"ghosty - electric space wizard" (gh0sty501)
03/04/2014 at 22:16 • Filed to: None
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"ghosty - electric space wizard" (gh0sty501)
03/04/2014 at 22:16 • Filed to: None | 0
| 7 |
If any of you read my earlier post today about removing my wing, you may have caught a small blurb about fixing my speedometer. Well I jacked up the car today to see what the ratio was between the rear axle and the driveshaft. When the rear axle spun 1 complete revolution, my driveshaft spun roughly 1.75-1.8 times. This make zero sense to me. Does anyone have a guess as to what I'm doing wrong?
vdub_nut: scooter snob
> ghosty - electric space wizard
03/04/2014 at 22:20 |
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Spin the driveshaft, count the amount of times it spins before the axle makes one revolution. The lowest I've seen on a regular car is 2.72.
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ghosty - electric space wizard
> vdub_nut: scooter snob
03/04/2014 at 22:24 |
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That is exactly what I did.
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vdub_nut: scooter snob
> ghosty - electric space wizard
03/04/2014 at 22:27 |
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It reads weird, sorry. Alternatively, google it. What make/model/year is it? Also, were both tires spinning at the same rate? If only one was spinning, or they were going at different rates, that would throw it off by up to 2x.
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ghosty - electric space wizard
> vdub_nut: scooter snob
03/04/2014 at 22:29 |
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No worries, sorry about the odd wording. It sounds like you're on to something. It's a 1998 Mustang GT. The GT's came with Posi rear differentials. So I assumed that only one wheel would need to spin. Is that where I made my mistake?
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vdub_nut: scooter snob
> ghosty - electric space wizard
03/04/2014 at 22:34 |
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If only one is spinning:
Posi my ass
it'll read "half of what it should be" : 1
Was the other wheel on the ground? If it was (or was somehow restrained totally from moving), just double the number.
Google says 2.73 : 1.
Source: I used to work on differential development at a Tier 1 supplier
Ramblin Rover - The Vivisector of Solihull
> ghosty - electric space wizard
03/04/2014 at 22:38 |
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Two remarks:
Limited slip is not no slip. Depending on type, it might be okay to block the other wheel and turn slowly, or to just turn the pinion not a wheel. If it's possible to turn them separately/ one can stay still, that's best. In that case, if one wheel turning works with one fixed, divide by two.
Second do more than one full rotation. It will give you a much better quotient to work with - enough turns and you might have two whole numbers to divide. Much more precise.
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ghosty - electric space wizard
> vdub_nut: scooter snob
03/04/2014 at 22:41 |
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One wheel was indeed on the ground. I don not believe the rear gears are stock, I'm fairly certain the previous owner swapped them if that's how you got the 2.73 from google. But going off of the 'multiply by 2' logic that'd put me right around 3.55 which is a very common swap for my vintage of Mustang. Thanks for the help!