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Old 12-15-2010, 06:05 PM   #1
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Default Shock Question - need some insight

What would be the difference between between building a shock with full rebound and a soft springs vs building a shock with 0 rebound and a stiffer spring to compensate for the no rebound? My last 2 races I have been having issues with my car losing ride height in a main after 8 or so minutes of driving which causes my chassis to start to slap. But after letting the car sit for a bit, the ride height is back to normal so I am just curious if this is something I could do to overcome that.
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Old 12-15-2010, 06:08 PM   #2
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sounds like you need thicker oil in your shocks... what buggy or truggy are you having this problem with?
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Old 12-15-2010, 06:29 PM   #3
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Yes, sounds like you are using too thin an oil and its heating and thermal break down is happening causing your oil to get thinner for the time it is hot.
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Old 12-15-2010, 06:34 PM   #4
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So let me see if I understand this right. The oil is what determines the ride hight. I thought the spring did that and the oil just controlled how fast the shocks move up and down.
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Old 12-15-2010, 06:47 PM   #5
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sounds like you need thicker oil in your shocks... what buggy or truggy are you having this problem with?
Yea that was what I was told by a good source also, but I was just curious if it would still happen if I were to add a stiffer spring and use no rebound at all?
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Old 12-15-2010, 06:58 PM   #6
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You should not be rellying on the oil to control the ride height.
Ride height can be adjusted with no oil in the shock, but due to the relative light weight of the vehicle, the oil will have a degree of effect.
Also when adjusting teh ride height, push the car completly down a few times and let it settle to its height, dont lift the car off the bench then place it down and ajust from that.

It sounds to me like you may not be "settleing" the springs before adjusting ride height, so the oil is having an effect on initial settings. Then once the oil is heating up, it will thin out and is allowing your car to sit lower.

In 1:1 scale best "handleing" is with lightest springs possable (that allow required ride height), and heavy oil on rougher track.
More twists and turns then more sway bar pressure required.

I am only guessing this transfers to 1:8 scale in the same way.
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Old 12-15-2010, 07:10 PM   #7
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Originally Posted by mcion View Post
Yea that was what I was told by a good source also, but I was just curious if it would still happen if I were to add a stiffer spring and use no rebound at all?
i was having the same issue with my O'donnell team buggy, it kept loosing its ride height about 5 min of running it. running thin oils ... i took the shock pistons and drilled every other hole to 1.2 with others being 1.1 and ran 50wt front and 40 wt rear and it fixed the problem... we tried different springs and rebound before going with thicker oil and it never worked.... you probably wont have to drill pistons but running thicker oil is what i think is best bet. oil makes a big difference in ride height if it breaks down and become thinner then ride height will get lower ... also run good oils, i know i ran some cheaper stuff and it thinned easy... the ones ive ran that didnt feel like they thinned is AE or mugen oils.
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Old 12-15-2010, 07:17 PM   #8
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Originally Posted by boxhead View Post
You should not be rellying on the oil to control the ride height.
Ride height can be adjusted with no oil in the shock, but due to the relative light weight of the vehicle, the oil will have a degree of effect.
Also when adjusting teh ride height, push the car completly down a few times and let it settle to its height, dont lift the car off the bench then place it down and ajust from that.

It sounds to me like you may not be "settleing" the springs before adjusting ride height, so the oil is having an effect on initial settings. Then once the oil is heating up, it will thin out and is allowing your car to sit lower.

In 1:1 scale best "handleing" is with lightest springs possable (that allow required ride height), and heavy oil on rougher track.
More twists and turns then more sway bar pressure required.

