RevedOut

I'm in need of some guidance on setting up my Ohlins DFV coilovers. Please chime in on my initial set up and adjustment procedures. Also, please share your front / rear preload settings and how much you lowered your car from the factory starting points.

Before we begin: I am somewhat new to setting up suspension. Yes, I searched and read many posts. I also found the Sakebomb Garage rear preload chart and did my best to interpret it. I just haven't found anything the answers the questions I have.

2004 S2k
Ohlins DFV coilovers with stock valving
Swift springs - 12kg front & 10kg rear
17x9 Volk CE28n +45
Bridgestone RE71-R 245-40-17 (square set up, brand new tires, equal pressures)
Fenders are not rolled
Zero additional suspension mods
Measurements are done with digital calipers

My set up so far is:
- 2mm preload on front and rear springs.
- I was told the stiffer 12kg / 10kg springs give me the preload equivalent of 7mm in the front and 9mm in the rear as they don't compress as much and have more resistance to bumps
- Since the DFV's have a +/- 15mm of adjustment, I would essentially have 8mm left to lower the car in the front and 6mm left in the rear to lower the car.Is this correct?????

More issues:
- My fender gaps are wildly noticeable on all four corners. Is adjusting the lower fork on an individual shock body the proper method to raise / lower the car as long as I stay within the +/- 15mm range?

Opinions Wanted??
- If you have the spring rates listed above, how low can the car be while keeping a safe amount of suspension travel (i.e. not hitting the bump stops or the fender)?

THANKS IN ADVANCE FOR THE HELP!

B serious

Use 0mm of front preload. You're fine at 2mm.

Use like 9mm of rear preload.

Those are SBG's recommendations...and I think they're good. I would use the same.

The car will go as low as the bottom brackets will allow after that. If you want it lower, you will then need to start giving up shock travel by lowering the spring heights/preload.

You need to set initial preload BEFORE installing. Did you? And if so, what number did you choose?

With bushings clocked, the car's ride heights should be close to even. *Measured on a flat floor*.

If they're not...adjust the bottom bracket(s) to whatever height you want.

RevedOut

2mm preload was set for each coilover and was set before I installed them on the car. I used my neighbor's brand new driveway as a flat surface. I know it is not the alignment rack but it is a very flat level surface and the best I could find.

This is where I get confused. Per Ohlins directions, I have +/- 15mm of adjustment after I set my preload. Does that adjustment lie within the up or down movement of the bottom bracket? Basically, do I only have 15mm that I can lower or raise the car?

I appreciate you chiming in!

noodels

lowered mine to max ie until rear fork had bottomed out

RevedOut

That has to be beyond the -15mm that Ohlins recommends??? Are the locking rings on the lower spring perch and lower mount touching?

B serious

Nope. With the body bottomed out in the rear cup, there is a gap of (IIRC) 15mm between the lock rings, if you're using 2mm of preload.

It will be very plain that the front should not be anywhere near fully bottomed in the cup because the car would actually be a submarine at that point.

I wouldn't RAISE the shock out of the lower cup too much because you risk breaking it via leverage.

The risk with lowering the cup too far is that the tire *might* hit the inside of the fender before the shock runs out of travel.

You can't run that wheel set on stock fenders. So you'll need a lip roll and bumper re-locate. I would cut the two "high risk" tabs off the front fenders to reduce the risk of damage.

If you wish to get 9mm of rear preload, put a dot on the uppermost perch with a paint marker. Loosen the two upper perches. Then turn the uppermost perch 360degrees counter clockwise by 4.7 turns.

That same dot can also be used to reference body turns when you want to adjust bottom bracket height.

RevedOut

B serious

More preload = later bumpstopping. You're raising the shock shaft out of the body because you're lifting the spring.

You need 7 more mm to get to 9mm.

Raise the spring up by 7mm.

Lower the shock into the bottom bracket by 7mm.

You are left with the exact same ride height as before.

7 up. 7 down.

Car Analogy

I feel like there some inherent confusion that op has with regards to lower fork adjustment. I apologize in advance if this is my misinterpretation or if most of the below is already understood.

The lower fork adjustment has no effect on the workings of the shock, it just shortens it. It has no effect on shock travel. It has no effect on preload.

Adjusting the lower fork allows you to keep all your preload and shock travel vs extension travel intact, yet raise or lower ride height.

So you set the preload to balance full range of shock travel between shock compression and shock extension (and in this car, at tbe rear, how far you are at rest from the bump stops is always part of that balance equation). Amount of preload needed is going to vary with weight of car and the spring rate you are using.

Preload is strange term. Once the shock is in the car and on the ground it will almost always compress past what preload compressed it. Preload has no effect on much the spring is compressed once shock is in use. So all preload really does is shift where along the shocks full range of travel it sits at rest (and as a side effect, alter ride height, which you will then use lower fork adjustment to dial out).

Since your car is probably stock weight or close to it, ideal amount of preload is really just based on your spring rates, and how much of the shocks full range of motion you want to be compression travel, and how much should be extension travel.

Then the lower fork adjustment adjusts ride height.

RevedOut

@Car Analogy - I am definitely clear on what you posted. After many phone calls, forum threads and emails I have came to and end and have the suspension set up. Thanks for your input.

My front preload is set to 2mm and rear is at 9mm. Using some basic math and the S2k specific install book that Ohlins provides, I found the new starting point for the lower fork . I had to account for the the Swift springs which are 205mm long, not 200mm like the Ohlins springs. From there I was able to adjust the lower fork +/- 15mm per Ohlins recommendation. I did lower the car -15 in the rear. The rear does sit a bit high as expected but I got the fronts to match up with in a millimeter or two. I actually had to raise the drivers side front a fair amount to get and even fender gap that matches the others. Being that I'm not one of those hella flush guys, I'm feeling good about where it sits for now. I'm also in the process of rolling my fenders and installing offset bushings for the upper A arms on the fronts so wheel fitment will not be an issue.

Lastly, I did adjust my fronts to different heights to match fender gaps. I know I will take some crap from the dedicated track guys who corner balance but my car is more a street car than track.

Bump for a good community of people who are nice enough to help a guy out.