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skom25

TT-02B/ DT-03 axle play

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Hi,

Same issue in TT-02B and DT-03. There is around 1mm gap between bearing and Hex. 

IMG-20230516-110045783.jpg

Why Tamiya did something that idiotic? I understand that with bushings some play is necessary, but 1mm is huge gap. 

There is no information what to do if bearings are used. You have to measure eveything and find proper parts, because Tamiya does not have them in catalogue.

Hub is so loose that bearing just pops out when model is touched.

I will name that directly: crap.

I really do not understand Tamiya design philosophy. Some solutions are very clever but there are many totally stupid ideas, which requires additional parts etc.

Unfortunately I am again very dissapointed with Tamiya quality. I know that it is entry model, but it is RC from big brand, not Chinese toy.

Solution: find and buy 5x8x1 or 5x9x1 washer.

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I know this set but I really do not want to put four ( at least!) washers on each side :D

You need 3x 0.3 + 1x 0.1 so one set is not enough. Of course it is possible to mix them but there will be five or more shims on each hub...

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They're the solution, it's up to you if you want to use them or not  ;)

I think you're expecting way too much from the entry level Tamiya kits if you think there should be tight tolerances everywhere!

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I do not agree. I understand play in suspension, because production process is not perfect. Material can shrink, bend a little etc.

In that case, you have two bearings, steel axle and Hex. Hub is only a place where you put bearings. There is really no reason, why gap is so huge and why Tamiya have not prepared solution, especially that they mention bearings in manual.

It is easy to say "it is entry level kit" and forget about all bad things but I just feel dissapointed, because it does not feel right. We are not talking about 0.1 mm or 0.2 mm gap but 1 mm. It was designed that way, which is crazy and hard to understand.

BTW. Those shims are crazy expensive. Tamiya could just add 1 mm shims ( even plastic!) in kit, to solve issue when bearings are used. Well, but it is Tamiya. It is better to make something like this and tell that you can buy set of expensive shims and use 4/6 of them on every hub. Sound like perfect plan!

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It's more expensive to manufacture plastic parts that are more perfect in size than those that have a larger tolerance - the machines have to be much more accurate.  Molds also wear as they are used so Tamiya would have to replace them more often too, again increasing the cost.   To get what you're asking for would mean the kit would probably cost too much for the market Tamiya are selling to.

I'm not saying it's an entry level kit just to gloss over what you've found, I'm saying it because that's what it is and this is the kind of thing you get when you build a kit to a price.

The DT-03 currently costs £77 on Amazon UK.  For a complete kit made in the far east, shipped to the UK, with VAT and final delivery and profit for everyone involved in getting it to your door included.

It's clearly not going to be at the level of a £500 racing buggy is it?

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Sorry, but I do not agree for the second time.

15 minutes ago, Twinfan said:

It's more expensive to manufacture plastic parts that are more perfect in size than those that have a larger tolerance - the machines have to be much more accurate

Part below is from Hubs sprue. There are 8 or even more, used as spacers for shock step screws.

IMG-20230516-124720400.jpg

They are perfect. Round and flat. They are little smaller, so do not fit on hubs.

It seems that it is not so hard if you want to...

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It is fine. We are on the Forum :D

I just want to say, that some things are related to low price and you have to accept them. Unfortunately, some things seems to be done on purpose, to force customer to buy additional parts.

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1 hour ago, skom25 said:

BTW. Those shims are crazy expensive. Tamiya could just add 1 mm shims ( even plastic!) in kit, to solve issue when bearings are used. Well, but it is Tamiya. It is better to make something like this and tell that you can buy set of expensive shims and use 4/6 of them on every hub. Sound like perfect plan!

In RC, little things like shims and screws are often overpriced. Maybe check your hardware store.

I don't beleive that Tamiya made the DT-03 sloppy to sell shims, a lot of entry level Tamiyas have loose tolerances due to how the parts are made.

I understand your dissapointment in Tamiyas quality though. I like a number of their designs,  but loose fitment is the norm for their entry level offerings, then you have their use of ABS plastic. Its completely at odds with something I'd want to hop-up.

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You cannot bring Tamiya's fit standards in their static kit to their RC, especially not to the entry level or rere RC kits. 1mm is a massive gap to fill in static but acceptable for entry RC. 

