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Old 08-18-2014, 06:41 PM   #1
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Default shock oils questions

I have been reading up on pro's recommendations, like Jilles groskamp, who says he changes to thicker oils ..700cst in really hot temps like in TITC. But what I don't get is exactly why. If you read the label on a shock oil bottle, the manufacturers guarantee that the oil properties do not change no matter the temperature extremes encountered, that their oils are 100% silicone. So why change oils when the temps change ?
Keep in mind this guarantee has been around since the late 80's.
Also regarding placement of shocks on the rear arms. There are usually 2 holes on the rear arms, one farther out and the other more inwards. Is it right to say that using the inner hole will give more body roll and traction ?
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Old 08-18-2014, 08:32 PM   #2
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I thinks it's more about tuning the car.

In hotter temps the tires will get more traction, and can overheat, or the car could traction roll. Going to a thicker oil will give the tires slightly less traction, as well as slowing the weight transfer around the chassis. So you run a harder tire with harder oils.
The opposite is true for if it's colder out. You then want to run a softer tire and softer oils, as there is less grip so you need to find more with the softer tires and softer oil.
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Old 08-18-2014, 09:19 PM   #3
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Although the oil is supposed to remain unchanged in high temps they feel different particularly in terms of shock pack.

I am certain the viscosity of the oil reduces as the temperature increases. If you get too bottles of the same shock oil and place one in the freezer and the other in the sun for a couple of hrs then move the bottle around of build a couple of shocks. You can clearly see a difference.

Increased grip is one aspect of using thicker oil but perhaps due to small changes in the shock body and bladder with temperature also effect the performance. If you build shocks when cold and then run on a hot day they tend to have more rebound.

To sum up I find that cooler weather thinner shock oil works best and in hotter weather thicker shock oil seems to work best.
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Old 08-18-2014, 09:40 PM   #4
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Quote:
Originally Posted by frozenpod View Post
Although the oil is supposed to remain unchanged in high temps they feel different particularly in terms of shock pack.

I am certain the viscosity of the oil reduces as the temperature increases. If you get too bottles of the same shock oil and place one in the freezer and the other in the sun for a couple of hrs then move the bottle around of build a couple of shocks. You can clearly see a difference.

Increased grip is one aspect of using thicker oil but perhaps due to small changes in the shock body and bladder with temperature also effect the performance. If you build shocks when cold and then run on a hot day they tend to have more rebound.

To sum up I find that cooler weather thinner shock oil works best and in hotter weather thicker shock oil seems to work best.
+1 on all you said too. My thoughts are just that the difference in performance and feel from changing or not changing shock oil is more impactful than just running the same oil when the heat changes.

So what I mean is people will change oil not mainly because of changes in oil properties (which I too am sure happens) but because of a needed change in setup. And therefore change in oil, and changes to the rest of the car.

I hope my point is getting across clearly.
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Old 08-19-2014, 03:42 AM   #5
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i had the same problem ,i had a great car when it was cooler but as the temps came up my car was still good but had to much grip and would slow in the corners,then i started trying thicker oils,now i have an understanding of what to try and when to try it,and now can get the car to work in hot temps as well as the winter conditions,totally different set ups
in winter ill use 350cst on a hot day i can go to up to 600 cst
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Old 08-19-2014, 08:44 AM   #6
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Great input guys. Something does puzzle me though. Its regarding shaft to o ring stiction. Many pros i know like to use looser lower friction o rings..which basically leaks quicker compared to standard o rings. Does it make sense to use thicker oils with low stiction o rings to compensate for the shafts quicker low friction movement.
From my experience with low wt oils and the shocks tend to rebound quicker. Are low friction o rings really a great advantage in handling..are they worth the trouble of rebuilding them every 5 packs or so ?
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Old 08-19-2014, 09:17 AM   #7
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Quote:
Originally Posted by alcyon View Post
Great input guys. Something does puzzle me though. Its regarding shaft to o ring stiction. Many pros i know like to use looser lower friction o rings..which basically leaks quicker compared to standard o rings. Does it make sense to use thicker oils with low stiction o rings to compensate for the shafts quicker low friction movement.
From my experience with low wt oils and the shocks tend to rebound quicker. Are low friction o rings really a great advantage in handling..are they worth the trouble of rebuilding them every 5 packs or so ?
I thought the idea of the lower friction o ring's was specifically to allow the oils and springs to do their work more easily without any extra friction coming into it.
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Old 08-19-2014, 10:42 AM   #8
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I thought the idea of the lower friction o ring's was specifically to allow the oils and springs to do their work more easily without any extra friction coming into it.
Exactly.

I prefer the best sealing rings I can get. It is just a bother to rebuild and retune shocks all the time.
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