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Old 12-01-2002, 01:50 AM   #1
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Default Traction/wheelspin Problem?????

Hi Guys,
I seem to have developed a rather slippery problem that I would like some opinions on.

I have a TA04S that I have basically hopped up to 04R Spec with all the trick bits. I have the racing hub carriers 2deg Rear toe in Hubs, Ball diffs etc etc. No one ways fitted on the car at all. I have about 1.5deg toe out at the front. I'm Running a fairly quick 10X4 Mod Motor. Most of the settings are as per Tamiya Instructions

Any how heres the problem.
After fitting all the new hop ups to my car it is very hard to corner without it doing little circles with the tyres spinning wildly. I will be flying down the straight and reduce speed coming in to a hairpin and when I turn the wheel the car will turn on a dime but as soon as I apply the power it will fish tail or just start doing doughnuts with the wheels spinning wildly until I back right off the power and virtually bring it to a stop again. It will do this at almost every sharpish turn and it is very annoying.
I drive on a medium smooth asphalt car park track using the same tyres that my brother uses on his stock TA04S. His car does not suffer this problem.
I think that the car just has massive oversteer but before I go fiddling about with settings I thought I would get some advise.

Can someone please shed some light on why it might be acting like this

Thanks
Steevo
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Old 12-01-2002, 03:53 AM   #2
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Well, a 10-turn motor is bound to break traction quite often - if your brother is running a slower motor, it's not surprising that his car appears to have more grip.

Things to check are for binding somewhere in the transmission - for example a bad bearing somewhere that's causing a wheel to come to a sudden halt when the weight is off it.

Or, more likely in my opinion, the suspension settings are off. I would swap the toe out for toe-in. If you're using hard springs, they'll make the car feel less grippy on a bumpy/low-grip surface than soft ones. Droop is also very important (and my guess is that this is the problem) - you MUST be able to lift the car a couple of mm at each end before the tyres leave the ground - i.e. don't have the car jacked up to the limits of it's suspension travel. The droop must also be set evenly side to side, but front to rear can be different (slightly more droop is used at the rear ususally). The TA04's I've seen seem quite easy to mis-set the droop on.

And softer, grippier tyres would help.
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Old 12-01-2002, 05:25 AM   #3
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Yes I agree and think that it is in the suspension set up somewhere but I'm not sure where or why.
The droop does appear to be around 2mm front and rear as it is though.
I think that I am just going to have to make some adjustments to the shock positions and toe settings and maybe change to a slightly softer spring set up. I can't drive the car on a tight course the way it is because it is like driving on Ice. I tried some belted slicks with very soft sponge inserts but the car just kept fishtailing and doing doughnuts at every sharp turn and drifted wildly around the others.
Any other suggestions would be appreciated.

Steevo
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Old 12-01-2002, 06:49 AM   #4
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sosidge is right, I'm not sure about using toe in, I would try zero toe first, as far as the springs I know exactly what you're talking about, I only run stock, but that was enough to break the rear end loose, I actually run blue springs and blue sway bar upfront,
this may seem a little stiff for asphalt (track is smooth but not very new) but it does the job, I run yellow springs in the rear,
what oil-spring combo are you running front/rear.
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Old 12-01-2002, 12:35 PM   #5
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I am using 600 wt oil and Tamiya Gold springs....
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Old 12-01-2002, 04:30 PM   #6
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Default Ball diff problem?

I'm running a FTTC3 and was having a problem similar to yours. The problem it seems was that the diff's weren't properly adjusted. The front was looser than the rear (Or vica versa) cant remember =)
Check if the diffs feel the same at both ends. This only applies if you're running ball diffs and if the suspension settings havent changed from your last rebuild. Hope this helps!
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Old 12-01-2002, 06:42 PM   #7
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Thanks,
Both Ball Diffs appear to be the same. They are both locked out (you can't rotate the diff pulley when both wheels are stopped from turning). I am going to try a few things starting with the dampers and take it from there.
Any other suggestions or thoughts from anyone are greatly appreciated.

Steevo
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Old 12-01-2002, 08:40 PM   #8
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Default Slippery Tamiya

R/C Cars with Ball diffs at both ends usually have the Front diff set a little tighter than the rear diff. Get it reversed and the Car will want to bring the Rear around.
The Toe-Out in the Front will cause MORE initial turn in but less steering exiting a corner. Too heavy of shock oil will not allow the car to weight transfer. If the Front ride height is lower in the front, the car will have a harder time transfering weight to the rear tires as you accellerate out of a corner. Not enough Front Droop can cause on power looseness, too much and you have on power push. If the problem appeared when you installed the Hop-ups, then examine what may have changed in your set-up that is causing your problem. (you DO keep Set-up sheets don't you?)

Last edited by popsracer; 12-01-2002 at 08:45 PM.
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Old 12-01-2002, 08:50 PM   #9
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Thanks Popsracer and everyone else who contributed.
I have checked my settings and softened the suspension a little (it was rock hard previously) and I reset the droop both front and rear. On the bench you can feel the difference in the suspension geometry. I am sure that there will be a difference, how much though we will soon find out. I am going to take the car for a quick spin this afternoon if I get the chance. I will post the results when I have them.

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Old 12-01-2002, 08:50 PM   #10
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Default Diff adjustment

steevo;

The pulley should NEVER turn when the outdrives/wheels are held tight. The difference is felt when holding the pulley and turning one outdrive/wheel and noting the resistance. The Front should have a little more. OR you can go by number of turns on the diff adjusting screws. Tighten the front 1/8-1/4 of a turn more than the rear. (after being adjusted properly first)
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Old 12-01-2002, 08:57 PM   #11
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Both Front and rear diffs seem to be "locked Out" when taken out of the car and tested. They will slip under extreme pressure but this is far more than what the motor could ever exert on the pulley. Both front and rear are the same. With the diffs installed in the car though, the rear wheels rotate a little more freely than the front so I suspect that this is the way they should be then.

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Old 12-08-2002, 02:52 AM   #12
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Default Problem Solved

OK, Thanks for everyones Input and I am happy to announce another problem solved.

My traction problem was caused by overly stiff suspension......
I recently fitted a set of Mugen Shocks with Tamiya springs to my car. I had to wind the collar right down onto the spring to make them rebound properly with the Tamiya springs. They also had a shorter travel than the Tamiya shockies.
Any way, the combination of the shorter travel and the excessive pre-load on the springs made for an extremely stiff set up.

I switched back to the standard Tamiya shocks with Gold springs as per the manual and bingo all is well again Wooohoo!!!

Steevo
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