Gear Ratio Question
02-13-2009, 05:49 PM
#2
your rpo codes which are in the center console or in the storage box lid, behind the seats. You can also climb under and look at the tag on the pumpkin. iDo you have stick or auto?
02-13-2009, 08:28 PM
#3
Racer
Member Since: Apr 2008
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Gear ratios
Old school way...
Raise the rear of the car, mark the rear end and drive shaft, rotate the rear wheels untill the marks turn 2 revolutions, and count the times the tires rotate. Three and three quarter turns of the rear wheel equals equal 3.73 gears, three turns equal 3.08 gears, three and a half turns equals 3.55 gears, 4 turns equals 4.10 gears etc., etc...
I think you get the idea. So simple it seems too easy to be true, but think about it...it'll soon make a whole lot of sense.
Raise the rear of the car, mark the rear end and drive shaft, rotate the rear wheels untill the marks turn 2 revolutions, and count the times the tires rotate. Three and three quarter turns of the rear wheel equals equal 3.73 gears, three turns equal 3.08 gears, three and a half turns equals 3.55 gears, 4 turns equals 4.10 gears etc., etc...
I think you get the idea. So simple it seems too easy to be true, but think about it...it'll soon make a whole lot of sense.
02-15-2009, 08:00 AM
#5
Le Mans Master
Member Since: Oct 2004
Location: South-central Missouri
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Say what???
Must be the way I interpreted what that says (to me). But, the fact is, input (pinion) rotation to output (tire) rotation gives the ratio: 4.11:1 is 4.11 drive shaft rotations to one tire** rotation.
**Now, if only one rear tire is lifted off the ground AND the rear end is not a limited slip (a la C4 Corvettes), the resulting rotation of the one lifted wheel will be double that of what it would be when both wheels are on the ground.
The way I do it on a limited slip diff (both rear wheels turning together) is to mark the drive shaft and rear wheel, rotate the rear wheel one complete rotation and count the number of turns the drive shaft makes: 4.11 rotations of the drive shaft for one turn of the rear wheels is (of course) 4.11:1, or 3 turns is approx a 3.09 rear gear, etc.
On a standard car without a limited slip diff, if one rear wheel (for any reason) is held still, then the spiders in the differential will end up halving the normal carrier rotation in respect to wheel rotation, and therefore will require two rotations of the one free wheel to get the correct drive shaft rotations to determine gear ratio. (Note: Even when both rear wheels are lifted on a standard (non-limited slip) diff, the slightest difference in rotating friction can upset the measurement. So, one has to be careful to see to it both rear wheels are synchronized for the full (one) rotation.
Now, mebby you were saying the same thing, but it didn't read that way (to me
) FWIW.
P.
02-15-2009, 07:18 PM
#7
