bcameron59

ROW M030 is the sport / performance version, and ROW M033 is the "comfort" version, similar to the standard USA suspension. They are both the same ride height.

If you don't track the car, you'll likely want the M033 / FSD combo for reduced height without sacrificing ride comfort. According to some, the M033 is better matched to the FSD than the M030, so you'd have that going for you as well.

If you do go with M030, the anti-roll bars should also be upgraded to match (they are larger diameter than the non-sport versions).

CeeTwoS

So that means FSD and M033 and the anti-roll bars are okay and don't need to be replaced?

Looking for others but thanks Brian!

bcameron59

Yes, M033 springs use standard ARBs (though you can upgrade ARBs for tuning purposes). FSDs apparently work well with the M033 springs, Carnewal (and perhaps others) sells the shocks and springs as a combo.

CeeTwoS

Great. I need to do this change in June so I am looking at what I need to do. Thanks. Looks like FSD and MO33 will get the lowered look but not the slammed look.

Thanks.

RonCT

Playing catch-up. It is my understanding that there are 2 versions of the Koni FSD for our 993s. Gert sells the correct one for ROW and it is threaded up front for some adjustment / corner balancing. There is another version I've seen that is not threaded. I purchased my set from TireRack after confirming with them that they stock the correct threaded set for ROW spring use. In a few weeks I expect to have my M033 / FSD setup installed and will report.

A few photos I found here and there (thanks to Gert and a fellow RennLister who posted while installing).

BesideTheBox

I have a set of ROW Turbo M030 springs - Thank you again Busta Rib!
The rear spring (993.333.531.16 - 3 red dots) height measures (outside to outside dimension): 11 5/8"

I also have Koni FSDs new in the box from Paragon.
The rear shocks have part number 8245 1253R/L on them.
From the lower spring perch to the shoulder below the threads for the top nut is 11 15/16"

Looks to me like the shoulder has a washer on top of it and it mates with the bearing in the rear shock top as pictured above in Brian's post. And it looks like the seat for the spring is 'further' away than the bearing. So I can see how there might be an inch or so gap.

Ron, can you post the same dimensions and part number for your Konis and springs?

Pictures to show how/what I measured:
ROW Turbo M030 Rear Spring


Koni FSD Rear Shock

BesideTheBox

I got a PM from a fellow member that measured a stock Monroe and the dimensions (perch to shoulder - 301mm) are the same as my Koni FSD.

11 15/16" * 25.4 mm/inch = 303mm

So I believe my version of the Koni FSD is designed for US length springs.

RonCT - Can you measure your FSD to see if they are the same?

RonCT

I just checked and it's about 12", so it looks like I got the same set you got. TR stated they are the correct ones for ROW springs, which is what I wanted. Also, based on part numbers, what I have is what's sold in Europe. So now I'm thinking there is just the 1 version and that the shock is partially compressed when sitting on ROW springs, but is not compressed when sitting on US springs. There's not that big a difference in spring length between ROW and US. 20mm front and 10mm rear is only 0.8" / 0.4". And the front can be adjusted to keep it about the same at +/- 1/2" lower. I'd be nervous if I was looking for Sport / RS height...

BesideTheBox

Ron -
Thank you for taking the time to measure.
I'm going with the idea that there is a single version of the FSD based on this info.

RonCT

I would think so. The reports early on was there were two versions because Koni made them originally without threads on the fronts. I believe it was Gert that pushed them to create threaded fronts for adjustment and per my local shop you can corner balance with just the front 2 struts having adjustment. I believe with 2 variable points you can shift weight forward or back, left or right.

And when I Google my part numbers I see the same shocks for sale in the UK, Europe, etc. And we're not talking about a big difference between ROW and US - only 8/10" up front and 4/10" rear.

Obie1

Trying to decide which route to go with my C4 which will never see a track. My shop recommends both Koni FSD and Billstein. They lean a little more to Billstein and had mentioned the adjustability factor. I went to Tire Rack site and when I spec'd out the Koni FSD they description still notes 'non-adjustable'. Is this a mistake? If there is only one version of Koni FSD then I am still confused based on many posts on this site saying the front is threaded and adjustable to some degree.

Also.....can someone give me a 'ball park' difference in cost for each based on recent purchases. Koni FSD with M033 vs Billstein with H & R Springs.
Thanks ahead of time.

P-track

Koni FSD's for the 993 are adjustable on the front, not on the rear. The adjustability is for minor height adjustment and corner balancing and not for major lowering as this may cause interference with the FSD system.

To my knowledge there was never any other version.

There is more on my blog if you want some more background info on different suspension options. The link is below my signature.

rbeggs

Don't mean to hijack the thread but thought maybe there's an answer to my vaguely related question.

Several years ago I moved my C4s to Bilstein HD's, MO30 springs and the heavier sway bars. Ever since, on a random basis, I get a small but definite dull, clunk/rattle action going on in the front end. sometimes it's much worse than others. I can feel it being transmitted through the steering wheel if it's on the stronger side. It's subtle but definitely there.

Once when it was sustained for several days I went to my shop and put the car on the lift. Nothing could be found amiss except that the springs had the vertical play mentioned in other posts here. Believing strongly in voodoo mechanics I rotated the springs thinking to align them with the seating notch described elsewhere in this thread. The clunking went away for several months only to return again.

I have given up, thinking that if it's a wear issue, I'll just wait till it gets so bad it'll be a cinch to find.

Any ideas?

Thanks,

rb

Spyder_Man

One of the local shops here described wrapping the springs and adding some shims to make up the play between the springs and the struts. You might want to look into doing that.

Have you replaced your front A-arm bushings yet?

rbeggs

Spyder_Man,

Yep, put in Walrod's when I picked up my Stage lll's.

Thanks,

-rb