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I have searched and cannot find...

What are you guys using for crush sleeves, the spacer which sits between the two bearings in each wheel hub, are there universal spacers that can accommodate any gap?

I want to clamp down on my wheels when doing them up with shims but realise my bearing won’t last long this way.

Apologies for an extra post from me, I’ll be out of your hair soon!

Cheers,

Al

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A crush sleeve like those used for pinion pre-load on full size differential assemblies? The single row ball bearings typically used in RC cars aren't really meant to accept side or thrust loads from a crush sleeve like a tapered roller bearing. As such, we commonly don't use them as spacers between to bearings in a hub or wheel. 

Edit: My apologies to Axle for misleading him. I was ignorant of the use of crush sleeves/tubes in RC cars with single row ball bearings and should not have replied. Thanks to @Lee76 and @Matty36 for setting things straight. Again, sorry for the mis-information.

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1 hour ago, Saito2 said:

A crush sleeve like those used for pinion pre-load on full size differential assemblies? The single row ball bearings typically used in RC cars aren't really meant to accept side or thrust loads from a crush sleeve like a tapered roller bearing. As such, we commonly don't use them as spacers between to bearings in a hub or wheel. 

Apologies, I’m unsure...

I knew what I was trying to do and so I did some research on it, I’m trying to reduce wheel slop and have successfully reduced it with x2 0.2 shims on the outside hub bearings, now when I tighten the wheel it can still move freely but the bearings are being pushed one side only which will be an issue over time, I can see how much space there is can perhaps I should just fill them with shims to make up the space...

Update – this works, just filled the space until it reached the same level as where the bearing sits then added an extra shim.

AC5780F6-262E-46D6-A12A-7F8D15B31036.thumb.jpeg.1af8a44a4e3df9041b9bededa447ff10.jpeg

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8 hours ago, Saito2 said:

A crush sleeve like those used for pinion pre-load on full size differential assemblies? The single row ball bearings typically used in RC cars aren't really meant to accept side or thrust loads from a crush sleeve like a tapered roller bearing. As such, we commonly don't use them as spacers between to bearings in a hub or wheel. 

I was trying to find where I saw this and the closest I could find was the way this buggy is setup on the link below, effectively made that spacer up in shims, I can feel a little click in every wheel when pulled, a tiny amount of movement from the free moving bearings, so they haven’t been squashed under load.

 

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1 hour ago, •Axle said:

I can feel a little click in every wheel when pulled, a tiny amount of movement from the free moving bearings, so they haven’t been squashed under load.

After I made my post, I was thinking of suggesting what you did. Sounds like you found a good solution by taking up the slack without imposing any thrust load on the bearings.

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12 hours ago, Saito2 said:

After I made my post, I was thinking of suggesting what you did. Sounds like you found a good solution by taking up the slack without imposing any thrust load on the bearings.

Thanks for the help, it was probably a question that never needed to be posted, shimming newbie here.

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1 minute ago, •Axle said:

Thanks for the help, it was probably a question that never needed to be posted, shimming newbie here.

Its no problem. All questions are worthwhile.:)

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Can I just jump in and add that although deep groove ball bearings are not intended to accept thrust loads they can accommodate a small amount, from memory it’s a little less than half the static load rating, static load example being the unsupported weight of the axle on the inner race. So some loads can be accommodated though on paper it will reduce the life of the bearing but, here is where it gets tricky.. If you were a pro racer you wouldn’t be worrying about bearing life so much since you can swap them every run if you liked.. but what you would need to do is weigh up the impact of increased frictional loss vs the effect of slop from clearances. There is another option other than shimming or clamping and that is a controlled spring load. For this scale belville washers are far too stiff, but there is something called a wave spring washer which can be very low load, you can often buy these in matched sizes to standard bearings. As @Saito2 mentioned you cant load it up as you would an angular contact bearing but you can use the calculation 0.5 x static load capacity to spec a suitable spring. ‘Bearing’ in mind (that pun is so hard to avoid) the type of bearings you get for hobby may not have the data available and going to even the most budget variety of a decent supplier FAG or SKF they may be far greater load capacities, so be super conservative with the values stated. I’ll have a quick look for data and come back to you on this once I’ve measured a bearing... 

