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TC4 diffs come loose during a run

Old 10-03-2007, 09:47 PM
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Slo-V Flyer
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Default TC4 diffs come loose during a run

Ok so I got my fleebay used-TC4 chassis rolling yesterday. And today I fixed up the front ball-diff with missing thrust plate and bearings for the screw, hoping it would stop coming loose (just enough to slip).

Well, it turns out with enough power (Mamba Max 5700 + 6 cell Nimh) or maybe with any amount of power, the front and to an extent the rear diff tightness setting becomes looser. I set the front to be tighter than the rear so it would hopefully help avoid the TC4 fish tailing under power. Well, turns out after just a couple of minutes at most, the diffs become a little loose, just enough to were it acts like an "open" diff, and after enough driving, the front just about slips under power.

Is there any way if at all to keep the ball-diff setting consistent and not become loose? It seems to be a common problem with ball diffs. My 18T has the exact same problem, I tighten the front down for "limited slip," and within a few minutes it becomes an "open" diff.

I am guessing by design the set screw just turns a little and comes loose as the 2 drive cups spin at different speeds in a turn. Would locktite remove this problem for sure? Or at least prolong the diff's tightness before needing to be tightened again.
Old 10-04-2007, 09:42 AM
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Default RE: TC4 diffs come loose during a run

Cleaning the adjustment srew that runs dount he middle of the diff, and replacing the lock nut would be the best means, aside from ensuring that the diff is complete.

Replacing the ocknut will give you a tighter fit, and cleaning the grease off will help bind the screw and locknut.

The diff really shouldn't some loose if all the parts installed corrrectly, which leads me to believe that you have one of the above problems.

Itis entirely possible that with the added power, you are heating up the composite material making it soft. This will allow the diff to slip. Upgrading to an aluminum spool or aluminum outdrives will fix this.
Old 10-04-2007, 10:10 AM
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Default RE: TC4 diffs come loose during a run

I already have the alloy diffs (shiny ones). And yes, I figured out just yesterday, after trying to re-tighten it for the 5th time, STRIPPING the locknut's nylon threading, that there IS a locknut, and that the screw doesn't directly bolt into the opposing drive cup. SO yeah I'm gonna hit the LHS and get the rebuild kit with the nut in it.

As for dirt, I cleaned and re-cleaned and sprayed and cleaned and sprayed the whole diff assembly, re-greased everything except the screw threading and nut, and it was still coming loose. I guess it was old and like you said maybe a new lock nut would help. The rear is the same, but not as bad.

Though that doesn't still explain how my then new 18T had the exact same problem with both diffs getting loose during a run. Maybe I'll get around to it and see what's up with it.

Thanks for the reply.
Old 10-04-2007, 11:16 AM
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Default RE: TC4 diffs come loose during a run

Ok so I just put in a new locknut in the diff. Lets see how it holds up.
Old 10-04-2007, 11:51 AM
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Default RE: TC4 diffs come loose during a run

I almost always have to upgrade to MIP ball diffs and if they still come loose, blue (non-permanent) loctite.
Be sure to check the tightness often, if you run them loose, it will eat them up.
Old 10-04-2007, 11:20 PM
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Default RE: TC4 diffs come loose during a run

Yeah I'm afraid if the diffs are loose enough to slip, it'll make the plastic gears melt like in the stories I've heard...

How are the MIP diffs different?

And that blue loctite sound like something I might have to try it this persists. I've not been able to run it today, but hopefully tomorrow noon I'll find out how the new nut holds up.
Old 10-05-2007, 01:11 PM
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Default RE: TC4 diffs come loose during a run

Well, I ran it today for about 5 minutes. The diffs seem to have kept their consistency. Of course, I was running my 3s lipo with the 5700....... so yeah.... that helped me figure out that I forgot to glue 2 of the inner tires' beads......

Man it gets pretty wild at anything over 50% throttle.. I've got it geared the lowest I can, 23/72(74?), I can't imagine 100% throttle... I'd need foams because it's one mistake and wipe-out cart wheels... which it did twice.. Nothing broke tough, it's one tough car I'll give it that. Barely goes over 40mph before it loses control. Need more traction. My Bandit by comparison with it's larger tires is easier to control at 55+ mph...
Old 10-05-2007, 02:25 PM
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Default RE: TC4 diffs come loose during a run

The MIP diffs have better balls (I think), plus the outdrives are better metal. I think, hopefully I'm not mixing them up with some other setup, it's been a while since I've modded the TC4. When I started using the mamba with 3-cell 5700KV motor, I had to change out the whole rear tranny, MIP CVDs, outdrives, etc. The stock tranny broke in the first 5 minutes or so.
Old 05-31-2008, 10:19 AM
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Default RE: TC4 diffs come loose during a run

I hate to bring up a old thread but did you ever resolve your diff issue?

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