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Ratio calculating
https://slantsix.org/forum/viewtopic.php?t=17821		 Page 1 of 1
Author:  RossKinder [ Wed May 31, 2006 11:49 am ]
Post subject:  Ratio calculating
This is pretty much a curiosity question. I finally found a Mopar yard in less than 90 miles driving distance. Since the rear end ratio tag on the one I was asking about was gone a guy did the mark-and-turn test. (He was referred to as one of the "2 best Mopar men" there and the owner's son, a nice helpful guy).

I had written down 2.93 on my ratio request, which I understand to be a standard ratio. His result was, and he enunciated this very distinctly several times, TWO NINE FOUR!

I've never done this to find a ratio. May I assume it isn't nearly a precision test and there was no reason to be so utterly specific as TWO NINE FOUR - as opposed to 2.93?
Author:  sandy in BC [ Wed May 31, 2006 11:51 am ]
Post subject: 
You are correct.
Author:  SlantSixDan [ Wed May 31, 2006 12:08 pm ]
Post subject: 
Depending on the year and the axle type, both 2.93 and 2.94 ratios were offered. Same goes for 3.21/3.23 and 3.54/3.55, 2.76/2.71...
Author:  RossKinder [ Wed May 31, 2006 8:35 pm ]
Post subject: 
Quote:
Depending on the year and the axle type, both 2.93 and 2.94 ratios were offered. Same goes for 3.21/3.23 and 3.54/3.55, 2.76/2.71...
Thanks. Just as identifiers, I hope.
Author:  RossKinder [ Wed May 31, 2006 8:36 pm ]
Post subject: 
Quote:
You are correct.
Thanks. I may yet turn out smarter than I look!
Author:  emsvitil [ Wed May 31, 2006 8:50 pm ]
Post subject: 
Quote:
Quote:
You are correct.
Thanks. I may yet turn out smarter than I look!
If that's your picture in your signature, I don't think it will be hard to be smarter than you look............

:twisted:
Author:  SlantSixDan [ Wed May 31, 2006 9:29 pm ]
Post subject: 
Quote:
Quote:
Depending on the year and the axle type, both 2.93 and 2.94 ratios were offered. Same goes for 3.21/3.23 and 3.54/3.55, 2.76/2.71...
Thanks. Just as identifiers, I hope.
As "identifiers"...? Huh? They were offered as actual ratios.
Author:  RossKinder [ Thu Jun 01, 2006 8:19 am ]
Post subject: 
Quote:
Quote:
Quote:
Depending on the year and the axle type, both 2.93 and 2.94 ratios were offered. Same goes for 3.21/3.23 and 3.54/3.55, 2.76/2.71...
Thanks. Just as identifiers, I hope.
As "identifiers"...? Huh? They were offered as actual ratios.
You add or subtract a tooth to change a ratio, right? It seems very odd to me that changing a whole tooth could give you anything nearly so fine as one hundredth in a ratio that short.

Thanks
Author:  SlantSixDan [ Thu Jun 01, 2006 9:05 am ]
Post subject: 
Quote:
You add or subtract a tooth to change a ratio, right?
No. The ratio is calculated by dividing the number of ring teeth by the number of pinion teeth. Therefore, depending on tooth size and pitch, there are numerous different ring tooth counts and pinion tooth counts that can be paired to arrive at any given ratio range (2.92, 2.93, 2.94, etc.)

For illustrative example, using numbers pulled out of the air and rounded off (because I don't have actual tooth count charts in front of me right now):

13 pinion teeth & 42 ring teeth = 3.23
15 pinion teeth & 48 ring teeth = 3.20
19 pinion teeth & 61 ring teeth = 3.21
22 pinion teeth & 71 ring teeth = 3.23

Etc.
Author:  RossKinder [ Thu Jun 01, 2006 2:58 pm ]
Post subject: 
Quote:
13 pinion teeth & 42 ring teeth = 3.23
15 pinion teeth & 48 ring teeth = 3.20
19 pinion teeth & 61 ring teeth = 3.21
22 pinion teeth & 71 ring teeth = 3.23

Etc.
I see what you're saying. Who on Earth would need to cut it that fine... Hey Joe! I've G-O-T to have a 3.54 instead of a 3.55!

Scene 998:<[Music under]; Ross walks away scratching head, while rubber burns in the background.>
Author:  emsvitil [ Thu Jun 01, 2006 3:54 pm ]
Post subject: 
Sometimes the 3.54 and 3.55 could be the same ratio and gears............

One place truncates the 3.545 to 3.54 and the other rounds up to 3.55..........
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