Square Ohlins DFV Damper and Sway Settings?

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11-19-2016, 12:46 PM

#71

Apex1.0

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Quote:

Originally Posted by SakeBomb Garage

Adding pre-load does not effect the rate of the spring during the dampers stroke. An 8kg/mm spring is an 8kg/mm spring regardless of the amount of preload is added. However until there is enough force on the wheel to overcome the preload force (accounting for motion ratio) the spring rate is infinitely stiff. The reason you do not want to add a ton of preload to a spring is because of the effects of the infinitely stiff portion. Basically with a short damper and a soft spring you have an infinitely stiff portion to overcome the preload, then a very soft portion when the spring alone is acting, then a very stiff portion again when the bumpstop is engaged. If you don't add the preload you avoid the infinitely stiff section but ride on the bumpstops more often, which is arguably just as bad. The bump stops are approximately 24kg/mm and additive so when the bumpstop is engaged you have the equivalent to a 32 kg/mm spring.

We generally reccomend moving to at least a 10kg/mm spring in the rear but an 8kg/mm can be made to work though it is not ideal with a damper of this length.

That is a great discription of the effects of too much preload. From my experience with my Koni setup, the ride actually improved when I went from 400 to 500lb springs. I was actually able to back down on the damping, because the spring rate wasn't spiking on the bump stop. It makes a lot of sense that a 10k spring would be more optimal on a short stroke damper like the Ohlins. Chances are if you like the car with more preload, you will like it with more springrate.

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SakeBomb Garage (11-19-2016)

11-19-2016, 07:04 PM

#72

SakeBomb Garage

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Quote:

Originally Posted by Apex1.0

That preload may be more optimal. It will be interesting to see if you suffer from having less droop travel.

Quote:

Originally Posted by noodels

Drive today proved very good over fast uneven 70+mph A roads corners that I have driven many many times, kept on line very well,
its stable and smoother, I felt I could have gone much faster with safe a feeling.
No chance of an open diff with me at the wheel ,I do not track the car

Not had the conditions for fast B roads its slippery here..
Damper adjustment with one click is noticeable, i believe any droop is within capabilities,
there was more than enough before and all would not have been used,
in what condition and how would one determine too much droop and reactions on car ?

edit :
will measure rear wheel droop asap for reference

Glad we could help noodles!

In our experience it is much more important to have sufficient bump travel than losing a bit of rebound. That's not to say that having lots of preload is good, just that having enough bump travel is better.

The difference between the two is:
Not enough bump travel -
Mid corner bump rear end get really stiff all of a sudden and rear end gets bucked off of road. Nearly impossible to save depending on conditions and severity.

Not enough rebound with lots of preload-
Inside wheel is skittish over rough sections. Power delivery tends to not be as smooth.

You tell me which one sounds like more fun. Really the solution is generally to run a 10Kg/mm spring on the rear. This drastically cuts down on pre-load requirements (though in our opinion does not eliminate the need). Even with 10 kg/mm springs we recommend around 10mm of pre-load. The issue with this is that you can't get as low as some people would like. However we have some things in the pipeline to fix this. If you are interested in trying out some 10 kg/mm Swift springs shoot us a PM and we can get you a good deal or if you are interested in getting lower with your DFVs let us know...

-Greg @ SBG

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11-20-2016, 02:56 AM

#73

noodels

Join Date: Nov 2013

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Thanks for offer,it would cost lots to send anything to UK !!
I like the Ohlins ride height and its only road use so a desired ride height.33.5cm its not a daily driven car.
Still testing regarding to see if its skittish on fast rough road condition ,if so will back off the preload damper adjustment from 11 clicks first,
if too bouncy will try removing spring preload until composure returns and back track on the damper adjustment.
Also I do agree on the 10kgs given the short stroke would be preferred it was not an option from my supply.
looked at Hypco or whatever they are called and swift springs availability and not much available here in UK
& Eibach don't seem to do the correct ID either