Glueing Bearings!?

[DaveB 151]

I'm in the middle of a rebuild on my DB01-R and I've come across the fact that the bearings are loose in the front hubs. This isn't because anything is worn, it's like this from new (have tried a bearing on a brand new hub). The outer race is not a snug fit, basically has too much clearance.

Now I'm thinking this isn't just an issue on my particular buggy, I'm guessing other Tamiya chassis suffer from this too. So I'm toying with the idea of actually gluing the bearing into the hub to stop the movement issues. Does anyone see any potential problems with this (aside from sacrificing the bearing and hub if they need replacing)?

[Yalson 514]

If the bearing is not snug with the recess, then glueing it is not going to help the wheel run true. If you glue it, then you are effectively fixing it in a place so that it will inevitably be fixed in an orientation that is not square to the rest of the model.

Imagine a vinyl record spinning on a turntable. If the hole in the centre of the record is too big (which is effectively what is happening to your wheel if the bearing is not snug with the hub), then the disc can move about and detrimentally affect the sound.

If you glue the bearing in, then you will inevitably glue it in slightly off centre, with the bearing touching one wall of the recess but not the other. If we return to the record analogy, you have now set up a situation where the hole in the middle is the right size (so the record can't move about) but it is now permanently off-centre, meaning the sound now has built-in problems as some sections of the disc move more quickly in relation to the needle than others.

Even worse, your wheel works in two dimensions, so glueing it in will inevitably mean it is permanently slightly buckled, too.

I think the only answer is to get new bearings.

[Grastens 2795]

It can depend on how you glue it. On bicycles with certain bottom bracket types (namely, the types involving bearings that press into the frame), using Loctite (242, I think) is standard practice. It does a decent job getting a secure fit into the frame, and is not too difficult to remove afterwards - and the forces going through those bearings are quite high, too.

However, the preponderance of ball bearings has me in agreement with Yalson that a new bearing is the better idea. Loctite will not work that well if the component is plastic - certain grades will actually melt it, so unless the DB-01R front hub is metal, you are best off trying your luck with another bearing.

As for finding loose fitment of bearings in Tamiya chassis, I have yet to experience that phenomenon.

[dannymulder 766]

The thing I do is use a thin plastic foil from a bread bag ore something,cut out round piece and make a hole in the middle and press the bearing in with the plactic foil job done.

Some tamiya cars have it, the sand scorcher rere gearbox that I had was the worse, the bearings where loose in the gearbox and fall out of it so I used the foil trick

[DaveB 151]

Thanks chaps, that's really interesting. 

To be clear, the bearings are not worn, new bearings are loose in new hubs, so it definitely seems like this was deliberate by tamiya? 

[Yalson 514]

48 minutes ago, Grastens said:

It can depend on how you glue it. On bicycles with certain bottom bracket types (namely, the types involving bearings that press into the frame), using Loctite (242, I think) is standard practice. It does a decent job getting a secure fit into the frame, and is not too difficult to remove afterwards - and the forces going through those bearings are quite high, too.

However, the preponderance of ball bearings has me in agreement with Yalson that a new bearing is the better idea. Loctite will not work that well if the component is plastic - certain grades will actually melt it, so unless the DB-01R front hub is metal, you are best off trying your luck with another bearing.

I agree that this would work if the bearing was already a snug fit and you're just trying to hold it in place (I have heard of this technique being used in other situations) but glueing in a bearing that is fundamentally the wrong size is never going to work for all kinds of reasons.

[Yalson 514]

48 minutes ago, DaveB said:

Thanks chaps, that's really interesting. 

To be clear, the bearings are not worn, new bearings are loose in new hubs, so it definitely seems like this was deliberate by tamiya? 

Are these ballraces or plain bushings we're talking about? It sounds like Tamiya have bought a consignment of bearings of whatever sort and they are just fractionally too small for the mounts, or just the wrong bearings. If you bought the kit from a physical shop then I would take the affected parts back and show them the problem. They may be able to give you some replacement bearings, replacement hubs or better advice on what to do. If they are 2WD front hubs and the bearings are just sliding out of the recesses in the hubs, rather than obviously the wrong size, then you might be able to pack out the front axle with washers to keep them in place while running. I had a set of after-market front hubs on a Grasshopper that had a similar problem. The bearings were the right size for them, but manufacturing differences meant the hubs wouldn't hold them in place. We put washers on the front stub axles to hold the bearings in and they worked fine.

[DaveB 151]

This is a known issue with DB01 hubs I think. The bearings are correct, standard axel size, used on pretty much all tamiya cars. 

[Yalson 514]

9 minutes ago, DaveB said:

This is a known issue with DB01 hubs I think. The bearings are correct, standard axel size, used on pretty much all tamiya cars. 

Ah. Just had a look at your build thread, so ignore my previous posting about 2WD hubs. Also saw that the car was imported from the US, so taking it back is maybe not an option. It might be that you have to source some new alternative-spec hubs instead.

[speedy_w_beans 4272]

I wouldn't worry about this too much.  The ball bearings themselves have some tolerance that can take up a little misalignment.  The best way to tell is spin the axle stub by hand.  If you want a more snug fit between the ball bearing and the hub, dannymulder's idea works, or you can put a layer or two of trimmed cellophane tape around the outer race.  I've used tape extensively on a TT02 build for suspension and steering points, and it tightened up the slop perfectly to the point I don't feel the need to buy a bunch of alloy.

[Yalson 514]

18 minutes ago, speedy_w_beans said:

I wouldn't worry about this too much.  The ball bearings themselves have some tolerance that can take up a little misalignment.  The best way to tell is spin the axle stub by hand.  If you want a more snug fit between the ball bearing and the hub, dannymulder's idea works, or you can put a layer or two of trimmed cellophane tape around the outer race.  I've used tape extensively on a TT02 build for suspension and steering points, and it tightened up the slop perfectly to the point I don't feel the need to buy a bunch of alloy.

Well there you go. Apologies for my response to @dannymulder's suggestion, but I couldn't picture his solution in my mind. And I also think Dutch bread must come in different packaging!

[Otis311 196]

I have noticed this in probably half my builds. Typically it is in the gearbox or hubs. I have ignored it assuming that under load the outer race will hold in placed due to the radial force applied. Looking back I should have added some cellophane as suggested above.

This made me think of the 3 speed gear box which indicates the dogs should have their bushings glued in place. This is a different scenario as they want the bushings to stay in placed during axial motion.

[KEV THE REV 2310]

6 hours ago, speedy_w_beans said:

I've used tape extensively

Me too