To: 1962to1965mopars@xxxxxxxxxx
From: waedison@xxxxxxxxxxx
Subject: Re: Rear-end gear ratios
Date: Wed, 25 Feb 2009 16:36:56 +0000
Thanks Don! This is a great topic for a lot of us. If you have a gps unit
in your car, even a portable one like mine, it shows mph and seems to be
really close. Eliminates having to have two vehicles involved and having
to work the variances on two speedos. /Butch/ Ferndale, WA
----- Original Message -----
From: "Don Dulmage" <big-d@xxxxxxxxxxxx>
To: 1962to1965mopars@xxxxxxxxxx
Sent: Wednesday, February 25, 2009 5:42:54 AM GMT -08:00 US/Canada
Pacific
Subject: Re: Rear-end gear ratios
Why not go for a drive. take the RPM and the MPh and just do the math. I
would have someone veryiythe speedo witha neewer car. I get My wife to
check
ine with her PT cruiser. I tell her to drive at 50 MPH which she will do
exactly and then follow and check mine. I correct my speedo error mentaly
After that read the tach . Do the math for the rear tire rollout. Work
that
back into the fifty MPH which will give you axle rpm per hour . divide
that
by sixty for axel RPM per minute. Divide that into engine RPM and Bingo!
minus a tu iny bit of torqueconverter slip you will have the number.
Since
gear ratios are only available in steps it is a simple matter then to
figure
out which one you have.
I know it seems like a bigdeal since we mostlyhate math but in fact a
matter
of minutes will do it. Certainly less time than to jack up the car.
Don
ie 28 inch tire rolls 87.92 inches per revolution. or 7.3266 feet
50 MPH is 50 X 5280 which is 264000 feet per hour divided by 60 which is
4400 feet per minute.
sincethetire rolls 7.3266 feet per revolution and 50MP is 4400 feet per
minute then 4400/7.3266= 600Axle RPM
if the engine is turning 2500 RPM at 50 then 2500/600=
4.1666666666666666
gear ratio. Since the nearestpossible gearratio is 4.30 then we know this
car has 4.30s. It could not be 4.10s because you cannont invent speedonly
ose a bit to driveline inefficiency.
Now i have only had one coffee today so my math may need correction but
the
idea is right. It is based on the same way we figure Gear ratio and speed
for racing except just working from the other end.
----- Original Message -----
Don
From: "SB" <polecat2@xxxxxxxx>
To: <1962to1965mopars@xxxxxxxxxx>
Sent: Tuesday, February 24, 2009 11:24 PM
Subject: RE: Rear-end gear ratios
>
> I'm working on an all-original '64 Dodge Polara 500, 383 2 barrel car
> right now. It has its original 3:23 sure grip.
>
>
> mikelj@xxxxxxx wrote:
>>
>>
>>
>> I am curious what the gear ratio is for the rear-end of my '64 Dodge
>> Polara 500. I can't find anything about that on the window sticker,
>> build-sheet, tag, etc. It seems like it is around 3:00, and I am sure
>> they didn't have many choices in the mundane 383 2 bbl. TorqueFlight
>> setup. Anyone know?
>
>
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>
----
Please address private mail -- mail of interest to only one person --
directly to that person. I.e., send parts/car transactions and
negotiations as well as other personal messages only to the intended
recipient, not to the Clubhouse public address. This practice will
protect your privacy, reduce the total volume of mail and fine tune the
content signal to Mopar topic. Thanks!
'62 to '65 Mopar Clubhouse Discussion Guidelines:
http://www.1962to1965mopar.ornocar.org/mletiq.html.
[Non-text portions of this message have been removed]
----
Please address private mail -- mail of interest to only one person --
directly to that person. I.e., send parts/car transactions and
negotiations as well as other personal messages only to the intended
recipient, not to the Clubhouse public address. This practice will
protect your privacy, reduce the total volume of mail and fine tune the
content signal to Mopar topic. Thanks!
'62 to '65 Mopar Clubhouse Discussion Guidelines:
http://www.1962to1965mopar.ornocar.org/mletiq.html.
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