Martin Crisp

Yes..for sure it lowers the over all CG in this case at the front of the car.

I would also add the following

1) since the weight was added at the front of the car this will make the car slide more at the front (i.e. push) when near the limit and actually cause more oversteer when not near the lateral limits of the tires (a good example can be the middle of a slow tight corner)

2) Reducing traction rolling has a lot to do with getting both ends of the car to roll into the carpet the same amount. if the car was traction rolling because the front of the car would would not roll into the carpet as much as the rear, then adding the weight can help this.

3) In general I don't recommend adding weight to the car unless you are under the min weight limit, as additional weight will ultimately produce less lateral grip, less acceleration and less braking = slower laptimes.

Good call. That danger was the reason I did not do this when I was younger...but as I got older, I still wanted to do it, and figured if I don't do this now I will never do it.

In rare and extreme cases this is a route to take. I used to do this before I figured out other techniques to reduce traction rolling. The issue with glue is that is too difficult to add a consistent amount of glue on each tire, and the glue comes off...making it a long day of chasing setups.

Yeah..it was not available on the apple store for a while, because I was not aware you needed to buy a developer license every year to be able to sell an app on the app store. So it was not available for a few weeks late in 2013.

Colbynobo

iTrader: (21)

I wouldn't be surprised to learn that it's precisely this lack of balance that's the cause of so many of my problems. I've blindly followed too many recommendations that one must always go with thicker oil and stiffer springs in the front. I'm sure I've taken it a bit too far and screwed up the balance. I will focus on this. Thank you for providing this insight. Off to the track I go to put this information into play!

rc car guy

This is off topic but im kind of out of options mr guru I am looking to take out traction of my car with out changing the handling too much what would you suggest my role centers are all the way down I took camber out im not at -1 I went up 75cst in shock oil im running jaco blues what else should I do to reduce traction and not change the handling too much?

Akhor

iTrader: (8)

If you are using traction compound then you can also use this as a tuning tool. Don't put any on the front.

Martin Crisp

Hi

When you say the roll centers are all the way down, can you clarify what you mean by that? Are you saying the roll center is low, and by this I mean you have likley a lot of spacers on the inboard upper link and the lower arms are as low as they can go inboard?

Also, why are you trying to reduce traction...what is the issue you are hoping to resolve by reducing traction....you mention this is off topic, so I assume you are not trying to fight a traction roll problem.

rc car guy

Um my arms are as low as the can go to the chassis I am running no spacers under my camber links im trying to reduce traction because I lost .2 off a lap and other guys could make changes to take more traction out of their car I cannot as of yet this was for the 3rd and main event its just slow and has too much tracrion in general no traction rolling

Cody227

how can you have too much traction when you don't traction roll? If it's too nimble for you, you can also reduce dual rate

Stealth_RT

iTrader: (5)

Glad to see you posting again Martin. Love the app! Even use it offroad for escale and etruggy, as long as the track being blown out isn't my biggest concern. (Need an offroad workbench app!)

rc car guy

Ya it just makes the car slower I have the car set up almost correct its just not as fast aa it should be when traction comes up a good amount

Lessen

iTrader: (2)

I've been battling this for some time now and could not wrap my head around why so many folks say you must soften the car up. In my head I had always looked at traction rolling as a direct result of too much roll.. limit the roll, limit the tip. Well, it's not that simple I don't think. The physics in carpet racing is very different due to what I might call traction/weight ratio. In the 1:1 world you could stiffen the car up to the point where you limit mechanical grip enough that the outer tires slide because they don't receive enough load. We have so much grip indoors that just doesn't happen, plus the speeds we race at aren't high enough to slide the car (albeit arguably) even if it is set up stiff. I believe there is a correlation between lateral load, vertical load and traction. When grip gets really high we essentially need less mechanical grip to get the car to turn at speed. The problem I think is that in doing so (stiffening the car), we are increasing lateral load and decreasing vertical load on the tire. This is a recipe for even snappier t-rolls. Theoretically, one may be able to stiffen it to the point it is able to break traction, but now you may have a setup that is quite skatey at the limit and just difficult to drive. If you go the other direction and soften the car I think what is happening is that you are effectively decreasing lateral load and increasing vertical loading of the tire (even more mechanical grip). I think it's the balance of this loading that is important here. However, because the car is sprung softly and the roll centers are very low, the chassis has a lot of leverage and less resistance to roll so you still need to limit it otherwise it'll still tip. Now one may be looking at a bit more ARB and things of that nature. Basically, instead of looking for ways to utilize the available traction in an energy efficient manner, we may need to look for way to waste it. By keeping the car softly sprung we are creating more mechanical grip that we actually need, but the direction of the loading may be what we need to keep the car from flipping over.

rramjet

iTrader: (5)

How weird Martin.

I just posted a recommendation to get your book on another thread today for someone looking for a source of good setup information. Had no idea you were on this site. Also had no idea there was an app. Is there one for us non Apple folks?

Skiddins

Is your car 'sticking' in the corners, not turning in at corner entry, overstter exiting a corner, or what?

You need to define where this extra grip is causing a problem before others can help.

Skiddins

rc car guy

Its one of the unexplainable things its working correcrly the car its steering fine its working great at the beginning of the night and as more traction gets layed down the car just starts feeling "stuck"

BadSign

iTrader: (15)

I think it comes down to weight transfer. Tahe a look at Carol Shelby's formula for weight transfer:

(static weight*center of gravity*g-forces)/track

With more traction compound laid down in the track, the faster you can corner. Of course, higher corner speed means more weight transfer and therefore more likelihood of the inside wheels lifting, bicycling, and then flipping over

So if you can reduce static weight (which we probably can't), lower the cg (difficult because of ride height minimum), go through the corner slower (why?), or increase the track (a possibility), you'll reduce weight transfer.

Stiffening or softening the car doesn't affect how much weight transfers. It affects how much the car will roll/ lean. If it is too stiff, the car stops rolling before the weight has all transferred. At that point the inner wheels lift and away we go. If the car is too soft, it'll just be too "stuck" and scrub corner speed. The odds of the suspension totally compressing because of a soft setup are almost nil.

bertrandsv87

iTrader: (2)

Well to affect weight transfer, and lower CG in turns you'll have to lower your droop significantly... Remember the Car has to still be squating down all the way through the turn long enough so you can exit the turn without traction rolling: too stiff a setup makes the Car not squat enough through the turn(early traction roll), and too soft a setup makes the Car squat too fast and bottom out (late traction roll)....