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Gizmo Racing USA Genesis TC Kit

Old 08-04-2019, 06:42 AM
  #241  
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Originally Posted by glennhl View Post
To me it doesn't matter that the shocks point to the contact patch. All I see is a laid down shock that compresses a lot less with upward movement of the suspension arm making it less effective at damping and less effective of the spring resisting upward movement of the arm. You are going to have to run a lot stiffer springs and a lot thicker oil to have the same effect of an upright shock. Kinematics 101.

If you really want to lay down a shock to get the CG lower, you are going to have to come up with a push or pull rod along with a rocker to actuate the shock/spring unit. Or you could come up with a rotary damper and leaf spring that is packaged very low. But some Russian genius already came up with that.
This is not really about lowering the cg so much as it is about getting that underdampened, under sprung feeling that you refer to that the awesomatix gives. We are aware that we need the stiffer springs, and we have been compensating for this. Raising and moving the lower pivot outwards, does matter though, because when moving the leverage point close to the tire, instead of inside of it, the motion ratio changes, making a 2.9 spring act much stiffer, which provides the extra leverage necessary to get the correct spring rate at the wheel. (As a side note, the awesomatix "lower pivot point for example, is right at the P04 right under the knuckle, this is the widest setting they could use, to support the car as much as possible allowing them to use as soft of a spring as they could with this set up.) You cannot do this by simply laying down the shock. At this point you would DEFINITELY need some massively stiff springs.

Our real reasoning behind this high angle shock set up is that the leaf spring does not provide pressure on the tire like a stand up shock, but instead just holds the car up and sort of "keeps" the car level. This is "Kinematics 101" as well. This allows for the car, even though it was a very low CG, to roll tremendously in the corners, but at the same time come back to center very quickly, which provides their super fast corner speed, (albeit at the loss of some forward grip like our high angle shock setting is proving so far) In the end, it is not the CG we are trying to replicate from the Awesomatix, (although this does lower it slightly and that can't be all that bad), but rather the damping and spring characteristic. The higher angle leverage provides a very similar effect to the Awesomatix suspension (or at least one that is approaching the effect more so than before).
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Old 08-04-2019, 09:23 AM
  #242  
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Originally Posted by CristianTabush View Post
This is not really about lowering the cg so much as it is about getting that underdampened, under sprung feeling that you refer to that the awesomatix gives. We are aware that we need the stiffer springs, and we have been compensating for this. Raising and moving the lower pivot outwards, does matter though, because when moving the leverage point close to the tire, instead of inside of it, the motion ratio changes, making a 2.9 spring act much stiffer, which provides the extra leverage necessary to get the correct spring rate at the wheel. (As a side note, the awesomatix "lower pivot point for example, is right at the P04 right under the knuckle, this is the widest setting they could use, to support the car as much as possible allowing them to use as soft of a spring as they could with this set up.) You cannot do this by simply laying down the shock. At this point you would DEFINITELY need some massively stiff springs.

Our real reasoning behind this high angle shock set up is that the leaf spring does not provide pressure on the tire like a stand up shock, but instead just holds the car up and sort of "keeps" the car level. This is "Kinematics 101" as well. This allows for the car, even though it was a very low CG, to roll tremendously in the corners, but at the same time come back to center very quickly, which provides their super fast corner speed, (albeit at the loss of some forward grip like our high angle shock setting is proving so far) In the end, it is not the CG we are trying to replicate from the Awesomatix, (although this does lower it slightly and that can't be all that bad), but rather the damping and spring characteristic. The higher angle leverage provides a very similar effect to the Awesomatix suspension (or at least one that is approaching the effect more so than before).
You are correct, you made up for the loss of spring force by moving the lower shock mount closer to the wheel, but you could have done that without laying down the shock on the top mount. I just don't like the loss of motion the lay down shock gives you. And I guess I don't understand why a leaf spring does not provide pressure on the tire like a stand up shock. A coil spring and a leaf spring are both springs and they provide a force that increases fairly linearly with compression (coil) or bending (leaf). Either spring provides a resistance force at the wheel/tire that tries to keeps the car level. And again, as I know you know, the amount the car rolls is a function of the height of the cars CG and how much this is above the roll center. Then the centrifugal force in the corner works on the CG and the car rolls more if the distance from the roll center (moment) is greater. And the only thing resisting the rolling is the spring force. In my mind it's just a force, it doesn't matter if it's provided with a coil spring or a leaf spring.

