53 replies to this topic

[MSwiss]

"Has anyone taken a bunch of these arms, removed the string from half and then run them all to destruction and tabulated the results?"
No.

A racer wouldn't waste his time because there is no end game. I doubt a manufacture would also waste their time.

Spend a $1,000 in their own labor time, to maybe save $1,000, in the future, in manufacturing cost?

$1,000 they can always pass on to the consumer in the price of the product?

[dalek]

What does "recommended shortest gear ratio" mean?

 

Would 3.00 be shorter than 3.27?

 

Tim Homola, would you please answer the questions, or at least verify the answers that anyone else gives, since the Hawk motors are your product.

 

Thank you.

[havlicek]

MSwiss, on 14 Nov 2017 - 1:12 PM, said:

A racer wouldn't waste his time because there is no end game. I doubt a manufacture would also waste their time.

Spend a $1,000 in their own labor time, to maybe save $1,000, in the future, in manufacturing cost?

$1,000 they can always pass on to the consumer, in the price of the product?

 
Yep! So I'm left to figure that it's being done (probably) as much for appearances as any real benefit. 

[havlicek]

dalek, on 14 Nov 2017 - 1:36 PM, said:

What does "recommended shortest gear ratio" mean?
 
Would 3.00 be shorter than 3.27?
 
Tim Homola, would you please answer the questions, or at least verify the answers that anyone else gives, since the Hawk motors are your product.

 
The terms "short" and "tall" can be confusing and people can both misuse and misunderstand them. For "me," a "tall" gear ratio is a numerically high one... so a 4:1 setup is "taller" than a 3:1 one, and the 3:1 ratio is "shorter" than the 4:1 ratio... but I could be wrong about that!

What I know for sure is that both too-tall (where the motor is continually winding-out) and too-short (where the motor is lugging/overworking) gears can be motor-killers.  People ask me what gears are best for a motor, and I tell them honestly that I have no idea. Best is to ask other racers.

[MSwiss]

havlicek, on 14 Nov 2017 - 1:36 PM, said:

Yep!  So I'm left to figure that it's being done (probably) as much for appearances as any real benefit. 

 

Not true.

On my Wednesday night racing, where we race on 12.2v, and racers quote getting 20 (16 minute) races with one motor, the comm tie is probably not doing much.

At raceways, where they run on up to 14.3v, it's probably real useful.

[havlicek]

OK... so then it "might" be doing something. 

That doesn't make my thought not true... just maybe not completely true 

[Cheater]

Tall vs. short gearing has always been a little bit confusing.
 
To me (and see below), a shorter gear ratio would be 5:1 vs. 4:1.
 
A taller gear ratio would be 3:1 vs. 4:1.
 
Long/Short gear: What does it mean?
 
The Lowdown on Gear Ratios
 
Rear-End Gearing Simplified
 
What is the difference between short and tall gearing in bikes and cars?
 

The consensus in the in the 1:1 vehicle world seems to be that "taller" means lower numerically and "shorter" means higher numerically.

[MSwiss]

I agree it's confusing and never use the terms, short or tall.

"Mike, my motor is running hot. What should I do?"

"Go to a higher numeric gear ratio".

"Mike, my car is running cool, but slow. What should I do?"

"Go to a lower numeric gear ratio".

[Gator Bob]

BITD If you have a Dana, 12 bolt or a 9" with 3:08s it's tall (or long)... think long as a top end gear that takes 'longer' to get up to speed or takes longer to get to the 'redline.'
 
5:13s it's short... short track, short time to get to 'the redline.'
 
It can be counterintuitive and easy to mix up.

[Eddie Fleming]

So lower is taller and shorter is higher?

 

I am so confused. 

[Cheater]

Eddie,

Lower "numerically" is taller and higher "numerically" is shorter... yes.

A 3:1 gear ratio is "taller" than a 5:1 gear ratio.

[Eddie Fleming]

I know.

[JK Products]

Hi Dale,

As others have stated, 3.0:1 is taller than 3.27:1 and not recommended. The typical recommended ratios for our motors are between 3.3-4.2:1.
 
The picture sure looks like about a 7-tooth pinion but let’s use the gearing you listed, 43/9 = 4.8:1 gear ratio. This is short. With one of our motors geared this short I would expect it to be slow down the straights as you are likely not getting enough top end speed for most tracks.
 
