went ahead and installed the lockout bolts.
Two weeks later, I had an opportunity to go back down to Tail of the Dragon, and even through the abuse I could throw at down there, the rear alignment didn’t budge. Problem fixed!
Finally, the first week of June, I could get on the track at Mid-Ohio on my new setup. But this again is where my luck worked against me. My first session, I took it easy but was cranking out time that were a few seconds under my last year’s time. I felt a slight understeer at mid-turn, and decided to take out a couple of clicks of compression out from the front coilovers to fight that. I went out for the second session, and only 4-5 laps in, the organizer decided to exercise the “emergency red flag” as a drill, and our session was cut short. My cell phone/Harry’s laptimer crashed also during this session, and I was not able to capture my laptime. But the setup was allowing me to drive more aggressively, and felt close to be “dialed in” even though I had not taken a lot of laps yet. After a lunch session, I was getting all geared up and ready to go. But the nature decided to not let me have any more fun. The sky opened up, and the track day was completely ruined. There were running water all over the track, and it was not worth my time for me to even check out the wet condition with the R888.
Even with these limited testing, I must say these Hipermax SP coilovers are HUGE improvement for a driver like myself. I do not daily my Z, and only drive about 3000-4000 miles a year. I trailer my car from time to time, so the driving comfort isn’t huge on my priorities. But I have taken a trip down from Ohio to the Dragon comfortably on this set up. I’m amazed how well damped these dampers are, considering how high the spring rates are. They must have some amazing valves on these. I still have ways to go before these are 100% dialed-in, but I’m confident to say these are probably one of the best, if not the best coilovers you can buy for under $2000.
If you have any questions, please feel free to contact me. Here are some photos:
