pizzai69

Sorry guys but I really don't understand the link between preload and ride height.
The Ohlins have 2 separate settings: one for ride height, and one for preloard. Right ?

flanders

Yes but preload affects ride height as well, if you have more preload the suspension will compress less under the weight of the car.
The reason why we need lots of preload is because of the limited travel.

noodels

If you Adjust the preload x amount,
then you must adjust the bottom mount to compensate x amount.
If not, ride height will be altered by preloaded amount.

pizzai69

Noodels: yes, this is sure. But i did not understand why you would have to touch the preload to adjust ride height.
What flanders answered makes sense: even if you can adjust ride height with its own setting, it is recommanded to also adjust preload in consequence, to reduce the damper travel.

B serious

Preload dictates shock shaft travel availability. It ALSO affects height.

In a case where you would LIKE to raise the height AND increase the travel, you can do it by adjusting just the preload. Same goes for reduction in height and travel.

In a case where you ONLY want to change shock travel, you would adjust preload (which also affects height as a side effect). You then adjust the height perches to compensate for that change.

Like...if you increase preload by 10mm to add 10mm of shock travel, the ride height would also raise up as a side effect. You could then lower the height adjuster by 10mm to put the ride height back to where it was when you started.

Make sense?

pizzai69

OK, so if what I want is a ride at -1" (compared to stock) without modifying ohlins standard shock travel, I can just keep Ohlins standard preload.

alSpeed2k

I don't plan to lower my car more than 25mm (0.98"), per the chart, this would be at the edge of the acceptable range with a 3mm recommended preload, which seems quite low. But yeah, maybe with a 1.25" drop, the lowering cups are needed.

alSpeed2k

Not sure when you bought your kit but if you go with Ohlins recommended preload, make sure you follow the up to date instructions for the HOSMI20. You can download it here. Note, that this is for the 10k/8k spring rate (not the updated 11k/7k setup ). Basically it recommends a 9mm preload (vs 2mm for the OLD instructions - don't use this number!).

noodels

And 2mm is incorrect instructions,
>From Ohlins..

alSpeed2k

Just to clarify (I'm asking because I'm not sure), the change is not linear right? ie. per the new manual:




If we used (most everyone's recommended preload of) 15mm, 191 now becomes 185 (decrease of 6mm), and the bottom gap 28mm (vs 22), if we leave the overall length at 420mm, the actual drop in the rear would be less than the 25mm specified in the manual. So, in order to get a 25mm drop we need to decrease the bottom gap by moving the height adjuster upwards thereby decreasing the overall shock length. In numerical terms, if the change were linear, we would decrease the bottom gap by 6mm (so basically the bottom gap is back to 22mm) and the overall shock length will be at 414mm.

Thanks in advance for everyone's help, it's a lot easier to figure this out now vs going by trial and error afterwards.