Shock Rebound

[SandvoldSlammer]

When you guys rebuild your shocks, how much rebound do you build into them for crawling? Full rebound, medium, some, none?

[Jboucher]

I used about 1/8 of an inch of rebound on my Bomber.
Gmade XDs 103mm shocks

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[Steve g]

I'm no comp crawler, but I did no rebound on my wraith, and as much as I could with my bashers. I'm assuming you mean rebound of the piston with no spring. I have blown out my caps with too much pressure from having high rebound and then launching it high in the air, so be wary of that if you have a faster rig.

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[SandvoldSlammer]

Good info! Other then blowing out the seal, is there any benefit to low rebound?

[2mtech]

I set mine to rebound about 1/8 full travel, after ingesting about a jigabyte of "opinion" on the subject. Works better than any other shock set up I've done...enough damping to know they're there but not so much as to overpressurize the caps off.

[Jboucher]

Originally Posted by SandvoldSlammer

Good info! Other then blowing out the seal, is there any benefit to low rebound?

I like the droop setup of low rebound.
It looks much better when the truck "sits" on it's own weight and you get about as much travel up or down.
It makes it look heavy like a real truck.

When it's on high pressure shocks, it looks like a toy, fully extended and springy.

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[2mtech]

Originally Posted by Jboucher

I like the droop setup of low rebound.
It looks much better when the truck "sits" on it's own weight and you get about as much travel up or down.
It makes it look heavy like a real truck.

When it's on high pressure shocks, it looks like a toy, fully extended and springy.

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Agreed. I adjusted the preload to achieve that effect. Too much pressure in the shocks and the preload feature becomes nonexistent.

[Steve g]

Yeah, looks better, handles better, and doesn't flip over on every corner you take when going over 3 mph...(at least a wraith, I know bombers handle better stock vs stock)

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[MAC FAB]

Originally Posted by SandvoldSlammer

When you guys rebuild your shocks, how much rebound do you build into them for crawling? Full rebound, medium, some, none?

Huh????? Can someone please explain the terminology. Full to none???? Huh???

[2mtech]

Originally Posted by MAC FAB

Huh????? Can someone please explain the terminology. Full to none???? Huh???

Refers to degree to which the shock piston (with no spring) self extends from full compression in one's hand after servicing & bleeding oil and installing cap.

Full: Shock self extends, or rebounds, to its maximum extension length; highly pressurized by maximum oil capacity fill.

None: Shock doesn't self extend at all but remains fully compressed; virtually no static pressure inside the shock body.

Or anywhere in between. Matter of application, theory and personal opinion what's "best".

[MAC FAB]

How does that not work itself into a neutral position from use? Or are you constantly having to screw with your shocks to keep ypur "tune"?

[2mtech]

Originally Posted by MAC FAB

How does that not work itself into a neutral position from use? Or are you constantly having to screw with your shocks to keep ypur "tune"?

That's an interesting question. Assuming no leakage, a shock should hold its "tune" until you open it up or your o-rings/seals wear sufficiently to allow leakage anyway. Removing a shock from a rig, removing the spring from a "used" shock and checking its rebound will give you an idea of the condition of the shock, assuming you had at least some rebound initially. If you had some, and now you have none, should indicate wear or oil loss.

I guess I could have said earlier that a massive amount of rebound after a build/rebuild could also be an indicator of hydrolock, or trapped air in the shock, from inadequate bleeding.

If one were really anal about their shocks I suppose constantly having to screw with them would be considered normal routine maintenance and a necessary evil. I'm not.

