OHLINS dfv question
02-05-2015 | 12:34 PM
#22
Joined: Apr 2009
Posts: 2,629
Likes: 39
From: Windsor, CA
For the included 8K springs, 30 mm of preload after spring-to-perch contact.
Springs will be compressed ~2.2" inches with preload and the car on the ground. The springs have enough travel to do this with no problems.
I think the DFV will be a great setup for what you want!
My own DFV are currently set up with 7" 12K rear springs (custom valved), so I have less pre-load than you would need on Ohlin's springs, but I still need to run a solid chunk of preload. You would still need positive preload on these shocks all the way up to 16K rears. My setup is working great so far, though I need less rear travel because my rear springs are 50% stiffer than what Ohlins includes.
Yup, you've got it. Yes, that's a whole lot of preload compared to many other aftermarket shocks, though the stock suspension also runs a fair amount of preload due to low spring rate. It doesn't hurt the spring any.
Yup, that's what I'm saying (though some others are respectfully disagreeing). 
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 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.
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.
I think the DFV will be a great setup for what you want!
My own DFV are currently set up with 7" 12K rear springs (custom valved), so I have less pre-load than you would need on Ohlin's springs, but I still need to run a solid chunk of preload. You would still need positive preload on these shocks all the way up to 16K rears. My setup is working great so far, though I need less rear travel because my rear springs are 50% stiffer than what Ohlins includes.
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.
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.
02-05-2015 | 03:33 PM
#25
Joined: Jan 2011
Posts: 5,650
Likes: 100
From: Mt. ________
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.
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.
Based on your calculations, how much preload do you think I should run with 10kg springs? Also it is safe to say whatever amount of preload I add, I should adjust the bottom perch the same amount and I should be at the same ride height correct?
02-05-2015 | 05:13 PM
#27
Thread Starter
Joined: Dec 2002
Posts: 485
Likes: 24
From: Seneca Falls
I also found this quote in twowhos OE sping data post which is stickied to the top of this sub-forum.
Perhaps it sheds some light on why the OHLINS rears are engineered as such?
Andrew, I'm no expert, but I don't think you would need to adjust the lower perch if you were only adjusting the spring perch for pre-load.
The bump stop in the s2000 is definitely part of the spring rate. It is a convoluted foam that has a progressive spring rate that is active in most high rotation turns.
I was really surprised myself went I worked on my AP2. It is similar to VW with a continuously engaged bumpstop. The density is less than celasto (Koni) but is is really long. With the weight of the car down it is in almost in contact with the shock.
I was really surprised myself went I worked on my AP2. It is similar to VW with a continuously engaged bumpstop. The density is less than celasto (Koni) but is is really long. With the weight of the car down it is in almost in contact with the shock.
Andrew, I'm no expert, but I don't think you would need to adjust the lower perch if you were only adjusting the spring perch for pre-load.
02-05-2015 | 05:43 PM
#28
Joined: Sep 2003
Posts: 2,476
Likes: 53
From: TX
There should only be 2mm of Preload. See linked detailed manual that comes in the box.
http://www.roadandtrackbyohlins.com/...MI_HOSMI20.pdf
The Spring is 200mm long, after tightening the top hat, raise the spring perch so the length of the spring is 198mm. Then set the set the bottom height adjuster by screwing the shock into the lower arm mount to the measured distance between the spring perch and the height adjuster matches the manual front (104mm) and rear shock (28mm).
From there, if you want to lower user the bottom height adjuster which screws the shock into the lower arm mount and not the spring perch.
02-06-2015 | 08:54 AM
#29
Joined: Sep 2006
Posts: 10,465
Likes: 49
From: ATL
This is just one of the many thinks that has been irking me lately is the number of people buying nice higher end suspension that don't even have a basic understanding of how it all works. If you don't know you don't need it. At that point people are just buying it because someone else said it was the best.
02-06-2015 | 12:28 PM
#30
Thread Starter
Joined: Dec 2002
Posts: 485
Likes: 24
From: Seneca Falls
steve, are you referring to me?
You're correct though, the whole time I was looking into upgrading my suspension, I never once took into consideration what you would think.
I do have a 'basic understanding of how it all works' I was just trying to clarify this pre-load issue.
You're correct though, the whole time I was looking into upgrading my suspension, I never once took into consideration what you would think.
I do have a 'basic understanding of how it all works' I was just trying to clarify this pre-load issue.