axl911

All,

I currently have RoW M030 springs, Bilstein shocks, M030 F+R sways, and 18 in. wheels on my car.

At anyting below 44psi front and 46psi rear (hot) tire pressure, the car is harsh over bumps and broken pavements. I feels like the shock is too much for the springs. Feels like rebound is too high for the M030 spring rate. The car felt it absorbed the impact then dip/crashes over because the spring cannot return/extend the shock back into position after the impact.

Upping the tire pressure to 44/46 hot (equivalent to upping the spring rate?) made the ride smoother.

Wondering if anyone run into this?

Also, if you're running Bilstein+M030+18" wheels, what are your tire pressures?

---
anthony

TRINITONY

I have the same set up but run 34/36 or 36/38 without any harshness.

Paul902

I run Bilstien HDs, RoW M030 springs and sways, stock pressures f/r (36/44 cold). Is this setup harsh? Well, compared to my g/f's A4, YES! Compared to a cup car, I doubt it!

WRT spring rates, I do feel that the M030 springs are on the light side for these dampers. This is just from my butt-o-meter. However, I do not know if going to stiffer springs would resolve your complaints.

axl911

Thanks for the input so far. Guess harsh is not the correct term I was going for.

What I meant should be "well damped". I don't think there is anything wrong with my car or my install, but I don't feel the spring and shock work well together unless I run 44/46.

JM993

I have the same setup and I agree. Frankly, I'm not a huge fan of Bilsteins but surprisingly we don't have much choice for our cars. My biggest compliant is the initial compliance of the Bilsteins - a little too stiff. As a result, the car hops around more than I would like on small bumps, though it's fine on large bumps. I really wanted Konis (which I have on my BMW), but unfortunately they don't make a shock for the 993.

Randy 1

This was the main impetus for my decision to go with the adjustable PSS9s. For similar money, it sounded like the soft end of the spectrum was more compliant than the HDs. I'm still fiddling with tire pressure, but this appears to have a significant role in wheel NVH.

Mark in Baltimore

From what I understand, the shock's rebound "setting" is responsible for returning the wheel back to the ground, not the spring.

Bilstein uses a high pressure de Carbon design which causes initial harshness. By comparison, Motons and JRZ's use a lower pressure, giving more compliance despite the higher performance.

air eater

I have the same setup and run 36/38 psi.
The ride is firm but not harsh.
What is your ride height setting?

axl911

My ride height is RoW except front is about -5mm since I've been playing with it. Any lower and I would run into bump steer.

Would ride height affect the damping characteristics of the shock/spring?

Dr. No

I'm confused: Why would your ride be less "harsh" at higher tire pressures?

And I'd think ride height could affect damping if set so low the shocks/springs are compressed. Does the front seem "harsh" but not the back?

chris walrod

Since the tire is a spring, in certain instances (and not necessarily on a road car, and doubtful in the above example), increasing tire spring rate can decrease damper compression rates as a result of an increase in piston velocity. Similar to the effect of altering damper canister pressures and the adverse results thereof.

Dr. No

Chris, I'm going to take your word on that one. God, I'm ignorant . . .

Mark in Baltimore

That makes two of us. Chris, I hope you never sell your 993 and/or leave the 993 board and/or decide to leave Swift and work for Ping or Spalding or some such.

AOW162435

+1

Andreas

chris walrod

LOL! You guys are too much. I just cant wait to get the Motons on the car and really learn how to tune dampers.

While not related, someone got a smokin' deal on a great brake package.
http://cgi.ebay.com/ebaymotors/ws/eB...152102709&rd=1