This is where I get confused. If you lay down the coil spring, the amount that it compresses during roll is less then if it is stood up. So during the rolling event the forces are actually lower because the spring didn't compress as much and the car will not return to level as quickly. So I don't agree with you that your laydown shock will make the car return to level more quickly. Also, during my career I would always try to take things to the limit to try and understand the effect. Taking laydown shocks to the limit in my mind is to lay them down parallel with the suspension arm. Then there would be no spring force on the wheels and the car would droop down on the suspension stops.

As always Cristian, I enjoy reading your posts, you are a sharp young man. I personally don't like shocks that are laid way down. I think they don't work as well as a stand up shock. I do like the fact that at least you moved the lower mounting point closer to the wheel so to make up for lost spring force, but you can't make up for the lost motion that lowers the spring force when the car rolls. I think the only real advantage is the lower CG.
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Old 08-04-2019, 09:33 AM
  #243  
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Originally Posted by thecaptain View Post
"A lot" is very relative, before I would run a silver axon 2.5 spring which is softer than an xray 2.5 spring. With the testing I did with the laydown style shocks the springs I used were xray 2.8 front and xray 2.7 rear, on Medium bite black carpet.

Regardless if all it does is lower the CG, it lower lap times and makes the car handle better. I think that there is more to it than that, but if you don't thats ok. The car isnt for everyone, we are trying something different, with the laydown style shock angles.

I guess what I mean to say is that, this is a public forum, and only negative comments are not helping us move the platform forward . But we are trying to move the platform forward, and from the initial testing of all the new parts its really good.

The newer kits are coming with a host of new design changes, they laydown shocks are an upgrade. That may not work great for everyone in all circumstances, we just need some more time to do some testing with them. I look forward to getting it back on the track, because it was a blast to drive the last time I went out.
Please don't consider my comments as negative, they are meant as constructive criticism. I like that you guys are trying different things, however, in this case I just don't get it. Maybe the lower CG offsets the fact that the spring and shock compresses less during roll. However, the last thing I want to do is to make you guys feel badly, so I will restrain from making any other criticisms, constructive or not. However, it would behoove you guys to try and understand exactly what you are doing.

EDIT: And one other possibility is that the loss of motion is a good thing. It allows the car to roll more in a corner creating a little more grip during the roll (less weight transfer during the longer transition). And possibly the car was over damped and the loss of motion fixes that problem. But again, understanding the change is essential to good engineering.
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Old 08-04-2019, 09:35 AM
  #244  
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Originally Posted by sps3172 View Post
I watch a couple of local guys struggle to work on those rotary damper/leaf spring cars, with a high degree of regularity.

I'm not sure 'genius' is the word I would choose here
Hahaha, I know what you mean. I think he is a genius, but you are also correct, it's a more involved car than the simpler coil over shock cars. But I will say, after you figure out the rotary shock/leaf spring setup, you realize they really are amazing.
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Old 08-04-2019, 11:30 AM
  #245  
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Originally Posted by glennhl View Post
You are correct, you made up for the loss of spring force by moving the lower shock mount closer to the wheel, but you could have done that without laying down the shock on the top mount. I just don't like the loss of motion the lay down shock gives you. And I guess I don't understand why a leaf spring does not provide pressure on the tire like a stand up shock. A coil spring and a leaf spring are both springs and they provide a force that increases fairly linearly with compression (coil) or bending (leaf). Either spring provides a resistance force at the wheel/tire that tries to keeps the car level. And again, as I know you know, the amount the car rolls is a function of the height of the cars CG and how much this is above the roll center. Then the centrifugal force in the corner works on the CG and the car rolls more if the distance from the roll center (moment) is greater. And the only thing resisting the rolling is the spring force. In my mind it's just a force, it doesn't matter if it's provided with a coil spring or a leaf spring.

This is where I get confused. If you lay down the coil spring, the amount that it compresses during roll is less then if it is stood up. So during the rolling event the forces are actually lower because the spring didn't compress as much and the car will not return to level as quickly. So I don't agree with you that your laydown shock will make the car return to level more quickly. Also, during my career I would always try to take things to the limit to try and understand the effect. Taking laydown shocks to the limit in my mind is to lay them down parallel with the suspension arm. Then there would be no spring force on the wheels and the car would droop down on the suspension stops.

