jayton41

OK GUYS I HAVE A COUPLE OF QUESTIONS FOR AFTERMAERKET SUSPENSION FOR THE C55...I AM MAINLY ASKING THESE Q'S BECAUSE IM PLANNING ON TAKING MY CAR TO THE TRACK



1.WHAT ARE THE SPRING RATE FOR THE BILSTEIN PSS9 FOR THE C55

2.WHAT IS THE BEST COIL OVER SYSTEM FOR THE TRACK THAT WILL FIT THE C55

3.ARE H&R RACE SPRINGS LINEAR OR PROGRESSIVE(LINEAR BEING FAVORED)

4.CAN I USE THE PSS9 SHOCKS AND COMBINE IT WITH H&R RACE SPRINGS

5.WHAT DO U GUYS THINK ABOUT WHEEL SPACERS


TRY UR BEST 2 ANSWER GUYS..I KNOW WERE 2 GET ALL THE POWER MODS BUT THE SUSPENSION MODS ARE HARD 2 FIND ..THANKS

jayton41

please reply guys i realy wanna know

Zeppelin

You will see very little difference between the stock C55 suspension and a coilover setup. I would stick with the stock suspension and see how it performs. You will see bigger gains from tires, brakes, LSD.

OPM

+1

I am assuming you have not yet tracked C55. If so, stock C55 is way more car than you need. It has much more capability than you do – GUARANTEED. The best advice I can give you – signup for HPDE and get a better feel for the car and what road racing is all about.

PSS9 will be waste of money. Rear swaybar and kmac is probably as far as you want to go unless you ready to turn your C55 into a racecar and willing to completely reengineer suspension. I am not sure why you are asking about wheel spacers, but at some point you do what to destagger your wheels. I’d go with 17” because of better and cheaper tire selection.

As Zeppelin mentioned, the need for race pads will come up long before suspension. And if you simply have money that are burning a hole in your pocket – get LSD. It will help waaay more than PSS9.

splinter

^ excellent advice.

I’ve witnessed Zeppelin’s chasing down and showing the quick way around to many a ‘faster’ machine.

jayton41

i wanted 2 get a front and rear sway bar ..i want the pss9 2 lower my car dont forget about a lower center of gravity..what is kmac and destagering wheels??

MACHC5

I tend to agree with the C55 being a 90% capable track day car.
Found the brakes if pushed hard, to be needing of a little help.
And the traction control with it's throttle shut down to be annoying.

What's your spin for wheels and tires to use on the C55's...

MachC5

jayton41

ok guy i appreciate the help so ill get a lsd i know about the tires already but wat is a k-mac and staggering tires mean??.......wat about the renntech Adjustable caster/camber kit willl that help any.........and when talking about brakes wat about therenntech 8piston brake system ....sorry about all the questions guys im just very very clueless..i wish ground control had a kit for my car i would make life alot easier

PC Valkyrie

If you read what the people here have to say, they are telling you to keep your car relatively stock if you are a beginner to road racing/lapping days on a track.

Take your stock C55 to the track and see for yourself what the car is capable of. If you find yourself lagging behind other cars, the most effective way to go faster is improving on your driving skill as opposed to any physical modifications to your car.

The C55 is already quite a capable track car in stock form for your average lapping days.

Even if you do start modding for the track, the biggest yields will come from better, wider tires (espeically up front), and better brake pads.

Destaggering the tires means having the same width tires front and back. Your stock C55 has 225 wide tires in the front and 245 wide tires in the back. By having the same (hopefully wider) width tires up front and back, you can rotate tires front and back after track days so your tires will last longer. The front tires will wear out a LOT FASTER than the rears if you can't rotate tires front to back.

jayton41

and a weichers strut bar will help me please reply if u think not

OPM

• Destaggering will also help to dial out some of the massive understeer. C55 plows like a truck.

• See my comments about swaybar in “Argument with an Evo...”.

• kmac = http://www.k-mac.com.au/ Do not worry about this yet.

• OEM calipers are fine. But at some point you’ll need race pads. As you improve you’ll probably will want better front rotors. OEM brake fluid is fine for your first event, but if you can, bleed 0.5 - 1 liter. OEM stuff is actually pretty good and oddly very inexpensive. As you improve you’ll need to get better fluid.

• The main benefit of C/O is ability to corner balance, which is pointless on a DD. Lowering may do more harm than good. It takes a true suspension expert to properly lower a car and in a DD it’s simply not worth the effort or $$$. Do not worry about center of gravity – you ain’t going to roll. You might spin, but not roll. If you lucky it will look like this http://www.youtube.com/watch?v=EScWw...eature=related, if you are unlucky it will look like this http://www.youtube.com/watch?v=KTF5ZnSVoH8. Just joking.