This is normally what you would see with gearing that is too tall or too short.
 
Too Tall (i.e. 30 tooth gear/12 tooth pinion = 2.5:1 gear ratio)
 
This will leave the motor with lower RPMs.
+ This normally leads to higher top end car speed if you have a long enough straight
- worse brakes as not as much motor EMF available
- less torque coming out of the turns
- motor runs hotter
 
(This can even lead to the car starting the straight slowly and then accelerating quickly as the RPMs finally pick up because they started too slow coming out of the turn.)
 
The car is often more difficult to drive but could be quick depending upon the track.
 
 
Too Short (i.e. 43 tooth gear/9 tooth pinion = 4.8:1 gear ratio)
 
This will leave the motor with higher RPMs.
- possible lower top end car speed if you have long straights
+ better brakes due to larger motor EMF available
+ more torque coming out of turns as the RPMs stay higher throughout the turn
+ motor runs cooler
 
The car is usually easier to drive but could be slow depending upon the track.
 
The other major factors that need to be considered in gear selection are weight of the car, track layout (slow speed [turny, flat road course] or high speed track [most Kings]), and tire diameter.

[Fast Freddie]

First of all anyone who races these motors knows that the brushes are installed bas ackwards.  If they were installed correctly it wouldn't take much to seat them and the motors would run very good from the jump.  Secondly running the motors with unseated brushes makes most of them seem like dogs.  When you use the non-recommended way of breaking in the motors, either in water or with Simple Green all you are doing, if your careful, is fully seating the brushes in a shorter span of time and with less heat.  Yes, using that method of break in does shorten the life span of the motor but only because the recommended break in is incomplete. If you use the recommended break in the brushes are still on the tips and not seated so technically they last longer.  I have done the recommended break in and when the motor was installed and on the track it didn't run even close to the motors with fully seated brushes.  If your goal is just to run your car for fun and longevity then there is no need for fully seated brushes but if your racing in competition there is and you'll just have to live with the shorter motor life.  Besides why would any motor manufacture be against shorter motor life?  They'll sell more motors especially if the motors run better.

 

One more thing.  Maybe you should be more concerned about FDR (final drive ratio) then gear ratios.  Would you ever gear an HR motor 13x36?  That's a gear ratio of 2.76 to 1.  Much steeper then the recommended ratio.  What if you paired it with .720 tires.  The FDR in this case is 3.85.  The most popular FDR in Retro racing using this motor is 3.83 with .8125 tires and a 9x28 gear ratio.  This FDR is something to consider.  Oh and by the way I've run this gear ratio using this same FDR and had no overheating problems and it ran very good.   

[tazman]

JK Products, on 14 Nov 2017 - 6:53 PM, said:

Hi Dale,

As others have stated, 3.0:1 is taller than 3.27:1 and not recommended. The typical recommended ratios for our motors are between 3.3-4.2:1.
 
The picture sure looks like about a 7-tooth pinion but let’s use the gearing you listed, 43/9 = 4.8:1 gear ratio. This is short. With one of our motors geared this short I would expect it to be slow down the straights as you are likely not getting enough top end speed for most tracks.
 
This is normally what you would see with gearing that is too tall or too short.
 
Too Tall (i.e. 30 tooth gear/12 tooth pinion = 2.5:1 gear ratio)
 
This will leave the motor with lower RPMs.
+ This normally leads to higher top end car speed if you have a long enough straight
- worse brakes as not as much motor EMF available
- less torque coming out of the turns
- motor runs hotter
 
(This can even lead to the car starting the straight slowly and then accelerating quickly as the RPMs finally pick up because they started too slow coming out of the turn.)
 
The car is often more difficult to drive but could be quick depending upon the track.
 
 
Too Short (i.e. 43 tooth gear/9 tooth pinion = 4.8:1 gear ratio)
 
This will leave the motor with higher RPMs.
- possible lower top end car speed if you have long straights
+ better brakes due to larger motor EMF available
+ more torque coming out of turns as the RPMs stay higher throughout the turn
+ motor runs cooler
 
The car is usually easier to drive but could be slow depending upon the track.
 
The other major factors that need to be considered in gear selection are weight of the car, track layout (slow speed [turny, flat road course] or high speed track [most Kings]), and tire diameter.