As always Cristian, I enjoy reading your posts, you are a sharp young man. I personally don't like shocks that are laid way down. I think they don't work as well as a stand up shock. I do like the fact that at least you moved the lower mounting point closer to the wheel so to make up for lost spring force, but you can't make up for the lost motion that lowers the spring force when the car rolls. I think the only real advantage is the lower CG.
You are not understanding what I am saying. I am agreeing with your observations, however, you are seeing this as a negative and I am seeing this as the desired result I want to achieve. My theory is that the Awesomatix Car is great in black carpet and high bite conditions not only because of the low CG, but also because of it's inherent reduced effectiveness at putting downward pressure on the tire (vs a more vertical shock design) in combination with said low cg. I am not sure if the advantage is as large on asphalt (although recent results at ETS Events are starting to prove otherwise), unless the bite is high enough or the track has long sweeping corners.

My observation is that the leaf spring does not have as much direct force down on a tire, as it just does not have enough leverage to push down.

Think of it in this term. Stretch your arm out parallel to the ground. With your hand push down on an object. How much force can you apply? You may still be able to keep it from moving upwards (the body roll control) but you won't be able to push down as much. Now change yourself to where you have a downward angle on your arm, replicating a shock angle. The more vertical you are in relation to said object and the more effective at putting force down you will become. The more I lay it down, the less effective I become at putting force on the tire and the more similar the effect becomes to a leaf spring. To a point. As you said, you make it parallel and there is no longer any effect.

When you combine this type of spring effect (ie leaf spring) and the falling CG, like on an awesomatix, you are able to get your roll momentum on the car to come back quicker to center than if you had a higher CG with said system. Would a stand up shock and lowest CG perhaps return the car to center quicker? Absolutely! However due to the design constraints of both, this is quite possibly impossible to achieve. Does it return quicker than a traditional TC as well? Maybe, maybe not. I think this would be really hard to measure. However what we have observed is that the traditional shock cars have a very different "look" on the track. The Awesomatix cars roll more, yet have a lower CG, because if you soften a regular TC as much to get the equal roll, the higher CG makes the car really slow to react (ie. come back to center). The result is an ill handling car.

In the end, what I am trying to achieve is a "less effective" suspension that is not as effective as putting force down on the a arms, so that in theory, we increase our corner speed. Our observation, is that An awesomatix does not have as "effective of a suspension as a regular TC". Rotary dampers do not act as effectively as a piston damper. Leaf springs are not as effective or consistent as coil springs either., and that is exactly my point. However, the system is effective enough, and when packaged with all the other features and extremely low cg, result in a phenomenal racing touring car. Especially in high bite.

In the end, wer testing with this as an optional set up system. Something we can do with our car due to the modularity of the suspension design. We have already found that in some conditions it is quicker (black carpet) and on asphalt, the pace is similar and the car is a little smoother/ more numb. Is it something we will always run or push going forward? I don't know, it's too early to tell. However the fact that we have access to this is not a bad thing and makes our car more tunable than others in the market.
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Old 08-04-2019, 11:53 AM
  #246  
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I don’t think there is a difference between coil overs and leafs. I don’t care how u create the force. Just look at the force at the wheel, that’s all that matters. It doesn’t matter if the force is applied through a long arm or directly down on the tire.

I’d recommend that you measure force at the wheel with an Awesomatix and your car. I’m betting you can adjust both to give you similar results. But I will stand behind my statement that a laydown shock will return the car to level more slowly than a standup shock because of the less compression during roll.

EDIT: Just to clarify, it makes no difference if you use a very stiff leaf spring working through a long lever or a softer coil spring pushing right down at the wheel. Both can be adjusted to give you the desired force at the wheel. I hope you do the experiment I suggested, I'd love to have some data. As we used to say at work, data are always your friend.