• As all gearheads you want to improve your car. But what you’ll quickly learn – “improve the driver, not the car.” Your stock C55 is enough of a car for many HPDEs. When you get hooked and if you become a track junky you’ll likely realize you need a separate dedicated track car.

So go to http://www.mytrackschedule.com/Schedule.asp?Year=2009 or http://www.motorsportreg.com/index.cfm/event/calendar or http://www.trackschedule.com/sched.html and schedule some track time. The night before get sleep and in the morning bring water and your C55. I promise it will be an eye opening experience.

jayton41

so the c55 has under steer is that correct....so wat is best way 2 balance it

OPM

Almost all street cars understeer. It provides a safety margin to noob drivers. No such thing as “best” solution. But here a few from least to most expensive.

1. Unwind (straighten your steering wheel)
2. Lift (remove you foot off the accelerator)
3. Squeeze (apply brakes ‘gently’)
4. Power-Over (step on the gas and induce power oversteer)
5. Over inflate rear tires
6. Under inflate rear tires
7. Destagger
8. Install thicker rear swaybar
9. Decrease (increase negative) front camber
10. Increase rear spring rate

Of course there are many other things you can do e.g. lower rear, remove weight from front, add weight to the rear, etc.

jayton41

thats the only thing how do i do th last one increase spring rates..here no coil over system exept i thing the pss9 that lets u do that but the pss9 springs are progressive and im looking for linear springs

OPM

What does C/Os have to do with higher spring rate? That was a rhetorical question. The answer is NOTHING.

If you knew which springs you needed you could custom order to your specs. Of course you most likely could find what you need from top manufactures like Hyperco or Eibach. They already make gazillion springs in all diameters, lengths and rates. Please do not be offended, but the point is - you have no idea what you need. Designing suspension is one of the most difficult aspects of racecar engineering. It is part art and part science. I was involved in building 2 suspensions - one track/street and the other pure race. Both prototypes were tested on my S4. The later is still on the car. This experience taught me that even automotive engineers who spent their entire life around motorsports and who have access to proper software have to go through numerous trial & error permutations before the final product matches their set goals.

Although you can get some off the shelf product which might marginally improve handling, know that any improvement will come at the cost of comfort and it will not make your C55 race worthy. So do yourself a favor - get a swaybar and enjoy your car. BTW, reasonably decent C/Os will run you around $4K and top notch is around $7K+. I believe there is a pic of my C/Os somewhere in this forum. Try “Calabogie” post - I think it’s there.

I do not know what your financial situation is, but trust me, I have wasted enough $$$$$$$$$$ on automotive pleasures to know it’s important to think twice before “upgrading”. If your goal is to brag to your friends, than buy whatever will yield most in bragging rights. If your goal is improved handling, than get a swaybar and see if you need further upgrades. If your goal is racing, than signup for HPDE. After few dozen days at a track you’ll better understand what you want.

Sorry if I sound harsh, but I am trying to help you to avoid a mistake. Look, the bottom line is that if we take 2 identical C55s and twin brothers. One is given $3K to upgrade his C55 and the other uses the same amount to attend 10-15 track events. Then we make them race – the bro with experience will easily lap the bro in upgraded car. IOW, he will literally drive circles around the upgraded car.

jayton41

No bro dont worry u dont sound harsh i appreciate that ur trying to throw a few words in 2 help me ....so a rear sway bar would definetly help my handling ..what would happen if i got a front one 2

OPM

C55 has substantial understeer. By adding only rear you’ll dial out some of that understeer and reduce roll. Adding thicker front will further minimize roll, but you’ll have to add a very thick rear to deal with understeering. Doing so will create problems on an uneven terrain. Even sharply turning onto a steep driveway will likely to lift inside wheel off the ground. So save money and labor and get only rear. The marginal reduction in roll is not worth headaches in the rear. I know little about C55 platform, so I cannot recommend a specific bar. But my guess is it should be about 7mm thicker than stock. Most have a few holes so you can set them to hard, medium or soft. Thus, if you get a bar about 7mm thicker – set it on hard and see if you like it. If it’s lets say 12mm thicker – I would start with soft and look for hints of oversteer. If there are none – I’d go to hard. Someone here might recommend a specific bar. Sorry, I only know Audi stuff.

e1000

are you talking about a sway bar or a strut tower bar???????????

jayton41

i said it right there a strut bar

jayton41

so what about aero dynamic like splitter spoiler diffuser carnards will that help ??

kent426

The first reason the front loses traction is the loss of contact patch. The rear has a degree of negative camber so under hard cornering as the tire rolls over, more contact patch is retained. The front has zero camber and as such, rolls over the shoulder. The front should at least equal the rear to dial that out. You can also play with tire pressures between front and rear to compensate for it, higher front pressure first. My car does not have any understeer with a 235/275 set up.

insame1

good info but this thread is 9 years old.