Project Evo IX – Part 12 – Carbon LSD And KW Suspension
By Joey Leh, Photography by the author
Project Evo IX’s last track outing, at the Redline Time Attack Spring Mountain event, did not go well. On top of being outgunned power-wise in the Street AWD class (our 350whp stock turbo setup always is), we discovered that our rear limited-slip differential had given up the ghost.
Flash back two events ago. In order to get the rear end to rotate the way we wanted, i.e. racecar-esque, we went with a massive 27mm solid rear swaybar. The result was less understeer on turn-in but LSD-killing three-wheeled exits on certain turns. Through high lateral-g load or off-camber corners, the stiff swaybar caused Project Evo IX to pull up its inner rear wheel like a dog peeing on a fire hydrant.
This constant loading and unloading wore out the holding power of the rear factory clutch-type LSD to the point that we were getting wheelspin in multiple corners at Spring Mountain. This is a problem since the whole point of having all-wheel drive is to have grip, not spinning wheels.
We knew that running too stiff of a rear swaybar with our setup would make the inside rear wheel pick up but we were weak and gave in to the temptation of oversteer. So it was back to the drawing board. Our solution was two-fold – we would need a new rear LSD and increased suspension droop travel.
As noted cheapskates, our first thoughts went towards using a new stock rear LSD and then towards re-packing the stock rear LSD to be tighter. We don’t enjoy spending money but, then again, we don’t like doing work twice either. Another stock rear LSD was now out of the question; if we need to take the car apart, an upgrade is going in. A re-packed stock rear LSD might be able to provide a tighter lock-up, but will the stock LSD clutches hold up to the on-track heat when repacked?
We wanted a stronger unit that would be able to hold more abuse than stock components can. Carbonetic answered our call.
As a sub-division of Across Corporation, a huge manufacturer of carbon c/c composites, Carbonetic’s entire line-up of products is carbon based. Carbon clutches and limited-slip differentials are their calling cards. Their Evolution rear LSD is quiet enough for street use but was designed with the holding power and heat capacity that we were looking for when on track.
With the use of their carbon composite clutch packs in the LSD, Carbonetic promised smooth lock-up characteristics and a long service life if the fluid was regularly changed. Carbonetic sells their own synthetic gear oil for use in the differential pumpkin. We cleared them out of eight gallons of the stuff. Yeah, we plan on going to the track a lot.
Installation of a rear Lancer Evo LSD is not difficult if you have access to a lift, air tools and two workers. Drain the pumpkin, pop out the rear lower control ball joint at the spindle, disconnect the swaybar endlinks and suspension, pull the axles, disconnect the driveshaft and undo the remaining four bolts holding the pumpkin to the rear subframe. We then undid the two side mounts and put the pumpkin into a vise to pull the stock LSD. All Evo 8 and 9 5-speed models use the same rear pumpkin and ring/pinion setup (43 teeth on ring gear, 13 teeth on pinion).
New LSD side bearings are a must (part #MN168441, you’ll need 2) and the Mitsubishi gasket sealant is highly recommended (part #MD997740). Once the rear LSD was swapped, we promptly drove ourselves into cross-eyed oblivion with the break-in procedure. Carbonetic recommended doing 15-20 minutes of figure-8s at 15mph and then changing the rear LSD oil. We found a deserted parking lot at night and did 25 minutes straight.
The break-in oil that came out the car was black with carbon particles. This is normal and should go away after we do another 200miles and change the oil again. The LSD’s carbon clutches give off a bit of powder and residue as they break in, that’s why the first two LSD oil changes must be done as recommended. We’ll report back soon after the Carbonetic rear LSD is put through its first test, competition at the Super Lap Battle time attack finals.
With Project Evo IX due to be displayed in the The Octane Report booth at the 2009 SEMA Show, we had even less time to prep for the track. The car would be sitting pretty (washed for once – Ed.) for a week straight, with its freshly installed and nearly OEM fitment INGS N-Spec bumper, and we wouldn’t be able to wrench on it while it was at SEMA. With two track events scheduled only three days after returning from SEMA, we would have to finish our tweaks before the show.
Luckily for us, KW Automotive came through big time. Three days before Project Evo IX was due to leave for SEMA, a box arrived to the OR office from Germany, via UPS express.
KW’s competition two-way coilover suspension had everything that we wanted – more droop travel, better valving, independent rebound and compression damping and more grip with less spring rate. The suspension isn’t cheap but the quality is well worth it. The bodies are stainless steel to resist corrosion and we also got the billet machined pillowball upper mounts.
If you’re looking for a true motorsport grade suspension for your car, KW will, or can, have you covered. Interestingly enough, the street-level Variant 3 and Clubsport coilovers use much of the same technology as the motorsport line-up, including the twin-tube design, differing mainly in terms of spring rate and damping curves.
The KW kit includes everything you need to get going except for the top mounting nuts, which are different than factory. You’ll need eight new 10×1.5 nuts to install the suspension. As we write this from the floor of the SEMA Show in Las Vegas, Nevada, we’ve only had enough time to test the KW competition suspension on the street. The ride is firm, but not unbearable, and exhibits good turn-in and feel. The largest difference so far is in terms of sharp bumps and highway expansion joints. Project Evo IX would previously lose contact with the ground and “jump” over ridges.
With the KW suspension now in place, we can feel the undulations are faster and much better damped, with the tires remaining in contact with the ground at all times. Our next test is to see if the KW suspension can maintain its compliance and feel over the curbing and harsh terrain of Buttonwillow Raceway. If you find yourself in fabulous Buttonwillow on November 11th, come stop by our pit and say hi. If not, keep an eye out here at The Octane Report for our report after the Super Lap Battle finale.
Sources
ENGINE
Tuning Technologies – Custom ECU flash
(909) 783-1200
www.tuningtechnologies.com
GReddy – SP2 catback exhaust, PRofec B-spec II electronic boost controller
www.greddy.com
Works – O2 housing, downpipe, high-flow catalytic converter
(415) 226-2500
www.worksevo.com
K&N Engineering – Oil filter
(800) 858-3333
www.knfilters.com
AEM – CARB-legal cold air intake
(800) 992-3000
www.aempower.com
Buddy Club – Racing Spec 272-degree camshafts
(909) 923-9188
www.buddyclub.us
SUSPENSION
KW Automotive – 2-way competition coilovers
(800) 445-3767
www.kw-suspension.com
M1 Fabrication & Development – chassis setup, alignment, carbon fiber front splitter, harness bar
www.m1fd.com
WHEELS
5Zigen – 18×9.5” +35 offset FN01R-C wheels
(310) 608-5575
www.5zigenusa.com
TIRES
Nitto – 265/35/18 NT05 high-performance street tires
www.nittotire.com
BODY
INGS – N-Spec front bumper, side skirts
www.ings-net.com
APR Performance – Rear carbon fiber wing, carbon fiber diffuser
(909) 594-3796
www.aprperformance.com
DRIVETRAIN
Carbonetic – carbon rear limited-slip differential
(310) 635-3555
www.carbonetic.net
Gruppe-S – ACD ECU flash
www.gruppe-s.com
Continue to Project Evo 9 – Part 11
Continue to Project Evo 9 – Part 13
Great write-up guys.