[gottorque]

None I guess. I suppose I let the fluid do all the work at controlling the compression and rebound of the piston

"Sits on its own weight" is simply ride height. How much the truck settles at ride height is static sag (as a percentage of up and down travel from ride height)

[MAC FAB]

Originally Posted by gottorque

None I guess. I suppose I let the fluid do all the work at controlling the compression and rebound of the piston

"Sits on its own weight" is simply ride height. How much the truck settles at ride height is static sag (as a percentage of up and down travel from ride height)

I totally get this, raise or lower with a little more or less preload. So why not run 2 shocks per wheel and run real bypass pistons allowing the shock to do the same thing as this "rebound" setup, making the rebound SLOOOOOOOOW? Or run shorter shocks at a neutral valving instead if ride height is the overall mission? My peanut brain isn't grasping the rationale for doing this....

[Teng]

Fast compression, reasonable preload ( depends on your purpose Fast to slow crawler rig with correct spring rate off cause ) and reasonable rebound ( depends how Heavy is your rig, type of crawler, and terrain etc )

[durok]

I'm initially sayin' screw it, and building my shocks (for this build, plain ol' Traxxas Big Bores w/Dlux top bushings, pictured below) using 40wt AE shock oil with no air bubbles... and a pair of 100mm chrome-bodied internal spring Xtra-Speed shocks with just enough lube to keep them from binding as dual rear shocks. Stock kit sway bar, perhaps adding some limiting straps that I have, dunno yet.

I have a of Gmade XD Diaphragm shocks w/hard springs that I will also be using at some point, whichever is stiffer goes on the heavier build in the end. The instructions for those have the option of a low-pressure setup or a high-pressure setup, I will try low-pressure first, because that sounds as if it will be more controlled on rebound and less prone to leakage. The heavier-weight build gets the Vanquish v2 sway bar as well.

I have 30wt oil to try if a set ends up too stiff, but neither build is a real lightweight...

[gottorque]

Originally Posted by MAC FAB

I totally get this, raise or lower with a little more or less preload. So why not run 2 shocks per wheel and run real bypass pistons allowing the shock to do the same thing as this "rebound" setup, making the rebound SLOOOOOOOOW? Or run shorter shocks at a neutral valving instead if ride height is the overall mission? My peanut brain isn't grasping the rationale for doing this....

On a full size bypass shock, it is essentially multi stage damping based on the position of the piston, eg a triple bypass has 3 damping zones.

Your first zone generally is very lightly valved so its nice and supple over small bumps and imperfections. Another way to put it...slow speed damping.

The second zone is moderately valved. Vehicle speed has increased and that piston will float in this second zone most of the time. When its in this zone, it bypasses the first zone (where the name comes from)

Third zone is heavily valved. Large whoops, jumps and G outs will get a vehicle traveling at speed into this zone. Idea being that the damping slows down the shock piston velocity enough to minimize the chance of shock bottom out, supplemented with hydraulic bump stops. First two zones are bypassed.


To date, I have not seen an RC shock that performs the same functions as a true bypass and its not really the same as a "dual rate" piston that has been done in RC before. Any time you see people running a second shocks its usually for looks or performs some additional damping to the primary coilover.

*Sorry for slight thread jack
*Spring rate determines ride height, not damping
**Except if your shocks are hydrolocked...pogo stick!

[MAC FAB]

Great info again , be it external or internal bypass shocks like Kings, FOA, ...... My 10 lb go fast car has 200% less rebound (faster)than compression via my bypass pistons, cycles 4-1/2" now with limit straps, like my Bomber build will. A friend and I were attempting to make a true bypass shock, too small for it to be anything more than a 1 tube, not worth the hassle.

So back to the OP question, the benefit is exactlly what in performance or handling with the various setups? Its got to do something to keep the wheels planted?

[2mtech]

This has been educational!

Since shock tuning relates directly to the application at hand, it would seem a multi-condition shock like the King above would be the best choice for a multi-application platform like the Bomber that goes straight from crawling to WOT air time for best all around performance rather than trying to set up a standard shock to work across its spectrum of driving.

Back on topic, then...in the case of a bypass shock is preset rebound even a consideration?

[Stormin2u]

I like a fast front rebound and a slow rear rebound.