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TriumphChris

Bearings Etc. Questions

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Having received my JIS screwdrivers and sprue cutters I've made a start on my first build, the Unimog 425 with CC-01 chassis.

Have bought a set of Carson ballraces and expected them to be friction fit but they push in easily and don't grip. Also the shafts are a loose fit in the bearings as well - I've only done the spur gears so far. This I feel is strange as the ballraces aren't working as they should as the shafts are just turning within them. I tried the kit plastic bearings and they are a loose fit also.

Second question is what does the part A4 do in step 1? It is a cap with a slot in the side which says to remove when you have fitted and tightened the grub screw securing the pinion gear? I just fitted the pinion without using it, is that Ok?

And they are are tight with the amount of grease they include given the number of places they indicate to use it aren't they? Fortunately I have some water-proof grease I use for my model boats which is for use with plastic and metal.

Chris

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A4 is a distance measuring tool. 

hqHTLR2.jpg

The pinion has to align with the spur gear.  When you can't see inside the gearbox, it's hard to know if it lines up.  That's why Tamiya gives you a tool to measure the distance.  If they don't line up, you would have uneven wear.  

The grease Tamiya gives you should be more than plenty.  I usually end up spending 1/3rd a tube and those models are perfectly fine after 20 years.  If you are used to greasing boats, that might be too much.  Also, waterproofing grease might be too sticky?  It's not going to kill the car, just that with a lot of grease, you drop the efficiency.  It's a small 1/10th truck. Sticky grease to 1/10th model is like putting muddy crude oil in real car's gear.  It's like saving efficiency by using ball bearings...only to kill the efficiency by using too much of sticky grease.  

How sticky is too sticky?  You put a dab on a coin, put a finger on it and try to lift it with stickiness.  Tamiya grease won't lift much weight.  Boat grease could lift a coin. That's how I test. 

If the bearings are too loose, I would get some new ones.  I've bought some cheap bearings in the past. Most are fine. But very few would be too tight or too loose.  No biggie, 1150 bearings are easy to find. Outside of Tamiya, they are called "5x11x4mm bearings."  You can find them on ebay, Amazon, or any place that sells RC cars.  

Good luck with your first build.

 

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Thanks Juggular. The instructions you show are better than mine and show A4 in position whilst the grub screw is tightened, much clearer. I'll take the pinion off and refit it!

As far as the bearings go I thought Carson were a decent make and they weren't the cheapest. I got them from Tonys-Tamiya. As I said though the plastic kit bearings aren't a tight fit either, about the same as the ballrace ones.

All good points about the grease but I don't use it in the prop tube because as you say it produces too much drag. So I don't have to worry about lubrication I use maintenance free prop shafts which have a ballrace at the top end, which is a tight fit and operates as a bearing should. The grease is for use in a stern-drive which has bevel gears in it so similar use. I will check it out though.

I made the point about the small tube of grease as the instructions seem to indicate that it should be applied to the plastic gears which would use quite a lot even if applied sparingly, is that right?

I'm enjoying the build though.

Cheers, Chris

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Carson is just the German brand of Tamiya. As for shafts "spinning inside bearings", happen to any of my kits. My experience is that they tends to sit tight in their "housing", but loose on the shafts. Probably all will be well after everything got tighten up and the shafts spins with centrifugal force when running, I don't know for sure, as by then, the bearing is not visible. Tamiya kits have a habit of "clicking" together towards the final steps of construction. 

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51 minutes ago, alvinlwh said:

Carson is just the German brand of Tamiya.

As far as I know, Carson is a brand of Tamiya's German distributor SIMBA-DICKIE-Vertriebs-GmbH. It is not a Tamiya brand. From my experience, their products are generally on the cheaper end of the spectrum, regarding both price and quality.

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9 minutes ago, FuzzyFlynn said:

As far as I know, Carson is a brand of Tamiya's German distributor SIMBA-DICKIE-Vertriebs-GmbH. It is not a Tamiya brand. From my experience, their products are generally on the cheaper end of the spectrum, regarding both price and quality.

Yah, you are right, my bad. Should be Carson is a cheap German Tamiya that makes cheap parts for Tamiya. I actually don't remember seeing them in the Far East, so probably only in Europe, but then it could also be Tamiya is so cheap in the Far East, there is no need to look at anything else.

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I wasn't looking for cheap bearings and chose some that appeared to be good quality sold by a Tamiya dealer i.e. Tonys-Tamiya.

A loose shaft turning inside the ballrace is not good as that is steel running on steel and over time will wear the shaft. And the ballrace turning in its housing is not good either.

As I said the plastic bearings are not a tight fit either but at least they won't produce as much wear. So I will do some accurate measuring and see how the plastic kit bearings and Carson bearings compare. I also have the Yeah Racing Conversion Kit and will see how the steering bearings compare. I'll consider getting some YR bearings to replace the Carson ones but as this truck isn't going to get a lot of use it may be that I use the plastic bearings and replace them as and when necessary which is better than replacing shafts. Another alternative as there doesn't appear to be a genuine Tamiya CC-01 bearing kit available is to get another kit that contains the bearings required and they must be a good fit shouldn't they!

All part of the fun I guess and different things to be overcome compared with my boats!

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Found another chassis kit than contains the bearings I need, 1150 and 850. Don't need those for the steering/front wheels as have those in the YR kit.

