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Old 10-17-2012, 11:19 AM   #211
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Question on gearing. Does it really matter the size of the pinion and spur? What I mean is, asside from the rollout, does running a 80t spur with a 40t pinion make it perform differantly than say a 88t spur and a 44t pinion. I would think it's exactly the same but someone at the track said differantly.
And I am getting the CRC 16 x 3/32 ball spur gears. You run all 16 smaller balls, correct?
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Old 10-17-2012, 12:54 PM   #212
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Question on gearing. Does it really matter the size of the pinion and spur? What I mean is, asside from the rollout, does running a 80t spur with a 40t pinion make it perform differantly than say a 88t spur and a 44t pinion. I would think it's exactly the same but someone at the track said differantly.
And I am getting the CRC 16 x 3/32 ball spur gears. You run all 16 smaller balls, correct?
Back in the brushed motor days we would run as large of spur gear as possible
Now days with brushless, it's not so important as it was, and the gear options are more limited due to the huge rollouts necessary

So yes, and no
You run all the balls on the outside row
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Old 10-17-2012, 01:31 PM   #213
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Question on gearing. Does it really matter the size of the pinion and spur? What I mean is, asside from the rollout, does running a 80t spur with a 40t pinion make it perform differantly than say a 88t spur and a 44t pinion. I would think it's exactly the same but someone at the track said differantly.
Yes it does make a difference, but not how you might think. With a bigger spur/pinion size you are mounting the motor further forward in the pod and nearer the pivot, so it accelerates and decelerates faster which means smoother pod movement. The motor near the axle and away from the pivot needs more force to get the pod moving and is harder to stop moving.

A quote from David Spashett:
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In what I have done in the past, moving the motor away from the axle so larger spur and gear always felt easier to control on and off throttle, smoother to drive. Smaller spurs and pinions so motor closer to the axle gave more drive, more turn in and generally more aggressive to drive. As to all the correct reasons why I really don't know as there is so much going on sorry.
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Old 10-17-2012, 03:34 PM   #214
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You guys all rock.
Thanks.
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Old 10-17-2012, 09:02 PM   #215
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Question on gearing. Does it really matter the size of the pinion and spur? What I mean is, asside from the rollout, does running a 80t spur with a 40t pinion make it perform differantly than say a 88t spur and a 44t pinion. I would think it's exactly the same but someone at the track said differantly.
And I am getting the CRC 16 x 3/32 ball spur gears. You run all 16 smaller balls, correct?
A larger spur gear allows you to make more minute (smaller) gearing changes when changing the pinion's tooth count. I almost always run an 88T 64 pitch spur to this end; but, also carry a 90T spur for in between gearing.

Testing, testing, testing will give you a good rollout range for racing. Testing is your friend...When I was more serious about improving my car setup (and driving), I tested at least twice as much as I raced.

And I do run the spur gears with the 3/16" balls (16); but, be very careful to not bottom out your adjustment nut on the axle threads. This can pull the threaded piece out of the graphite axle. Using Brian Bodine's Slapmaster Thrust Bearing Assembly is the cat's meow in my book. And Brian can help you pick the proper width assembly for your application...3/16" balls take a wider spacer than 1/8" balls.

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Old 10-17-2012, 09:46 PM   #216
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Very important for you to use a flangeless bearing in the CRC spur gears for correct spacing with the smaller balls.
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Old 10-17-2012, 10:33 PM   #217
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Very important for you to use a flangeless bearing in the CRC spur gears for correct spacing with the smaller balls.
CRC manuals always show unflanged bearings in the spur.

Is there any reason to run a flanged bearing in a spur gear?

Negatives: more cost; heavier; contrary to instructions.

I cannot think of one positive; but, could be uninformed...Not a first...LOL

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Old 10-17-2012, 11:10 PM   #218
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CRC manuals always show unflanged bearings in the spur.

Is there any reason to run a flanged bearing in a spur gear?

Negatives: more cost; heavier; contrary to instructions.

I cannot think of one positive; but, could be uninformed...Not a first...LOL

Bill
Many people use flanged bearings, probably just because they have them. In a gear with 1/8 balls it will work OK, but with the 3/32 balls in the CRC gears, it's too wide and the diff won't tighten properly. So, I just put it out as a warning, that you MUST use an unflanged bearing in a CRC gear for it to work.
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Old 10-17-2012, 11:29 PM   #219
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Many people use flanged bearings, probably just because they have them. In a gear with 1/8 balls it will work OK, but with the 3/32 balls in the CRC gears, it's too wide and the diff won't tighten properly. So, I just put it out as a warning, that you MUST use an unflanged bearing in a CRC gear for it to work.
When you use a flanged bearing on a 1/8" ball spur gear, does the flange have to be in a certain direction? Guessing it has to be towards the inside. Still pondering this...LOL

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Old 10-17-2012, 11:42 PM   #220
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Your right. It doesn't tighten down. The bearings inside the diff are not flanged either. I may need to look ad a Crc instruction download.
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Old 10-17-2012, 11:57 PM   #221
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When you use a flanged bearing on a 1/8" ball spur gear, does the flange have to be in a certain direction? Guessing it has to be towards the inside. Still pondering this...LOL

Bill
If I were using a flanged bearing (and I'm not, though I know people who do) Then I would put it to the inside so that it would not rub on the hub bearing.
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Old 10-18-2012, 12:01 AM   #222
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If I were using a flanged bearing (and I'm not, though I know people who do) Then I would put it to the inside so that it would not rub on the hub bearing.
Makes sense! I may try that.

Thanks.

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Old 10-18-2012, 12:05 AM   #223
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Your right. It doesn't tighten down. The bearings inside the diff are not flanged either. I may need to look ad a Crc instruction download.
If you are using the standard CRC parts, you can add a washer on top of the spacer to increase the clearance. Otherwise, the Slapmaster Thrust Bearing assembly (with a wider spacer) is a cleaner solution. www.slapmastertools.com

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Old 10-18-2012, 12:12 AM   #224
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IRS axles come with a flanged bearing for the diff gear and can be used with either flanged or unflanged. Flanged will certainly not work with the CRC diff.
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Old 10-18-2012, 12:13 AM   #225
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What happed with me just now is that the nut did not fully bottom out. The diff action started to lock up but the gear was still just spinning.
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