Are Tamiya pinions really that bad?

[markbt73]

No.

And I'm prepared to show my work.

Every few months, a thread pops up about lubrication, usually with someone being concerned about not having "enough" grease supplied in a kit. And every time, I preach the gospel of "less is more, and maybe none is best." Well, today, after another such thread, I decided to take a look at a few of my long-running models to see just how well those infamous aluminum pinion gears are holding up.

First up, a CC01 Pajero Metal Top Wide. I can't remember exactly when I built this car, but it was sometime arnoud 2009-2010. It has been modified six ways from Sunday, cut up, abused, and recently put back to somewhat close to stock with some improvements. I've changed out the motor in this thing several times, from the stock 540 to various crawler motors, and even a cheap brushless setup for a while, just to see. It now has a 55 turn motor, runs amazingly well, and is still in regular use. The screw holes for the gearbox cover are so stripped that in one of them I have to use a wood screw. But I have never cleaned or re-lubricated the gears.

All right, let's crack it open and see how it's doing.

The spur gear, of course, has the familiar gray sheen of aluminum dust, but you'll notice the gear teeth all look fine. And in fact, this gearbox runs very smoothly and quietly. I put one tiny dab of grease each place two gears touched, and just ran it to distribute that grease. That's all you need. But what about that infamous pinion? Let's take a closer look.

Yeah, OK, it has some wear, but the teeth still have their profile. And as I said, it still runs smoothly. No reason not to just stick it back in and bolt the cover down, which is exactly what I did.

Let's check out another one, this time one I literally have not seen since I built the car in 2013. This is a Honda City Turbo re-release, the WR-02C chassis, with dozens of runs on it since new, mostly on gravel as a rally car, as evidenced by the wear underneath.

Let's see how it looks.

Not bad at all! There are a couple of nicks in the teeth, like some sand got in there and bounced around a little bit, but must have worked its way out again. Again, this was one tiny dot of grease at assembly. Now, granted, this is only the kit-supplied 540 motor, but I have not been gentle with this car. Lots of reverse-to-forward wheelies and other drivetrain-jarring stunts - and the pinion gear seems not to have cared at all.

And last but certainly not least, here's one I see all the time: a good old Hornet 18 toother. I bought this one new, a couple of years ago, and it has been used in a whole bunch of Grasshopper/Hornet gearboxes, some new, some very old. I took it out of the bag, stuck it on a motor, and went - this gear has never been greased, and it's been used on several motors. Whatever lubrication is has had has been from residual grease on the spur gear, and some of them were new and I just ran them dry. I'm beginning to think this is the way to go.

So - Should you replace the aluminum pinion gears with steel? Sure, if you want. Do you have to? Not by a long shot. I never do, and I've built probably a hundred Tamiya kits over the years. Do the aluminum pinions last longer with less lubrication? It's looking like that's the case. How much lubrication do the other gears require? Basically none, but if you put a tiny dot on each mating surface, they'll run quieter.

By the way, I have an MF-01X that I built up completely dry except for the internal diff gears. I'll crack it open in a couple of years and see how it's doing.

[Hypoxic]

Interesting post and at a good time. I can’t seem to find a 0.8mod 15T steel pinion for my incoming Blockhead Wild One. Everyone is out of stock so I may need to run the kit part for a while.

[Kowalski86]

8 minutes ago, Hypoxic said:

Interesting post and at a good time. I can’t seem to find a 0.8mod 15T steel pinion for my incoming Blockhead Wild One. Everyone is out of stock so I may need to run the kit part for a while.

You can use a 32p pinion gear and you'll be fine, they're close enough to work.

[TurnipJF]

My experiences echo yours - in part at least. I am of the "fit a steel one at the outset - it its cheap insurance" school of thought, but my brother-in-law is of the "replace it when it breaks or wears out" school. When I replaced the motors on his Wild Dagger (same gearbox as your WR-02C) after at least two years of reasonably regular running, I was surprised to find minimal signs of wear to the pinion teeth.

Likewise when I restored a very well-used Hornet for a colleague - there were many signs of heavy use including front stub axles that had been grooved by the plastic bushings, but the stock pinion was still serviceable.

However when I cleaned up my brother-in-law's TL-01B after about a year's use, the pinion looked like this:

 

All the aforementioned cars were running silver cans with comparable levels of gearbox lubrication, so I'm thinking there must be something about the chassis themselves which affects pinion wear. All use different motor mounting holes for different size pinions rather than a slotted motor mount, so the mesh is fixed - possibly more accurately on some chassis than others?

It would be interesting to see how the MF-01X pinion survives, given its design similarities to the TL-01.

 

[Kowalski86]

3 minutes ago, TurnipJF said:

Likewise when I restored a very well-used Hornet for a colleague - there were many signs of heavy use including front stub axles that had been grooved by the plastic bushings, but the stock pinion was still serviceable.

