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-   -   Springs "destroying" shocks? (http://www.the370z.com/brakes-suspension/38927-springs-destroying-shocks.html)

cossie1600 07-05-2011 01:51 PM

before i start, let me just say you are right about the basic principal of how to build a shock, except the shock you mentioned are the ones used for small applications like rc cars or machine dampeners....

modern car shocks use fluid and air (nitrogen normally) to dampen the energy from the spring. the shock converts the energy into heat as it dampens the load bfrom the spring. when you increase spring rate and load on the shock, what do you think happens to the oil that is inside it. it heats up beyond what they are designed for. go see what your engine oil looks like after a track day vs a few weeks cruising on the interstate.

also using your theory, we would never have blown shocks since they can just install over size valves and extra reservoir for oil are useless

tyyping on a phone, sorry for the typo

CFZ 07-05-2011 04:19 PM

Cossie, Seeing as though I actually build shocks all the time for my late models, I know a little more than some about shocks. Yes Nitrogen gas is used to put pressure into the shock to prevent hysteresis. I do not know anything about RC cars.....

The oil is not transferred into heat, There is no warm up period of a shock or anything like that. It is restricted through the valving of the shock. The oil goes through the piston of the shock and is restricted through the stacks of shims. the more shims the less they flex making the valving stiffer. Now this is done on both sides of the piston to adjust rebound on one side and compression on the other. The shock oil generally does not change color. There are different weight oils depending on valving of the shock, but most racers in my experience uses a very lightweight shock oil and adjusts valving through the shims. It is actually the opposite of what you are saying, heat is one of its enemies.

When I say changing the valving of a shock I dont literally mean changing out the valves like you would in an engine. By valving I mean changing the dynamics of the shock through the shim stack. Which is a common term.

When you use shocks for a long period of time the oil does get inconsistent, but this is because of few things, When racing for long periods of time they obviously heat up like any hydrolic system.
Twin-tube shocks are even worse off because the nitrogen and the shock oil physically mixes itself up causing cavitation.

The reason why shocks blow is because the seals and o-rings eventually wear out. Or bottoming out the shocks.

Signs on a twin tube shock
-leaking
Signs from a monotube
-leaking
-the shaft does not push itself back out when compressed (gas is in a seperate chamber so the secondary piston seal is blown)

I dont know where you are getting your information from but either Im not understanding you (which is likely the case) or you have some weird shock made but some kind of mad scientist.

From what you are saying warn out oil is the cause of blown shocks. Which does not make much sense. From our experience oil temps going up does increase inconsistencies but nothing makes it blow. And like I said before the stiffer spring minimizes movement in the shock, A soft spring will obviously increase movement, but the speed of the movement in a stiffer rate spring will be increased.

cossie1600 07-05-2011 07:39 PM

I think you might have misunderstood me on some issues. Here is what I meant to say. Heat is one of the factor why shocks fail. I am saying lowering springs and stiff springs can contribute to that as the shocks have to work harder to absorb the motions from the spring (This spring might not be low enough to ride the bumpstop, but that can kill the shocks too). All the extra motions create heat, which then breaks down the oil. Oil is a lubricant, the constant heating and cooling of oil will break it down eventually. Seals can fail on a shock for variety of reasons, the breakdown of oil can certainly be a part of it.

Nitrogen in a street car's shock is to prevent aeration (foaming bubbles), not sure how it causes it. I can see it when you completely overheat the shock.

Quote:

Originally Posted by CFZ (Post 1204566)
Cossie, Seeing as though I actually build shocks all the time for my late models, I know a little more than some about shocks. Yes Nitrogen gas is used to put pressure into the shock to prevent hysteresis. I do not know anything about RC cars.....

The oil is not transferred into heat, There is no warm up period of a shock or anything like that. It is restricted through the valving of the shock. The oil goes through the piston of the shock and is restricted through the stacks of shims. the more shims the less they flex making the valving stiffer. Now this is done on both sides of the piston to adjust rebound on one side and compression on the other. The shock oil generally does not change color. There are different weight oils depending on valving of the shock, but most racers in my experience uses a very lightweight shock oil and adjusts valving through the shims. It is actually the opposite of what you are saying, heat is one of its enemies.

When I say changing the valving of a shock I dont literally mean changing out the valves like you would in an engine. By valving I mean changing the dynamics of the shock through the shim stack. Which is a common term.

When you use shocks for a long period of time the oil does get inconsistent, but this is because of few things, When racing for long periods of time they obviously heat up like any hydrolic system.
Twin-tube shocks are even worse off because the nitrogen and the shock oil physically mixes itself up causing cavitation.

The reason why shocks blow is because the seals and o-rings eventually wear out. Or bottoming out the shocks.

Signs on a twin tube shock
-leaking
Signs from a monotube
-leaking
-the shaft does not push itself back out when compressed (gas is in a seperate chamber so the secondary piston seal is blown)

I dont know where you are getting your information from but either Im not understanding you (which is likely the case) or you have some weird shock made but some kind of mad scientist.

From what you are saying warn out oil is the cause of blown shocks. Which does not make much sense. From our experience oil temps going up does increase inconsistencies but nothing makes it blow. And like I said before the stiffer spring minimizes movement in the shock, A soft spring will obviously increase movement, but the speed of the movement in a stiffer rate spring will be increased.


wheee! 07-05-2011 08:07 PM

On Swifts own website, they say that the stock shocks will work fine but they recommend that performance shocks be installed.

Quote:

Originally Posted by swift
2. Increase in spring rate to further enhance cornering speed through entry & exit. The increase in spring rate is based on the vehicle factory stock valving settings. Sport Springs Spec-R is increase to the optimal rate that the stock shocks can handle. Higher performance shocks are not required, but recommended.


DJ-of-E 07-06-2011 07:10 PM

Quote:

Originally Posted by wheee! (Post 1204942)
On Swifts own website, they say that the stock shocks will work fine but they recommend that performance shocks be installed.

If that's the case, what would be "performance" shock for the 370z? KYB AGX hahaha :roflpuke2:

Waiz 07-06-2011 07:24 PM

Quote:

Originally Posted by xdeslitx (Post 1199595)
just personal preference...but it looks pretty nasty without spacers after a drop.
I dropped mine and wasn't planning on spacers but after less than a week, i ended up getting them.

:icon17:

You had no choice, Brian was going to unfriend you :roflpuke2:

Andy124 07-08-2011 10:55 PM

Quote:

Originally Posted by whoLEEoh (Post 1203828)
i guess you dont know much about suspension...yes your shocks will blow prematurely because the spring is shorter and not only that the spring rate is way more aggressive than what the stock shock is valved for. if someone with swift springs last 20-25k miles on them id be surprised.

so,did you change your shock after applying Eibach Pro-Kit?:)


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