I am only guessing this transfers to 1:8 scale in the same way.
No I press it completely down, the problem is I set the ride height when really cold outside, then the car warms up as I am driving after several minutes those are the 2 times it has happened during cold races. In the summer I never had that problem. The consensus seems to be oil to light, but I am still curious to know what is the difference between 100 rebound soft spring vs 0 rebound with stiffer spring
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Old 12-15-2010, 07:22 PM   #9
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Originally Posted by jmaxey51 View Post
i was having the same issue with my O'donnell team buggy, it kept loosing its ride height about 5 min of running it. running thin oils ... i took the shock pistons and drilled every other hole to 1.2 with others being 1.1 and ran 50wt front and 40 wt rear and it fixed the problem... we tried different springs and rebound before going with thicker oil and it never worked.... you probably wont have to drill pistons but running thicker oil is what i think is best bet. oil makes a big difference in ride height if it breaks down and become thinner then ride height will get lower ... also run good oils, i know i ran some cheaper stuff and it thinned easy... the ones ive ran that didnt feel like they thinned is AE or mugen oils.
I was running Losi Oil. My pistons are 1.2x8 So I was assuming that I could run light oil and get away with it and get good pack, but I guess not.
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Old 12-15-2010, 08:08 PM   #10
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I was running Losi Oil. My pistons are 1.2x8 So I was assuming that I could run light oil and get away with it and get good pack, but I guess not.
losi oil is fine... what buggy or truggy is this? and what oils are you currently running? and does the buggy/truggy have alot of time on it?
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Old 12-15-2010, 08:13 PM   #11
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rebound is mainly for how fast you want the shock to shoot back out, 100% rebound with soft springs will fill the same as 0 rebound with soft springs. its really hard to explain over a computer,... ive just played around with it and experimented for myself. the BEST solution is running thicker oils.
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Old 12-15-2010, 08:35 PM   #12
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rebound is mainly for how fast you want the shock to shoot back out, 100% rebound with soft springs will fill the same as 0 rebound with soft springs. its really hard to explain over a computer,... ive just played around with it and experimented for myself. the BEST solution is running thicker oils.
Ok lol so what about 0 rebound with stiffer springs vs 100 rebound with soft springs. Would the stiff spring not make it shoot out faster?
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Old 12-15-2010, 09:00 PM   #13
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Ok lol so what about 0 rebound with stiffer springs vs 100 rebound with soft springs. Would the stiff spring not make it shoot out faster?
changing springs will make so much difference on handling, it will make it worse, less traction etc, take the rebound out of the equation and its the same thing pretty much, ignore rebound right now. but you will still have the same problem 5-10 min of running, you need thicker oil, rebound and springs will NOT fix the problem, ive TRIED it and in the end it was my oils, just went 10wt thicker and the problem was fixed, ran a half gallon straight with no fade on ride height, just run everything like you have but go thicker oil ...... what buggy or truggy do you have?? and what is your current weight oil???
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Old 12-15-2010, 09:08 PM   #14
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changing springs will make so much difference on handling, it will make it worse, less traction etc, take the rebound out of the equation and its the same thing pretty much, ignore rebound right now. but you will still have the same problem 5-10 min of running, you need thicker oil, rebound and springs will NOT fix the problem, ive TRIED it and in the end it was my oils, just went 10wt thicker and the problem was fixed, ran a half gallon straight with no fade on ride height, just run everything like you have but go thicker oil ...... what buggy or truggy do you have?? and what is your current weight oil???
808, but im using kyosho tki2 shocks, oil weight was 32.5 front and 27.5 rear with 1.2x8. I am going to go up 5 on both. I was just curious if there would have been a difference in regards to rebound though, but you answered that.
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Old 12-15-2010, 09:45 PM   #15
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808, but im using kyosho tki2 shocks, oil weight was 32.5 front and 27.5 rear with 1.2x8. I am going to go up 5 on both. I was just curious if there would have been a difference in regards to rebound though, but you answered that.
did you not like the Xray shocks? and how did you get the Kyosho shocks to work? i thought the xray shocks were longer but yeah 37.5 front and 32.5 will be better IMO. you running tapered pistons? if so run the taper down.
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