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So, a quick look at one type of deep groove ball bearing, the std sizes in my kit are 11 x 5 x 4mm and the static load rating is 0.14kN so half this is 700N which sounds a huge load for a small bearing...But bearing in mind (pun alert) the average load for a decent m4 fastener i think is about 7kN,  any form of clamping would be instantly above this limit. If you’re interested for pure academic purposes, let me know the shim stack height you used and I’ll see what spring washer I’d have selected.. 

I will add a caveat.. I’m an engineer but I am very new to RC I’ve recently built my first cars and as with most things in life the practically experienced people here may well know better.. I’m still on the steep learning curve. :)

A good read on wave spring pre-load.  

https://www.smalley.com/blog/how-and-why-you-should-use-wave-spring-bearing-preload

I’d also add that for this particular application and given the small size I’d also consider an elastomer as a pre-loader.. But then I’ve always been a bit of a cowboy...

598D170A-7EAE-4615-831B-6B83609CF453.jpeg

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Apologies, when I get my daughter to bed tonight I’ll get one of the wheels off, I’ve used 0.2 shim until the last one where I might of used an 0.1, depending on movement.

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What size are the bearings and how wide does it need to be, the ones I have for my race buggy and truck use thin ones between the front bearings, the rear bearings have the piece machined into the rear driveshaft so none are needed. I think they are 3mm diameter front crush tubes, but are only about 1mm thick.

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These are team associated b5m crush tubes, I think they measure at 4mm internal diameter and 2mm thick.

 

20200729_195421.jpg

20200729_195441.jpg

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32 minutes ago, Matty36 said:

These are team associated b5m crush tubes, I think they measure at 4mm internal diameter and 2mm thick.

 

20200729_195421.jpg

20200729_195441.jpg

Awesome, thanks for that.

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12 hours ago, Lee76 said:

So, a quick look at one type of deep groove ball bearing, the std sizes in my kit are 11 x 5 x 4mm and the static load rating is 0.14kN so half this is 700N which sounds a huge load for a small bearing...But bearing in mind (pun alert) the average load for a decent m4 fastener i think is about 7kN,  any form of clamping would be instantly above this limit. If you’re interested for pure academic purposes, let me know the shim stack height you used and I’ll see what spring washer I’d have selected.. 

I will add a caveat.. I’m an engineer but I am very new to RC I’ve recently built my first cars and as with most things in life the practically experienced people here may well know better.. I’m still on the steep learning curve. :)

A good read on wave spring pre-load.  

https://www.smalley.com/blog/how-and-why-you-should-use-wave-spring-bearing-preload

I’d also add that for this particular application and given the small size I’d also consider an elastomer as a pre-loader.. But then I’ve always been a bit of a cowboy...

598D170A-7EAE-4615-831B-6B83609CF453.jpeg

So from the blue anodised sheath to the screw thread side goes like this;

0.2

Bearing 5x11x4

x10 0.2 x1 0.1

Bearing 5x11x4

x2 0.2

The thing that I do understand is that it’s a problem to only put pressure on the inner bearing sleeve, it’s only metal on metal contact all the way through.

1B699758-D306-41E8-8E0A-918704D82EB3.thumb.jpeg.8afb7a0880711ce76cc49d62a5e45edb.jpeg

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1 hour ago, •Axle said:

The thing that I do understand is that it’s a problem to only put pressure on the inner bearing sleeve, it’s only metal on metal contact all the way through.

Yes, metal through metal is fine, but the float would take place between the inner and outer somewhere, so as long as there’s either allowable clearance or a controlled preload at this point you’re good. I imagine most people just have a little float. I have massive float on my monster beetle... I’ve not had a think for a fix on this yet. I’ll let you know.

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I'm not an engineer, but just looking at your first pictures, I believe that the hubs are machined for the outer bearing, just like most buggys, you should therefore have a crush tube between the bearings then you can tighten the wheel nut fully and there should be no play at all. If i leave the crush tubes out of my race car, it would probably last about a 5 minute race before ruining the inner bearing race. The bearings for reference are 5x10x4 in the team associated front hub. The rear driveshaft is machined to run on the inner race so removes the need for a crush tube, the rear hubs are machined for the outer bearing race, but it also has larger bearings for inner and outer, due to the design of having a captive pin inside the bearing, I will take it apart one day and take pictures of it.

