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Old 06-19-2007, 04:14 AM   #1
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Default driving sideways evenly in 4wd

I have been playing around with my xxx-4 on my practice track, trying to get a good setup and some good skills. The track is kind of hard packed, but it easily gives up some fluff when you scratch it, so there is a light fluff layer in the groove, and holeshots seem to be the matching tire -- except I run taper pins on the front because the front holeshots are "hooking" at some point in the turn and are thus a little unpredictable.

There is one thing that I would like the car to do better, which is rounding slow speed corners, such as a simple 180-degree turn. Right now I am playing with drifting around the corner, but let's say I am coming up a little bit short, and I need to blip the throttle to clear the corner. Well, then I have the rear to swing out more than the front, and it ends up that I nose into the pipe anyway. Should I pursue finding a setup where the front and rear will slide sideays more "evenly", and what would be a good way to do that? I will also occasionally spin out in a sweeper, maybe from a small bump (not sure), but I would like to reduce that too.

One thing I do not have is a one-way. The other facts about the current setup are front = (#60 pistons, 30wt(Losi), blue spring, normal positions), rear = (blue pistons, 30wt(Losi), white spring, normal positions, swaybar). The rear tires have a good amount of -camber, and the front doesn't have much. There is not much toe-in on either end. No overdrive pulley or anything else odd.
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Old 06-19-2007, 06:41 AM   #2
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are you running stock or mod set up to try is green springs front yellow or pink rear oil wt is ok centre hole top of shock towers front and rear , hole shots should be ok for front 2 deg. camber rear 0 deg. front slight toe out and try adjusting diffs having front diff tigher will pull you out of the corner more and having the rear tighter than front hopefully will spin the back wheels and sliding around the corner ( mod motor ) if this is for racing sometimes taking corner tight is not the best race line making a corner bigger you can keep the speed up and go quicker around a corner
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Old 06-19-2007, 07:31 AM   #3
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GAB,

Thanks. I went towards the soft rear and stiff front for better rear traction (both side and forward). Whereas on an indoor clay track, my setup would be way to wobbly and I would have to stiffen it up in the back.

I like the idea of taking wide swooping line around the curves, and that is where my four-wheel drift is going a bit loose in the back. If I could get it to slide more evenly or consistently, that would achieve my goal -- at least in the outdoor dirt.

It is a MM 5700 motor, which is too much for my small track, but about right on the MARCCA track (marcca.com) which has very similar dirt to mine.
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Old 06-19-2007, 08:18 AM   #4
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Boy, nothing provides turn in steering like a one-way. I'd just bite the bullet and pick one up. If it's a track where you need a lot of brake, go ahead and dial some ABS in on your radio or speedo to keep the rear end from hooking.
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Old 06-19-2007, 08:51 AM   #5
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I was thinking the one-way would be coming into my life sometime, but I wanted to see what I could do without it, and I was thinking of moving up to LCDs to see if that would help. BTW, I also don't have any drag brake dialed in right now. As far as ABS, doesn't that only work for nitro -- if it works for electric, I need to wake up!!!

As far as using the one-way, I think I have collected enough data on it -- you have to score where the outdrive fits into the bearing zone, and you have to file down the CVD pin so that it does not catch on the outdrive saver ring -- all in an effort to not let the outdrive up work its way off or something like that.
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Old 06-19-2007, 02:22 PM   #6
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Man, there are just too many ways to do it. You could run a shorter camber link up front, you could run some toe out, you can run less kickup, etc. You could underdrive the rear by running a smaller pulley. But, every change you make will change the car over bumps, or in the middle of the corner, etc. The surest way to add turn in is with a one way. Never run one in my XXX-4, but I've done it in TC. And yes, ABS is for electric too.
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Old 06-19-2007, 06:33 PM   #7
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What does the ABS do? I think I have it on the Futaba 3PK, but I though it was for blipping the gas during braking, which I can't picture how that would work in electric.

cjtamu, I think I will try out some of those ideas and see what they do. Thanks.
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Old 06-19-2007, 08:37 PM   #8
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ABS just pulses the brakes just like in a real car. On my KO you can set the pulse width, etc. With a TC I would start at full brake, then add ABS until I could hit "full" brake without the rear end getting skittish. Some ESC's have an ABS program now also.
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Old 06-19-2007, 08:40 PM   #9
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You should see cjtamu drive before you listen to him. trust me.
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Old 06-19-2007, 09:46 PM   #10
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I've got a Futaba 3PM and a XXX-4 with brushless, my first 4WD, I kept wanting to swing the rear-end around like a 2WD. With a 2WD I would accelerate to the corner, hit the brakes and turn, then gas it on the way out. I changed my driving style a bit.

For my driving style, I use ABS so I can brake hard in a straight line very consistently (before the corner). And then I accelerate at about 1/4 throttle through the corner. This is the best way I have found to take very tight 180 corner. The rear end doesn't break loose and the turning radius is very tight. I feel that the car is much more controllable than if I was swinging the rear end around.

I do not use a one-way because the braking with all four wheels helps the car stop quicker so I can stay on the throttle longer... then brake for a quick second to get to cornering speed then ease through the corner on power.

I run the front diff looser that the rear because, again for my driving style, it helps my cars turn-in under acceleration.

Another plus to the ABS is it controls the belt skip under braking on high traction surfaces.

Just a different idea if you want to try it out.

-Nathan

I'll add this too... The car is basically set-up from the manual with a small amount of toe-in, battery fwd.
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Old 06-19-2007, 10:01 PM   #11
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You didn't mention it but do you have a rear sway bar installed? You might want to give it a try to get the rear to come around a little easier and more predictable. I'd start with the .055 bar.
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Old 06-20-2007, 04:16 AM   #12
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I will have to try the ABS thing out.

BTW, for the belt skipping, I have the HD belt tensioner from Losi and the belt hold-down from I&Q Tuning. I have the belt somewhat loose. The slipper is basically locked down. The belt does not skip much, just a few teeth -- it kind of takes over the job of the slipper. The diffs seem fine with this (they have the Losi spring that replaces the washers, and I just started using the xxx-CR caged thrust bearings).
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Old 06-20-2007, 05:17 AM   #13
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You may want to rethink your strategy as far as the slipper goes. In my experience, any time the belt skips is not a good time.
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Old 06-20-2007, 08:00 AM   #14
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Quote:
Originally Posted by Jerry23 View Post
You should see cjtamu drive before you listen to him. trust me.
Don't listen to him. He's been ducking me for weeks. As far as the belt, you want to run it as loose as you can without it skipping under acceleration. It may skip a tooth or 2 under braking, but that's okay. I got that info from Tol Thomas, who's been running Losi for a long time, and he showed me how to set the belt. BW, you can see there are a lot of options. Change one thing at a time and see how it works. And yeah, run the battery forward in that car if you're not already.
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Old 06-20-2007, 08:15 AM   #15
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I could run the battery forward, but it won't be the same as you think. -->

I have a 4000mAh LiPo. To balance the chassis left-right (and to just make minimum weight), I poured some lead weights that just fit into the 7 battery slots. Then I milled down some of the chassis nubs to let the LiPo sit nicely.

I have been running the battery to the back, BTW.
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