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Tamiya TB Evo 6

Old 08-25-2014, 09:37 AM
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Originally Posted by metalnut
Grinding the hole for the smaller 10mm bearing cured the case rocking side to side? That seems odd to me, as my rock on their own with no bearings or anything inside. In fact, I think they rock on the edge opposite the input shaft, that is the edge I ground down in one of them to make them fit right. It's just difficult to tell what makes the gear diff (side) bearings bind when the case is screwed down.
Oh damn... yours rock w no bearing?! Mine were good until you set the bearing in... than top case fit bad and bound everything up. I wish these kits were better fitting. My chassis (tb04) is warped too.
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Old 08-25-2014, 10:14 AM
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Originally Posted by Wade....
Oh damn... yours rock w no bearing?! Mine were good until you set the bearing in... than top case fit bad and bound everything up. I wish these kits were better fitting. My chassis (tb04) is warped too.
Yeah, the top case rocks side to side if you hold down the input shaft side... the opposite side has ~1mm of space between the back screw holes. Furthermore, if you just press the case down in the center, it rocks side to side given that ~1mm of warpage. The input shaft bearing would not fit at all in my top cases, no matter how hard I pressed, I measured the hole to be just over 9mm in diameter

I agree about the fitment issues. I'll see what the Tamiya officials had to say about my cases (they made their way to TCS nationals ), but for now I'm just hoping Exotek or someone will have mercy on us and produce some blue anodized alternatives
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Old 08-25-2014, 07:44 PM
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The case halfs straighten out when you tighten them together, don't they?

Seriously....I never checked that part for trueness. I just always put the parts in the lower case, and slowly tightened the screws in a crossing pattern. If both of them are bent, as long as they flush up.....the bearings are tight on installation. If they don't fit in with an interference fit, you will destroy the gears when they walk around on you.



I will check them again on the next one I build.
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Old 08-26-2014, 03:12 AM
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Thanks guys for posting helpful tips on the solutions you have come up with, It has helped me get my cars alot smooth. I also put 6, 3mmx0.3mm shims between the two case halves so the top case doesn't squash the bearings as much made huge difference.
I'll post a picture soon
Attached Thumbnails Tamiya TB Evo 6-pic2.jpg  

Last edited by E-clip; 08-26-2014 at 03:46 AM.
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Old 08-26-2014, 07:00 AM
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There is no way smashing the steel bearings in a plastic case is going to bind the transmission. I remain confused by all of this.

Tonight, I will build the transmission out of my other EVO6 kit, and take pictures. I will attempt to replicate the problems other users are having.

Originally Posted by Wade....
My chassis (tb04) is warped too.
They all are. You can fix that with some carefully applied heat from a heat gun, a dead flat surface, and a couple of C clamps. Heat up a piece of scrap Tamiya plastic till it melts so you can figure out what the "hot enough to start stinking but not melted yet smell" smells like. It it starts to blister, that's too hot.

Then, clamp it up and heat the chassis with the tweek to the "smell" point. You can unclamp it and bend with your hands if it's really bad.
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Old 08-26-2014, 07:52 AM
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Originally Posted by Electr0n
As mentioned before the modification is very simple and maybe the original small 16T bevel gears will also be good enough. Use a 9 or 10 mm wood drill bit, drill approx 1.5 mm from the top of the 16T bevel gear ( small end ) to copy the indent that is in the TB-04 EVO 6 16T bevel gear so the c-clip will fit. I did it by hand and it took about 30 seconds to do.

The 39T bevel gear or TB EVO 5 One-Way gear is a direct fit.

Never had a problem driving 13.5 Boosted 12T(Tamiya) or even 6.5T with the Evo 5.

Andre
Thanks for your advice, Andre! Will try out your method.
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Old 08-26-2014, 08:14 AM
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Originally Posted by CraigMBA
There is no way smashing the steel bearings in a plastic case is going to bind the transmission. I remain confused by all of this.
Why is that confusing? If you put enough pressure on a bearing, it will warp it enough to cause binding. I'm not talking about seizing the bearing, but it does slow it down enough that free spinning is affected.

Keep in mind also that these plastic cases seem to vary greatly in quality control. Perhaps you got really nice ones?
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Old 08-26-2014, 09:08 AM
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Originally Posted by metalnut
Why is that confusing? If you put enough pressure on a bearing, it will warp it enough to cause binding. I'm not talking about seizing the bearing, but it does slow it down enough that free spinning is affected.
I politely disagree.
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Old 08-26-2014, 09:19 AM
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Originally Posted by CraigMBA
I politely disagree.
Haha, I'm not offended or angry man, but color me confused. I've spent HOURS with these cases, trying to identify what is preventing my bearings from free spinning, and it has to do with the pressure the case applies to the bearings when screwed together. Adding shims between the case halves actually improves the situation, but results in too much up/down movement in the bearings.

If you can prove me wrong, please, please do it! If you can guide me to a free spinning drive train I'll love you for ever
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Old 08-26-2014, 09:26 AM
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Originally Posted by metalnut
Adding shims between the case halves actually improves the situation, but results in too much up/down movement in the bearings.
I just balance out not too much up/down and let the bearing press little. The gear will be gone fast if too much up/down.
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Old 08-26-2014, 09:34 AM
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Originally Posted by TamiyaW1688
I just balance out not too much up/down and let the bearing press little. The gear will be gone fast if too much up/down.
Right, that's why I'm running 0.1mm shims on only two of the 6 holes, one the side opposite the input shaft. That lifts the case just a bit and levels it out where it's warped. Still, my totally assembled driveline only free spins for about 6 seconds.

I do wonder if the metal miter gears and/or the metal gears in my diffs add to that problem. More friction between the miter gears, more rotational weight with the heavier diffs.
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Old 08-26-2014, 10:38 AM
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I too have come across this problem of compressed bearings in my trusty ta05. I imagine it's a potential problem for any injection molded part.
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Old 08-26-2014, 11:40 AM
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seeing how long a car spins for is not really that important, it doesnt really dictate that it will be better at accelerating or faster.

The most important thing is to ensure that its just free so that the force that is required to accelerate the car to its maximum velocity and to maintain it.

This is all down to the mass of the drivetrain, and the friction it has along it. A car that freewheels for a long time may have a heavier drive train than one that freewheels for less time, but assuming they are both free then the lighter drivetrain will be the better one.

Years ago I got obsessed with all of this, I had a TBevo3 that span for ages, but once I became clued up and swapped out to lighter components the car was much quicker on the track despite the wheels not spinning for as long.

As long as its not binding, and it moves on a slight incline I am more than happy with all of my cars nowaday (Belt and shaft)
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Old 08-26-2014, 01:51 PM
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Nice car but a lot of niggly bs for the price,hope it is really,really good for the amount of you have to do to it.
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Old 08-26-2014, 02:00 PM
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Originally Posted by GasGod
Nice car but a lot of niggly bs for the price,hope it is really,really good for the amount of you have to do to it.
What issues have you been battling with? Just curious if it's stuff I saw, or things I should still watch out for. Thanks!
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