andrewhake

It's not even a matter of pre-load. Mike put the rear shock through it's range of travel with no springs and the wheel/tire mounted. At his ride height of ~1" lower than stock there is still plenty of travel. The bump stop came in contact when the tire was nearly fully tucked into the wheel well. I recommend looking at his thread.

If you think a 12mm rear RCA will shift the wheel travel by over 1" then it might be a concern, but it doesn't.

andrewhake

I set them up myself, put paint marks on them, and had them installed. Height was adjusted using lower shock body perch to re-adjust ride height to accommodate for the RCA. Preload is Ohlins recommended. But yes I am 550b springs (9.8kg/mm) compared to Ohlins included 8kg/mm springs.

It's possible preload in the rear was re-adjusted, but not to my knowledge.

Gernby's DFVs do not have the fairly large rubber piece in between the top of the spring and the top hat.

saving4one

Gernby's DFVs do not have the fairly large rubber piece in between the top of the spring and the top hat.
This^
I need to go through my packaging and find these pieces. I have not made a move on assembling these, all of this input is great, as andy_intel commented. Andrew, I did go through SHG_Mike's posts on this subject, and asked what his pre-load was and then I went back a page and found he's not running the OTS spring either. I think I do comprehend what you are saying about the pre-load not being the issue. It seems I will end up setting pre-load per OHLINS specs, installing then checking bump stop etc.

andrewhake

Yep install and test and see what comes of it. I think some of the earlier DFV kits didn't come with the rubber top hat piece. It could even be possible there are more differences between kits than that for all I know as well.

Looking at SHG_Mike's post, I just don't see how what Gernby and Thomsbrain posted could be correct. But who knows. If you install and measure make sure the bump stop is actually fully seated, probably easiest to look at all this with the car on an alignment rack.

//steve\\

The rubber upper spring thing was added. When I had my first set it didn't include them. That's the only thing that was different from older kits to new.

thomsbrain

My set does have the rubber spring-mount/bushing. Doesn't make much difference other than causing the lower perch setting to be slightly different for a given pre-load.

Andrew, you're right that you can "tuck" the tire into the fender with the given amount of travel. I have plenty of MRLS-corkscrew photos of my car with the rear mostly tucked. Keep in mind though that fender tucking is an arbitrary indicator of travel, especially when there are shock body adjustments in the mix. What matters is how far the wheel can move up and down from the stationary position on the ground, which is determined solely by the shock's total available travel and motion ratio. 2" at the shock is very little travel to work with. The front DFV has twice that much travel available. External-reservoir designs like Bilstein PSS/PSS9 and KW have gobs more rear travel to work with, so much so that they have to run helper springs just to soak up some of the travel before the main spring gets loaded.

Another easy way to think about this:

The front DFV has 4" of total available travel and runs a 10K spring. With the recommended 2mm preload, it sits exactly even in the travel range on the ground. Ohlins recommends it, math predicts it, observations confirm it. 2" available bump and 2" available droop. Perfect!

The rear DFV has 2" available travel and runs an 8K spring with the same recommended 2 mm preload. If we already know from the front that 2 mm of preload and the S2000's corner weights will compress a 10K spring 2", how much will 2mm of preload and the same weight compress a softer 8K spring? Short answer: More than 2". If you have 2" of space and compress more than 2", you're squishing the bump stop.

Short of Ohlins issuing a correction, we can only guess why they printed the wrong rear pre-load. But I think it's pretty clear they knew the rear would be height-limited because the dampers are internal-reservoir and super-long, chose a pre-load that would disguise that limitation for the hard-parkers who can't tell the difference when bottoming out and just want their car low, and knew that the dedicated track junkies would figure out how to set up their cars correctly regardless of what the manual said. The DFV are still a very good shock for the money for people who drive their car on the street or need SA or internal reservoirs for competition points. My car handles better on track and street than it ever has. Just a shame that so many S2000 DFV buyers will never experience their full potential because of some misleading setup guidelines.

s2000ellier

so whats the correct preload for the rears then?

buldozr

How to set preload the redneck way. Tighten all spring perches till hand tight. Then mark spring perch nut with a sharpy and give each nut two full turns. DONE. Where's my beer?


EDIT: Woah, I am off base, sorry fellas. Trying to add rear spring load to maintain rear shock travel... I got it. I don't like it. $2500 and you have to resort to interesting settings, yeah I don't like that.

saving4one

s2000ellier, according to thomsbrain it should be 30mm. OHLINS supplied literature says 2mm. thomsbrain, with that pre-load and the weight of the car how compressed are your springs? Sounds like they are working well for you. I need to run all this info past my alignment guy to get his advice also. Thanks again everyone for your input, this is what makes this site so useful.

I bought these dfv's to replace my stock AP1 suspension/shocks that are leaking (11+ yrs. old 50k miles). I would have just bought OEM but they are discontinued and even the different years are not re-buildable. I'm not looking to lower my car anymore than the min. lowering that these come set at. I was looking for good street comfort, re-buildable/serviceable, some auto-x/track and hill climb racing. I'm not even too interested in the adjustability aspect, I just want to set them up properly and drive. I was willing to spend the money for quality and longevity, and from the reviews I have read they will fulfill these expectations.

steven88

So you're suppose to hand tighten until the spring and perch touch, then add 30mm more?

Please educate me, but isn't that a whole lot of preload? I mean isn't that effectively turning the stock 8 inch Ohlins spring into a 6.8 inch spring? And that's before the wheels are put on, and the car is even lowered to the ground. The rear spring is massively compressed at all times.