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Old 02-02-2013, 10:39 PM   #1
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Default pinions spurs and fdr's

Hi,
Im wondering if anyone can clarify a few questions i have about pinion / spur sizes.

-Does a 36t 48p pinion put more strain on a motor than a 36t 64p pinion?
reason for asking: a much lower fdr can be achieved using a 36t 48p pinion, so why would you use 64p pinions. If they are different, does anyone know what the equivalent size pinions from 48p to 64p?

-A range of FDR's can be achieved from the use of different spurs when using 1 particular pinion, Is it more beneficial to use the smallest spur that will fit the pinion or the biggest? Does the spur size affect the motor temps like pinion size?

I'm using a TC6.1 so even if you could post ur pinion/spur size and motor turn it would be helpful. Only really interested in 13.5, 17.5 and 21.5.

Thanks
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Old 02-02-2013, 11:31 PM   #2
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A 36t 48p pinion is physically larger than the same size in 64 pitch.
Spurs and pinions have to match, pitch-wise.
To convert from 48p to 64p, divide the teeth by 1.5, then multiply by 2.
In your example, a 36t pinion is the same size as a 48t 64p pinion.
To convert from 64p to 48p, divide by 2 and multiply by 1.5.

Your statement "a much lower fdr can be achieved using a 36t 48p pinion, so why would you use 64p pinions" isn't really correct. You can't put a 48p pinion on a 64p spur.
64p just give you finer adjustments.
For example
48p:78t spur, 36t pinion=2.166:1
go down one tooth on the pinion
48p: 78t spur, 35t pinion=2.228:1
.062 difference
Convert to 64p
64p 104t spur, 48t pinion still=2.166
go down one tooth on the pinion
64p: 104t spur, 47t pinion now=2.212
.046 difference

No matter the pitch, a greater change is made from one tooth on the pinion than one tooth on the spur.
60/40=1.5
60/39=1.538 (+.038)
61/40=1.525 (+.025)
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Old 02-02-2013, 11:32 PM   #3
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Quote:
Originally Posted by Jez81 View Post
Hi,
Im wondering if anyone can clarify a few questions i have about pinion / spur sizes.

-Does a 36t 48p pinion put more strain on a motor than a 36t 64p pinion?
reason for asking: a much lower fdr can be achieved using a 36t 48p pinion, so why would you use 64p pinions. If they are different, does anyone know what the equivalent size pinions from 48p to 64p?

-A range of FDR's can be achieved from the use of different spurs when using 1 particular pinion, Is it more beneficial to use the smallest spur that will fit the pinion or the biggest? Does the spur size affect the motor temps like pinion size?

I'm using a TC6.1 so even if you could post ur pinion/spur size and motor turn it would be helpful. Only really interested in 13.5, 17.5 and 21.5.

Thanks
64p is a finer pitch. So a 36t pinion in 64p will be smaller. However they ofcourse don't fit on the same spur.

Yes spur size does affect motor temps and speed just like a pinion does. You have to think of both. Bigger pinion has the same effect as changing to a smaller spur.

64pitch runs smoother and you have more options since its finer. The disadvantage is that it is weaker than a 48p.
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Old 02-03-2013, 12:33 AM   #4
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thanks very much,
you were both of great help.

What i meant Jeckler was the lowest fdr u can achieve with a 36t 64p pinion and spur is 5.5 as the chart says any smaller than a 100t spur and they wouldnt mesh.
Where the 36t 48p has much lower possible 'meshs'

maybe this is different for other cars, but that is what the manual says.. (''Blank spaces in the charts designates a gear ratio that will not fit in the vehicle'')

But you both answered my questions so im all good.

Thanks
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Old 03-08-2013, 10:51 AM   #5
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Default Which pinion

Guys

I need pinion 22 or 23t for spur 48p 81t, and not sure what will fit.
Can you help me to found it in http://www.tqrcracing.com/shop/produ...Pinion&pg_no=1

I have a big order in the cart and want to add the pinion before order it.

That's
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Old 03-08-2013, 11:44 AM   #6
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This is the correct 23t pinion gear to match that spur gear if you have a 540 size motor. http://www.tqrcracing.com/shop/produ...w.asp?p_id=151


Quote:
Originally Posted by kavee View Post
Guys

I need pinion 22 or 23t for spur 48p 81t, and not sure what will fit.
Can you help me to found it in http://www.tqrcracing.com/shop/produ...Pinion&pg_no=1

I have a big order in the cart and want to add the pinion before order it.

That's
Eran
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Old 03-08-2013, 12:16 PM   #7
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Simple math.

nTeeth/pitch * pitch = converted gear of the same diameter

75 tooth 48 pitch/48 * 64 = 100 tooth 64 pitch

48 pitch 75 tooth spur is the same diameter as a 64 pitch 100 tooth spur.
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Old 03-09-2013, 05:55 AM   #8
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Originally Posted by anr211 View Post
This is the correct 23t pinion gear to match that spur gear if you have a 540 size motor. http://www.tqrcracing.com/shop/produ...w.asp?p_id=151

I'll have this motor :

http://www.hobbyking.com/hobbyking/s...dProduct=22598

Will it fit?

Thanks
Eran
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Old 03-09-2013, 09:46 AM   #9
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A few things for the OP (original poster)

- Since you are running a TC6 (TC6.1), I would suggest posting/looking through the TC6 thread here on RCTECH - (http://www.rctech.net/forum/electric...c6-thread.html). Other people running your car should be able to answer specific questions.

- RC manuals don't always include every possible spur/pinion possibility (usually due to limited space in the manual). It appears that the TC6.1 manual page 27 has a fairly large chart, but it doesn't include every available pinion or spur sizes. (http://www.teamassociated.com/pdf/ca...1ft_manual.pdf)

- To go with the above point, some people modify their motor mounts and/or buy aftermarket motor mounts which allow for additional gearing options.

- There have been many online discussions about the mechanical advantages (for the motor) of running different size spur/pinion gears. Some think that you should run the biggest spur possible and others think that a ratio is a ratio. The one thing most people agree on is the size of the spur can affect motor placement on the car - which has an affect on the balance of the car. This can be used as a tuning aid.

- Here are some links to companies that make r/c gears
(http://www.robinsonracing.com/tips.html)
(http://www.precisionracingsystems.co.../About-Us.html)
(http://kimbroughracingproducts.com/s...view&page_id=3)

Other manufacturers sell assorted gears such as HPI, Tamiya, Trinity. Some chassis manufacturers make specific spur gears for their cars due to proprietary design.

- Here is a link to a basic (101) video on youtube by Horizon Hobby that discusses most of the basics about gearing on r/c cars. It is a good video for someone new to the hobby. (http://www.youtube.com/watch?v=IevcWhk_7es)
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