Anyway, if you want to get cheap spacers, this is where I get mine.

https://a.aliexpress.com/_EGSdAGD

 

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Like the others have said, it’s a cheap entry level kit, don’t expect it to have the tight tolerances of a high end kit. Yes Tamiya is a Japanese kit, but just like Toyota, if you bought a cheap Yaris, don’t expect the quality to be like that of a Land Cruiser. 

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Most cars require shims from 53587 to make the axles spin without either perceptible play nor binding. It's just how they are engineered and made. The alternative is to design the car with a spacer in between the two bearings inside the knuckle like the higher end chassis have. On these, when you tighten the wheel nut you bring the whole stack in compression (inboard shoulder of the knuckle / inboard bearing / spacer / outboard bearing / wheel hex / wheel-wheel nut). This mechanically cleaner but requires very accurate plastic molding for the knuckle and an accurate machined spacer as well to ensure bother bearings are exactly concentric and spin freely.

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I already ordered 5x9x1. I have also 5x8x0.5, 5x8x0.25 and 5x10x0.5.

All will fit fine, except of last one. They are little too wide, so can rub on outer race. They can be used if smaller washer will be used as first.

I ordered 5x9x1 because I did not want to have few shims on hub, because it is easy to loose them during maintenance.

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30 minutes ago, skom25 said:

I already ordered 5x9x1. I have also 5x8x0.5, 5x8x0.25 and 5x10x0.5.

All will fit fine, except of last one. They are little too wide, so can rub on outer race. They can be used if smaller washer will be used as first.

I ordered 5x9x1 because I did not want to have few shims on hub, because it is easy to loose them during maintenance.

Ok, so it's 5x8x(thickness) in mm you should look for?

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34 minutes ago, Dan1891 said:

Do you know the dimensions of these shim's? So you can get alternatives to these Tamiya ones?

They are 5mm ID and 7mm OD. In my experience attempting to source alternative parts often ends up with the same expense or more and a poor result, such as the shim rubbing on the race in this case.

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Just now, Pylon80 said:

They are 5mm ID and 7mm OD. In my experience attempting to source alternative parts often ends up with the same expense or more and a poor result, such as the shim rubbing on the race in this case.

Thanks!

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5x8 will work fine for sure. I have them in DT-03.

I am not sure about 5x9. I will check them tommorow, but should be fine.

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8 minutes ago, skom25 said:

5x8 will work fine for sure. I have them in DT-03.

I am not sure about 5x9. I will check them tommorow, but should be fine.

So you will say these will work?

5x8x.0,8 They are 2.30 euro for 8 of e'm:

Brickor Stål 5x8x0,8mm (10 st.) HongNor (kullagergrossisten.se)

reason for these are very low shipping cost for me.

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Yes.

Today I bought 20 5x9x1 for about 2 Euros ( 4 with shipping).

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Just now, skom25 said:

Yes.

Today I bought 20 5x9x1 for about 2 Euros ( 4 with shipping).

Thanks, perfect!

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I'll also add that in my experience I have seen around 0.7mm of shimming required per wheel, although that will vary slightly with the axles being used. I usually do 0.3+0.3+0.1.

Also, to make maintenance easier, I always use the same amount of shims on the left and right, even if that means having one side ever so slightly looser than the other side. This way you don't need to remember which side had which shims when you put the car back together after cleaning.

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My theory is that they intentionally design in slop to make the parts easier to assemble and disassemble for kids and first timers. It's almost comical wobbling about on some of our favourite kits.

Acknowledging that it isn't easy to mould parts to tight tolerance, and moulds will wear out over time, I just can't see this being the reason. I've never seen a Tamiya R/C moulding that's anything but dimensionally "exact" (not perfect) and many of the parts simply wouldn't function or assemble if they were out by significant fractions of a mm. They also include many small and high precision moulded plastic bushings in many kits. When you see distorted or defective parts in build threads online, it always looks like poor (temperature/ humidity) storage at the back of some warehouse. This isn't Lego that needs to friction fit a straight edge to a consistent force across many sizes and pigments.

Look at mini4wd, which is smaller, but very cheap and snap locked so there's very little room for tolerance. Works every single time.

So, I think it's all intentional. And they won't complain if we obsess over getting the proper branded shims and fittings for those of us who care about tolerances B)

The high end kits are much better, or don't even try - and make you ream/file parts to spec. (Opposite of salt in your food, you can always shave more off the part but you can't add it back on).

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