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Fox flipped the rear shock - why?

6K views 18 replies 7 participants last post by  VR Trooper 
#1 ·
My old version Fox rear shock, the the reservoir/shock body is on the bottom and the shaft is sticking up when mounted. With the new version of Fox (and other manufacturers too), the shock body/reservoir is mounted on top and the shaft is pointing down. Why did they flip it? The shaft on the lower ground will be mar by rocks/debris whereas if it's on top, there are less chance of this...
 
#2 ·
I quoted this from a rc car site. Im sure alot of the same principles apply to cars... Most sportbikes also have inverted shocks...


1) Upside down shocks lowers the truck's center of gravity. It's not so tippy in the corners.

2) Reduces shock oil leakage. When your truck sits, unless your seals and shaft are brand new, a tiny bit of fluid leaks out of the o-ring seal. Over time, this adds up. With the shocks upside down, the oil is now contained by the better seal, at the cap of the shock.

3) The air bubble is now moved to the other end of the shock piston's stroke. Let's face it, who doesn't have a tiny bit of air in their shock? With your shock right side up, the piston enters the air bubble when the shock is at maximum compression, such as when you come off of a big jump. This is exactly when you DON'T want this to happen. When the piston enters the air bubble, all resistance to movement is gone and the truck bottoms out. Upside down shocks eliminate this problem. The only time the piston enters the bubble is when the shocks are at maxximum extension (such as when your truck is in the air). I think it's beneficial to have a little bubble at this time since your shocks more easily reach maximum extension.

4) It draws a lot of attention. When I first bashed with other people with my shocks upside down, everyone noticed. Some people thought they were being funny by telling me I accidently mounted my shocks upside down. Well, the smile was wiped off of their faces when they saw my truck's increased performance.

So far, there are two negatives I can think of:

1) Upside down shocks increase the truck's unsprung weight. In theory, the lower unsprung weight relative to the sprung weight, the more responsive the suspension will be. However, given the already high unsprung weight of an e-maxx, I don't notice any difference.

2) The shock's body is more apt to be hit by debris. So far, though, I haven't had a problem with damage since the upper a-arm shields it pretty well.
 
#8 ·
see below in red.

I quoted this from a rc car site. Im sure alot of the same principles apply to cars... Most sportbikes also have inverted shocks...


1) Upside down shocks lowers the truck's center of gravity. It's not so tippy in the corners.

Okay so this is inverted.


so the above doesn't make sense. Obviously inverted (or up side down) the heavy part is on the top which in a small way throw off the center of gravity (less stable in cornering)

2) Reduces shock oil leakage. When your truck sits, unless your seals and shaft are brand new, a tiny bit of fluid leaks out of the o-ring seal. Over time, this adds up. With the shocks upside down, the oil is now contained by the better seal, at the cap of the shock.



Again, looking at the pic above, the leak would like down the shaft at the bottom...which doesn't reduces shock oil leakage to me.
3) The air bubble is now moved to the other end of the shock piston's stroke. Let's face it, who doesn't have a tiny bit of air in their shock? With your shock right side up, the piston enters the air bubble when the shock is at maximum compression, such as when you come off of a big jump. This is exactly when you DON'T want this to happen. When the piston enters the air bubble, all resistance to movement is gone and the truck bottoms out. Upside down shocks eliminate this problem. The only time the piston enters the bubble is when the shocks are at maxximum extension (such as when your truck is in the air). I think it's beneficial to have a little bubble at this time since your shocks more easily reach maximum extension.



With inverted shock, the air column sits on the top which is when the shock is at max compression...opposite of what stated above??

4) It draws a lot of attention. When I first bashed with other people with my shocks upside down, everyone noticed. Some people thought they were being funny by telling me I accidently mounted my shocks upside down. Well, the smile was wiped off of their faces when they saw my truck's increased performance.

So far, there are two negatives I can think of:

1) Upside down shocks increase the truck's unsprung weight. In theory, the lower unsprung weight relative to the sprung weight, the more responsive the suspension will be. However, given the already high unsprung weight of an e-maxx, I don't notice any difference.

2) The shock's body is more apt to be hit by debris. So far, though, I haven't had a problem with damage since the upper a-arm shields it pretty well.
 
#9 ·
Im not a shock expert at all. Maybe someone else will chime in. But these are my answers. I might be wrong, like i said i copy and pasted. Hell, none of this could be right.

1. If im not mistaken, the shock bodies are alum in most shocks and the shaft is typically solid steel i believe and weighs more than the body with fluid/gas filled.

2. With them inverted, oil is constantly on the seal and keeping it lubed and wet, so i would assume it seals better. Just like rubbing oil around your oil filter seal when you put it on. With the shock the other way, air may sit at the top and dry the seal out?

3. I dunno.
 
#14 ·
Unless I missed it in my reading, and I do have a fever right now...

Nobody has posted the main reason suspension companies and nearly all race cars run inverted shocks is to reduce unsprung weight. This greatly improves the shocks performance characteristics.

There are other advantages in some applications but that's the general consensus in the auto world.
 
#15 ·
My post mentions it but i copy and pasted from a r/c car site. Im sure their shocks weigh different proportionally than a actual cars because they state is the opposite LOL


I did keep reading on motorcycle websites that that's why but didn't know if same principals applied here
 
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