42099 CV joints damage after use

[Zerobricks]

I noticed CV joints from 42099 are very prone to damage, even at low torque conditions.

Here's an example of the CV joint which is visibly damaged after being spun in my hands at maximum angle without the use of any gears or axle to increase torque:

Next is a damage done to a CV joint by an old XL motor at some 25 degrees when stalled:

Finally I checked my Wildcat which uses the new hubs.

The hubs at the rear axle are at some 20 degree angle, here's what happened to the rear wheel drive ones. Mind you, they are powered directly by an RC motor without any additional gearing:

Finally I checked the front CV joints, which when steered use the maximum angle the joint allows:

I am quite dissapointed by the fact these joints are so easy to damage, compared to the universal joints. The sad truth is, this really limits the use of the new hubs for me.

Anyone who built/modified 42099 noticed the same wear, maybe @efferman?

 

Edited August 28, 2019 by Zerobricks

[Homersapien]

thank you for sharing this!!

Edited August 28, 2019 by Homersapien

[Maaboo the Witch]

£200 for this? What a load of shite.

Edited August 28, 2019 by Maaboo35

[efferman]

28 minutes ago, Zerobricks said:

Anyone who built/modified 42099 noticed the same wear, maybe @efferman?

have checked my 16 new style u joint and no one has a visible wear. But i guess i have only one hour of drivetime and only with c+ motors.

[allanp]

Might be a good idea to use some lubricant just on these parts. I normally despise using it as it covers all my pieces but just on these parts should be fine.

[grego18f]

This is very surprising indeed... Especially for parts which were specially designed to handle high torque. Thank you for pointing this out, it will help to take precautions and maybe TLG will see this post and will try to correct this...

[Zerobricks]

If TLG would simply us the already existing cardan joint instead of the CV joint, we could have a much stronger, efficient transmission that works at higher angles.

[PetSild]

I checked the pins and on my 42099, found minimal  wear, used 5 min mod.

- The front axle of 13.5 degrees.

- Rear axle 21.6 degrees.

- Steering angle 19 degrees.

- Model currently weighs 1470g with the battery.

[rm8]

LOW loaded transmision = less troque on drive shafts = high speed  on drive shafts =  more wearing. that's fair price of high 1:5.4 gear reduction in wheel hubs. Every PROS have CONS.

[msk6003]

I think all parts in 42099 is prone to wear than parts before 42099.

I tried XL(C+)->20->12->20->12 gear combination(same as 42099, all parts from 42099)in 3~5min, but last 12t's axle(6L) have some dust.

[suffocation]

Amazingly, intense RC applications appear to require specifically RC-designed parts.

Edited August 28, 2019 by suffocation

[nerdsforprez]

I am not sure this is news.  Its ABS - its gonna happen.  Also, I don't see "damage" - I see "wear and tear" - its a normal part of the process when using ABS.  Even mechanical parts that use steel and metal are prone to wear and tear.   

Its funny how easily we forget this is a kids toy.  We use parts for more adult applications and then critique Lego when it does not hold up to our applications.  I think its funny.  

Silicone lubricant will help a lot. However, if driven in the dirt, outdoors, etc. then I don't think it is a good idea.  The lub. can attract the dirt, etc. and cause more problems. 

[JunkstyleGio]

No wear and and other disformations after many hours of play

.

[ben20]

The biggest problem of the wear is how you drive your model. Easy in door or extreme outdoor. If you are on a steep sand climb and turn when ridding up, there will be damage due to stress and sand that acts as a grinder. Also wheelie's are extreme bad for this type of joints.  Compared to the universal joint they are stronger, a joint direct connected to an xl breaks, but indeed no or less wear with the older joint

1 hour ago, nerdsforprez said:

I am not sure this is news.  Its ABS - its gonna happen.  Also, I don't see "damage" - I see "wear and tear" - its a normal part of the process when using ABS.  Even mechanical parts that use steel and metal are prone to wear and tear.   

Its funny how easily we forget this is a kids toy.  We use parts for more adult applications and then critique Lego when it does not hold up to our applications.  I think its funny.  

Silicone lubricant will help a lot. However, if driven in the dirt, outdoors, etc. then I don't think it is a good idea.  The lub. can attract the dirt, etc. and cause more problems. 

Yes indeed it's made for kids, but if you made such a model you know they will take it outside, and when design new parts why not test them hard?, is not that expensive. I don't get why TLG build parts that also suits the expert builder, i guess there is no person in the team that has that experience, otherwise you would design the part with four contact points instead of two, reduce the stress in half

There are many parts that could be stronger at the same cost but Lego don't have intrest in it for a strange reason

Edited August 28, 2019 by ben20

[Gray Gear]

Parts like this, and especially the Gears of the Plantay gear should have been made of Steel. I  was basically waiting for complaints of broken Planetary gears, but I guess the CV Joint will give way before that happens.

