Shock Angle

[Hardline]

2. Up to a certain shock angle from vertical--dictated by chassis design/link arrangment, your damping rate will be progressive.

I'm having trouble seeing that. The shock/spring has maximum leverage on the axle when vertical. "Progressive" means the rates increase with compression, agreed? Any angle of shock will increase with chassis compression therefore digressive. To become progressive the shock would have to stand straighter up with chassis compression. True, I'm thinking mostly of spring rate, but I don't see why damping rate would be any different.

Vertical gives the most shock stroke with chassis travel. Laid back gives less shock stroke for the same chassis travel. How can that be progressive?

It may have something to do with your use of "ride" travel which appears to be some horizontal component I'm not familiar with vs the vertical wheel travel I'm thinking of.

 

[K.O.M.]

I'm having trouble seeing that. The shock/spring has maximum leverage on the axle when vertical.

Correct. And only correct when the shock is mounted directly on the axle.

"Progressive" means the rates increase with compression, agreed?

Yes.

Any angle of shock will increase with chassis compression therefore digressive. To become progressive the shock would have to stand straighter up with chassis compression. True, I'm thinking mostly of spring rate, but I don't see why damping rate would be any different.

I beleive you are only thinking about INITIAL damping rate. A shock that has a rate of say 100 at vertical, will only have a vertical rate of roughly 70 when laid at 45 degrees (100 cos 45 = 70). However, as Calderwood mentioned in his post, up to a given shock angle, the angle between the shock and lower link increases, in effect the shocks are standing themselves up with relation to the lower link, increasing the leverage the shock has, so it may start off at a rate of 70, but it only goes up from there at an exponential rate as the shock compresses.

For example, imagine starting with your lower link horizontal and your shock is at 45 degrees, both attached at the same point. If you had enough travel and stroke that the lower link can rotate up to 45 degrees, the angle between the lower link and the shock will approach 90 degrees (shock is fixed at two points, so all it can do is get shorter), so the shock is now increasing its leverage.

Vertical gives the most shock stroke with chassis travel. Laid back gives less shock stroke for the same chassis travel. How can that be progressive?

Don't confuse travel with actual suspension damping rate.

It may have something to do with your use of "ride" travel which appears to be some horizontal component I'm not familiar with vs the vertical wheel travel I'm thinking of.

Ride travel is just simply both front or both rear wheels compressing together at the same time, no horizontal component.

 

[Hardline]

"...up to a given shock angle, the angle between the shock and lower link increases, in effect the shocks are standing themselves up with relation to the lower link, increasing the leverage the shock has, so it may start off at a rate of 70, but it only goes up from there at an exponential rate as the shock compresses."

Not from where I sit. But we're making progress. Maybe we're talking different type rigs is the problem.

Yes the link angles change with chassis travel, but my rigs have upper and lower links which essentially form a parallelogram. So the axle mostly goes up and down without rotation. It's the direction of axle motion the shock is working against so once again my point -- ANY shock angularity reduces the leverage of the shock/spring. Max leverage is when the shock is parallel to the plane of axle motion, which I'm calling vertical.


EDIT. Okay, the axle motion is only vertical(ish) for small motions. Overall, it still has to work through an arc established by the links, so maybe it could "stand up" a shock. Point taken. But I'd like to see a suspension model to show that's actually significant over regular chassis travel. It seems like we may be talking a couple degrees or so, but way less than the 45 degrees that many shock lay-backs use. It may be such a small factor it's moot.

.

 

[6sharky9]

So let me ask what is the bad part about if any to angle your shocks using a 4 link...I was plenty aware before even doing that I would lose shock travel but gain more wheel travel..No dispute that's what happens when you do angle them...So my dilemma was I wanted more travel without raising COG..so I went from a stock 90mm shock to a custom set of 93mm.

I mounted them 90 degress and didn't like the results as COG was higher and it seems a bit stiff...So I try softer springs and it gets better but still has a higher COG.

Now I decide instead of buying ugly looking brackets that mount all over the stock shock hoops to make some lightweight extensions to give me what im looking for...I moved the shock forward I believe more than 10mm to regain my ride height.

Now I notice I get the upward travel increase I wanted but lost some due to angle...But all is not bad because 93mm was too much and the tires would rub with the shock mounted 90 degrees..So now ive found the maximum travel I can possibly have with no rubbing issues on upward travel based on my tire diameter and the body I use..just say a STOCK honcho as an example.

I also get the added 3mm of downtravel I had no matter how they were mounted..That didn't change for me.

But in all its made the shocks softer mounting them at an angle..So I corrected that with more tuning..Thats now not an issue.

So in all how is it so bad to do this or recommend it to someone??

Its certainly not hurt my performance but only increased it..maybe the better shocks as one suggested as to why I saw a performance gain. I don't dispute it helped..But I don't believe its just that.

Despite what some say A rock crawler does very well on the rocks and general terrain using this angled mounting..An I think depite having better shocks this is also helping improve the crawling abilities of my Honcho and how it tracks over the terrain...I can see the suspension react much different over the terrain and its just a big difference to me .

