Traction Rolling - how to solve it
02-12-2014, 10:02 AM
#136
no not plow disks. these are like 5" across. plastic maybe 1/2" height. i touch em and im done. anything to upset the car and over it goes. i see other guys just brush them like its nuthin. like half the car width like a breese. mine even slightly touches them whilst cornering and over it goes. i got something wrong and i have not figured it out yet. ill find the issue.
02-12-2014, 12:45 PM
#137
The Hangar has crazy grip, apex bumps (or dips, more like), and is very tight. All a recipe for traction roll. But with Scale Spec on VTA tires, it shouldn't be too hard to keep the car shiny side up. If you make the race tonight, I'll see if I can spot anything in the way the car is moving, the setup, or the way you're driving it.
-Mike
02-12-2014, 12:50 PM
#138
yeah no prob. ide appreciate the help. i made a boo boo last sat. i loosened the upper plate and it threw the tweak way off on the car. handled like crap. going to do martins trick for removing tweak in a little bit before i come down tonight.
ps, i hate the dots lol. if they wouldnt upset the car so much ide have no problem driving over them.
ps, i hate the dots lol. if they wouldnt upset the car so much ide have no problem driving over them.
02-12-2014, 01:26 PM
#139
Although I agree that tweak will cause traction roll in one direction, I must point out that traction rolling in the other direction will be extremely reduced to the point where the car can be thrown in the corner at full speed without traction rolling... A little tweak in the fast turns can be beneficial....
02-12-2014, 01:35 PM
#140
-Mike
02-16-2014, 10:43 AM
#141
Tech Fanatic
Thread Starter
Hello Martin.
I purchased your app a couple days ago, and I was reading up on wheel load transfer.
You mention (correct me if I'm wrong) the larger the difference between front R and L wheel loads will result in poor handling. i.e lack of steering.
How can you minimize this wheel load difference? I don't have the app in front of me at this moment.
Furthermore, I am also using another setup program that illustrates wheel loads going into a corner. I noticed if I go up one spring rate it will help reduce the difference between front R and L wheel loads. Now, if I go any higher with the spring rate it becomes worse, and if I go any soft it does the same.
Why is that?
I purchased your app a couple days ago, and I was reading up on wheel load transfer.
You mention (correct me if I'm wrong) the larger the difference between front R and L wheel loads will result in poor handling. i.e lack of steering.
How can you minimize this wheel load difference? I don't have the app in front of me at this moment.
Furthermore, I am also using another setup program that illustrates wheel loads going into a corner. I noticed if I go up one spring rate it will help reduce the difference between front R and L wheel loads. Now, if I go any higher with the spring rate it becomes worse, and if I go any soft it does the same.
Why is that?
Here is how I think through this. First to reduce the difference in load between the inside and outside tire, you can raise the roll center, which reduces the roll. This is a key reason why a higher roll center will produce more lateral grip.
In terms of your question about the harder springs...and why do they seem to take away grip. I have a couple of comments. If you want more steering and you think lets stiffen the front springs to reduce the difference in vertical load between the front inside and outside tire, you need to remember that a stiffer front spring will reduce the weight transfer to the front tires and in face increase the weight transfer to the rear tires. This would give the rear more grip and the front less grip. So then you think...ok, lets stiffen the springs at both ends of the car. To a point this will work, but I believe you can go too stiff, preventing enough longitudinal (front to rear to front) weight transfer, which means you can't get the car to turn much. Yeah it might have good lateral grip, but if you can't make it turn, so what. Also I believe the if you go too stiff the tires will just skip across the surface at some point. So as with most things in setup don't take things to the extreme. It is always about compromise and how everything works together.
i also just purchased the app but have not read into it too much. we have little orange dots all over the track. my car likes to roll if i even just graze one. drives me nuts. my car is so on the edge and it loves to roll. going to read into it a bunch and see if i can cure the issue.
I see you are signed up for the Cdn Nats, Martin. Very cool! Looking forward to racing with you again. I've had a bit of a break from racing recently too, though not as long as yours. Welcome back!
See you soon sir.
See you soon sir.
