Pinion material

[alvinlwh 5895]

I never gave this much thought until recently. We all know not to use the alum kit standard pinions but the aftermarket ones seem to come in a range of materials. Looking at my collection, there seem to be:

1. Tamiya kit standard alum (sold as Spare Part packs) 

2. Tamiya hardened alum (sold as Hop Up packs) 

3. Steel (Black, typically from Surpass) 

4. Copper? (Gold color, I am guessing copper) 

5. Some kind of bronze color? (Typically from 3R, I am guessing hardened alum) 

Which material will be best? Actually does it matter? Or is it just anything else is better than the kit alum ones? 

[Saito2 6686]

3 hours ago, alvinlwh said:

4. Copper? (Gold color, I am guessing copper)

This is likely brass, commonly found in the long Blackfoot pinions and even longer Lunch Box pinions, although I have run into standard length brass pinions as well.

You will probably get a lot of opinions on this. Personally, I always toss standard Tamiya kit-supplied aluminum pinions for Robison Racing Steel pinions. I've never had a RR steel pinion "go bad" or cause any issues in the decades I've run these cars. I have had stock aluminum pinions wear out and spread aluminum particles throughout a gearbox, staining the plastic gears in the process. 

I have have very little issues with brass pinions. Although, I've seen evidence of wear (unlike steel, which last forever), they seem to last for years in my case. 

 

On the other hand, while most suggest a steel pinion (along with bearings for any Tamiya kit), I have had folks defend the use of aluminum pinions as being adequate or state that brass pinions wear faster. Despite these suggestions running  counter to my own, in the interest in disclosing all facts, I felt it wise to offer them as a counterpoint.  I can only give you my personal experience for what little it is worth. Your mileage may vary.

 

Edit: Here's a worn aluminum pinion pulled from one of my restorations next to a new one.

[alvinlwh 5895]

@Saito2  as my wife say, I have so many cars and can only drive one at one time, I think mine will last a long time as well, brass or otherwise (now that you mentioned it, I also have some RR steel ones). 

What about the hardened alum ones? Typically marked as hop ups? Are they good or bad? 

[Jonathon Gillham 4606]

I have a lot of hardened aluminium ones from Yeah Racing, 3Racing and Surpass. None are showing any signs of wear after up to 5 years of use.  I have seen a lot of people using them and no one has ever commented on pinions being a wear item, like say bearings are, so i can only assume that they are fine.

[Juggular 4964]

3 hours ago, alvinlwh said:

What about the hardened alum ones? Typically marked as hop ups? Are they good or bad? 

The consensus is that hardened aluminum is good.  

I suspect that it's powder coated with a hard material, the aluminum itself is not hardened. Whatever the coating is, when I tried to scratch off the hard coating, it was like trying to scratch glass surface. Not easy to scratch at all (with the backside of a stainless steel blade). 

 

On the other hand, I could shave off stock aluminum with alarming ease.  

I'd say hardened aluminum is at least 2-3 times stronger than stock aluminum.  

So... if I were to rank up in a totally Unscientific way...

The strongest: Steel (will last 50 years.)

2nd strong: Hardened Aluminum (will last 20 years)

3rd; Brass (will last 3 years)

The weakest: stock aluminum.  (will last 1 year: or about 30 charges)

 

[alvinlwh 5895]

@Juggular can always trust you to provide the most detailed explanation! 👍

[SlideWRX 785]

I would only add that a stock 540 (or 380, for that matter) and NiMH might last several years on the standard aluminum.  I think adding a torque tuned 540, or Lipo batteries would significantly increase the wear.

[WillyChang 1814]

3 hours ago, Juggular said:

I suspect that it's powder coated with a hard material,

I think hard coating is an anodizing treatment

Alu forms an invisible alu oxide layer on exposure to air. This alu oxide can be anodized with various chemicals to dye its colour &/or improve its surface properties eg wear resistance.  

lately have discovered some bigbore shock bodies (not T) that haven’t been ano treated on the inside. Within just a few races the cylinder wears to oval & the round piston don’t seal as well anymore. Shock oil goes grey from all the metal worn off. 

Not T but another longtime JP rc brand. Their previous shocks aren’t that fast wearing by the racers that used them, just the latest lot. 

[Big Jon 684]

It's been my experience that hardened aluminum pinions are perfectly adequate for any application that isn't dusty, as long as the spur is plastic.

A steel spur requires a hardened steel pinion, and the pinion will still wear out sooner than you think.

Very dusty conditions wear out pinions quickly, even steel ones. The stock aluminum pinion on my TT-02 rally car didn't make it through the first pack at the dusty track we were using that day, and all of us have had wear issues due to the dust.

Brass pinions are a wear item, just like stock aluminum, except they last a little longer.

The machining on most of the hard aluminum pinions I've seen has been superb, even under magnification, unlike the Robinson M0.6 steel pinions, which look like they were hacked off with a dull blade.

[WillyChang 1814]

Gearboxes should be dustsealed ideally. 
 

If ppl aren’t installing the green papery disc between motor & mounting... vents in motor can front will let dust into gear cavity. 

[OoALEJOoO 3127]

Tamiya also offers fluorine-coated pinions (26,27,28 and 29T if memory serves right). Is the durability of these similar to the hard-coated aluminum? They are of a darker color, similar to other fluorine-coated parts such as bushings, step-screws, etc.