Zahhak DN-01 pinion/spur and tyre questions

[Manix92 121]

I will be using a Superstock BZ on the Zahhak which both should arrive shortly.

For just general use which ratio would you start with on the pinion/spur setup?

I will have the following available with the parts I have ordered

9.34, 9.10, 8.93, 8.70, 8.56, 8.34, 8.22, 8.01

(22T, 23T, 24T, 25T pinions with either 77T or 79T spur)

 

With the tyres (Dual Block Tire K) they 'look' OK for most surfaces but loose gravel looks like it could be a problem, is this correct?

What would be a decent alternative for gravel if that is the case?

Thanks

 

[Finnsllc 917]

it takes 48dp not mod pinion just fyi

[Juggular 4964]

Finn's right, get 48 pitch gears.  

Super Stock is a fairly hot motor.  It can handle Zahhak even if the ratio was 7.  But hotter motors have lower torque at lower RPM; meaning hot motors require lower gear ratio.  From about 8.0, it should be alright.  But few things to consider.

1) Consider motor bearings.  Super Stock comes with bushings.  Bearings would increase RPM only by 50 to 100.  It can increase torque by small amount and use a lot less electricity.  [The size for the 540 motor bearing is 1/8 x 3/8 x 5/32.  I thought it would be metric, but it's actually imperial]  You can get ten bearings for about $7 USD. https://www.ebay.com/itm/R2ZZ-Ball-Bearing-1-8-x3-8-x5-32-Shielded-Z2-Lever-Bearings-10pcs/392561410572?hash=item5b667bc20c:g:RJIAAOSwbLpeqF-y 

2) Heat can weaken motors, so watch how hot the motor becomes every time you change your pinion.  

3) Rougher ground needs lower ratio like 8.5.  Conversely, if you are using a neatly paved flat area, you can even do a taller gearing of 6. 

4) These things are compounding factors.  If your new tires are heavier, you want to go lower on the ratio, close to 9.  If the tires are larger, you want to go lower also, like 9.5.  If the tires are both larger and heavier and going off road, start from 10-ish.  Heat on the motor can tell you if it's suffering under load.  

 

[Manix92 121]

Thanks Finnsllc,

that's what I have ordered 48 pitch. Just ended up ordering the TRF-201 options as they should fit.

https://www.plazajapan.com/4950344542178/  22T/23T tamiya 54217

https://www.plazajapan.com/4950344542185/ 24T/25T tamiya 54218

https://www.plazajapan.com/4950344542192/ 77T spur tamiya 54219

 

Thanks for the info Juggular

1) Never realised the super stock came with bushings, may look into that but my wallet is a fair bit lighter at the second. Probably do it on the first round of upgrades.

2) Yes don't want to fry the motor, will keep an eye on that. I have ordered the aluminium mount plate which I guess helps a bit

https://www.plazajapan.com/4950344542765/  tamiya 54276

3-4) OK so I see. With that in mind I will probably go with the 8.56 (24T pinion/79 spur) for initial setup with the supplied Dual Block Tire K in the kit.

Looking at the manual download the lowest I can go with tamiya advised parts only takes you to 8.01 so getting to the 6 i'm not too sure how I would do that. Saying that I doubt it will see much super flat hard surfaces.

With tyres then, if I change out the Dual Block Tire K I need to check weight and diameter then adjust the ratio again.

[Juggular 4964]

Only now I'm starting to grasp the high and low gear thing. (and I started RC in the 80's!  I'm a slow learner...)  

"High" or "tall" gearing meas fast speed.  More burden on the motor.  But the gear ratio (FDR) shows low numbers like 5 or 6.   

"Low" gearing means slow speed.  Less burden on the motor.  But the gear ratio (FDR) shows high numbers like 8 or 10.  

It's confusing when people say "low gear ratio of 10" & "high gear ratio of 6."  The term is from 1:1 real car's stick shift.  1st gear= 3.5,  2nd gear 2.5 ... 5th gear 0.7.  So the lowest gear would have 3.5 ratio while the highest gear would have 0.7 ratio.  

Zahhak has relatively low gearing from 8-10, which is why I wouldn't worry too much about the gear ratio.  But 8.5 is a good starting point. 

Little warmth on the motor won't harm it.  If you imagine the motor to be much larger, and if you think you can put your cheek on it and sleep on it (about 40C), that's fine.  If you can't hold your finger on it for more than a few seconds, that's too hot.  Just a rule of thumb.  

As you can see in below graph, if the temperature goes up from 30 degrees to 75 degrees Celsius, the motor loses the magnetic strength by half.  So you'd want to keep it just few degrees warmer than body temperature. 

