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Internal springs on shocks

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Internal springs on shocks

Old 07-07-2020, 11:06 AM
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Default Internal springs on shocks

So the new exotek F1 car has a standard TC damper like all F1 cars but uses a very small spring on the inside of the shock just under the piston n...this has been done on RC crawlers for quite some time but I was wondering what it will do on say a touring car has anyone tried or experimented with this? curious to see and hear your thoughts and opinions thanks
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Old 07-07-2020, 12:29 PM
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Like what Delta did in the 80's worked well on my Fireball, Phaser and Villian. Although shocks then were more of a grease based dampening with the spring in unison.


Consider too, if the inner spring fails... your shock body will be trash. There are some that may have tried this in 1:8 Onroad more recently, Roelof or Merlin may have tried?
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Old 07-07-2020, 02:11 PM
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Originally Posted by fat500 View Post
So the new exotek F1 car has a standard TC damper like all F1 cars but uses a very small spring on the inside of the shock just under the piston n...this has been done on RC crawlers for quite some time but I was wondering what it will do on say a touring car has anyone tried or experimented with this? curious to see and hear your thoughts and opinions thanks
The only reason I see for an internal spring is to achieve 0 rebound with a mechanical help. Since the TRF super short shocks I find it very hard to get 0 rebound at all. But damaging/scratching the piston rod is a danger.
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Last edited by Tom1977; 07-07-2020 at 02:30 PM.
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Old 07-07-2020, 08:20 PM
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there are probably a few reasons but a damper doesnt do much at 0 velocity and mechanical slop rears its head during the reversal of a piston. slowing the piston at the end of stroke quickly and reversing it quickly helps with the slop and minimizes the distance it takes to reaccelerate the piston. this makes the damping more consistent and a little more forgiving to mechanical slop.
a spring should keep most mechanical gaps on the leading edge rather than falling to the lagging edge during a reversal. at least during critical damping moments.
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Old 07-08-2020, 01:03 PM
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Kyoso F1 from the late 1990s had internal springs. This was more for cosmetics, so one did not see the springs, since F1 cars from the time did not have visible springs.

The prototype De Carbon Gas pressurized shock was pressurized to keep air from getting into the oil through the shaft seal during compression. During compression, significant negative pressure is generated between the piston and the seal, which would draw air inward around the seal, save for the high pressure in the gas chamber. I build my model shocks the same way, to keep air from getting in. A De Carbon shock with no rebound is shot.
  • Shock absorber

    Patent number: 4274515
    Abstract: A shock absorber of the hydraulic-pneumatic type includes a cylindrical casing closed at both ends and partially filled with a liquid damping medium. A piston is reciprocable in the casing, has valve controlled passages and a piston rod thereon extending outwardly through a packed opening in one of the ends. A quantity of gaseous fluid under super-atmospheric pressure occupies the space above the level of the liquid, and a perforated partition forming an anti-splash device is disposed slightly below the liquid level. The partition is stationary in the casing and is frictionally held in place against the inner surface of the casing but is displaceable under the effect of a force greater than that applied to it by the movement of the shock absorber as a whole or of the liquid damping medium upon reciprocation of the piston.
    Type: Grant
    Filed: March 28, 1979
    Date of Patent: June 23, 1981
    Inventor: Christian Bourcier de Carbon

Last edited by ic-racer; 07-08-2020 at 01:15 PM.
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Old 07-09-2020, 11:12 PM
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On pan cars the main shock extends under acceleration (pod rotates back). This spring may be to control that movement - from "equilibrium" when no power is applied (or coasting through a corner) to full shock extension under hard acceleration. I tried similar on my Pro10, but was wasn't happy with the results. I think Mike would have put a lot more effort and science into his shock!

It may also be introducing a 2-stage spring load. Once the inner spring is fully extended during compression, the effective spring rate will increase as the two springs are no longer opposing each other. All depends on how long the springs are, and the shock travel.
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Old 07-10-2020, 02:46 AM
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I've looked at the manual and effectively it is just a soft droop-stop for the rear pod.

I don't know enough about settings on pan cars but I would guess that including the spring makes the rear end feel a little grippier under braking, because it slows down the weight transfer as the pod reaches maximum droop.
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Old 07-13-2020, 07:14 PM
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Awesome answers thanks guys
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