Originally Posted by
razo125
I'm loving your results Icecyc1
Temp increase affects two things.
1. Oil viscosity thinner- hotter the oil the lower the viscosity
2. Internal Air Pressure increases as the temp increases in the shock. This adds rebound and 8th scale guys notice this most if they run a long race with emulsion shocks, less so if they run bladder with air above the bladder. and the none if they run vented foam. During the long races the ride height can change quite a bit just from the increases air pressure inside the shock body. (vent bladders have consistency issue for other reasons)
To test how much temp increase affects shock consistency, try a couple shock dyno experiment as follows:
____________
Exp #1 test consistency of shock oil damping as shock body temp increases.
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Exp #2 test consistency of shock rebound(internal air pressure) as shock body temp increases.
______________________
Most guys here can already predict the results, but it would be interesting to show the data to so we can all align on something on RC tech. hehe.
Thanks for the additional feedback on the shock fade. I very much agree with your heat and air (pressure) comments. The ride height effects makes sense too.
Those tests sound good, but honestly, I don't know that my dyno can handle 45min of continuous runtime, so I'd want to try to accelerate the test. If we are only looking at the heat factor changing the shock's damping and internal pressure, that is easy enough to accelerate with a heat gun or hair drier while running for only a few minutes. We know the piston moving in the oil generates heat through the friction of the fluid, and it can also emulsify the oil by pulling the air out of solution while running. So, if the key ingredient is heat, getting it warm while running it should at least show how much the damping and rebound should change after experiencing a higher temperature. What we won't get from an accelerated test is knowing how fast a piston/oil combination generates heat. And that I feel could be an extensive study.
I'll think about this a little more. It may be later this year. I'm deep into collecting Impact (pack) data now, and I hope to be able to report the results in the next few weeks once we figure out the best way to interpret and relate the data. (I've been reviewing the data with Bob Wright of RC Crew Chief, and Ray Munday Team Associated factory driver.)