I think it would be silly to spend all that money for a fast motor, but run it hot and lose the magnetic strength by half.  When it runs too hot, it would be barely better than the silver can.  (the taller the gearing, the hotter it will run. also this is another reason why bearings are a good idea, bushings get hot)  

 

[dannymulder 766]

I run 32p  52 tooth associated  spur , I strip the tamiya ones to easy and did not like 48 pitch for bashing.

I use a 16 tooth pinion, the biggest pinion you can use is 17 and the smallest I think it is 10 tooth, no Idea what the fdr is with this, but I am running a 5700kv motor in mine and it is fast.

[ThunderDragonCy 7881]

7 hours ago, Manix92 said:

Thanks Finnsllc,

that's what I have ordered 48 pitch. Just ended up ordering the TRF-201 options as they should fit.

https://www.plazajapan.com/4950344542178/  22T/23T tamiya 54217

https://www.plazajapan.com/4950344542185/ 24T/25T tamiya 54218

https://www.plazajapan.com/4950344542192/ 77T spur tamiya 54219

 

Thanks for the info Juggular

1) Never realised the super stock came with bushings, may look into that but my wallet is a fair bit lighter at the second. Probably do it on the first round of upgrades.

2) Yes don't want to fry the motor, will keep an eye on that. I have ordered the aluminium mount plate which I guess helps a bit

https://www.plazajapan.com/4950344542765/  tamiya 54276

3-4) OK so I see. With that in mind I will probably go with the 8.56 (24T pinion/79 spur) for initial setup with the supplied Dual Block Tire K in the kit.

Looking at the manual download the lowest I can go with tamiya advised parts only takes you to 8.01 so getting to the 6 i'm not too sure how I would do that. Saying that I doubt it will see much super flat hard surfaces.

With tyres then, if I change out the Dual Block Tire K I need to check weight and diameter then adjust the ratio again.

If you want lower gearing you need to move away from Tamiya parts. Associated B4 spurs fit just fine and are available in 72t or 69t. Any 48dp pinions fit. 72/28 gets you about 7FDR. 69/30 gets you down to 6FDR.

[Manix92 121]

6 hours ago, ThunderDragonCy said:

If you want lower gearing you need to move away from Tamiya parts. Associated B4 spurs fit just fine and are available in 72t or 69t. Any 48dp pinions fit. 72/28 gets you about 7FDR. 69/30 gets you down to 6FDR.

Thanks

Knowing that will pretty well cover any eventuality

[Manix92 121]

 

13 hours ago, Juggular said:

Only now I'm starting to grasp the high and low gear thing. (and I started RC in the 80's!  I'm a slow learner...)  

"High" or "tall" gearing meas fast speed.  More burden on the motor.  But the gear ratio (FDR) shows low numbers like 5 or 6.   

"Low" gearing means slow speed.  Less burden on the motor.  But the gear ratio (FDR) shows high numbers like 8 or 10.  

It's confusing when people say "low gear ratio of 10" & "high gear ratio of 6."  The term is from 1:1 real car's stick shift.  1st gear= 3.5,  2nd gear 2.5 ... 5th gear 0.7.  So the lowest gear would have 3.5 ratio while the highest gear would have 0.7 ratio.  

Zahhak has relatively low gearing from 8-10, which is why I wouldn't worry too much about the gear ratio.  But 8.5 is a good starting point. 

Little warmth on the motor won't harm it.  If you imagine the motor to be much larger, and if you think you can put your cheek on it and sleep on it (about 40C), that's fine.  If you can't hold your finger on it for more than a few seconds, that's too hot.  Just a rule of thumb.  

As you can see in below graph, if the temperature goes up from 30 degrees to 75 degrees Celsius, the motor loses the magnetic strength by half.  So you'd want to keep it just few degrees warmer than body temperature. 

I think it would be silly to spend all that money for a fast motor, but run it hot and lose the magnetic strength by half.  When it runs too hot, it would be barely better than the silver can.  (the taller the gearing, the hotter it will run. also this is another reason why bearings are a good idea, bushings get hot)  

 

Useful info.

Thanks everyone for the input. Think I am clear now on the pinion spur setup.

[Finnsllc 917]

grab some extra diffs, or the trf201 diffs, i melted mine running it pretty hard

[Manix92 121]

Finsllc OK, looks like they aren't too hard to get hold of (no need for ordering from Japan/China) and relatively cheap.

Hopefully this week I should get the kit, the tracking says it is in this country (UK) now.

[Finnsllc 917]

well keep in touch @Manix92

[Howards 456]

Amazed nobody has mentioned the slipper clutch - it's pretty essential if going for hot motors. 

Ran mine with a 4000kv motor and the stock spur and a 23 pinion yesterday. It got too hot on rough grassy ground so sacked it off after five mins. will drop the pinion down to 20/21/22.