Waterproof axles??

[NoGrip]

I just had my first failure with the RTR TRX4. The front axle just seized solid whilst out on a run. Once I stripped the axle it became clear that some water had gotten in and the inner pinion bearing had collapsed and seized the gears. The rig has very rarely been in axle deep water even though they are sold as 'waterproof', but I am a bit shocked when I see the driveshaft fitting in the end of the front axle. Should there be a seal here or should I knock up some of my own?



At the smallest access point the difference in diameter between the drive shaft and axle opening is 1.5mm (60 thou). Is this how they are meant to be?

[Jay-Em]

The trick is to never ever trust rtr-claims of “water resistant”. If You plan on travesing watery places, there is no way around having to strip everything where gears and ballbearings are involved, and fill it with (if possible marine-) grease. Completely stùff it with grease.

Most standard greases that are packed with kits from Axial, or even Tamiya, are fine. I’ve even successfully used plastic-friendly white grease for bikes. Added advantage: it’s cheap. The thicker, stickier stuff mìght influence running for a tiny bit, but since crawling isn’t really about speed, I don’t mind.

I live in a vèry wet country (think Pacific Northwest in the fall, but then all year around ), run in rain quite often, and have never gotten something to seize after stuffing gearboxes, axles and whatnot with grease.

Something to keep in mind: even after packing all rotating interior bits with grease, it’s still prudent to let the car dry indoors in a not-too-cold place with good ventilation, thoroughly after running in wet conditions. If only to prevent water from staying inside electronics (another headache. “Water resistant electronics” doesn’t mean they take nicely to being flooded. Usually the whole “waterproof-shtick” means nothing more than “can take some splashing and rain”

Hope this helps.

Oh, and that play around the axle is just there. No right way to fill that. Just put as much grease in the portal boxes as possible. Messy, but it works. Rotate the gears some when closing the gearcase, so the grease oozes out for a bit, then screw it together.

Come to think of it : since You live in Ireland, there’s probably no way around running into wet bits evey now&then. Best tip I can give: Get Yourself a big spraycan of silicone lubricant, and spray rotating parts on the outside of axles, shafts and portals after running. The silicone spray creeps under the moisture, and prevents further trouble with seizing. Try not to get it on the tires, or they will be slippery for days :P

[Meatwad]

Nothing mechanical is waterproof, only water resistant. A coating of spray silicone will let water bead off of surfaces and hardware. You'll still get water into the axles through the bearings, somewhat.

If you play in salt water, always spray off with fresh water.

Sent from my XT1650 using Tapatalk

[o0wiz0o]

I pack mine with marine grease. Still going strong. :-)

[number9]

I had the same thought when putting my kit together OP. That’s a large entry point for water for sure.

[meatmonkey]

I too noticed the large gap between the front inner shaft and the housing. Best I can figure is there is no support bearing, like in an Axial, because of the amount of flex and distortion inherent with the large spacing of the C-hub and leverage of the portal setup.

I thought that possibly a couple O-rings between the shaft and the housing may help, but I didn't have any proper ones on hand.

I play submarine with a couple of my Axials, and they all get a hole drilled in the trans and axle housings for a 3mm grub screw "fill-plug". I then purge the water out at the end of the day with a grease gun and needle fitting. It's a bit concerning seeing how much water comes out of the pinion bearings after just a few hours of submersion. It's also funny how after this process the housing is full of grease, so water "shouldn't" be able to get it, yet it does. Water is just that good.

Why all that is relevant to a TRX4 is that I tried it, and unless you run spools it doesn't work. Almost any grease at all on the locking collar engagement sprags overwhelms the weak stock locking servos and flimsy plastic shifting fork. The locking engagement must be run basically dry, which goes against my natural instinct as a redneck. I guess it's because it's metal on plastic it just slides very easy.

I did manage to whittle a hole through the inside of outer portal housing with an exacto knife into a bolt bore. This way I can remove the bolt and use my needle fitting to purge the portal.

Disclaimer: all my trucks are a greasy mess that my friends don't want to pickup, so if your worried about grease flinging into your wheels and onto the underside of your truck, this isn't for you.

Because I cant purge the axles, I no longer play submarine with my TRX4, which is a shame since the portals are helpful for avoiding unseen underwater obstacles. Maybe when the lock servos die it's get spools and a single speed so it too can submarine with the best of them.

I had the axle pinion bearings die early on, upon disassembly I discovered that the slip sections of the driveshafts basically didn't slip. I tore them apart for cleaning and inspection and my conclusion was that the tolerances where slightly off. I replaced them with MIP's and have been problem free since. I will say my newer kit has driveshafts that slip much nicer, almost perfectly free, compared to my original RTR. The froze slip joints side load the heck out of the pinon and trans output bearings, and I figured where the root cause of my particular failure.

[NoGrip]

Thanks for the replies guys: Seems like it is 'as designed' and I'll just have to grease it up well. Thanks for tip meatmonkey about avoiding greasing the diff-lock engagement: The water repellant grease that I use is quite sticky! It did give me the opportunity to check the spider gears in the diff - no grease or oil in there at all. There was plenty of rust though!

