Why?
The goal of this project is multi-fold. I can’t say it’s purely aesthetic or performance. The fact of the matter is that the two are intimately intertwined.
Lowering on to ramps
Performance Goals:
Lower Vehicle center of gravity (CG)
Reduce body roll
Improve steering wheel feedback
Increase vehicle direction change responsiveness
Reduce ‘squat’ upon acceleration
Increase cornering speed
Aesthetic Goals:
Reduce fender gap
Reduce ride heightPerformance Dings:
Lowering vehicle affects suspension geometry. Namely the roll center will be affected by altering the angles for which the factory control arms were designed to operate at. Installation of Roll Center Adjusters (RCA), which are essentially spacers, can help re-align the geometry
Aesthetic Dings:
Scrape scrape
Increase potential damage to vehicle underbody
Increase potential damage to bumper, exhaust, and any other low hanging components
Get stuck in driveways if suspension is too stiff. Not so much of a problem with a vehicle equipped with a Limited Slip Differential (LSD). Was a noticeable problem on my 240SX with an Open Diff.
Tools
Required tools:
8mm wrench
14mm wrench
17mm wrench
19mm wrench
10mm socket
12mm socket
14mm socket
17mm socket
Allen key
Car Jack
Jack Stands
Breaker bar
Torque Wrench (test to make sure it works beforehand)
HKS Kit Comes with:
4 bolts – lower shock absorber bolt
8 spacers – for each side of lower shock absorber bolt
8 zip ties – to hold brake line/abs line away from danger
2 spanner wrenches – to adjust coilover settings
2 small screws and nuts – for brake line bracket
2 clamps – for brake line bracket
2 small metal grants – ?
1 flexible damper adjuster – with a set screw
1 small Allen key – for set screw
1 fixed Allen damper adjuster key
Procedure
Find a friend with a garage
Find a friend with tools
Sequence:
Start with Front Right Corner
Next, Front Left Corner, should be similar to Front Right
Move to Rear Left Corner (may be the most difficult side due to fuel filler neck unmounting)
Finally, Rear Right Corner
Front:
Removal
Remove 10mm bolt for ABS Cable from Upper Control Arm
Remove 2 Upper Control Arm Bolts (17mm)
Undo Bracket that holds ABS Cable to Arm to relieve tension with Lower Control Arm Bolts…
Undo brake line that are bolted to the strut body
Undo lower bolt of suspension (17mm)
Undo 2 bolts (14mm) for the top-hat in the engine bay
Remove coilover shock+spring assembly
Install
Insert new shock+spring assembly into place
Install lower control arm bolt, don’t torque yet
Hand screw the top-hat bolts, don’t torque yet
Torque Lower Control Arm Bolt [FTS (Factory Torque Spec): 47 lb-ft]
Hand screw bolts for upper control arm [FTS 76 lb-ft]
Reattach ABS Cable
Reattach brake line to the strut (using newly purchased bolt)
WAIT TO TORQUE TOP HAT BOLTS UNTIL CAR IS UNDER LOAD
Originally Posted by Krazykoreankid View Post
When u say ***Suspension MUST be loaded prior to torquing any bolts in the suspension system***
Repeat for Passenger Side
Torque Specs:
Front Coilover Lower Bolt: 47 lb-ft
Front Upper Control Arm Bolt: 76 lb-ft
Front Coilover Top Hat Bolts: 36 lb-ft
Front ABS Sensor line bolts: 7.2 lb-ft
Front brake line bracket bolt: 16 lb-ft
Rear:
Removal
Removal Prep
Start with Driver’s Side Rear
Remove Gas Cap
Remove 3 bolts (8 or 10mm)
Remove spare tire and spare tire trunk lining [Lining that is to be removed will have a back and metal piece to hold onto so they can be removed]
Bend back passenger side of liner to expose the top strut bolts and gas filler line
Remove 10mm bolt on gas line
“Firmly but gently” pull the gas line neck back, should pop out of place and dangle
Reinstall gas cap to protect the gas line contents
Coil Removal
Remove bottom bolt [can undo suspension link first instead, to relieve pressure from lower arm]
Hex key + 14mm wrench to unscrew link from under the car
Bolt is on the back side of the 4 circular dots, below the bottom left of the strut behind the ABS Cable
Only need to undo one side
Unbolt the top hat mounts (14mm)
Install
Install lower bolt and torque [FTS: 47 lb-ft]
Hand tighten top suspension bolts and wait to torque until loaded
Move on to passenger side, should be easier without the fuel line
Once both rears are installed, reattach the suspension link
Use the hex key to ensure the link doesn’t twist while tightening the nut [FTS 22 lb-ft]
Torque Specs:
Rear Coilover Lower Bolt: 47 lb-ft
Rear Upper Control Arm Bolt: lb-ft
Rear Coilover Top Hat Bolts: 36 lb-ft
Rear ABS Sensor line bolts: 7.2 lb-ft
Rear brake line bracket bolt: lb-ft
Rear swaybar endlink [control arm end]: 22 lb-ft
Once Fronts and Rears are Mounted
Install Tires
Lower vehicle from jacks
Torque top hat bolts at each corner to 36 lb-ft Install process complete!
