View Poll Results: What rear preload setting did you use?
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Ohlins DFV rear preload settings
09-10-2016, 11:55 AM
#1
Ohlins DFV rear preload settings
Yes I have searched, and yes there are a lot of threads, but no real consensus. When setting up Ohlins dfv shocks for the rear, do you run the Ohlins spec of 2mm, or more pre load to add some compression travel?
09-10-2016, 02:24 PM
#2
Awaiting results 
AP2<though its an AP1 facelift here in UK> with 10/8kgs standard Ohlins and set to uk ohlins spec sheet.<2mm>
No ARB upgrades
225/45&255/40/17s.
Have 11 front 10 rear from full stiff
AP2<though its an AP1 facelift here in UK> with 10/8kgs standard Ohlins and set to uk ohlins spec sheet.<2mm>
No ARB upgrades
225/45&255/40/17s.
Have 11 front 10 rear from full stiff
09-10-2016, 02:48 PM
#3
I'm at 2mm preload. My car weighs like...100-140ish LBs less than stock.
My rear shocks/springs compress 1.53" at static ride height. Car glides over stuff, is quick on track. I can feel bumpstops every now and then. My street damper settings are 11/11.
Always set preload BEFORE installing.
My rear shocks/springs compress 1.53" at static ride height. Car glides over stuff, is quick on track. I can feel bumpstops every now and then. My street damper settings are 11/11.
Always set preload BEFORE installing.
09-11-2016, 08:03 AM
#6
Assuming they start at 2.125. Mine compressed to 1.53. So about 0.6".
What I plan to do:
-Remove one of the rears.
-Remove the boot.
-Put it back on at 2mm, sans boot.
-measure distance to bumpstop.
-Add preload til I get 1".
-If I can still get to my desired ride height (aesthetics) via the bottom bracket, I will leave 1". If not...I will lessen preload as needed.
-Mimic the setting on the other side.
-Remove the shock again and reinstall the boot.
-Go to the track again and make sure I'm not getting wheel lift from the added preload (I shouldnt).
I would recommend that anyone who is "not sure" about their factory settings follow the above procedure with the boots. Don't guess or stay up trying to calculate how many days you have left in your life. Just make a direct measurement.
09-11-2016, 09:33 AM
#7
As I see it >
Quote: damper fluid having a consistent path of flow in both directions
^ the thing that puts me of messing with preload,there is 2 ports above and below the shaft jet bleed.
If its out of reach with extra adjustments would be the issue of concern here,
Ie:
the rebound may not work the same amount as compression stroke,so not a DFV system anymore,so putting extra loads & an internal wear factor.
Figure 1: (Compression flow) At low shaft speeds, oil flows mostly through the shaft jet bleed (lower dotted arrow). At higher shaft speeds, oil flows mostly through the compression ports in the piston (upper dotted arrow). At very high shaft speeds, or during sudden shaft accelerations, oil can also escape through the compression ports in the DFV, increasing comfort.Figure 2: (Rebound flow) At low shaft speeds, oil flows mostly through the shaft jet bleed (lower dotted arrow). At higher shaft speeds, oil flows mostly through the rebound ports in the piston (upper dotted arrow). At very high shaft speeds, or during sudden shaft accelerations, oil can also escape through the rebound ports in the DFV, maintaining tyre contact with the road.
Seen here.
http://www.ohlinscoilovers.co.uk/dfv-technology
Quote: damper fluid having a consistent path of flow in both directions
^ the thing that puts me of messing with preload,there is 2 ports above and below the shaft jet bleed.
If its out of reach with extra adjustments would be the issue of concern here,
Ie:
the rebound may not work the same amount as compression stroke,so not a DFV system anymore,so putting extra loads & an internal wear factor.
Figure 1: (Compression flow) At low shaft speeds, oil flows mostly through the shaft jet bleed (lower dotted arrow). At higher shaft speeds, oil flows mostly through the compression ports in the piston (upper dotted arrow). At very high shaft speeds, or during sudden shaft accelerations, oil can also escape through the compression ports in the DFV, increasing comfort.Figure 2: (Rebound flow) At low shaft speeds, oil flows mostly through the shaft jet bleed (lower dotted arrow). At higher shaft speeds, oil flows mostly through the rebound ports in the piston (upper dotted arrow). At very high shaft speeds, or during sudden shaft accelerations, oil can also escape through the rebound ports in the DFV, maintaining tyre contact with the road.