I'll have a rumage around and see if I can find something that could seal the gap. If my laser cutter was working I would try a thin rubber gasket and try it between the axle & C-hub. A nice bit of laser kerf angle would have let me create a lip seal for the shaft, but I'll have to resort to scissors and a hole punch for now. Now I know it's there, I suppose my greatest concern is about sand getting in.

Sand-resistant?

[number9]

Hmm........I don't know what the axle diameter is, or the hole diameter, but...........may be.........you could use some shock boots to make some "CV" boots like on a 1:1?

Safety wire the small end tight around the axle shnaft against the portal cover and thread the larger end through the hole??



https://www.ebay.com/itm/1-10-Scale-...wAAOSw9NxTu3kF

[o0wiz0o]

I think you folks are over thinking this. As said I put marine grease in the portals and diffs. You don’t need a mass in the diff and it will not affect the locking mechanism. 80+ miles on stock bearings and components. Am sure am not just lucky. Alls still slimey in there. :-)

Oh and I’ve just been through a typical UK winter...snow, rain, mud...sand, grit...you name it the Landy has trudged through it all. Hehe....

[meatmonkey]

I don't care if I am over thinking it, I would totally buy cv boots that fit properly and helped seal the cvd and housing. Kinda nerding out over the thought really...

I've also pondered a diff cover that would completely section off at the middle carrier bearing. This would at least allow grease purging of the ring/ pinion gears. The damned small carrier bearing and locker selector would still suffer from corrosion though.

[crazee horse]

No maintenance done here apart from a hose pipe wash down and silicon spray. 6 months no failures apart from 1 micro servo. You can overgrease something causing resistance and stress on the motor.

[HumboldtEF]

Maybe the bearing that failed was no good from the start? just a thought

[meatmonkey]

Well, my biased opinion (based on owning several traxxas vehicles over the last decade) is that all Traxxas bearings are a few packs away from being junk right out of the box. The worst was seizing an E-maxx wheel bearing on the second pack. I'm the type to regularly check pinion and wheel bearings for play to avoid catastrophic failure to gears and cvd's.

[92LILREDYJ]

I think gluing a piece of closed cell foam in the axle housing with a small hole for the axle shaft and let it brake it self in, grease it, and grease the gears and bearings.

[92LILREDYJ]

Could also ruff up the inside of the axle housing, then grease the axle shaft, then fill the axle tube with RTV. Greased axle shaft should break away and spin free, on first run.

Edit: Would have to do one side at a time, with the truck on its side.

[cmbscx10]

I don't have mine apart to measure but coul you use a grommet?

[rm25x]

That section of the tube can have water come & go without issue. A seal on the end will just make it harder for any moisure that does make it in there to escape back out. The diff side bearing seals the diff cavity. If anything maybe just a small hole in the bottom of the tube to make it easier for the water to drain back out, but it may also weaken the axle tube.

Axles are not a forget about it thing. They need to be opened and maintained, bearings checked & repaced (I run DSM Off-road bearings myself), greased, ect.

[cmbscx10]

Originally Posted by Natedog

Would have to be a really soft grommet, bet bet is some nice soft high quality closed cell foam glued in with E6000 and a little grease around the shaft.

This is a Trex500 canopy grommet that's soft but rigid enough to seal on a 4mm AR60 axle. Just a thought to hopefully help you water logged folks.

[AggressorBLUE]

Originally Posted by o0wiz0o

I think you folks are over thinking this. As said I put marine grease in the portals and diffs. You don’t need a mass in the diff and it will not affect the locking mechanism. 80+ miles on stock bearings and components. Am sure am not just lucky. Alls still slimey in there. :-)

Oh and I’ve just been through a typical UK winter...snow, rain, mud...sand, grit...you name it the Landy has trudged through it all. Hehe....

Agreed. In my first season on the truck I went 3 months with some really nasty driving (lots of mud and muddy wading up to the wheel wells followed by long sections of dry, silty dust), and the front diff got very "crunchy", which is when i put some red'n'tacky in, which kept things good till end of the season. At the very end, the diff would engage, but was very sticky, essentially acting like it was locked in most situations. Not too shabby for such minimal maintenance and such a complex drive-train.

That said, having just done a full tear down of the front axle, I've found the gearing on portals and the diff was fine, but the bearings were heavenly worn. Some of them still spun, while others were basically bushings. I replaced all of them with fast-eddy sealed bearings. I did wind up needing some new portal and diff parts, as some of the bearings were seized solid to them. I'll likely treat all axle bearings as consumable items on a yearly basis, with my level of submarine action.

[92LILREDYJ]

Originally Posted by Natedog

Good idea, but there's more up/down play in my steering knuckles than other trucks (inner shafts have some float too) and this would tend to bind the axle shafts against the relatively harder RTV silicone.

Could only fill the tube a half inch, or if you installed a gourmet or closed cell get it as close to the bearing as possible that way the axle has movement at the end.