Last edited by glennhl; 08-04-2019 at 12:43 PM.
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Old 08-04-2019, 01:34 PM
  #247  
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You can achieve similar forces at the wheel under roll, undoubtedly. However the stand up shock/coil spring design is more efficient vs a rotary/ transverse leaf spring for the same reason that leaning over a shock is less efficient than standing it up. Coil springs are more effective at reducing bounce and keeping better road holding characteristics due to inherent design and superior geometrical support. Yet, even though we come across this situation, when running on black carpet, the one thing you always hear the std shock guys is "I need to take away grip, the car is too stuck". We do this by reducing camber, toe, increasing glue, softening suspensions and many other things. Often all these things are effectively making the car "worse" at getting traction. It's for the same reason this sort of geometry is used on nitro cars with foam tires, we did not invent this type of geometry after all. This is just another way of doing it as well.

When you say this: "But I will stand behind my statement that a laydown shock will return the car to level more slowly than a standup shock because of the less compression during roll." I never said this was not the case, if all things are equal. What I am saying is that with a lower cg you can sometimes achieve a faster return to center with a more laydown suspension than with a more vertical shock with a higher CG because the forces are more compact. There are many shades of gray in between, much like so many other things in RC.
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Old 08-04-2019, 02:13 PM
  #248  
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Good discussion and interesting development with the Genesis. Regardless of the theory, improvement of consistent lap times is what matters.
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Old 08-04-2019, 05:13 PM
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Originally Posted by CristianTabush View Post
You can achieve similar forces at the wheel under roll, undoubtedly. However the stand up shock/coil spring design is more efficient vs a rotary/ transverse leaf spring for the same reason that leaning over a shock is less efficient than standing it up. Coil springs are more effective at reducing bounce and keeping better road holding characteristics due to inherent design and superior geometrical support. Yet, even though we come across this situation, when running on black carpet, the one thing you always hear the std shock guys is "I need to take away grip, the car is too stuck". We do this by reducing camber, toe, increasing glue, softening suspensions and many other things. Often all these things are effectively making the car "worse" at getting traction. It's for the same reason this sort of geometry is used on nitro cars with foam tires, we did not invent this type of geometry after all. This is just another way of doing it as well.

When you say this: "But I will stand behind my statement that a laydown shock will return the car to level more slowly than a standup shock because of the less compression during roll." I never said this was not the case, if all things are equal. What I am saying is that with a lower cg you can sometimes achieve a faster return to center with a more laydown suspension than with a more vertical shock with a higher CG because the forces are more compact. There are many shades of gray in between, much like so many other things in RC.
I don't agree that the laydown shock will return the car to level more quickly because of the lower CG. I would think the little amount you lowered the CG would be more than offset from the reduced force from the lower spring compression. Again, time for some data gathering. Roll the car to a set angle and then let go and watch it with high speed video to measure the time to level. Maybe I'm wrong and you are right, but we will never know without some experimentation.

Also, not sure why you think a leaf spring just holds the car up and sort of "keeps" the car level. This makes zero sense to me. Again, a leaf spring just provides force to hold the car up and when the car rolls, the leaf spring bends and provides more force to level the car. They are just springs, no different than coil springs.

Then in your latest posting you state "Coil springs are more effective at reducing bounce and keeping better road holding characteristics due to inherent design and superior geometrical support." Again, leaf springs and coil springs are just springs, neither has hardly any internal damping so one should bounce just the same as the other. But you state that it's due to inherent design and superior geometrical support. Again, I do not agree. You will have to convince me with something more than inherent design or superior geometrical support. Like I said, put the car on scales, then compress the car by 1mm at a time and measure the load at each wheel. Do this with your car and the Awesomatix car. You will be able to adjust either car to give you what you want. You need to gather data instead of trusting of what you think you know. It may be eye opening, it may not, but at least you will know for sure. A good engineer bases his designs on data. Again, I'm not trying to be obstinate, I'm just trying to get you to gather data and look at all possibilities. But I will stop. I am sorry if I ruffled some feathers by questioning your new design. Good luck in your future endeavors.

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Old 08-04-2019, 06:38 PM
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If Cristian says is better I would take his word for it , he has been designing cars and upgrades for a while with great success ,
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Old 08-04-2019, 06:55 PM
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Christian, just send me a Gizmo and I'll woop up on Glenn at the track and he will then know what's faster. Ha Ha
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Old 08-04-2019, 07:34 PM
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Originally Posted by glennhl View Post
I don't agree that the laydown shock will return the car to level more quickly because of the lower CG. I would think the little amount you lowered the CG would be more than offset from the reduced force from the lower spring compression. Again, time for some data gathering. Roll the car to a set angle and then let go and watch it with high speed video to measure the time to level. Maybe I'm wrong and you are right, but we will never know without some experimentation.