Next Steps
Let the car sit for a day or two before doing anything
The springs can take up to a week to settle/set
Wait a week until getting alignment done
Photos
Front Passenger Side
First coilover removed, side-by-side comparison
Front Right Side
Shock Removed
2nd Corner
Installing Brake Hose retainer clamp
OEM Shocks are Heavy!
Lowering on to ramps
Fuel filler neck relocated to trunk
Gas line work
Yes, we actually removed the fuel filler
Ready to lower
Seen through the wheel
Increased fender gap up front
After Install
Height Adjustments
Interestingly enough, after installation the rear fender gaps decreased, while the front fender gaps increased. This is with the standard out-of-the-box shock body lengths.
Front Left, Front Right, Rear Left, Rear Right:
To Adjust the ride height, I shortened the shock body length by the following amount:
I adjusted the driver’s side shock body to just 2mm shorter than the passenger side, as the driver side fender gap was almost half an inch lower than the passenger side.
Bear in mind these shocks have a lever ratio of 1.5mm, so for every 1mm of adjustment of the shock body length, the ride height is adjusted by 1.5mm.
Other locations where I measured the original ride height include:
After Adjustment
Driving Reflections
After the install, I’m very impressed with the ride quality. It’s firmer than stock, but not jarringly stiff, like you might expect on track springs. It honestly feels pretty close to before, in terms of stiffness and the response to bumps on the road. While cornering, however, the car feels incredibly flat and composed, mashaAllah.
I have yet to adjust the damping knobs and see how that affects the car’s behavior as well!
Update: Day 3
Now that I’ve driven around town a bit, I am ready to get the alignment done to ensure I don’t prematurely wear these brand new tires. I figure some light driving will help the suspension ‘settle’ into a more natural state, be it the control arms that were fiddled with during install, or the brand new gas shocks which are supposedly yet to reach their ‘idle’ resting position, as expected to occur within one week.
Looking down at the tires from the top or behind the car, both the front and the rear especially the rear, clearly show negative camber.
I’m truly astounded by how similar to stock the ride quality feels. Bumps and undulations in the road seem very similar to how they did before, on stock suspension. In fact, the stock suspension may even have been a bit more harsh on certain bumps, although they do have 100k+ miles on them. My last set of fully adjustable coilovers had 8k/10k springs on them, while these are 8k/7k which is not too far off from stock (4-5k ish rates), so I expected an incredibly stiff ride. Instead, I was pleasantly surprised by the feedback of these.
I’m equally in awe of how flat and stable the car feels while taking turns. The steering does seem a tad bit heavier (perhaps due to altered suspension geometry?), but the car feels so much more composed when requesting a direction change. Body roll, at least on around town driving, freeway onramps, and minor turns appears to be eliminated. I’ve yet to see how the car will behave during more aggressive driving, such as autocross, track days, or otherwise.
HKS advertises this suspension as providing ‘both sportiness and comfort’. It’s too soon to give a detailed analysis, but the immediate reaction is that they live up to that description.
Resources
Here are some excellent resources I’ve come across while reviewing how to install these:
Comments