Greetings! Looking for advice on full suspension upgrade for Autocross/SCCA. Have full set of adjustable rear components coming Ground Control, adjustable camber fronts, AMG front bar & bushings so far. Looking for baseline (or race set) setting for suspension. Also, which coil over kit to get. My preference is for Bilstein B16/PSS9 set. Do not know about Ground Controls or K&W kits. Feedback appreciated. This is a spare no expense full rebuild.

 

So I put the K&W spring kit it does allow some adjustments to the ride height, but you have to compress the springs to change height. Koni sports are adjustable and let you change stiffness easily. STRONGFLEX sell polyurethane bushings for the R170 MB that you can use, also you might want to look at the Brake upgrade you can do with the 345mm front disk, I did a big right up on it with photos in the brake section.
MJPowers use to race a XFire and can give you some info if he still monitors this site, I bought some of his racing parts when he moved up to a fast class.
Dan

 

Thanks! Good information here. I will let you know how it goes!

 

Are you changing classes? Are you moving to street prepared, STR, or ? I'd stay in DS. If you do, any springs, brakes, etc. are not allowed. I would change wheels to 17x7.5 in the front and 18x9 in the rear. I'd get the lightest wheels that I could find. I'd mount 225/40s on the front and 275/35s on the rear. Less weight would help. Then I'd use crash bolts in the front to get the negative camber and proper caster in the front. You've already changed front sway bars; so you don't need anything there. Good luck.

 

Crossfire in Street Touring seems to fall with STU. It is not officially placed in Street Touring class, and my regional club and I have been trying this out. There's an argument for STX, but it is weak.

I'm currently trading with this fully ST prepped 350z with a good driver at the wheel, and I'm currently only in ST due to brake rotor changes. However, this weekend I am going to begin an experiment (installing today) with the firmer SRT6 springs with first test courses the first weekend of June.

Keep in mind, that if you choose a suspension upgrade which moves to "true coilover shock" design, then the car is no longer Street / ST (I think it is the same for SP as well) class legal.
Also, if you want to run in ST (I really enjoy the competition at this level in my area), then you'll need to compromise on the adjustable linkage to either only the top arms or only the bottom (my research recommends the top arms be adjustable). That should be plenty though, as you can use the top two arms as a camber controller.

So your upgrades depend on if you want to build to a class, or build more for maximum fun / performance! Are you planning on keeping it daily worthy?

Cheers!
Jack

 

csetjack15, is your car corner weighted? What are you racing a Crossfire or a 350z? I'm confused. If you stay in ST class and corner weight a Crossfire did you change the Mercedes spring pads?

 

Sorry for the confusion, I definitely drive a Crossfire and am currently competing in STU! lol

I've not corner weighted my car yet, but they seem to have shipped with ~55/45 weight distribution (checked at a weight station), so not terrible at least to start with.

Just yesterday I swapped in SRT6 springs that I bought off of another forum member, I used dot2 pads on the front, and kept dot1 pads in the rear. Overall my ride height stayed basically the same (which was my current desire). I appear to have the same ride height up front (its literally +/- a mm or two from base factory), and the rear end lost ~1cm from the SRT6 spring change. So I've got ~67 cm front height and ~71 cm rear height now.

Also, everything I buy is pretty much "Mercedes", a few places seem to have actual Crossfire tagged parts, but it is all the same anyway.

Tangential, but slightly related note, don't try to use a spring compressor on your rear springs unless you want a nice set of holes in the rear top perches (I couldn't find where they entered the body, if they even did). Take out the inner lower control arm bolt, and pivot the arm to the floor, the spring will just fall out.

edit: I see in your description you have your mods list and did the throttle body upgrade, so I think you should be in DSP or DP or something higher, if I recall there is no Street class which allows modification past engine inlet. Also a dumb rule is because our air filters are built into the plastic engine cover, that would also knock you out of Street class to do the cold air intake.. if you'd like I can help you figure out your proper class if you want to compete with SCCA at all

 

Thanks for the reply.
I installed H&R rear springs, shocks and sway bar (I'm still working on the front end). I used a mercedes type spring compressor that runs up inside the coil and compresses two plates . It was difficult to get it to a full extension, before I started the compression, but found it worked pretty good. I still had to release the lower control arm as you did to get it out, but at least all the tension had been removed. I do not run auto cross, but do occasionaly make a track day. I decided against adjustable shocks as I thought I could find a sweet spot with the spring pads alone and corner weighing. Once I get it close even with adjustable shocks I'm certain I would not be messing with it. Just didn't seem to be worth the expense for my use. With the H&R sport cup kit I think I'll be good to go. It will lower the car about 1.5", maybe a little less.

