TRF511 + Vector X12 - Pinion doesn't reach Spur?

[djmcnz]

Hi all,

Am building my TRF511 and have a new X12 to install. It's obvious that the pinion wont reach the spur gear when install properly on the motor shaft... it's perhaps 5mm or 6mm short. Motor shaft is typical length.

Is it a property of this chassis design that long pinions are required? The kit pinion is long enough to reach but it's a big pinion.

Do I need to shelf my existing pinions and get special longer ones for this kit? If so, any recommendations? Am currently using RR hardened pinions.

Thanks in anticipation!

[Dyna]

The dedicated Tamiya pinions are the ones to use - some other makes do fit fine ( best search old threads, there has been posts on this problem before ) but the Tamiya's are readily available, have numerous sizes and fit perfect :)

[djmcnz]

Thanks Dyna.

So anybody else make suitable pinions or just Tamiya?

[MHeadling]

HPI and Corally make medium and long boss pinons, AMC would be worth a look for Corally ones, have a look on HPI website for pinions and go to the shop finder to find your local shop

[djmcnz]

Thanks guys, apprecaite your assistance.

[djmcnz]

Lol, back again...

So, the my 511/X12 8.5T combo wants a 27 tooth pinion as per the calculation below and I can't find a Tamiya 48p one. I'd like a hard steel one, does anybody have a Tamiya part number for this (ideally a 26/27 combo pack). Obviously in line with the advice above it needs to be a long one.

X12 8.5T 4WD Off-Road LRP Recommendation = 7.0:1
TRF511 Gear Ratio (91T Spur / 27T Pinion x 2.06) = 6.94:1

Thanks... :)

[Fredrik Emilsson]

I think 21T is the biggest, #53966
Buy a smaller spur gear.

[Dyna]

Brain fade, sorry....

[jimmy]

I've used the 87t associated spur and that will allow you to use a slightly smaller pinion - not sure how small you can go with the spur tho - possibly an 84t associated?

[Fredrik Emilsson]

No worries Dyna.:)

He would need a 72T spur with 21T pinion.;)
Don´t know if it will fit.

[djmcnz]

Surely the 8.5T X12 isn't too 'light' for this chassis? I'd need to go to a 6.5T to use a 20 or 21 tooth pinion and whilst I will eventually get there thought I'd start with the 8.5 and work up - it's been a while so I need to re-learn car control.

As stated above my spur options are limited...

Is is out-of-order for some reason to go 8.5T / 91T / 27T or is this safe and just not catered for by Tamiya?

If you all think it's sweet, I'll just get another brand of pinion.

[jimmy]

Tamiya don't make a big range of pinions for this car- other manufacturers do make pinions that fit and are in a wider range of sizes. I know what you mean with the short motor shaft - personally I've not had a problem with running standard pinions on most of my motors, though they are close to the edge.

[djmcnz]

...personally I've not had a problem with running standard pinions on most of my motors, though they are close to the edge.

Jimmy, do you mean that the entire faces of your spur/pinion don't mesh? And you've not had a problem? If so this is encouraging (although I don't have a 27t pinion of any sort lol).

Tamiya obviously weren't thinking brushless with the kit spur and pinion... not unless they expected all owners to use 3.5 turn motors. :wtf:

[jimmy]

I mostly used the AE 87t spur - its wider so even if you don't get full contact because of a short motor shaft you still have a decent amount. I found the AE spurs lasted better also.

But no - generally I found I could run my favorite EDIT pinions without problems or poor contact. I've not tried an lrp x12 so that might be a little shorter than most, I'm not sure. Get a AE 87t tho!

[Fredrik Emilsson]

Do you really need to run 7:1 ratio? Have never tried a 8.5T.

With X12 6.5 I run 12.5:1 (15T pinion/91T spur) on smaller tracks. With a 8.5T it would maybe be something like 9,74:1 to get the same top speed? (21T/91T). Anyone who knows?

I also run 9.8:1 (19T pinion/91T spur) on large tracks. The TRF team ran that ratio on the Bilbao track.
With a 8.5T it would be 7,6:1? Again, not sure.

Why not try 21T/91T? It´s 8.9:1. Or 21T/87 (8.5:1)

For the X12 6.5T they recommend 9:1, but I think the car will be to fast with that gearing.

[djmcnz]

@ Jimmy: Sweet, thanks I shall do... just the standard B4 one? I know nothing about Associated stuff sorry.

@ Fredrik: Was just a little concerned about temps and efficiency that's all... but perhaps it's worth a try on the AE87 - I will need a 20 and 21 if I want to run 9.0 when I get a 6.5 anyway. ESC's a SPX Bullet Brushless so it shouldn't mind.

Wicked help guys, much appreciated.

[jimmy]

The b4 uses an 81t as standard I think - the 87t is from the T4 truck so it's not as easy to find as the smaller spurs, but shouldn't be too hard.

[4wdfull]

The gear ratio mentioned above sounds way too low unless you're running on asphalt (oval). An LRP x12 8.5 should be around 91/20 on a proper dirt track. My x12 6.5 uses 15 to 17 tooth pinions on US dirt tracks. Plenty of speed...right temp. I may be wrong however.

Does anyone know if there is a brand of long shank pinions that does not rub the belt with the shank? I have some old TIR long shanks that I used on my Cat3000 but their shanks rub the belt slightly.

[djmcnz]

The gear ratio mentioned above sounds way too low unless you're running on asphalt (oval). An LRP x12 8.5 should be around 91/20 on a proper dirt track. My x12 6.5 uses 15 to 17 tooth pinions on US dirt tracks. Plenty of speed...right temp. I may be wrong however.

Seems to be the general thinking... I was just going raw off the manuals because my existing (comprehensive) set of steel pinions aren't long enough and I didn't want to go out and buy all ten 17 - 27 pinions for trial and error lol.

Am trying to source some Corally long pinions in 20, 21, 26, 27 and a AE T4 87T spur... haha and I thought my build was close to complete...

[4wdfull]

Pls let us know if the Corally shanks don't rub the top side of the bottom front belt. Make sure that they don't rub before you invest (obviously):D.

With the TIR pinions that I have, it just barely rubs. A little turning on a lathe would eliminate the problem but I haven't tried it. Good luck.

[djmcnz]

Will do.

Anyone know what ones the team guys use?

[djmcnz]

Okay, quick update...

Got the AE87 and at first it looked the same width as the Tamiya but indeed it is fractions wider (why did I doubt you Jimmy?!?).

The extra width, plus some "ecomony" with the motor shaft depth into the pinion has given me (apparently) sufficient spur/pinion overlap. Fingers crossed.

I will try the ratio suggestions from Fredrik as I now can use my 21 - 23T pinions... :) Will see how ~8 goes instead of 7.0.

@ 4wdfull - Not road tested yet but my X12 motor, Robinson Racing pinion, AE87 spur combination leaves plenty of clearance for the belts - the pinion and belts do not overlap in my install.

Pics of my build to follow in a new thread... am quite pleased with it actually - a gem compared to the 501X.

[jhammond]

"djmcnz" - Really looking forward to seeing those pictures. :)