Egress gearing question

[Rb4276 803]

What brushless set ups and gearing are you guys using? Right now i am running a hobbywing justock 10.5 and started with a 21t pinion, top end was nothing special, as was off the line. I tried to tinker with my other .6 pinions I had. I tried 19t and my lowest 16t, there was literally no difference from my 21t i used. Im assuming since i cant gear up past 22t on a re re egress that my FDR is way off. I have read that the egress fdr is really meant for a stock motor. I was adviced by a local racer to gear down and try a tekin spec 13.5 or 10.5 motor since they run much higher rpms geared low and should fix my issue. My other option i was told was try a cheap 9.5 brushless motor and turn the timing way down or try a goolrc combo setup. Sorry for the long read, any advice or help is appreciated. 

[Saito2 6676]

I can't add anything meaningful, just that, I too, am perplexed by brushless gearing. Most Tamiyas have only one available spur, limiting you to pinion changes. I also gathered that Tamiya's in general are geared for stock motors. Am I to understand that originally, they couldn't be geared low enough to use high rpm brushed modifieds from back in the day and now can't be geared high enough to take advantage of faster brushless motors?

[Rb4276 803]

1 hour ago, Saito2 said:

I can't add anything meaningful, just that, I too, am perplexed by brushless gearing. Most Tamiyas have only one available spur, limiting you to pinion changes. I also gathered that Tamiya's in general are geared for stock motors. Am I to understand that originally, they couldn't be geared low enough to use high rpm brushed modifieds from back in the day and now can't be geared high enough to take advantage of faster brushless motors?

Yes it seems that way, but i have seen videos of peoples brushless in egress’ & avantes and they are flying. I dont need a rocket ship but the 10.5 is honestly not much faster than a stock. What i think i am going to do it throw the justock in my zahhak or optima and see if it truly is the gearing. Also since the goolrc is so cheap i bought a 3900kv for $32 and will try it. If it doesnt do the job ill save for my next kit. 

[ThunderDragonCy 7873]

For 10.5 brushless you need a FDR around 8 to 8.5. I have a 4000kv 10.5 in my TRF211 on a 8.1 and it's blinking fast! 

You don't mention but if you are still running nimh batteries it is probably the battery. 10.5 brushless pull a lot of current and nimh simply don't deliver a big enough current compared to lipo. 

[Rb4276 803]

It is def the FDR on the egress since you are limited. I am using 2s lipo 

[Fuijo 880]

The quoted FDR for the Egress 2013 seems a bit off. After pulling mine apart and counting the teeth on the gears, it seems the internal ratio is 2.778:1  **

The final drive ratio with the stock 22t pinion should be 8.3333:1, or just FDR 8.3333

21t pinion FDR 8.731

20t pinion FDR 9.167

19t pinion FDR 9.650

18t pinion FDR 10.186

17t pinion FDR 10.785

16t pinion FDR 11.459

 

Assuming the Superstock BZ motor pictured in the manual is what Tamiya intended to be fitted, it's a bit confusing that they included a 22 tooth pinion.

The recommended ratios for the BZ are from 9.1 to 11.1. Probably the 9.1 would be for a light 2wd car, and the 11.1 for a heavy 4wd car. The Egress is fairly light, but 4wd. So somewhere in the middle, say around

10.1 might be a good place to start. So why didn't they go for an 18 tooth pinion?

 

A 13.5 brushless motor gives approximately the same KV as a superstock BZ with no load, but should have quite a bit more torque and easily be able to turn a bigger pinion than the BZ.

You say you've tried pinions from 16 to 21 teeth, and not noticed much of a difference? quite frankly it should absolutely fly on most of those ratios with a 10.5 turn brushless motor

unless the battery can't supply the current (are you using LiPo?), or the diffs are slipping.

 

 

**Internal gearing, going on front gearbox

Spur gear 66 teeth

Spur pinion 18 teeth

Counter gear spur 20 teeth

Counter gear pinion 12 teeth

Diff gear 30 teeth

 

22 tooth Pinion to spur ratio 66/22

spur pinion to counter gear spur ratio 20/18

counter gear pinion to diff ratio 30/12

 

FDR with a 22 tooth pinion (66/22) x (20/18) x (30/12) = 

3 x 1.1111 x 2.5 = 8.3333 (working to 4 significant figures)

 

 

[Rb4276 803]

I am using lipo and i too thought the diffs were slipping but they are almost at full lock

[Fuijo 880]

If there was no difference in acceleration between the 16t and 21 tooth pinions, I don't believe it's a gearing issue.

[Rb4276 803]

30 minutes ago, Fuijo said:

If there was no difference in acceleration between the 16t and 21 tooth pinions, I don't believe it's a gearing issue.

What do you think then? I have tried  the diffs, gear mesh, looked to see if anything was causing drag

[Fuijo 880]

23 minutes ago, Rb4276 said:

What do you think then? I have tried  the diffs, gear mesh, looked to see if anything was causing drag

It depends on whether the motor was getting up to full rpm or not.

