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Old 09-03-2008, 07:25 PM   #1
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Default 8ight roller question

Hi,

A little background. I got a really nice deal on a "used" Losi 8ight a while ago. By used, I mean the guy bought the 8ight kit, put it together, and decided to sell it without ever running it (the tires aren't even glued).

I'm taking my time to slowly convert it to brushless, as I can't really run nitro.

However, I have a few concerns about it. The guy seemed to know what he was doing, and the buggy is put together pretty well.

But, one thing that kinda bothered me is that without any motor in there, it doesn't roll that easily. I mean, it feels like there's quite a bit of resistance in the drive train. If you set it down on the floor and give it a hard push, it'll probably roll less than a meter and come to a stop.

So, I kinda started taking it apart to figure out which part of the drivetrain is giving the most resistance.

To my surprise, I found that it's the front two wheel axis (without the wheels on) that are the hardest to rotate.

I took all 4 wheel's CVD/dogbone thingies out of the differential outputs and compared how easily I can turn each one.

Both the front two wheel axis are giving a lot of resistance to rotation. Both the rear wheel axis rotate very smoothly (as smooth as any of the diffs and everything else) with little resistance.

I've compared the construction of the rear hubs vs. front spindle/steering blocks, and it seems they are identical. Both use a larger 1/2" x 3/4" ball bearing on the inside, and a smaller 8x14x4mm bearing on the outside. The CVD goes inside, and it's the same.

Then why don't they turn equally easy?

I'd really like to solve this problem (if it's abnormal) as it'll be causing unnecessary load on the motor.

So what I wanna find out is this:
Is the described above effect done on purpose, or is there something wrong? Should all 4 CVDs rotate equally easy in all 4 hubs when the wheels are off?

My one guess is that since the buggy has been put together a LONG time ago and been sitting on a shelf ever since (it's probably 6-12 months old, if not older), perhaps for some reason the front bearings went bad and now have more resistance to rotating? Is this something that'll disappear once they get "worked out" sufficiently enough? I've tried rotating them by hand a little, it didn't do anything.

My next step would be to take it apart even further and compare the ball bearings on the front and rear. I didn't do that yet because that would require me to mess with loctite/threadlock/grease to put it back together afterwards, and I'm kinda scared of messing with liquids lol. Besides, those ball bearings are pretty expensive. @@

Sorry for a long post and probably mis/using wrong terms. I'm kinda new at this. Ty in advance for any advice!
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Old 09-03-2008, 07:38 PM   #2
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well if it's been put together and never ran i'd say more than anything it's because nothing has worn in on either the diffs or the bearings.

They need a little time on them before they spin/roll freely thats the way it is with my 8ight when i change drivetrain bearings
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Old 09-03-2008, 07:42 PM   #3
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It takes about a gallon to break these in. I'm not sure how much that coverts into "electric run time".
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Old 09-03-2008, 07:46 PM   #4
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Are you guys saying these front hub ball bearings simply need to be broken in, and they'll have less rotation resistance?

It just seems weird, because *every single other* ball bearing in the buggy has very little resistance. But those 2 in each of the front hubs are pretty tight with quite the high resistance. Assuming it is in fact the ball bearings and not something else in there that's causing resistance... Only way to find out would be to take it apart, I guess.

Even the new ball bearings I recently bought for my B4 had low resistance right away.
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Old 09-03-2008, 07:52 PM   #5
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If I remember both of my eights were the same way. But take it apart to see if it is ok. I remember it was pretty tight up front though.
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Old 09-03-2008, 07:57 PM   #6
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Hmm, that's interesting. Okay, thanks. I sure wish I could've put the kit together myself from scratch though...

Anyway, if I unscrew a screw that had loctite applied to it, will I need to reapply it when I put it back? What about grease that goes in there?

Thanks again.
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Old 09-03-2008, 08:01 PM   #7
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If youre talking about the grub screw that goes threw the 17mm wheel nut. Yes to the locktite, but just 1 drop. I pull the cvd out to regreese it. I've never tryed to put it in threw the grub screw. interesting thought.
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