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Thread: ball diff's

  1. #1
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    ball diff's

    My car wont turn, I must need a ball diff, do I need front and rear, or does just front work ????

    I also have a wiggle (rear end seams to swing back and forth at high speed, maybe dbox ???) Do I need 0deg toe in the back ???

  2. #2
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    your diff dosnt affect steering. if you cant turn it is most likely your servo
    traxxas hates signatures

  3. #3
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    It has a bad "push", I think if I had a ls Diff it would pull front end around.

  4. #4
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    Are you an ETAC grad yet, or does the nav still have that school ?

  5. #5
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    Too much "cornering body roll" under acceleration will cause the front end to lift higher than the droop allows, thereby lifting the inside front wheel, & reducing the steering. Look at the bottom side of the chasis plate. Scratches that are really built up in one area means you are bottoming out and some suspension adjustments need doing.

    Sometimes, several small adjustments work better than one big one.

    Try using soft or medium foam inserts in the front tires and use hard inserts in the rear tires. I put swaybars on my 4-tec this weekend and that helped. I installed them in the second hole from pivot point, both front and back. Just as a side note I use 6mm of preload clips on all four corners.

    I am a Nascar nut so I shoot for balance and stability in my car. The 4-tec is really fast out of the box. So I go for handling.

    The racing surface and tire type are really important. Figure out what type of surface you run on and then get tires for that surface type.

    If after some of these adjustments you are still having issues with the inside wheels spinning free then I would get the ball diff from Traxxas.

    Hope this helps, Happy driving!
    Last edited by Robbie_D; 01-28-2007 at 08:29 PM.

  6. #6
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    I have the swaybars in same pivot point place, running "nitro shoes or feet" for tires (rears all the way around) 6mm preload clips and white springs in front, have the blue alum shocks from powerline adjusted to make car level. the surface is real smooth asphault (sprayed recently with the black stuff, a little shiny still).

    I do drive to hard into the corners, comes from my WC/BGN/Legends car racing days in Charlotte and I cant seem to scale down yet.
    Oh yea, I was Jr's Neighbor and Painted for the Wallace's (7)/Waltrip's(99)/SHawna (99) and a few more for a couple seasons too. Thankless job but it was cool.
    So I most likely need a lesson in tires for these things, And Ball diffs.

    And I will appeciate any suggestions. Thanks

  7. #7
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    You mean it pushes on entry? the ball diffs won't help you here, they help in the center and if you tighten them, they pull a little better on exit. A locked diff will pull even harder on exit, but lacks some in the center when coasting. Only run a locker in the front unless you like the car really loose. Try braking earlier and then rolling it through the corner, also increasing the front camber a bit and running the caster so the king pin is more vertical will increase front steering response. Which body are you using, because this makes a really big difference in handling. A LOLA body is awesome, but running a stratus or an alfa romeo is better for a touring style. They have a good balance aerodynamically. The stock body looks cool, but it really doesn't handle that great. Going with the 0 deg. rear hubs will increase your ability to "rotate", but if the car is already a bit loose in the tail, this will make it worse. I assume that since it is pushing, that it is loose on-throttle and not off. Soften the rear suspension a bit in order to get more weight transfer to the rear on-power.
    -Terry
    "The best part of wakin' up....is Nitro" i

  8. #8
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    In my experience with the 4-tec;
    On treaded tires, I noticed if I use the spongy foams that come with tire-sets, the sidewalls would fold over too much, during high speed cornering, and cause a wear pattern that felt like a groove in the tire when I ran my finger across it. Plus the outer edge of the rims were scuffed up.
    If I stretch the tire, like it would be under a cornering load, the tread leveled out. So I would highly recommend "hard" rubbery tire inserts for high speed cornering. The hard inserts work "ok" for me at low speed, but the "softer" rubbery tire inserts let the tires grip and roll better for tracks with alot of tight curves. I won't run foams that come with tires anymore because of the weird wear patterns.

    Ball differentials were best explained in the sticky posts at the main 4-tec forum page. But the quick explaination is:
    With gear diff- wheel with least traction has most power transferred to it.
    (gear diff adjustment done by changing oil weights, must be disassembled)
    With ball diff - power transfer between the inside/outside wheels can be adjusted with the turn of a screw.

  9. #9
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    I like foams because they are more consistent than rubber/inserts. But When using the rubber/insert combos, definitely do not use the cheesy stock foam. The molded inserts that come with the car are good, but the pro-line stock rubber wears too quickly. If you have a good surface (clean and prepped with sugar water, soda, or other traction additive) you can run slicks. with hard/med molded foam inserts, but then foams work better on a surface like that so why bother? With one exception......concrete. I used to run on a prepped concrete surface, and foams never worked. Tried all the way down to 30 shore and they just slid in the corners. Thought it was just me, then everyone else had the same problem. Unfortunately, rubber ran well for about 5 laps then got hot and started going away. Then you'd have to back off for about 5 laps to cool em off and start hot lapping it again. Talk about inconsistent. One other thing. Stretching the tire to flatten the tire or sort of decrease the sidewall thickness to prevent the folding over, is called inch up. This is what Traxxas does with the stock rubber. The Traxxas wheels are actually slightly larger than the standard wheel the tire is designed for. It's basically the same concept that was used on a lot of street cars before they actually started designing low profile tires.

    Another rubber tire tip. Freshen up a set of rubber by cleaning it with simple green, then coat it with Wd-40 for about 5-10 min and wipe of the excess. They will be as sticky as they were when you pulled them from the package. I never use traction compound on foam tires when running nitro. Your better off finding the right shore to begin with. The stuff lasts for the 5-8 minute runs you have with electrics, but will eventually fling out and dry off in the long runs you get running nitro. So unless you like to re-sauce your tires each time you fill the tank, I would stay away from foam tire juice.
    -Terry
    "The best part of wakin' up....is Nitro" i

  10. #10
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    That was good info Terry.
    I have never run foams yet. Me and my friends run in parking lots we clean with blowers. The nearest track is about 100 miles away, but we are planning a "road trip".

    What I meant by stretching was, I picked up the car grabbed the tire and pulled it inwards toward the chassis(on the outer tires) then ran my finger across the tires then let go of the tires. Sorry about not being clear on that...opps!

    I can't wait to try the simple green/WD40 procedure on my racing slicks. Thanks for that info!

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