Genuine Tamiya and due to arrive tomorrow so fingers crossed!

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25 minutes ago, TriumphChris said:

Genuine Tamiya and due to arrive tomorrow so fingers crossed!

Keep us posted on how the real Tamiya ones go. 

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I noticed that rc bearings do often have a feeling of slightly loose fit on either shaft or housing in a way I'd consider to be wrong on a bigger scale. However I wonder whether the assembly is intended to deal with it, perhaps by way of a little preload axially to the housing or gear or whatever it is? On a bigger scale we'd generally be pressing a bearing into a part and tightening something else against it along the axle, where, except at the wheels, in RC I've just seen things slot together freely. Yet it all seems to work just fine.

I suspect if a bearing was rotating relative to housing or axle you would feel it in some additional friction once assembled. Not much perhaps, but noticeable. Where I have had a bearing seize recently, it turning in its housing or relative to the shaft was very obvious, albeit that was at the wheel. 

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Some level of play is fine, meaning as long as there is no vibration from the looseness you can see or hear, nothing to worry about.

These cars can run with plastic bushings... bushings where I can literally see light from the other side. When I was a kid I could not afford bearings and just used plastic/metal bushings.  It had huge vibration especially the front tires due to wear.. even so, still no issue..drove like it should.  :D

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The 1150 Tamiya bearings (made in China!) are a slightly larger outside diameter measuring 11mm against the Carson at 10.99mm. This means that they are a slightly tighter fit but not as tight as I'd like. Couldn't measure the internal diameter accurately but they do grip the shafts tight enough that the ballraces  actually do what they should!

The 850 bearings were too loose in the housings and on the shaft so I'm probably going to use the kit bearings which look as though they are bronze.

One solution suggested to me for securing the bearings was to use medium strength bearing compound. Was going to order some but thinking some more I feel this is overkill for a model and whilst it allows for dismantling it is basically an adhesive and could result in damage  to the plastic housings.

The bearings only need slight resistance to stop them turning in the housings so I'm going to try clear silicone sealant which I already have.

 

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When it's just a bronze ring it's not a bearing at all, just a bushing. And ball bearings (even when just a tad loose) will be much better than any bushing on an RC. Also no need to fix anything in its housing. I believe you are way overthinking this (as many people with experience from heavier equipment or real, full size cars tend to do).

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I could have used the word bush, but it's still a bearing, being a plain bearing.

I've been conscious that I may have been over thinking this for what is essentially a toy but the fact is that ballraces are used as they offer less friction and better location of moving parts. If this is not going to be achieved by the bearing being secured in the housing and on the shaft then why bother? May as well use the plastic "bearings" (as they are called in the instructions!). Also the bearing possibly turning in the plastic housing isn't good as it could wear the plastic and become an even looser fit.

Part of my determination with this is that someone I know who built a CC-01 chassis, albeit 4 years ago said that his bearings were a good fit.

It's not difficult using a bit of silicone sealer and if it works then great. If not, hey ho, it's not the end of the world.

 

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The bearings are fine. Even on high-end RC race cars, the bearings are a "slip fit" on axles and transmission shafts, and at best a light press fit into plastic parts. Put it under a little bit of a load, and the bearings spin like they should.

As for the grease, the tube Tamiya supplies with most kits is enough to do 3 or 4 typical 4WD cars. A tiny dab on each gear meshing surface will distribute itself nicely after a minute or two of running, and unless it gets contaminated, should never need to be re-greased. Don't grease the dogbone ends or any suspension parts; the grease attracts dirt and makes things wear out. Better to run them dry.

Bottom line: don't over-think it, trust Tamiya's engineers, and have fun.

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IMHO, if it is such a issue, one can always do one of the following:

1. Buy 100 or 1000 bearings. Check and measure each one and match each bearing to each location based on precise measurements. 

2. Buy AAA grade (or whatever bearings are graded at) with guaranteed measurements and performance, at probably 10 times the costs. Use them to discover that the Tamiya holes and/or shafts are the ones that are not "correct" in size. 

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Thanks for the replies.

Haven't touched the build partly because I was waiting for some lubes to arrive. Not only for use on the Unimog but my boats and other things as well.

Back on it today though and set the bearings in place with a small amount of clear silicone applied with a cotton bud. Left it for awhile and then tested with a cotton bud and then the shafts and the ballraces were turning as hoped. Job done! 

Chris

IMG_5786.JPG

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Hi

I have some plastic ARTR boats, 2 yachts and 3 power boats, that I use for club racing. But my main interest is scratch building the Fairey Marine boats of the 1960s onwards. Currently building 5 with 2 more in the pipeline.

 

Scott1.jpg

 

IMG_4323.JPG

5 Builds Underway.jpg

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Sorry for going off topic.

Very nice.  I do like the Faireys and Vospers.

What are your powerboats and what club are you a member of?

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No problem, particularly as this thread has pretty much come to end as I've sorted the ballrace problem.

The club is at Knightcote in Warwickshire. The white power boat is a Hobbyking Marine Scott Free which is a bit fast for our small lake. The larger orange one is a Club 500 and the small one a Joysway Lite Warrior.

Must get the Faireys painted this year. They are all brushless with one having a stern drive.

Stern drive 13-1.JPG

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