Seen here.
http://www.ohlinscoilovers.co.uk/dfv-technology
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09-11-2016, 10:51 AM
#8
As I see it >
Quote: damper fluid having a consistent path of flow in both directions
^ the thing that puts me of messing with preload,there is 2 ports above and below the shaft jet bleed.
If its out of reach with extra adjustments would be the issue of concern here,
Ie:
the rebound may not work the same amount as compression stroke,so not a DFV system anymore,so putting extra loads & an internal wear factor.
Figure 1: (Compression flow) At low shaft speeds, oil flows mostly through the shaft jet bleed (lower dotted arrow). At higher shaft speeds, oil flows mostly through the compression ports in the piston (upper dotted arrow). At very high shaft speeds, or during sudden shaft accelerations, oil can also escape through the compression ports in the DFV, increasing comfort.Figure 2: (Rebound flow) At low shaft speeds, oil flows mostly through the shaft jet bleed (lower dotted arrow). At higher shaft speeds, oil flows mostly through the rebound ports in the piston (upper dotted arrow). At very high shaft speeds, or during sudden shaft accelerations, oil can also escape through the rebound ports in the DFV, maintaining tyre contact with the road.
Seen here.
http://www.ohlinscoilovers.co.uk/dfv-technology
Quote: damper fluid having a consistent path of flow in both directions
^ the thing that puts me of messing with preload,there is 2 ports above and below the shaft jet bleed.
If its out of reach with extra adjustments would be the issue of concern here,
Ie:
the rebound may not work the same amount as compression stroke,so not a DFV system anymore,so putting extra loads & an internal wear factor.
Figure 1: (Compression flow) At low shaft speeds, oil flows mostly through the shaft jet bleed (lower dotted arrow). At higher shaft speeds, oil flows mostly through the compression ports in the piston (upper dotted arrow). At very high shaft speeds, or during sudden shaft accelerations, oil can also escape through the compression ports in the DFV, increasing comfort.Figure 2: (Rebound flow) At low shaft speeds, oil flows mostly through the shaft jet bleed (lower dotted arrow). At higher shaft speeds, oil flows mostly through the rebound ports in the piston (upper dotted arrow). At very high shaft speeds, or during sudden shaft accelerations, oil can also escape through the rebound ports in the DFV, maintaining tyre contact with the road.
Seen here.
http://www.ohlinscoilovers.co.uk/dfv-technology
And there's no flow path on the cylinder wall. Its a monotube shock...and it would be a bad design to have a port that could become obstructed in the range of operation.
09-11-2016, 12:12 PM
#9
Thanks for that
I had another look at the diagram
I had another look at the diagram
09-11-2016, 04:29 PM
#10
So some quick measurements on mine...
About 2.1" of total clear piston travel (shock body to bump stop).
About 3.2" of total potential piston travel (disregarding bump stop).
Any way you slice it, it's not a lot to work with. If you factor a 1.5" drop on 2mm preload, the Ohlins spec leaves about 45% potential travel for extension and 55% compression. Normally that would be fine, but throw the bump stop in and it's more like 65% extension and 35% comp. The issue is no one really knows what's the total possible compression of the bump stop.
That's ultimately what I think Ohlins was going for. The rear springs are fairly soft, my thought is they expect significant engagement of the bump stop, effectively adding to the spring rate. They are using the bump stop to turn a linear spring into progressive.
About 2.1" of total clear piston travel (shock body to bump stop).
About 3.2" of total potential piston travel (disregarding bump stop).
Any way you slice it, it's not a lot to work with. If you factor a 1.5" drop on 2mm preload, the Ohlins spec leaves about 45% potential travel for extension and 55% compression. Normally that would be fine, but throw the bump stop in and it's more like 65% extension and 35% comp. The issue is no one really knows what's the total possible compression of the bump stop.
That's ultimately what I think Ohlins was going for. The rear springs are fairly soft, my thought is they expect significant engagement of the bump stop, effectively adding to the spring rate. They are using the bump stop to turn a linear spring into progressive.