However when I cleaned up my brother-in-law's TL-01B after about a year's use, the pinion looked like this:

 

All the aforementioned cars were running silver cans, so I'm thinking there must be something about the chassis themselves which affects pinion wear.

 

If I had to guess, the larger teeth on the Hornet pinion and the much simpler drivetrain played a role. The Hornet only has a handful of bushings/bearings, vs the 20-something in a TL01.

In the old 2wd models I don't mind running the stock pinions, but I prefer steel or coated aluminum on modern models with their 0.6 teeth.

[TurnipJF]

36 minutes ago, Hypoxic said:

Interesting post and at a good time. I can’t seem to find a 0.8mod 15T steel pinion for my incoming Blockhead Wild One. Everyone is out of stock so I may need to run the kit part for a while.

https://www.ebay.co.uk/itm/387506360657

[TurnipJF]

39 minutes ago, Hypoxic said:

Interesting post and at a good time. I can’t seem to find a 0.8mod 15T steel pinion for my incoming Blockhead Wild One. Everyone is out of stock so I may need to run the kit part for a while.

https://ttpmodels.com/products/carson-500013405-15t-steel-pinion-gear-0-8-08-module-tamiya-hot-shot-bigwig

[skom25]

I always used steel pinions, but once decided to use aluminium, because I was not sure about FDR in TT-02. I ran it with Torque Tuned motor for 10-20 packs and when I opened gearbox, grease was really dirty and it was hard to clean parts. It never happened with steel or even hard coated pinions.

Shortly speaking: they are crap.

 

[Hypoxic]

21 minutes ago, TurnipJF said:

https://www.ebay.co.uk/itm/387506360657

Out of stock. 

[Hypoxic]

24 minutes ago, TurnipJF said:

https://ttpmodels.com/products/carson-500013405-15t-steel-pinion-gear-0-8-08-module-tamiya-hot-shot-bigwig

Thanks, seeing the part number helped me.

[Otis311]

I appreciate your examples and from my experience the stock pinions can last a while but I will still never use them. I think there are way too many variables to draw any conclusions. There are probably different grades of aluminum used in the variety of kits. The composition of the opposing spur gear may also play into the equation. As you mentioned lubrication type or lack thereof would also play a role. Being that upgrade pinions are basically the cheapest hop-up you can install there is no reason not too. Unless of course they are not available. Once a pinion begins to lose it's profile, it will get exponentially worse and in the end will also destroy the spur. That and it is very noisy which I detest. Let us not forget about the aluminum counter gears that Tamiya uses in some of their transmissions as well. Bad stuff. I will note though that in all the cases of my aluminum pinions wearing excessively I was using the basic yellow grease that came with the kits. All that said it probably took over a hundred packs of hard running, which is impressive. If I had installed a steel pinion right off the bat though I would have had better performance and likely zero wear for $5.

[MadAnt]

I've had a few or so aluminum pinion gears wear to the point of like what @Kowalski86 has shown or worse. They either make noise, or strip the spur gear because the teeth on the pinion become razor sharp from years of wear. This happens more often on cars that have more load or abuse on the drivetrain, like monster trucks or heavily used buggies. When the time comes to replace the pinion gear, get the steel or coated gears. 

Anyone that says the stock aluminum pinion gears never need to be replaced might be worng depending on the conditions. Slap in a 3800Kv brushless motor and a 3S LiPo into a monster truck or buggy, or whatever in-between, then run the poor car like a mad man on a regular basis and watch that aluminum gear whittle away in about a year or two. 

[markbt73]

My point, with all of this, is to counteract the effects of the typical "you absolutely MUST replace the pinion with a steel one IMMEDIATELY or your car will be UTTERLY RUINED" narrative that always seems to pop up in beginner-advice threads. The truth is, you can build any Tamiya kit straight out of the box - yes, plastic bushings and all - and have a blast driving it. We did it in the '80s, no reason someone can't do it now. I'm always worried that too many pieces of "advice" about "required" extras thrown at beginners will scare them off.

You can, of course, replace the stock pinions if you want. But telling people that they need to do so is, in my opinion, bad for the hobby.

[alvinlwh]

I file this under the "someone said so, so it must be done" that got passed down forever. 

There are a few more. 

Never use dogbones. Only universals, or DC will do. The only car that I have that must have universals is The Frog. Everything else, dogbones works fine. 

Another one is only use machine screws. Kit self tappers must never to be used. 

[toyolien]

2 hours ago, skom25 said:

Shortly speaking: they are crap.

This ^^ is my experience too. I won't use them again.

[Super ally]

I have a thunder shot kit to build and bought a steel pinion gear for it as i have noticed members say to replace the aluminium pinion.All my other cars have the stock pinion and most have the silver cans and a few sport tuned so im not bothered.

[F-150]

I use aluminum in my mudboss and custom works outlaw4. Light weight means more speed. Little to no grease on the gears.