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2 minutes ago, Lee76 said:

Yes, metal through metal is fine, but the float would take place between the inner and outer somewhere, so as long as there’s either allowable clearance or a controlled preload at this point you’re good. I imagine most people just have a little float. I have massive float on my monster beetle... I’ve not had a think for a fix on this yet. I’ll let you know.

Apologies, now you’re going understand what you’re dealing with by me asking this question...

What is a float, or do you mean a slight gap / amount of play on the outer part of the bearing?

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2 minutes ago, •Axle said:

Apologies, now you’re going understand what you’re dealing with by me asking this question...

What is a float, or do you mean a slight gap / amount of play on the outer part of the bearing?

There should be a small amount of lateral movement, between the bearings, unless everything is designed to be tightened up solid and not bind. On my truck, both front and rear driveshafts/ hubs are fully tight with zero play, but my older cars have some play with everything tightened up, which to me shows that they had some inbuilt free play.

 

20200729_215348.jpg

20200729_215431.jpg

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7 minutes ago, •Axle said:

What is a float, or do you mean a slight gap / amount of play on the outer part of the bearing?

Sorry, float is the axial clearance, how much freedom the bearing or wheel etc can slide on the shaft.

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Yep, I’ve searched for a spacer in the kit I have, the Yeah Racing kit partially uses the original parts to complete it, and there is the clearance on the outer bearing allowing you not to touch the bearings at all, presuming it’s mostly to look pretty with this kit, I just didn’t like the amount of wheel wobble.

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29 minutes ago, Matty36 said:

should therefore have a crush tube between the bearings

Does the crush tube in an RC model actually crush? Designed to have plastic deformation? Or is it just a clamped spacer? I’ve not had anything like that in my models.

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29 minutes ago, Matty36 said:

I'm not an engineer, but just looking at your first pictures, I believe that the hubs are machined for the outer bearing, just like most buggys, you should therefore have a crush tube between the bearings then you can tighten the wheel nut fully and there should be no play at all. If i leave the crush tubes out of my race car, it would probably last about a 5 minute race before ruining the inner bearing race. The bearings for reference are 5x10x4 in the team associated front hub. The rear driveshaft is machined to run on the inner race so removes the need for a crush tube, the rear hubs are machined for the outer bearing race, but it also has larger bearings for inner and outer, due to the design of having a captive pin inside the bearing, I will take it apart one day and take pictures of it.

The first time round I attempted this I had a slight amount of understanding of what I was trying to achieve – getting rid of wobble, but did exactly what you said and in the process knackered 8 Fast Eddy bearings within the 5 minutes. I then decided to put everything away not to touch it again as I had no understanding and didn’t want to waste money…

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14 minutes ago, Lee76 said:

Does the crush tube in an RC model actually crush? Designed to have plastic deformation? Or is it just a clamped spacer? I’ve not had anything like that in my models.

It is an aluminium tube, its job from my understanding is to sit between the two inner races and allow the hex to be tightened up fully as it cannot damage the bearing in any way, but the hex can only touch the centre race, not the outer race. When I rebuilt my losi xxx4, I forgot to use the shims between the bearing and hex, which meant that on tightening the wheel nut, the wheel wouldn't spin, hence why I now make sure that all shims are in the right places.

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On 7/27/2020 at 9:56 AM, Saito2 said:

A crush sleeve like those used for pinion pre-load on full size differential assemblies? The single row ball bearings typically used in RC cars aren't really meant to accept side or thrust loads from a crush sleeve like a tapered roller bearing. As such, we commonly don't use them as spacers between to bearings in a hub or wheel. 

Edit: My apologies to Axle for misleading him. I was ignorant of the use of crush sleeves/tubes in RC cars with single row ball bearings and should not have replied. Thanks to @Lee76 and @Matty36 for setting things straight. Again, sorry for the mis-information.

I think everyone has a little case of that on this thread.. I’ve not had a car with crush sleeves in, but the names a little misleading, they are more anti crush sleeves... It strikes me the design should have a solid clamp line through  the inner races and the spacer tube, then on one of the faces that the wheel meets an outer race they could have put a half groove in and an elastomer for a very cheap preloader and no shims required, at least not for all the recreational car versions. Race boys might want to spend more money on jibs and measurements...

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