I like your descriptors of running 9/43 ratio with 72 pitch gears. What you described is exactly the performance our cars have especially running on a small flat track - no long straightaways or a huge bank. Keeping the rpms up is the key for our track and that motor I broke in earlier just did not respond. It did not help with the way the twine was tied and the excess twine was pointed towards the motor hole. Sniped the excess twine off, some improvement but NO DICE! I pulled the motor apart and the stacks kind of looked normal except there was no balance marks on the stacks! All of my other H7 had balance marks - mistake or was it a perfectly balanced arm?

Sent from my SAMSUNG-SM-N920A using Tapatalk

[tazman]

JK Products, on 14 Nov 2017 - 6:53 PM, said:

Hi Dale,

As others have stated, 3.0:1 is taller than 3.27:1 and not recommended. The typical recommended ratios for our motors are between 3.3-4.2:1.
 
The picture sure looks like about a 7-tooth pinion but let’s use the gearing you listed, 43/9 = 4.8:1 gear ratio. This is short. With one of our motors geared this short I would expect it to be slow down the straights as you are likely not getting enough top end speed for most tracks.
 
This is normally what you would see with gearing that is too tall or too short.
 
Too Tall (i.e. 30 tooth gear/12 tooth pinion = 2.5:1 gear ratio)
 
This will leave the motor with lower RPMs.
+ This normally leads to higher top end car speed if you have a long enough straight
- worse brakes as not as much motor EMF available
- less torque coming out of the turns
- motor runs hotter
 
(This can even lead to the car starting the straight slowly and then accelerating quickly as the RPMs finally pick up because they started too slow coming out of the turn.)
 
The car is often more difficult to drive but could be quick depending upon the track.
 
 
Too Short (i.e. 43 tooth gear/9 tooth pinion = 4.8:1 gear ratio)
 
This will leave the motor with higher RPMs.
- possible lower top end car speed if you have long straights
+ better brakes due to larger motor EMF available
+ more torque coming out of turns as the RPMs stay higher throughout the turn
+ motor runs cooler
 
The car is usually easier to drive but could be slow depending upon the track.
 
The other major factors that need to be considered in gear selection are weight of the car, track layout (slow speed [turny, flat road course] or high speed track [most Kings]), and tire diameter.

I like your descriptors of running 9/43 ratio with 72 pitch gears. What you described is exactly the performance our cars have especially running on a small flat track - no long straightaways or a huge bank. Keeping the rpms up is the key for our track and that motor I broke in earlier just did not respond. It did not help with the way the twine was tied and the excess twine was pointed towards the motor hole. Sniped the excess twine off, some improvement but NO DICE! I pulled the motor apart and the stacks kind of looked normal except there was no balance marks on the stacks! All of my other H7 had balance marks - mistake or was it a perfectly balanced arm?

Sent from my SAMSUNG-SM-N920A using Tapatalk

[tazman]

JK Products, on 14 Nov 2017 - 6:53 PM, said:

Hi Dale,

As others have stated, 3.0:1 is taller than 3.27:1 and not recommended. The typical recommended ratios for our motors are between 3.3-4.2:1.
 
The picture sure looks like about a 7-tooth pinion but let’s use the gearing you listed, 43/9 = 4.8:1 gear ratio. This is short. With one of our motors geared this short I would expect it to be slow down the straights as you are likely not getting enough top end speed for most tracks.
 
This is normally what you would see with gearing that is too tall or too short.
 
Too Tall (i.e. 30 tooth gear/12 tooth pinion = 2.5:1 gear ratio)
 
This will leave the motor with lower RPMs.
+ This normally leads to higher top end car speed if you have a long enough straight
- worse brakes as not as much motor EMF available
- less torque coming out of the turns
- motor runs hotter
 
(This can even lead to the car starting the straight slowly and then accelerating quickly as the RPMs finally pick up because they started too slow coming out of the turn.)
 
The car is often more difficult to drive but could be quick depending upon the track.
 
 
Too Short (i.e. 43 tooth gear/9 tooth pinion = 4.8:1 gear ratio)
 
This will leave the motor with higher RPMs.
- possible lower top end car speed if you have long straights
+ better brakes due to larger motor EMF available
+ more torque coming out of turns as the RPMs stay higher throughout the turn
+ motor runs cooler
 
The car is usually easier to drive but could be slow depending upon the track.
 
The other major factors that need to be considered in gear selection are weight of the car, track layout (slow speed [turny, flat road course] or high speed track [most Kings]), and tire diameter.