If the acceleration to top speed is almost instant with all the pinion gears you tried, then the pinion is too small. But for this to be the case, the top speed would be different with each pinion.

If the motor is quickly reaching sustained full rpm, but the car is slow to accelerate and has a low top speed, then either the pinion is slipping on the motor shaft,  the power is overwhelming the diffs and they're slipping, or the wheels are spinning inside the tyres.

If the motor is not reaching sustained full rpm, then either the pinion is too big, the battery can't handle the demand, the wheels are bigger than standard, or something is binding. Does the motor get hot?

This is all assuming neither the motor or battery are faulty.

 

It's probably worth inspecting the diffs anyway. Even if they were adjusted correctly to begin with, and the spring was compressed a few times before installing, there's probably going to be a bit of bedding-in required.

They should probably be readjusted after the first battery pack. Signs of slipping or not will likely be visible when you strip them down.

[Rb4276 803]

4 hours ago, Fuijo said:

It depends on whether the motor was getting up to full rpm or not.

If the acceleration to top speed is almost instant with all the pinion gears you tried, then the pinion is too small. But for this to be the case, the top speed would be different with each pinion.

If the motor is quickly reaching sustained full rpm, but the car is slow to accelerate and has a low top speed, then either the pinion is slipping on the motor shaft,  the power is overwhelming the diffs and they're slipping, or the wheels are spinning inside the tyres.

If the motor is not reaching sustained full rpm, then either the pinion is too big, the battery can't handle the demand, the wheels are bigger than standard, or something is binding. Does the motor get hot?

This is all assuming neither the motor or battery are faulty.

 

It's probably worth inspecting the diffs anyway. Even if they were adjusted correctly to begin with, and the spring was compressed a few times before installing, there's probably going to be a bit of bedding-in required.

They should probably be readjusted after the first battery pack. Signs of slipping or not will likely be visible when you strip them down.

The car is definitely slow off the line regardless of what pinion. The battery is a brand new protek 2s lipo, the battery is fine i used it in my optima too. The diffs i will check again later on and i found a .6 13t pinion i will try just to see if there is any difference with that. The tires are glued also, so that eliminates that. I think it is the diffs or the fdr still. Hopefully i cann figure it out

[ThunderDragonCy 7873]

@Rb4276 Does the motor have end bell timing adjustment? If it does and it is set to zero it will be fairly slow and would also explain the lack of performance across the board. Also, just to eliminate everything, double check your throttle end points setup on your ESC and Tx, and any other adjustments for performance the ESC might have? 

[Rb4276 803]

39 minutes ago, ThunderDragonCy said:

@Rb4276 Does the motor have end bell timing adjustment? If it does and it is set to zero it will be fairly slow and would also explain the lack of performance across the board. Also, just to eliminate everything, double check your throttle end points setup on your ESC and Tx, and any other adjustments for performance the ESC might have? 

There is no timing on the hobbywing justock 10.5. It is fixed, the hobbywing esc i use and the hobbywing program card does not let me boost or up the timing. I can only adjust the rotation, brakes ect. 

The throttle endpoints i actually have to turn up alot to give me the performance i have now. 

[Rb4276 803]

Ok so it seems the problem is solved, the front ball diff was very loose. I had tightened it when i installed the new motor but obviously became loose again. The rear was pretty tight so i left as is. Now i have nice acceleration and better top end. Tomorrow i will change back to a 21 or 22t pinion to see if i get better top speed. Thanks for all the advice. I did order a goolrc 3900kv combo, i will save that for my next kit. Possibly a re re ultima

[Fuijo 880]

Glad you fixed it.

[slimleeroy 241]

My lad has got a leopard 12.5t brushless in his egress with standard pinion size (albeit steel) and it flies even with a NiMH.  Don't think I would want it any faster.

[Rb4276 803]

6 hours ago, slimleeroy said:

My lad has got a leopard 12.5t brushless in his egress with standard pinion size (albeit steel) and it flies even with a NiMH.  Don't think I would want it any faster.

Are t those leopard 4 pole motors? My hobbywing 10.5 is 2 pole, right now with a 17t pinion it def does not fly, but is much faster since tightening the front diff. Later today i will put a 21t back in it and then see

[Rb4276 803]

So all is well now, put in a 22t pinion. Acceleration and top speed is good, not a rocket ship but so much better.  

[Barnoid 71]

You can fit a 24t in there too if you need more top end...

[slimleeroy 241]

On 9/25/2019 at 2:59 PM, Rb4276 said:

Are t those leopard 4 pole motors? My hobbywing 10.5 is 2 pole, right now with a 17t pinion it def does not fly, but is much faster since tightening the front diff. Later today i will put a 21t back in it and then see

It is the 380 size rotor with the orange can.  Goes like stink