Shock oil

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synamies

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Hi all,

What is the deal with silicone "hobby" shock oil? When I first got my XRC every shock leaked and was filled with some kind of chinese hand lotion :no:. Needless to say that the shock absorbing was almost non existent.

I then replaced the shock oil with one designed for snowmobiles, and what a huge difference that made! When i pressed the back or front end, it bounced back lightning fast. What also surprised me was that the new liquid actually stayed inside the shocks, though compared to the greasy and stiff silicone oil it is like water.

Now, I was still curious to try some "official" silicone shock oil, and replaced the snowmobile oil with Ansmann silicone. Even the preset jelly was better! Push the car down, and it pretty much stays there. Totally useless, and damn expensive! Shocks don´t leak and they kind of work (the shaft returns s..l..o..w..l..y), but their performance is pathetic. What am I doing wrong?

Back to snowmobile liquid...
 
when you push the shock shaft in with no spring on it, the shock should stay bottomed out. if the shaft pushes back the shock is overfilled. overfilled shocks can lead to leaks.
 
The thicker oil you use the heavier spring you need to return the piston to fully extended.If ,as you say,you pushed on the shock down and it rebounded instantly,then its not working properly.It should go back with some resistance.I suggest you use 5000WT FG oil and 2.5mm springs,you will notice the difference.
J.
 
The Ansmann oil was pretty thick (don´t remember the actual viscosity) but I think it is mainly intended for 1/8 nitro cars, so these larger springs should have enough resistance to extend the piston fully.

With the snowmobile shock oil and without the spring the shaft doesn't´t actually bounce immediately back. It returns nice and slowly, but not too slow as with silicone oil. The quick bouncing happens only with the spring on and seems to me far better action than the silicon oils "keep it down forever"-action :)

So I´m quite happy with my springs now :), though I´m still wondering why they don´t work properly with "proper" oils...
 
Syna,I have loads of different shock oils and every terrain is different,its just a case of trial and error,you'll find a happy medium if you experiment.
At the moment I have 6000 in the back and 4000 in the front but my springs are 6 years old and its starting to tell.I need to uprate my springs and then try different oils.
Good luck.
J.
 
Sharkey said:
when you push the shock shaft in with no spring on it, the shock should stay bottomed out. if the shaft pushes back the shock is overfilled. overfilled shocks can lead to leaks.
Click to expand...

I would agree. If your piston is extending out when there is no spring then you have a pressurized shock/overfull. If you have a cheaper shock they will leak right away. The more expensive shocks will rupture on load.
The thicker the shock oil the slower the rebound. Unless you get a different spring.
If you want thicker oil due to leakage you can try enlarging or adding some shock plunger holes to allow the fluid to run from top to bottom faster.
 
I used to use 60-80wt silicone oils but have switched to hpi oil now...and have gradually gone from 40wt to 20wt (using 5b shocks on a rampage with adjustable pistons second notch from full open) i"ve found that over damping really kills the handling thru lots of trial and error,...now my truck returns real quick to ride height when you push down on it so the wheels can follow the terrain yet the shocks damp perfectly when "shocked" off the jumps...I think a real common fault with alot of people (i include my past self) is to over damp the shocks...when you press down on a real cars' fender it'll return alsmost immediately and rc's are no different IMO...the handling of my MT has been transformed since i went way lighter on my shock oils
the viscosity you use depends on the size and amount of piston holes but the desired rebound will be the same...buy a bunch of different weights and start experimenting...it's tediuos but worth the benefit you'll get when you find the sweet spot
(fg oils use a different wt measuring system their 1000wt = about 80 in silicone)
 
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