[Zerobricks]

As I said before normal U joints would totally fit inside the hub and would be able to carry the power without any friction, since there are no sliding surfaces. As long as the second U joint would be aligned, there wouldn't be any vibrations either.

They could also increase the number of grooves from 2 to 4 or 6 to spread the load more evenly.

But it seems we got the laziest solution with 2 CV joints per wheel sliding a large portion of the supplied torque into friction and dust. 

[HorcikDesigns]

How does the planetary reduction "hole" look like after damaging the joint? Is there visible also that wear, or is the material used there harder?

Edited August 28, 2019 by HorcikDesigns

[Zerobricks]

Just now, HorcikDesigns said:

How does the planetary reduction "hole" look like after damaging the joint?

No damage to be seen on the inside, even the pins look nice and round. It seems the male CV joint is the weak link. 

[suffocation]

1 minute ago, Zerobricks said:

[...] But it seems we got the laziest solution with 2 CV joints per wheel sliding a large portion of the supplied torque into friction and dust [...]

Laziness is TLG's new paradigm. Their "new and improved" (  ) website speaks volumes about their new direction.

[Maaboo the Witch]

11 minutes ago, suffocation said:

Laziness is TLG's new paradigm. Their "new and improved" (  ) website speaks volumes about their new direction.

Oh, the Technic site is total shite! I remember it being awesome in 2013 when I got back into Technic, with the set animations, designer bios and industrial feel. It has no personality now.

[suffocation]

My main gripe is that B&P didn't work for months in most countries, then they got it up and running again... and now payments won't go through.

Sorry for going off-topic, although it does say a lot about how they handle things nowadays.

[Sariel]

I haven't noticed any such drastic wear in my 42099... but I DID notice that the new CV joint "socket axles" show some wear around the section that was inside the 5x7 frame. Sorry, don't have a picture at the moment.

[allanp]

This is probably a very clever design from TLG. The expensive part is the hub, the cheaper part is the CV joint, so if there must be wear then it's better to have the cheaper part be the one that's intentionally made softer to avoid wear on the more expensive part. You see this in industry all the time and it's a good decision. And we are all adults here, supposedly, so if we want to use them in a more demanding application then we are free to apply a bit of lube! I do agree however that only two pins is a bit naff compared to having 4 to spread the load, but then it would be even more expensive, and would still wear. Not sure how a UJ would work, unless it was built it, there isn't room for a UJ. And I think most of the friction is from the hub itself, not the CV joint.

 

Edited August 28, 2019 by allanp

[Gray Gear]

9 minutes ago, allanp said:

snip

I do agree however that only two pins is a bit naff compared to having 4 to spread the load, but then it would be even more expensive, and would still wear.

snip

How the F would having 4 pins instead of 2 make the part more expensive? Just use a different mold from the getgo thats all there is to it...

And "even more expensive"? You mean for us buyers, right? Because these pieces cost almost nothing to make for TLG, not even close to 10ct/piece, more like

0.1 ct/piece. These Prices are just greedy, nothing else.

[Attika]

9 minutes ago, allanp said:

 in a more demanding application we are free to apply a bit of lube!

I agree, don't even understand why it wasn't obvious at the first place. Don't have the set, but bought a set of 8 from these hubs and joints. Knowing that they gonna get assembled into a 3 kg 8x8 straight away, driven by 4 buggy motors.  Accordingly I've started with dipping the cv's into silicone wd40 before the 1st use. Let's just be real. TLG's application of this parts was in a low torque setup. If then it goes under high rpm, high torque, then no surprise, something's gonna give. Lucky us that it is the cv, not the hub. 

Even in the genuine RC crawlers, where all the gears and cv's made out of steel, lubrication is crutial, while the weight-rpm data is quite similar to our experimental builds. So I guess that would be news, if there wasn't any wear on them.

For the record, my cv's on the two rear axles on my truck have some minor signs of wear, but nothing on the front axles. Spent about 2 hours climbing ditches and very loose, dusty slopes and I wasn't gentle. Then I've concluded, that it does no good to the hubs, nor the buggy motors, so the experiment is over. Gonna spawn some short video anyway. 

I'm still happy what we got from TLG. I think these hubs elevated the level of possibilities well above, than what we had before. If an outsider is reading this topic, he's gonna think that it is really hard to make us happy.