Fork Oil (theory) Q

[MotoPsycho]

I did some digging around and I haven't found an answer that satisfies me.

If I were to have forks rebuilt could you mix weights for a desired outcome ? Assuming valving cannot be changed:

Say 7wt rides like a dump truck and 5wt rides like a pogo stick. If the same manufacturer was used can you mix equal parts of each to get 6 ? Or maybe 60/40 mixed 5wt & 10wt ?

I have no experience with this sort of thing so this is more of a curuiosity more than anything.

[Norm]

As long as it's the same kind of oil (not neccessarily the same brand) it's fine. I use Redline & always carry a bottle of 30wt and "like water" so I can make minor adjustments on the bike with a siringe. Don't forget to try different volumes as well. If you have the older fixed Showas, they respond well to +10cc.

[EEL]

I have no experience with this sort of thing so this is more of a curuiosity more than anything.

So just a footnote. In case you somehow decide to take your curiosity to a new level. Start with learning suspension tuning before you head out into the realm of oil mixing. Once you get the hang of the basic preload,rebound and compression setting adjustment, you'll get a good feel for how varying oil weight will work.

Also, from what i've heard (not FHE so correct me if i'm wrong) oil weights do mix but an unused bike can have heavier weights settle in layers until the suspension warms up. From what I know its more of a mixture not a solution.

[clubhousemotorsports]

you can mix weights of oil But I would try and use the same brand and version oil.
going from a 5 weight to a 7.5 weight is a fine tuning mixture for sure.  There are some forks that I will use different weights in each leg because the way each leg is valved.
Oil height will effect the bottoming resistance depending on the fork, more oil will ramp up pressure at the end of the stroke due to the air above the fluid being compressed.

[rose351]

Oil height will effect the bottoming resistance depending on the fork, more oil will ramp up pressure at the end of the stroke due to the air above the fluid being compressed.

So the bottoming resistance will be increased for instance in the old showas if you add 5-10cc of fork oil?  And by increasing the bottoming resistance you are effectively increasing the "spring constant" of the fork, right?  Or is it more for the damping effects?

[clubhousemotorsports]

Oil height is effecting the "air spring" on top of the oil. you cannot compress the oil but you can compress a gas such as air. as the ais gets compressed the pressure goes up exponentially.

The higher oil level will add pressure to the fork sooner so the fork will stiffen up sooner. It could be said that this "stiffer air spring" will add compression damping.
The problem with doing so is that you are making the lower portion of the travel much harsher, earlier in its travel.

 most ducati forks will struggle to reach full travel due to the factory oil levels, place a zip tie around your fork leg and try your hardest to use all the travel. 80% will stop short about an inch from the bottom.