 

Thanks for information! Was thinking of tire size changes after this Saturday's abysmal showing of 8th in a field of 12...first five were RS, RS, RS, Type R, RS, Mini... Anyhow... Was thinking of stock rims in front (with spacers) running 255/35-19F and 275/30-19R. Crazy right? Desperate to fix the understeer...it is slowing me down big time. I will look into your smaller/lighter wheel suggestion. Thanks again!

 

Do you have a rear sway bar upgrade yet? That would help you get rotation and deal with the understeer. I've had a pretty easy time beating more than one Type-R I've seen at my local events.

I have stock wheels/tires, stock sway bars, and I regularly see top 20-30 out of average of 80 entrants. What tires do you run? I use the Michelin PS4Ss and they seem to do a great job for me and the weather conditions in the NW.

 

Thanks for response. I currently am running stock size rims with Bridgestone RE71R's for the smooth fast tracks and Federal RS-RR's for abrasive runways. 30psi front and 28psi rear. I have not found an upgrade rear sway bar yet even under the R-170 searches. I can always take the AMG front bar off and reinstall the stock sway. I can run the slalom faster than most just have tough time with rotation around the sweepers.(a carry over from running the slalom so quickly). Just trying to get the whole thing together. Ran 59.3 second lap to a class best RS at 53.4 and Civic R at 55.0. Any half second tip would be appreciated...

 

I bet you want to keep the front sway bar ultimately.
I haven't purchased from these guys myself yet, but it is on my wishlist next time I have spare cash for car parts.

https://www.ecstuning.com/Mercedes_B...sion/Sway_Bar/

Also you could take the part numbers they have from the H&R bars and try to find them somewhere else too.

 

How is the rear H&R springs with the stock ones at the front? How is your ride height? The rear in stock form is ridiculous. Do you have a pic? Do you know the spring rate?

Thanks!

 

H&R makes the rear sway for the SLK R170. It's out there.

 

Here is some info which may be helpful:
Sway bars Limited- Front OEM 25mm
Rear OEM 19mm

SRT6- Front OEM 28mm
Rear OEM 19mm

H & R- Front 30mm
Rear 20mm

The numbering for the H & R parts if ordering as a set is different in the American market and the European market. However, the sway bars are they same. American 72769, European 33769.
I have both sway bars here at my house. Bought on ebay from Germany. The actual number on the bars are, front 33769HA VO, rear 33769VA IM.
To install a new sway bar on the rear requires you to drop the carrier frame and that is not easily accomplished.

 

Thank you. I have ordered the H&R rear bar as I already have the AMG bar up front and like it for slalom. Full set of Timkin bearings installed with Redline CV-2 synthetic grease. Currently looking for specs for my mechanic for front end set up...i.e. camber, toe, etc... any help hear would be appreciated as we are at Pocono this weekend! Thanks!!

 

What do you run for your front set up as far as camber, caster, toe, etc... I have the opportunity to get it set due to needing aligned after wheel bearing replacements and access to trailer to track. Any input would be appreciated. Thanks!

 

Greetings! Do you have any specs you would be willing to share on the front cast/camber/toe for autocrossing. Information has not been readily available. Correct me if this is wrong....camber should be between -1.5 to -3.0...toe should be zero front and rear...caster ?? Any input would be appreciated. Thanks!

 

As I said I do not auto cross, but do run an occasional track day, so I am no expert. Advice given to me by a very experienced racer was to keep camber reasonable, with just a little more in the rear than the front; give or take a little around -2. I like to keep a little toe in as it helps "feel " the center when steering. Big help is more rubber in the front using 8 inch rims width and LIGHT TIRES AND RIMS. Caster isn't really adjustable from my understanding on our cars. Once the camber and toe is set the caster is what it is, as the upper control arm has no adjustment without modification.
I just returned from the alignment shop this morning and have -2.2 in the front and -1.8 in the rear. I have the adjustable bolts on my lower control arms in the front and have them in the full inboard position. On the cars rear it has adjustable camber arms, trailing and lateral arms. I just got the H&R sway bar, springs and shocks installed on the front, so I'm now H&R both front and rear.

 

I used to compete in what is best described as time attack with my car. Street rubber as well as Hoosiers. At the time my car was lowered to the point it was on the bump stops under heavy braking. The camber arms (Ground Control) would hit the rear sway bar at traction limits in the corners. So don't go too low if your racing! Mostly higher speed tracks with old paved surfaces. Slick, rough, etc. Best front camber was anywhere from -1.8 to -2.2, 38 to 39 psi hot. Rear was best from -1.5 to -1.8, 36 to 37 psi hot. My car liked rear toe in, anywhere from 1/8 to 1/4. 0 toe front. Get as much rubber on the front as possible. It makes a huge difference in braking. Cornering, too, but not as much as you suspect. The sweet spot is magic when you hit it. But that spot moves around depending on the surface, speed, temperature, etc. Have fun and learn to use all the tools at your disposal. (tire temp probe, calibrated air pressure gauge) I had good success but believe if I'd raised my car up a bit it would have been better.

Les