Also, not sure why you think a leaf spring just holds the car up and sort of "keeps" the car level. This makes zero sense to me. Again, a leaf spring just provides force to hold the car up and when the car rolls, the leaf spring bends and provides more force to level the car. They are just springs, no different than coil springs.

Then in your latest posting you state "Coil springs are more effective at reducing bounce and keeping better road holding characteristics due to inherent design and superior geometrical support." Again, leaf springs and coil springs are just springs, neither has hardly any internal damping so one should bounce just the same as the other. But you state that it's due to inherent design and superior geometrical support. Again, I do not agree. You will have to convince me with something more than inherent design or superior geometrical support. Like I said, put the car on scales, then compress the car by 1mm at a time and measure the load at each wheel. Do this with your car and the Awesomatix car. You will be able to adjust either car to give you what you want. You need to gather data instead of trusting of what you think you know. It may be eye opening, it may not, but at least you will know for sure. A good engineer bases his designs on data. Again, I'm not trying to be obstinate, I'm just trying to get you to gather data and look at all possibilities. But I will stop. I am sorry if I ruffled some feathers by questioning your new design. Good luck in your future endeavors.
I don't know what to say. It is ok if you don't want to agree with me, but you are really just trying to be a contrarian if you believe a spring is just a spring. I don't think I should need to "prove" anything to you on something that is a factual statement. You need me to prove the Earth is round too? Research is really easy to do nowadays with Google. Read a couple of articles comparing and contrasting the advantages and disadvantages of each type of spring. The most important things that apply to our application is that Leaf springs bare loads better, while coil springs handle oscillations better, provide a smoother ride, are adjustable in their angle and also function over longer travel. I am not just pulling this out of a hat. This is consensus amongst anyone with any type of suspension knowledge.

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Old 08-04-2019, 08:01 PM
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Originally Posted by CristianTabush View Post
I don't know what to say. It is ok if you don't want to agree with me, but you are really just trying to be a contrarian if you believe a spring is just a spring. I don't think I should need to "prove" anything to you on something that is a factual statement. You need me to prove the Earth is round too? Research is really easy to do nowadays with Google. Read a couple of articles comparing and contrasting the advantages and disadvantages of each type of spring. The most important things that apply to our application is that Leaf springs bare loads better, while coil springs handle oscillations better, provide a smoother ride, are adjustable in their angle and also function over longer travel. I am not just pulling this out of a hat. This is consensus amongst anyone with any type of suspension knowledge.
You can find a lot on the internet. Google has certainly made everyone an engineering expert. But I have to tell you I have never heard that coil springs bounce less than leaf springs. I guess you will just have to point me to the link that shows that. I am sorry if I doubt your engineering expertise, but it seems to me that most of your engineering knowledge is anecdotal. I'm curious, do you have a mechanical engineering degree? Not that it's required to design RC cars. Heck, some of the best engineers I've known did not have a degree, they were just amazingly sharp people.

As I said before, I will stop critiquing your car designs because I'm just coming across as a hater and I am in fact the opposite, I have always liked your unique designs. But I really think you need to gather more data on some of your design changes. It will help you understand your designs better and allow you to make effective improvements. And in my opinion, the suspension experts out there most likely use coil springs because they package better and allow more flexibility with progressive spring rates and geometries.

EDIT: I did the google search and did find a reference that leaf springs actually bounce less than coils. But that's because most automotive leaf springs have multi leafs that rub on each other while compressing thus creating some damping via friction. But sorry, I can not find your reference that coil springs bounce less than leaf springs. I swear, this is the last I will write on this subject. Sorry for being so contrarian.

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Old 08-04-2019, 09:38 PM
  #254  
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Glen, there are articles literally all over the internet. Letís just agree to move along. You are just derailing the thread at this point.


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Old 08-04-2019, 10:03 PM
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Originally Posted by CristianTabush View Post
Glen, there are articles literally all over the internet. Letís just agree to move along. You are just derailing the thread at this point.


You couldn't find it either.
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