I will be racing the CSO v2 car, for my buddy Mark Frechette, and ORCA has been kind enough to send some motors, esc and batteries, thanks to Keith Yu. I have nothing so I bough a used Radio, and will need to get everything again...like tools, pinions, transponders, bodies, tires..etc etc. I hope everything arrives in time for the race.
02-17-2014, 08:02 AM
#142
Yes...going with thicker oil, smaller holes or less holes can help reduce laziness in chicanes.. however it makes it worse in normal corners, because the car rolls slower.
Going a little stiffer on the swaybars will help reduce overall roll and thus reduce some laziness....but you will loose some lateral grip with the stiffer swaybars.
Going up on the spring rate is also an option.
In terms of how much rebound for the different surfaces....
First, I don't like to run any rebound in my shocks...ever. The purpose of the shock is to slow down the speed of the spring.... both during the compression of the spring (ie. bump) and the extending of the spring (i.e. rebound). So if you build your shocks where the shock shaft comes out on it's own after you press it into the shock cynlinder, then in my opinion you are not building your shocks correctly.
Having clarified that, lets talk about how much dampening you will want for the different surfaces. where more dampening will slow down the spring compression and rebound. The reality is there is no simple answer for this. One might think that for low grip tracks you want less dampining and for high grip tracks you want more dampening. However if you take this too far having too much dampening on high grip tracks will cause a traction roll because it is not allowing the car to roll into the carpet fast enough before it pole vaults over the outside wheels.
Also you don't want to go too thin on the oil or make the holes to big or plentiful so that you have too little dampening as that will make the car very twitchy, because it transitions too fast.
One thing to keep in mind is how bumpy the surface is. the more irregularities or bumps on the surface the lighter the dampening you will want.
Also another thing to think through is how the hole size affects the high speed bump v.s. the low speed bump. For example a thin oil with small holes tends to have a lot more dampening on a high speed bump than a thicker oil with larger holes.
Going a little stiffer on the swaybars will help reduce overall roll and thus reduce some laziness....but you will loose some lateral grip with the stiffer swaybars.
Going up on the spring rate is also an option.
In terms of how much rebound for the different surfaces....
First, I don't like to run any rebound in my shocks...ever. The purpose of the shock is to slow down the speed of the spring.... both during the compression of the spring (ie. bump) and the extending of the spring (i.e. rebound). So if you build your shocks where the shock shaft comes out on it's own after you press it into the shock cynlinder, then in my opinion you are not building your shocks correctly.
Having clarified that, lets talk about how much dampening you will want for the different surfaces. where more dampening will slow down the spring compression and rebound. The reality is there is no simple answer for this. One might think that for low grip tracks you want less dampining and for high grip tracks you want more dampening. However if you take this too far having too much dampening on high grip tracks will cause a traction roll because it is not allowing the car to roll into the carpet fast enough before it pole vaults over the outside wheels.
Also you don't want to go too thin on the oil or make the holes to big or plentiful so that you have too little dampening as that will make the car very twitchy, because it transitions too fast.
One thing to keep in mind is how bumpy the surface is. the more irregularities or bumps on the surface the lighter the dampening you will want.
Also another thing to think through is how the hole size affects the high speed bump v.s. the low speed bump. For example a thin oil with small holes tends to have a lot more dampening on a high speed bump than a thicker oil with larger holes.
Drill hole in top ,or less oil or ?
02-17-2014, 10:17 AM
#143
Assemble the shocks and fill up with oil then fully compress the shock (ie piston all the way to the top of the shock body) before screwing on the cap and bladder. That is zero rebound. Fully extending the shock before installing the cap and bladder is full rebound.
02-17-2014, 02:22 PM
#144
snap oversteer
There are few things to try, but I would start with Lowering the front roll center, by raising the inboard portion of the upper links. Other options to consider, but would make the corner entry push more would be...
- increase rear toe
- raise rear roll center
Often when you have a high front roll center and you are running a spool you can get a huge snap oversteer coming out of the corner and a push into the corner.
- increase rear toe
- raise rear roll center
Often when you have a high front roll center and you are running a spool you can get a huge snap oversteer coming out of the corner and a push into the corner.
Then you also say that high front RC with spool creates pushing into corner and snap oversteer out of corner.