Where did I go wrong choosing to take this route?

 

[K.O.M.]

@Hardline: The AXLE is travelling at more or less a vertical path. However, look at the links--upper or lower, doesn't matter--they always follow an ARC. Now look at where the shock is mounted on say an SCX10, same mounting position as lower link, so the lower link connected at the axle and lower shock mount are following the same arc as the suspension is compressing. I think that you agree or will agree up to this point.

Now you have to do some vector analysis. I'm simplifying here since this is difficult to convey without a free-body diagram; we're also assuming that axles and suspension components have no mass . The bump force is going up, the axle is more or less travelling upwards, but the shock, the way that it is mounted doesn't care about that straight vertical force. All that it cares about is the resultant vector (combination of the initial vertical bump + horizontal redirection done by the lower link). The resultant vector is tangent to the arc created by the lower link mount (remember, the lower link constrains the path the lower shock mount travels). That vector changes as the suspension cycles up, and becomes more and more parallel with the shock as the suspension compresses.

Disclaimer: For the fellow engineers, mathematicians and physicists--I fully realize that we are getting into angular momentum once everything is considered (like the lower link actually pulling to help reduce the resultant vector).

 

[EeePee]

To achieve a progressive rate shock (spring and dampening) action, the shock will end in the perpendicular position to the lower link at full compression. Thus, at ride height or rest or fully drooped out, the shock will be leaning towards the center of the vehicle viewed from the side just a little bit. Not much.

It's as easy as grabbing your truck and compressing a shock and looking if your shock and lower link are at 90 degrees to each other.

The extreme falling rates of a comp crawler could be countered with progressive rate springs. And even some funny pistons if you're gonna get really crazy. RPM or Proline or someone made a piston that had a needle that grew in diameter going through the hole, making the hole more restrictive through its travel. Seems pretty pointless though with the stuff the comp crawlers are doing these days.

 

[Hardline]

Yeah I'm thinking you can only get a progressive nature for maybe 10 degrees of layback. And layback shocks are usually much more angled than that resulting in very little progressive and a lot of digressive behavior.

I'm not married to that 10 degree number. I just picked a couple values of link length and chassis stroke. But I think extreme angle leads to extreme digression and that might lead to poor performance due to diminished damping and spring rate. Personally, I like to not angle further back than 45 degrees at ride height to ensure effective damping and springing. I think more upright works even better but gives weight and cg disadvantages.

 

[EeePee]

layback shocks are usually much more angled than that resulting in very little progressive and a lot of digressive behavior

Not progressive at all unless they are approaching 90 degrees to the lower link. If they are moving away from 90 degrees, it's always digressive.

And it doesn't matter if they're laid back, or angled forward. Same thing. Move away from the final point being 90 degrees, digressive.

A right triangle between the lower link, shock, and screw that locates the top of the shock and the screw that locates the lower link at the chassis, at full compression.

Nevermind Tamiya's cantilever stuff that was easy to feel it go from progressive to digressive or all the combos you could think of because they give you a dozen option to mount everything. Fun tinker toys, but too much.

 

[Duuuuuuuude]

So in all how is it so bad to do this or recommend it to someone??

Its not.

Where did I go wrong...?

By spewing technojargon that you didn't completely understand. As a few others have found (myself as well), you are just about the only person on the english speaking www that has put "alpha angle" and "shock" in the same sentence. Your inability to expand any further beyond that little nugget of tech only reinforces that lack of understanding.

Upgrading your shocks from stock is still your biggest performance gain here, but you did well by positioning and limiting them to achieve the wheel travel you were after.

Remember that any time you replace one part with another, you have to take into account the benefits that they themselves provide before you fiddle with adjustments and claim that the resulting improvements were all from you. In this case, you gained smoother and better dampening right off the bat because of their superior design, which you've experienced. Your added tweaks gave you the wheel travel and ride height you wanted.

 

[Androtaz]

There yah go "thumbsup" Now i see why he gets rode like a stolen go cart :lmao:

Its not.



By spewing technojargon that you didn't completely understand. As a few others have found (myself as well), you are just about the only person on the english speaking www that has put "alpha angle" and "shock" in the same sentence. Your inability to expand any further beyond that little nugget of tech only reinforces that lack of understanding.

Upgrading your shocks from stock is still your biggest performance gain here, but you did well by positioning and limiting them to achieve the wheel travel you were after.

Remember that any time you replace one part with another, you have to take into account the benefits that they themselves provide before you fiddle with adjustments and claim that the resulting improvements were all from you. In this case, you gained smoother and better dampening right off the bat because of their superior design, which you've experienced. Your added tweaks gave you the wheel travel and ride height you wanted.

 

[6sharky9]

Its not.



By spewing technojargon that you didn't completely understand. As a few others have found (myself as well), you are just about the only person on the english speaking www that has put "alpha angle" and "shock" in the same sentence. Your inability to expand any further beyond that little nugget of tech only reinforces that lack of understanding.

Upgrading your shocks from stock is still your biggest performance gain here, but you did well by positioning and limiting them to achieve the wheel travel you were after.

