Shocks... because somebody had to do it.

[Dust]

What are they?
What do they do?
What different types are there?
How are the different types used?
How does size effect the function?
How does shaft size change function?
How do the various manufacturers stack up as used on recreational Broncos/trucks?

What did I miss?


Oh, who here represents/sells what shock manufacturer...

[Polarcub]

What are they?
What do they do?:Control the rate of reaction due to forces exerted upon your suspension (ie Springs)
What different types are there?Emusion,reservoir,bypass (internal/External) Air shocks, and coilovers may be viewed as a variant of reservoir/emulsion shocks that combine your primary spring
How are the different types used?All are used to control your suspension during compression or rebound, bypasses provide a higer degree of tuning throughougth the stroke of the shock,typically used in competition applications such as desert racing, reservoir shocks are used when an increase of dampening and longevity is needed that a standard emulsion shocks cannot provide, used from race to street, emulsion shocks are non tuneable once built, they contain a smaller volume of hydrallic fluid and gas (usually N2) used primarily in street applications

How does size effect the function?THe larger diameter shock the greater the dampening ability by virtue of the larger internal components. THe larger shocks will have the ability to work longer at lower tempratures
How does shaft size change function?
How do the various manufacturers stack up as used on recreational Broncos/trucks? I have experiene with Bilstein/King all good, Sway away and FOX are also used by many with good results.

What did I miss?


Oh, who here represents/sells what shock manufacturer...

I am sure that others will be able to add value to the portions I have attempted to answer.

[Dust]

What is a Shock?
A Shock as we use them is a mechanical device that uses a working fluid (Air or Oil) to convert mechanical motion into heat and to dissipate that heat to the atmosphere. This of-course is the actual reason for global warming however that is a separate subject.
The basic common design is a closed cylinder with a shaft driven piston, and an Oil of a light weight, or viscosity; the body (cylinder) is attached to one point and the shaft is attached to another point, the points being located on the chassis and on the suspension. As the piston is moved the pressure on the compression side increases while the pressure on the extension side is reduced. If there is no passage that connects the two sides of the piston the effect is the piston will not move as for all intents Oil is incompressible. The passage can be in the piston or it can “Bypass” the piston, through the piston, internally to the shock, or externally to the cylinder body. If the passage is large enough the piston will move freely and the oil will be simply displaced from one side of the piston to the other without restriction. However, if the passage is smaller or has a specific restriction in the passage piston movement will be reduced in speed proportional to the restriction and the movement of the piston speed will be restricted in both directions.
Thus it is possible to have two passages one for each direction and it is possible to use different restrictions for the different directions and so to have different rates for different directions.

[baja-chris]

All good except one point regarding larger shocks. Your second point on that is spot on, larger shocks can do more work for a given temperature rise due to the larger volume of oil. But even a tiny 2" shock can be valved just as stiff as a 4" shock can. The difference is on how long it can do that before it gets too hot. In physics terms, Work = Force x Time. Little shock can do as much Force as big shock but much less Work. In other words, if you just need a shock to control your bronco for jump contests, then you can make it perform just as good with a quality 2" shock as you can with a 4" shock. But if you want it to perform at the end of a 50 mile whoop field then you better have a big shock or a way to cool the little one.

And Joel Ward is the Bilstien shock guru on this site. He knows his stuff and is super helpful with all brands.

What are they?
What do they do?:Control the rate of reaction due to forces exerted upon your suspension (ie Springs)
What different types are there?Emusion,reservoir,bypass (internal/External) Air shocks, and coilovers may be viewed as a variant of reservoir/emulsion shocks that combine your primary spring
How are the different types used?All are used to control your suspension during compression or rebound, bypasses provide a higer degree of tuning throughougth the stroke of the shock,typically used in competition applications such as desert racing, reservoir shocks are used when an increase of dampening and longevity is needed that a standard emulsion shocks cannot provide, used from race to street, emulsion shocks are non tuneable once built, they contain a smaller volume of hydrallic fluid and gas (usually N2) used primarily in street applications

How does size effect the function?THe larger diameter shock the greater the dampening ability by virtue of the larger internal components. THe larger shocks will have the ability to work longer at lower tempratures
How does shaft size change function?
How do the various manufacturers stack up as used on recreational Broncos/trucks? I have experiene with Bilstein/King all good, Sway away and FOX are also used by many with good results.

What did I miss?


Oh, who here represents/sells what shock manufacturer...

I am sure that others will be able to add value to the portions I have attempted to answer.

[Dust]

How would the shock valving (front) be different between a SA and a TTB with both shocks being located behind the axle center-line?