So does high RC increase or decrease lateral grip? I'm so confused...
02-17-2014, 04:36 PM
#145
Shock rebound is the amount the shock shaft extends by itself after being compressed.
IE if the shaft extends 50%, 50% rebound.
Import to test the shock after you build to check they are even.
02-17-2014, 07:43 PM
#146
Tech Fanatic
Thread Starter
Thanks Martin. You mention in your app that low RC front with high RC rear will give more steering due to forward leaning attitude of the car. If that's the case, what you mentioned above(lowering front RC and/or raise rear RC to remove snap oversteer) doesn't seem to be going to resolve it.
Then you also say that high front RC with spool creates pushing into corner and snap oversteer out of corner.
So does high RC increase or decrease lateral grip? I'm so confused...
Then you also say that high front RC with spool creates pushing into corner and snap oversteer out of corner.
So does high RC increase or decrease lateral grip? I'm so confused...
Let me try to clarify some things....try
In that roll center section of the app there is a lot more information that needs to be taken into context, but I guess I should look at how I can improve that section to make it easier to understand. Having said that here are some key summary points that I think will help clarify things for you.
1) a lower front roll center will give you more steering on initial off-power turn in, but will push in the middle and on-power exit of the corner
2) a higher front roll center will push on initial off-power turn-in but give you more steering in the middle and on-power exit of the corner.
The reason why you can't just take the approach of assuming a higher roll center means more grip in all situations, is that you need to consider the longitudinal weight transfer (front to back to front) as you enter a corner off power and exit a corner on power.
For example,...
....the lower front roll center allows more weight transfer to the front of the car while turning in off power. This initially can offset the loss of lateral grip in the front due to a low roll center.
This changes through the corner however.
In the middle of the corner when the car is at neutral power not as much weight is being transferred to the front of the car and now the lower front roll center having less lateral grip than the high rear roll center will be more dominant, causing the car to push more in the middle.
On power corner exit, transfer even more weight on the rear tires causing it to push even more than in the middle of the corner.
02-17-2014, 08:02 PM
#147
Tech Fanatic
Thread Starter
My understanding this is a good way to create a zero rebound shock but is not the definition of rebound.
Shock rebound is the amount the shock shaft extends by itself after being compressed.
IE if the shaft extends 50%, 50% rebound.
Import to test the shock after you build to check they are even.
Shock rebound is the amount the shock shaft extends by itself after being compressed.
IE if the shaft extends 50%, 50% rebound.
Import to test the shock after you build to check they are even.
In full size car shocks bump refers to when the shock is compressed, and more bump means the shock resists more when being compressed. The Rebound in full size car shocks refers to when the shock is extending and more rebound means the shock resists being extended.
However the way we seem to define rebound in RC car's is the amount the shaft extends on its own after being compressed. The more it extends the more rebound it has. So in RC cars, more rebound means the shock will extend more easily, which is the opposite of full size cars.
02-17-2014, 08:19 PM
#148
Great reminder I have had this app for a couple years and haven't transferred it to my latest phone. I haven't been racing much over the last year other than mini Z's on my rcp garage track.
How have you been Martin are you racing again? Last I spoke to you, you were into other endeavors
How have you been Martin are you racing again? Last I spoke to you, you were into other endeavors
02-18-2014, 12:35 PM
#149
Tech Fanatic
Thread Starter
Great reminder I have had this app for a couple years and haven't transferred it to my latest phone. I haven't been racing much over the last year other than mini Z's on my rcp garage track.
How have you been Martin are you racing again? Last I spoke to you, you were into other endeavors
How have you been Martin are you racing again? Last I spoke to you, you were into other endeavors
02-22-2014, 01:27 PM
#150
What is the best order to set the car up camber then toe then ride height.and recheck?
When do you put it on the 4 scales. After the tweak is set? And then rebalance with weight
Also when I do the sway bar check it doesn't seem to lift the other arm up unless I put the heavier bar on, so should I go to the heavier one so it is working or stay light?
When do you put it on the 4 scales. After the tweak is set? And then rebalance with weight
Also when I do the sway bar check it doesn't seem to lift the other arm up unless I put the heavier bar on, so should I go to the heavier one so it is working or stay light?