Remember that any time you replace one part with another, you have to take into account the benefits that they themselves provide before you fiddle with adjustments and claim that the resulting improvements were all from you. In this case, you gained smoother and better dampening right off the bat because of their superior design, which you've experienced. Your added tweaks gave you the wheel travel and ride height you wanted.

So let me get this right..You feel I didn't think replacing small bore plastic crap shocks with Losi big bores would've been an improvement to begin with?.

..For those who did't know replacing your shocks with big bore quality shocks will improve your performance.. they do...Duuuuude says so.

Do you also think I didn't try the shocks in different positions first as I mentioned more than once I have ..If you want the life story on things ive tried with the stock shocks and the new ones I can provide that for you..Dont assume I only tried one or 2 things.

Do you not think maybe I researched the matter doing what I did before I did it?

You can come at me once again with your analytical bull crap and assume all you want that I don't know anything.

One thing I do know is im going to walk off from this thread because I can already tell you want this to be an argument based on your insulting comments and thats not going to happen.

 

[MRCrackhead]

Newbie General Section

Feel free to post here, without fear of being criticized for your thoughts...............sometimes.

 

[Duuuuuuuude]

So let me get this right..You feel I didn't think replacing small bore plastic crap shocks with Losi big bores would've been an improvement to begin with?.

As far as I can recall, you jumped right into alpha angles and never mentioned anything about how the new shocks were better units than the stock ones. Those aren't even really "big bores"...

Do you also think I didn't try the shocks in different positions first as I mentioned more than once I have.

I'm sure you did.

Do you not think maybe I researched the matter doing what I did before I did it?

Again, I'm sure you did.

You can come at me once again with your analytical bull crap and assume all you want that I don't know anything.

I'm not analyzing anything, just pointing out the flaws in your "teaching". I'm sure you do know stuff, just not as much as you'd like to think you do. What I'm trying to tell you is to talk less and listen more. If you are happy with what you have done, just leave it at that. You consistently get in over your head trying to defend yourself. There are many ways to accomplish a particular goal with these rigs...

I've already said that tweaking the shocks to your liking was a good thing. What got my attention was that you paid no mind to the fact that you were using overall superior shocks to begin with and attributed all of your success to your methods.

One thing I do know is im going to walk off from this thread because I can already tell you want this to be an argument based on your insulting comments and thats not going to happen.

One thing I know from experience is that you won't walk far, or for very long.

Newbie General is a flame-free section...so no, I am not here to pick a fight.

 

[WHITE-TRASH]

Newbie General Section

Feel free to post here, without fear of being criticized for your thoughts...............sometimes.

Which is why I've stayed out of it. :lol:


As a rule leaning the chassis mounted end of the shocks towards the mounting points of the fixed end of whatever suspension system you are running be it links, leaf springs etc will result in a softer valving and a bit more travel. Mounting the shock in line with the line of travel the valving stays linear. I didn't realize this was an odd concept to grasp but I guess this is the newbie section so it's the right place to learn.

 

[Duuuuuuuude]

As a rule leaning the chassis mounted end of the shocks towards the mounting points of the fixed end of whatever suspension system you are running be it links, leaf springs etc will result in a softer valving and a bit more travel. Mounting the shock in line with the line of travel the valving stays linear. I didn't realize this was an odd concept to grasp but I guess this is the newbie section so it's the right place to learn.

Anyone who has ever read a Traxxas manual knows this. Its not a proper way to tune a suspension, but its the quickest and easiest.

 

[WHITE-TRASH]

Anyone who has ever read a Traxxas manual knows this. Its not a proper way to tune a suspension, but its the quickest and easiest.

Never held nor read a traxxas manual, I learned about suspension tuning by actually doing it on full size vehicles.

 

[Duuuuuuuude]

Never held nor read a traxxas manual, I learned about suspension tuning by actually doing it on full size vehicles.

The hell you say...on both counts.

 

[WHITE-TRASH]

The hell you say...on both counts.

:lol: Hard to believe that someone has never bought a new rc evar especially a traxxas product since all their money went into building wheelers that a human actually fit in.

 

[Highmark]

I learned most of what I know from messing with pro-street cars :lol:

 

[MountainStorm]

As Mister Spock would say: "Fascinating Captain."

I'm a newb to RC but my brain works okay. All I did to try and figure this stuff out is actually move the shock around a whole lot and see what it looked and felt like. Practical testing weeds out specious theories pretty quick.

A mental technique I employ is visualization and going from one end of the spectrum to the other. If the shock is dead vertical it is doing the most work. If it is completely horizontal it is doing no work (or almost no work). How hard can it be to understand that?

Normally shock is what limits up and down travel of the links for the most part . You hit the stops on the way up or the way down. The more angle off vertical the more travel and the less resistance from the springs and damping.

What I think of as "tuning" is looking for that sweet spot where the travel, resistance, ride height, damping all do something useful. That sweet spot is probably not going to be the same for different vehicles or drivers....

But like I said...I'm a newb.

Am I on the right track?