[Polarcub]

Good question, IMO they would not be much different as every truck is different to begin with. You have to tune to your application. You can get a starting point but there are enough variables that will affect final valving. In my case I know the front can get a bit better. It is close with a .012 stack but I think once I can get a tune session that the valving up front will change some. I think that the biggest factors are spring rate and shock location to find that starting point.

[Dust]

How would the valving be different with the rear shocks under the body ~vs~ coming up through the floor?

Or between a rear leaf set-up ~vs~ a link set-up?

[gunit]

The difference is shocks under the floor are laid down instead of vertical which affects the motion ratio of the shock. The shocks at an angle must have stiffer valving to have the same damping effect as a shock mounted vertically, which builds more heat.

Similarly, on a link suspension like most desert trucks have, where the shocks are mounted on the trailing arm in front of the axle, the shocks have to have stiffer valving than for a leaf spring application because of the lever effect.

On a straight bar link suspension where the shocks are mounted on the axle like most short course trucks have, then the valving would be similar to a leaf spring set up.

[Dust]

All things being equal will a stiffer valved shock run hotter?

[randomthoughtsracing]

All things being equal will a stiffer valved shock run hotter?

The intuative answer is yes, although maybe not for the reasons off roaders expect. The discussion here might think of "stiffer" as being compression only when quite a bit of the heat may be coming from rebound... So, we need to think of heat generated by both compression and rebound.

To play devils advocate and say no, it could be said that at some point a shock can be so stiff that it dosent cycle very much and the temps may be pretty low (as well as vehicle speed).

[Dust]

All things being equal will a stiffer valved shock run hotter?

The intuative answer is yes, although maybe not for the reasons off roaders expect. The discussion here might think of "stiffer" as being compression only when quite a bit of the heat may be coming from rebound... So, we need to think of heat generated by both compression and rebound.

To play devils advocate and say no, it could be said that at some point a shock can be so stiff that it dosent cycle very much and the temps may be pretty low (as well as vehicle speed).

Great answer!

[randomthoughtsracing]

...
How does shaft size change function?

Oh, who here represents/sells what shock manufacturer...

There are a number of effects that the rod has on shock function. Contrary to popular trends, and male mochismo, a larger shaft (beyond what is needed strength wise) isnt always desirable. There are actually a number of undesirable effects of a too large shaft (air shocks are another story).

-Expense...

-weight...

-seal stiction... more seal surface = more drag and more breakaway friction

-increased displacament chamber size or pressure ramp up... Shaft displacement has to go someplace. If the Gas chamber isnt made larger then the pressure will change more drasticaly from full extension to full compression.

-IFP cycling speed (depending on reservoir diamater)... IFP speed slows as res diamater increases. Faster piston speed = faster seal wear and other undesirable effects.

-increased hose size componentry... Shaft diamater can effect hose diamater.

-rock hits... as shaft diamater increases the exposure to debris increases. The rod also has a "flatter" surface than a smaller rod increasing the likelyhood of a "head on" rock strike instead of a glancing hit.

[Dust]

In the case of a Shock absorber; Emulsion, Rezzy, Bypass what is an adequate shaft size?
For example I (personally) have never run more then a 5/8" that I can remember... I have never had a problem and that said I have seen many, many bent shafts on Coilovers with shafts in the 3/4" range.

[BDKW1]

Usually when shafts bend it's for something else failing or poor setup. If everything is set-up correctly, 3/4" is plenty large enough for anything. 5/8" is good enough for 75% of the stuff out there.

[Polarcub]

In the case of a Shock absorber; Emulsion, Rezzy, Bypass what is an adequate shaft size?
For example I (personally) have never run more then a 5/8" that I can remember... I have never had a problem and that said I have seen many, many bent shafts on Coilovers with shafts in the 3/4" range.

I feel that the majority of bent shafts are form improper setup such as angles or shock mounts and for the rest it seems to be the result of a non typical force such as accident or failure of other parts causing non designed forces acting on the shaft. It is my opinion that the 5/8-7/8 range is more than enough for the majority of people. There is a place for the monster 1" shafts for some applications though but I am not familiar enough with what they are. I would guess that the larger shafts are desired for applications where the vehicle weight and mounting locations exceed the norms of the normal shaft sizes.

