Shock Angle

[WHITE-TRASH]

Am I on the right track?

Yup, moving the mounts around is helpful but actual "tuning" involves spring, piston and oil weight changes as needed.

 

[K.O.M.]

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 yes, softer INITIAL damping rate when compared to the same shock stood vertical and a bit more travel yes, if and only if, the shocks were limiting the travel to begin with (not chassis members, links, etc…) OR if the upper shock mount moves down more than it does over, which also raises ride height--with the exception being RC comp crawlers where there is no "frame" to limit the up travel, only the links running into other hard parts. Mounting the shock in line with the line of travel the valving stays linear. Yup 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.

Well, as we've proven, it' can be an odd concept to grasp, and even those that say they understand, don't TOTALLY understand.

 

[Hardline]

Come on guys. If you get progressive geometry from vertical to 10 degrees, then goes divergent with greater angle, what does that mean? If the shock is in line with the initial motion, call that zero degrees layback and the cosine is 1.000. If instead the shock is laid back 10 degrees as per example, the cosine is 0.985. We're talking 1.5% difference for your "softer INITIAL damping". I gotta think that's noise.

Highly divergent layback however has a pronounced effect. Cos 45 = .71 so a 29% reduction in resistance.

 

[K.O.M.]

From Post #42: I had already worked out the math there.

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.

Re-read my example with the links starting at parallel with the ground, shocks at 45 degrees.

We already have established that at 45 degrees shock angle, we're at 70 if you start with a rate of 100 at vertical. Now move that wheel up any distance, you will have to re-draw the triangle. The lower link is always perpendicular to the resultant force vector. Force vector is tangent to the arc created by the lower link, which means it is always perpendicular to the lower link. But what happens to the angle between the force vector and the shock? It goes from 45 to 44 to 43 to 42 etc…as the lower link sweeps the arc on suspension up travel. So the rate of the shock is going from 70 back up to 100 (to simplify) when the lower link and shock are back to perpendicular when the lower link has rotated 45 degrees. So given that, is the shock rate not progressive?

 

[Hardline]

Yes it is. But my comment was on whether it was of a significant magnitude. If it moves from 45 to 44 to 43 all the way back to 0, yeah, that's a big deal. If it moves from 45 to 44 to 43 and bottoms out, then no. I didn't do the trig but I'd bet that's not significant.

So my question becomes what are real world numbers on a non-weird crawler? I didn't take a bunch of measurements etc, but I fondled my Scorp and I don't see the shock angle to motion direction changing much at all over it's range of travel. Maybe scale rigs are different.

 

[Duuuuuuuude]

So my question becomes what are real world numbers on a non-weird crawler? I didn't take a bunch of measurements etc, but I fondled my Scorp and I don't see the shock angle to motion direction changing much at all over it's range of travel. Maybe scale rigs are different.

IMO that is highly variable. I've had rigs that I didn't really consider "weird", but had shocks that were fairly laid down. I've also had one or two that were definitely "weird".

Chances are though, if you've got a rig with some severe shock/spring angles, you've already accounted for it in tuning.

 

[WHITE-TRASH]

Well, as we've proven, it' can be an odd concept to grasp, and even those that say they understand, don't TOTALLY understand.

Not understanding suspension tuning and not taking the time to explain all the nuances involved in the tuning thereof aren't necessarily exclusive. ;-)

 

[K.O.M.]

Yes it is. But my comment was on whether it was of a significant magnitude. If it moves from 45 to 44 to 43 all the way back to 0, yeah, that's a big deal. If it moves from 45 to 44 to 43 and bottoms out, then no. I didn't do the trig but I'd bet that's not significant.

So my question becomes what are real world numbers on a non-weird crawler? I didn't take a bunch of measurements etc, but I fondled my Scorp and I don't see the shock angle to motion direction changing much at all over it's range of travel. Maybe scale rigs are different.

I think that to you and I (and a lot of other people), as long as we're in the ballpark, then the small incremental changes to wether the thing is progressive/digressive are insignificant as far as we're concerned. If I was chasing tenths or hundredths of a second per lap that was keeping me from the podium in my real car in a time trial, then that's a different story.

I'll apologize for getting tunnel vision on the whole damping rate theory, but I saw the mis-use of terminology (alpha angle anyone?), so I totally nerded out on the calcs.

And no, scale rigs, because of the even smaller amounts of travel and available configurations return even smaller differences in rates.

 

[javi]

I have to be honest this time I didnt quite understand a lot of what was thrown out in this thread.
I thought maybe I would get a simple answer but the more info the better it will be.:shock:
I was just curious if the shock at a small angle give me more articulation.
You guys really know your stuff though I made some small brackets for the front suspension and I did notice the drop in ride height so I might make the actual aluminum bracket a lot smaller.
Thanks for all of the info.

 

[EeePee]

I was just curious if the shock at a small angle give me more articulation.

Yes.

 

[6sharky9]

OP...If you are using stock shocks your best spot to mount them for what little gain you will get is the last holes on the shock hoops leaning them toward the transmission both front and rear.

But you wont necessarily get any real noticeable travel due to the fact its very small..maybe 1/4 of a millimeter gain if that and you will have no increase in downward travel at all.,,And if you lean it down too far you will lower your vehicle which is fine but actually lose travel because your tires will rub and not allow all the travel you have.

You really need some longer shocks to take advantage of this method...If you are using a stock body and tire diameters ive personally found 93mm to be the sweet spot (@ stock ride height) to gain travel and not have rubbing issues or raise the COG.

Not that there aren't other ways to accomplish the same goal even mounted 90 degrees with longer shocks but i just found this method less expensive and with minimal weight added.

Despite any improvements or added weight I got from better shocks the principle still remains the same...I made my stock shocks work pretty darn well mounted at 90 degrees but I wanted more travel...I may try a set of wraith 103mm shocks and limit those to 93mm and see how they work..If I like it then I lose some weight as well which is a benefit.

 

[6sharky9]

And by the way I tried to explain in simple terms...I stand by how I explained everything to you ...Good luck with your truck and I hope you find something that works for you.

 

[KillerBlackbird]

Some gasoline to go with your matches: What angle to mount a shock - OFN Forums

Obviously for 1:1's, but gives explanation with a link to Pirate4X4's extensive knowledge.

 

[javi]

And by the way I tried to explain in simple terms...I stand by how I explained everything to you ...Good luck with your truck and I hope you find something that works for you.

You did, and once I started reading all of the other responses I got confused.
I will keep reading and trying to understand the suspension in scale rc... well heck any rc for that matter but will do some trial and error adjustments.

Thanks to all who replied to this thread.