I like your descriptors of running 9/43 ratio with 72 pitch gears. What you described is exactly the performance our cars have especially running on a small flat track - no long straightaways or a huge bank. Keeping the rpms up is the key for our track and that motor I broke in earlier just did not respond. It did not help with the way the twine was tied and the excess twine was pointed towards the motor hole. Sniped the excess twine off, some improvement but NO DICE! I pulled the motor apart and the stacks kind of looked normal except there was no balance marks on the stacks! All of my other H7 had balance marks - mistake or was it a perfectly balanced arm?

Sent from my SAMSUNG-SM-N920A using Tapatalk

[tazman]

JK Products, on 14 Nov 2017 - 6:53 PM, said:

Hi Dale,

As others have stated, 3.0:1 is taller than 3.27:1 and not recommended. The typical recommended ratios for our motors are between 3.3-4.2:1.
 
The picture sure looks like about a 7-tooth pinion but let’s use the gearing you listed, 43/9 = 4.8:1 gear ratio. This is short. With one of our motors geared this short I would expect it to be slow down the straights as you are likely not getting enough top end speed for most tracks.
 
This is normally what you would see with gearing that is too tall or too short.
 
Too Tall (i.e. 30 tooth gear/12 tooth pinion = 2.5:1 gear ratio)
 
This will leave the motor with lower RPMs.
+ This normally leads to higher top end car speed if you have a long enough straight
- worse brakes as not as much motor EMF available
- less torque coming out of the turns
- motor runs hotter
 
(This can even lead to the car starting the straight slowly and then accelerating quickly as the RPMs finally pick up because they started too slow coming out of the turn.)
 
The car is often more difficult to drive but could be quick depending upon the track.
 
 
Too Short (i.e. 43 tooth gear/9 tooth pinion = 4.8:1 gear ratio)
 
This will leave the motor with higher RPMs.
- possible lower top end car speed if you have long straights
+ better brakes due to larger motor EMF available
+ more torque coming out of turns as the RPMs stay higher throughout the turn
+ motor runs cooler
 
The car is usually easier to drive but could be slow depending upon the track.
 
The other major factors that need to be considered in gear selection are weight of the car, track layout (slow speed [turny, flat road course] or high speed track [most Kings]), and tire diameter.

I like your descriptors of running 9/43 ratio with 72 pitch gears. What you described is exactly the performance our cars have especially running on a small flat track - no long straightaways or a huge bank. Keeping the rpms up is the key for our track and that motor I broke in earlier just did not respond. It did not help with the way the twine was tied and the excess twine was pointed towards the motor hole. Sniped the excess twine off, some improvement but NO DICE! I pulled the motor apart and the stacks kind of looked normal except there was no balance marks on the stacks! All of my other H7 had balance marks - mistake or was it a perfectly balanced arm?

Sent from my SAMSUNG-SM-N920A using Tapatalk

[Ramcatlarry]

Logically the arms are tied and balanced before the arms are assembled in the can.  Alteration of the tie would alter the balance.  The China balance is not a high precision balance, I believe.  I test the balance by how much the motors bounce around on the test bench. Some are better than others.

[Rob Voska]

A while back someone posted about using a speaker & meter to measure vibration..... anyone remember that?

[bluecars]

All this talk about recommended gear ratios doesn't mean SQUAT unless you know and add (divide) tire size into the calculation.

[Ramcatlarry]

Absolutely, Red.  The Proslot website has some 'relativity' gear charts to use to figure that out. Use the recommended power ratio and the the tire size on your car to find the range of gear ratios to try.

 

Since I use the same motor in three different car classes with tires ranging from .700 - .810 - 1.05, it helps a lot to keep a motor running better.

[Fast Freddie]

Didn't I say that in Post #39?  The Final Drive Ratio (FDR) is much more important then the gear ratio.  The FDR is readily changed without removing the motor or gears, just change the tire diameter.  The FDR also changes during the race due to tire wear and this must be taken into account before you decide on beginning tire size. 

[bluecars]

Yes you did.

[gotboostedvr6]

Ramcatlarry, on 14 Nov 2017 - 05:21 AM, said:

8-9/43 is gearing we used for built Grp 12 C-cans good for 100K RPM for the ISRA Worlds production cars. Still need a bigger pinion.

9:43 on A production cars? Highly doubt that was a good idea with positive results.


With respect of course..