[Dust]

With regard to the bent shafts I have been wondering if there is a...
In one case I having removed the springs and the Ni-charge articulated the axle to the extremes with out the straps or bumps (I did not build it, just helping a friend with a used toy) and there simply was no place I could find a bind. However, in the middle of the season a banana shaft.
There was not a mark on any component indicating a hit . When I looked at things closely the only conclusion I could come up with was the lower shock SRE bound up, and because the shock was not perpendicular to the travel requiring ~20° rotation, it twisted the shock.
FWIW the SRE's were all new, so neglect was not the issue.

[Polarcub]

With regard to the bent shafts I have been wondering if there is a...
In one case I having removed the springs and the Ni-charge articulated the axle to the extremes with out the straps or bumps (I did not build it, just helping a friend with a used toy) and there simply was no place I could find a bind. However, in the middle of the season a banana shaft.
There was not a mark on any component indicating a hit . When I looked at things closely the only conclusion I could come up with was the lower shock SRE bound up, and because the shock was not perpendicular to the travel requiring ~20° rotation, it twisted the shock.
FWIW the SRE's were all new, so neglect was not the issue.

I can see how that would affect things, after some thought on this while on the beach today I also got to thinking about extreme shaft length may play a part into some of the bending. With the shaft at full extension it is possible IMO that slight misalignment's that are soaked up by misalignment spacers may fatigue the metal? I know that I found a surprise in my front lower mounts that will need to be corrected. The tabs were not installed correctly and the rod ends at full extension would bind. Not a horrible as I am strapped to prevent full extension but something that needs to be corrected. Good questions I think this thread may help a few people as a quick reference.

[Dust]

How is valving discussed? Where do you start with it.
There are some familiar terms such as compression and rebound.
When I started road racing we used percentages, and you only needed one of the two.
So a 70/30 shock was just a 30 and “supposedly” was valved 30% (Rebound) of the Compression side, though I always struggled with the 70 because; it was 70% of, 100%, of what, and even turned around it makes no sense, and the only thing that made sense is we all knew what we were talking about so the work got done.
If you go to the FOA site you see valving listed from, Zero to Extra Firm, with a Med. Round about the middle… If Zero means WFO (no restriction) then Ex. Firm is what…
Staying with FOA for the moment What is Medium?
Now, I am not picking on FOA because the Bilstein catalog lists 5 stages of valving and the middle of the range is about ~180/75… At least there is a definition of the number is, the force in, “Newtons at 0.52m/s” which is great and in reality because I have never had a Data Acquisition system available to put on any of my trucks, I can guess at the force, and I can guess at the shaft speed. The reality is, the numbers are completely useless except that it is about the middle, or Medium. Be that as it may how would one set about “Guessing” where to pick the C or R valving because be it medium or 180/75 what/how will it ride/perform?

Put it another way my DD Ranger has at least 35,000-miles on a set of 'whitecans' (RS5000) that had 10k on them when I picked em up used... so I should put shocks on it if I wanted to have exactly the same valving as I have now what would I choose?
(actually it rides nice and works well enough in the dirt being basically stock)


Digressive Valving. What is Digressive Valving and why is it used on rock crawlers, once referenced to the Rear of a Bronco….

[randomthoughtsracing]

How is valving discussed? Where do you start with it.
...
Digressive Valving. What is Digressive Valving and why is it used on rock crawlers, once referenced to the Rear of a Bronco….

Valving steps...
-Have the mfg spec a valving for your application and usage.
-Use the supplied valving as a reference point to increase or decrease comp and rebound.

Digressive valving delivers damping with a distinct change at some shaft speed. Most Bilstein 5100 applications are digressive. The digressive curve can be compression or rebound depending on which way the piston is flipped. For rock crawling the valving philosophy goes way off on a tangent, digressive allows precise control at low speed but increases damping greatly at higher shaft speeds. The RCS valving we sell for Rock Crawling is not intended for use over bumps at speed. Ill try to post some reference pictures.

I am working on a revised valving sheet for 60mm Bilstein shocks that is a bit more user friendly but still utalizes the copious number of valve shims that we have available.

[shockseals.com]

On top of what Joel said...with bilstein the number 170/80 actually means something quantitative. Its a damping force at a specific shaft speed.

With Fox its a reference to their valve stack configurations. Nothing quantitative.

Ive never seen a numbering system from King or SAW with relation to shim stacks or damping forces.

I find it humorous when people come to me and tell me they need 10 percent more this or 30 percent less that or any kind of percentage for that matter. Or when they ask so how many percent did you change it? My answer: "Well I didnt dyno it so I couldnt tell you and anybody who gives you a percentage and hasnt dyno'd every shim stack configuration for your particular shock piston is flat out lying to you."


Just explain what its doing to somebody experienced and let them decide what it needs.