If that helps 

 

[Wooders28]

I'll just leave this here....🫣

 

 

[Hypoxic]

@TurnipJF Thanks. I was able to find and order a steel pinion with the aid of your linked part number. 

[Seanster43]

Excellent write up and very informative! I think like you say it’s not essential, just another hop up for some folk for the sake of a few £’s/$’s etc it’s easy enough to do. Lots of different scenarios I guess. 

[Wheel_Nut]

Worn pinions are bad news from a mechanical perspective.  1) It puts higher pressure on the remaining material to transmit the same torque.  2) the vibration of gear mesh is generally increased.  

Both factors reduce efficiency and once the pinion loses it’s shape, the damage only accelerates.

 Steel pinions have so much lower wear rate on nylon gears.  To me it seems like a cost effective upgrade because I don’t want the gears to destroy themselves.

[Saito2]

Are Tamiya aluminum pinions really that bad ? I think skom25"s answer sums it up:

16 hours ago, skom25 said:

Shortly speaking: they are crap.

 

At least that's how I initially thought (still do for my personal use cases). Its a part that can be replaced from the start, quite cheaply, with a zero-maintenance part that will last forever. Why not do it and recommend it to new-comers? Even if they weren't destructive as @Wooders28 photo clearly shows, it would be worth for it alone not to have that gray mess staining the next gear in line for me at least.

But then Mark posted this...

14 hours ago, markbt73 said:

My point, with all of this, is to counteract the effects of the typical "you absolutely MUST replace the pinion with a steel one IMMEDIATELY or your car will be UTTERLY RUINED" narrative that always seems to pop up in beginner-advice threads. The truth is, you can build any Tamiya kit straight out of the box - yes, plastic bushings and all - and have a blast driving it. We did it in the '80s, no reason someone can't do it now. I'm always worried that too many pieces of "advice" about "required" extras thrown at beginners will scare them off.

You can, of course, replace the stock pinions if you want. But telling people that they need to do so is, in my opinion, bad for the hobby.

...and I get where he's coming from. A short time ago I raised the unpopular opinion (in that thread's context at least) that using supplied Tamiya tapping screw was okay for new kit builds. I also stated its basically a fun hobby and if folks wanted to tap screw holes and use aftermarket machine screws that was okay too. We all have our ways of doing things.

So taken to the far extremes, we have a side that might say you need a machine screw set, thread forming tap, steel pinion and bearing set (and possibly Lipo batteries/brushless motors if we want to go down that rabbit hole, lets not for now) before even starting a Tamiya build. The other side would say to build it stone-stock like many of us did in the 80's and everything will be fine. I'm sorry, but extremism is one part of how my country got into the mess we're in. Common sense is down the middle with compromise and few people seem to go there anymore. I agree with @markbt73 that these bold declarative statements are not good for the hobby.

While I don't think doing away with suggestions of steel pinions and bearings is the answer, I think how we couch or frame those suggestions to newcomers should be just that...suggestions not "YOU MUST". Us folks deep in the hobby all have our idiosyncrasies about how we like to go about doing things. We can get really into the weeds. This hobby is about fun and trying new things and finding our own way of doing things.

I've gotten flack for still using nimh batteries and (gasp!) mechanical speed controllers in some of my rigs. But technically, if I want to fully adhere to the Tamiya-way, I would be using aluminum pinions too and checking them for wear periodically for replacement. Its in the Tamiya RC Guidebooks. Granted, better things have come about since those books were printed, but doing things the old way is fine too. They are model ("toy" offends some folks it seems) cars, not open heart surgery.

[ucacjbs]

20 hours ago, markbt73 said:

The truth is, you can build any Tamiya kit straight out of the box - yes, plastic bushings and all - and have a blast driving it

Yes,  this is important to remember.
Conversely, if you end up not getting into it, spending on components whose longetivity benefits you’ll never see just adds to the dissatisfaction. 
 

Edited December 7, 2024 by ucacjbs
Missed a key conjunction.

[markbt73]

Funny that almost no one has mentioned the other half of my point - overlubrication seems to accelerate wear of rhe aluminum gears. Since I have time on my hands these days, I'm going to do some more experimenting with different types and amounts of lubrication and see if I can come up with a way to make them last. (Even though they seem to last just fine for me; maybe I should try to see what exactly wears them out?)

Why? Because I'm one of those contrarian types who hates to just accept something as gospel, without investigating it for myself. I have a feeling that very light and dry lubrication, like powdered lithium grease, might be the answer, though Teflon-based liquid lubricants might work well too.

In short: I'm not dropping this, but I'm also not telling anyone else what to do - which it sounds like some are accusing me of. Buy steel pinions. Enjoy them in good health. I just don't think they're strictly necessary.

[JRG00]

I wonder if the varying amount of pinion gear wear is also related to how much initial clearance is set between it and the spur.