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Old 02-12-2014, 06:11 PM   #1
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Default Internal gear ratio...how?

Trying to figure out how/the formula one uses to get the internal ratio of a transmission...for example, a TL01 has a internal ratio of 4.47 but where does that number come from? TL01 has 3 total gears with two different tooth sizes...motor drives a 32T/24T counter gear that spins the 52T spur, which in turn spins a 19T to drive the 39T diff. Anybody?
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Old 02-12-2014, 06:24 PM   #2
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In most TC's it's the size of the main diff's etc divided by the centre pulley (which the spur attaches to)
In the current Xray's, we use a 38t pulley for the diffs etc and a 20t centre pulley.
divide 38/20 and we arrive at 1.9, the internal ratio.

I'm not sure how the transmission on the car you're talking about works so it's not easy to understand the ratio's

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Old 02-12-2014, 06:31 PM   #3
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Originally Posted by Skiddins View Post
In most TC's it's the size of the main diff's etc divided by the centre pulley (which the spur attaches to)
In the current Xray's, we use a 38t pulley for the diffs etc and a 20t centre pulley.
divide 38/20 and we arrive at 1.9, the internal ratio.

I'm not sure how the transmission on the car you're talking about works so it's not easy to understand the ratio's

Skiddins
Yea...modern tourers make is simple as there's all but a pulley/counter and diff but I was wondering how it worked on older vehilces with multiple gears...son is writing a paper on internal gear ratios and I thought it would be a simple equation but with multiple gears and different teeth per gear, i'm not certain. I'm sure there are some engineers/math techs who would know around here though.
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Old 02-12-2014, 06:33 PM   #4
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Originally Posted by ta03 tuner View Post
Yea...modern tourers make is simple as there's all but a pulley/counter and diff but I was wondering how it worked on older vehilces with multiple gears...son is writing a paper on internal gear ratios and I thought it would be a simple equation but with multiple gears and different teeth per gear, i'm not certain. I'm sure there are some engineers/math techs who would know around here though.
here is a pretty good synopsis on the subject http://www.teamassociated.com/pdf/ca...ear_ratios.pdf
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Old 02-12-2014, 06:37 PM   #5
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here is a pretty good synopsis on the subject http://www.teamassociated.com/pdf/ca...ear_ratios.pdf
Yea...read that but for the life of me, could not get to that magical number of 4.447...another stickler is that the counter/spur are 42 pitch metric but the main diff gear is 32 pitch...wonder if that factors in.
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Old 02-12-2014, 07:26 PM   #6
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(39/19) * (52/24)

How's that sound? I'm not sure how the transmission looks besides your description, but the math works.

Pitch doesn't matter, just tooth counts.
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Old 02-12-2014, 07:31 PM   #7
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(39/19) * (52/24)

How's that sound? I'm not sure how the transmission looks besides your description, but the math works.

Pitch doesn't matter, just tooth counts.
DING DING DING DING DING!!! We have a winner!! Nice job samnelso!!!
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Old 02-12-2014, 07:39 PM   #8
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Yea...read that but for the life of me, could not get to that magical number of 4.447...another stickler is that the counter/spur are 42 pitch metric but the main diff gear is 32 pitch...wonder if that factors in.
Looking at the pics in the manual and which gear meshes with which, I get

52/24*39/19 = 4.44736......... The 32t is actually the spur that meshes with the motor pinion so I didn't use that to find the internal ratio.

Different pitch gear doesn't affect the ratio calculation. Only the number of teeth do.

HTH

Oh guess I took too long looking at the manual. Lol
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Old 02-12-2014, 07:57 PM   #9
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Looking at the pics in the manual and which gear meshes with which, I get

52/24*39/19 = 4.44736......... The 32t is actually the spur that meshes with the motor pinion so I didn't use that to find the internal ratio.

Different pitch gear doesn't affect the ratio calculation. Only the number of teeth do.

HTH

Oh guess I took too long looking at the manual. Lol
Nonetheless, thank you also!
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