Stuid question re: Spring setup

[Nitroaddict]

okay - the mill i put in my new RC10GT is a lil too torque happy, and i cannot keep the front end down. i have the slipper pretty loose, so if i make it any looser it will run the risk of burning it up. Which way do i adjust the springs? I have all the sets. right now I am running silver in front, and red in the rear. will stiffer springs in the front, and softer in the rear keep the nose down, or is it the other way around?

 

[militarymaxx]

I can tell you that in my Maxx, softer springs in the rear absorb more power than stiffer springs. If I want to wheelie, I put the stiff ones in the back, and to keep the front down on the ground when racing, I go with soft ones. So, I think you have it right.

 

[Nitroaddict]

lol - i just answered your thread, milmaxx, funny. So do u think that if i put some nice soft green springs in the rear, but leave the front stiff that will help?

 

[militarymaxx]

I think so. As throttle is applied, powered is naturally transferred to the rear. Your rear wheels act as a pivoting point between moving forward or pulling wheelies. Softer springs in the rear will absorb some of that power transfer long enough to get the vehicle moving forward, and subsequentially overcoming the urge to wheelie. Similiar to brake bias. When you brake hard at speed, weight transfer shifts forward and puts approx. 70% of the vehicle weight on the front wheels and very little on the rear wheels. Related to your problem, but backwards.

 

[Nitroaddict]

kewl - thanks bro.

 

[SkyMaxx]

There are a number of things that I can say are both right and wrong with the information here.

The basic premise that allowing the truck to squat (by giving it a softer rear suspension) will remove the wheelie bug is not 100% accurate. I'll agree that the rear wheels act as the pivot point for the wheelie. I'll agree that the basic idea is that the truck has a "lighter" front end when a wheelie is about to come on. BUT there is more to what causes a wheelie than just the springs in your suspension.

Allowing the truck to squat under power does a few things. Yes, it does absorb some of the power. But it also pulls the center of gravity of the truck further to the rear and lower. It also reduces the arc that the moment arm of the truck has to swing through to produce a full on wheelie...making it easier to lift those wheels off the deck. Look at it as putting the rear wheels in a position to drive up under the front wheels.

Now, the question is what to do to resolve this. You can either re-gear to reduce the torque, giving you a more gradual acceleration and a higher top speed. You can set up your suspension to handle the problem. You can adjust the weight of your truck so that it is a little more front heavy than rear heavy. You can just plain not slam it to WOT right out of the gates (no fun in that). So what to do....hmmm.

You could keep the gearing where it is and stiffen up the rear suspension. This will keep the truck from squatting as readily and allow a more gradual transfer of power and reduce that shifting of the CG. It will also keep the wheels more in line and increase arc the moment arm the truck has to work against to get the wheels off the ground (basically keeps the wheels in the same plane making it harder for the truck's rear wheels to drive up under the front wheels).

A softer suspension might do the trick...but I say that it will only allow the truck to squat more readily giving it a better chance of pushing a wheelie up.

I think the set up is up to you. The bottom line is that you are combatting a shifting CG, torque and the moment arm of the truck.

I have been running with a super stiff rear suspension and engines geared for low end grunt to give me rapid acceleration off the line, and have yet to see a wheelie. When I ran with a softer rear suspension I could wheelie on demand. Do as you choose and let us know how it works out.

 

[Çh®i§tiªñ]

What radio do you have? Some radios also have settings to help with this. :radio: I've been experiencing the same issue with my Losi XXX-NT and I just moved the spacers down on the rear a bit and lightening the spring. The goal was to keep the rear arms level at idle and let the springs absorb the launch shock.

I ultimately just had to lay into it lightly from a dead stop.

One thing to consider is whether or not you are going to loose steering while on-power as well. A whole new issue hehehe

The possibilities are endles. But yes, softer shocks in the rear will help. Just make sure those arms stay level at idle. Or maybe even 1 to 2 degree downward. Dont let it sag at all. You will defy the shocks if you do.

I also try to keep my front spring relative with my rears. I never liked the results of stiff fronts with soft rears or vice versa. Maybe a hair difference, but not drastic.

Soft rear/slightly softer fronts.

The ultimate goal is to keep it as level as possible, with reduced roll both in and out of the turns while on and off power. Not THAT sir is the ULTIMATE challenge heheheheheh

I'm a babbling idiot tonight, sorry.

 

[Candyman]

And also a carb restrictor may help. Take some of the hp out of the engine. Just a thought...

 

[Nitroaddict]

okay - it rained when i got home, so i didnt have a chance to try anything.

sky - i dont want to re-gear, and i love WOT, so that forces me to deal with this problem via the suspension

christian - i am using a Lynx 3D FM. it does have exponential rates, and i never thought about that. good idea.

candy - carb restrictors suck, lol.
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I would like to keep as much power on tap as i can, so if i am correct, SKymaxx, you are saying that the rear should be stiffer than the front? i currently have it the other way around. Please excuse my ignorance, as much of my knowlege revolves around onroad suspension, which i am finding out is quite different.

 

[militarymaxx]

So let's look at this problem in reverse. What could you do to
'make' it wheelie ? Increase torque ? (Yup). Shift weight to the rear ? (Yup). Increase rear wheel grip/bite ? (Yup). Change suspension spring rates ? (Yup). But here's where it gets tricky.
If you decide to increase torque but don't shift weight or improve grip, did you increase torque enough to overcome the other two ?
It can easily turn into a 'counter-productive' situation. For example: Increase torque but add weight to the front. Will it wheelie? Not likely, unless your increase in torque overcomes your added weight. See where this is going ? So at one end of the spectrum you have a buggy with very tall gearing, no torque, bald tires on dirt, squishy shocks, and 5 pounds of lead sitting on the front bumper. Not your basic wheelie king. On the other side you have a low geared torque monster, slick tires on hot asphalt,
no suspension (just like on drag cars), and all the weight sitting right over the rear end (just like on drag cars). Wheelie king - Oh Yeah ! So now that we have all given you our 2 cents worth. Go out and try a bunch of stuff and see what works best for you.
Me, I'm going to try and fix this flat spot on my forehead that I got from banging it on the wall.

 

[FastEddy]

The guys above did a great job of answering your question.
What you need to do know is ask the right question for your issue.

How do I limit or smooth out the torque on takeoff?

Another way to look at this is from the torque end of the issue.
If your clutch is engaging to hard and to fast it will cause over torque.

If you can get the clutch to engage later and softer you will eliminate your wheelie issues.

MIP make an adjustable clutch. If you set it on the inside holes with no weights added it will engage softer and smoother. I had to use it on my GT after installing an OS .12TR.

You need to reserve the suspension setup for jumping and handling performance. If you commit your suspension setup to overcoming torque it will handle like crap on the track.

You will also want to play around with the slipper and gearing once you get the clutch swapped out.

 

[Çh®i§tiªñ]

And then you get into 'leading' and 'trailing' edge clutch setups. Trailing is the best for smooth take-offs and longer clutch life. While leading is WHAM BAM THANK YOU MAAM hookup and shorter clutch life. The second hold on the MIP clutch will have great effect if you try it. Then, loosen the slipper enough to compensate, but not too much, or you will melt your slipper.

Recommended reading: Setup and Tuning Guide by XXX-Main. This is some of the BEST reading I have gone through and still reference all the time.