FW: [Chrysler300] Rear End 300F-MORE fUN WITH NUMBERS

["Rich Barber" <c300@xxxxxxx>]

Not to beat this to death, but for clarity:  High gear is direct drive
through the transmission on all of our '55-'72 300's, letter or sport,
PowerFlite, TorqueFlite or stick.  Engine speed might be slightly higher
than driveshaft speed in high gear due to torque converter slip.  The
driveshaft rotates MUCH FASTER than the rear axles.  The differential ratio
is the ratio of the number of teeth in the ring gear (axles) to the number
of teeth on the pinion gear (driveshaft) and thus is the ratio of driveshaft
speed to axle speed in RPM.  The higher the ratio, the slower the axle speed
for a given engine RPM.  

 

300's prepared for drag racing would have a high ratio rear end to enable
maximum power development at lower car speed.  300's prepared for best
economy would have lower ratio rear ends to slow the engine down at cruising
speed.  300's prepared for maximum speed runs would have a rear end ratio
enabling  the engine to develop maximum horsepower at the point where the
horsepower required and the horsepower required curves intersect.  Example:
the 1955 Chrysler 300 hemi is rated for maximum horsepower at 5,200 RPM.  At
5,200 RPM, 3.54 axle and a 29.1" OD 8.00x15 Goodyear Blue Streak tire, speed
would be 127.2 MPH.  This is very close to the 127.58 MPH top speed
accomplished at Daytona in the flying mile in 1955, making it numero uno in
American stock cars that year.  

 

I have found it interesting that the Chrysler hemi and the Cadillac V-8 of
1955 had the same 331 cubic inch displacement (and the same bore and stroke)
and had the same horsepower rating of 250 HP at 4,600 RPM with a single
4-bbl carb and hydraulic valve lifters.  The Cadillac Eldorado engine was
rated at 270 HP @ 4,800 RPM with hydraulic lifters and dual quad
carbs-gaining 20 HP with the dual quads and perhaps a performance camshaft.
The hemi engines in the '55 300's had solid lifters which enabled the hemi
engine to rev to 5,200 RPM without valve float.  The higher RPM added about
33 HP and the dual quads and the performance cam added the additional 17 HP
to make the magic 300 HP level.  As a teen, I noted the collective gasp of
car guys and the public in general when they found out they could buy an
American luxury coupe with 300 HORSEPOWER right off the dealer's floor.
1,725 did and the rest is history.

 

C-300K'ly,

Rich Barber

Brentwood, CA

1955 C-300, 1964 300K Conv.(Tomorrow??)

 

From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On
Behalf Of The Richardson Family
Sent: Sunday, August 28, 2011 8:17 AM
To: Chrysler300@xxxxxxxxxxxxxxx
Subject: Fw: [Chrysler300] Rear End 300F-fUN WITH NUMBERS

 

  

The math seems to make sense but, that's assuming the final drive through
the transmission is a 1:1 ratio. I don't think that's right, is it?

On a limited slip - turn the drive shaft 1 complete rotation and count the
revolutions of the wheel - that should give you the correct rear end ratio -
or is it the other way around? I don't recall exactly but, I do remember
getting 3.55:1 on my "Letter L", which is the pumpkin that was installed by
my Stepfather. That's as much as I can contribute to confuse things.....

Dan Richardson
300L Family Heirloom

----- Original Message ----- 
From: Rich Barber 
To: 'jean-yves chouinard' ; chrysler300@xxxxxxxxxxxxxxx
<mailto:chrysler300%40yahoogroups.com>  ; 'Thomas Cox' 
Sent: Sunday, August 28, 2011 1:31 AM
Subject: RE: [Chrysler300] Rear End 300F-fUN WITH NUMBERS

I've spotted a reference for the 9.00 X 14 tire on the 300F as having an OD
of 28.68". 

Assuming no slippage:

MPH=(3,000*Pi*28.68*60)/(3.23*12*5280)=79.2 MPH. 

RPM @ 60 mph=2,273 RPM

Axle Ratio to give 60 MPH @ 3,000 RPM: 4.26 One reference says the
available ratios ranged from 2.73 to 3.91.

From: Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com>
[mailto:Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com> ]
On
Behalf Of jean-yves chouinard
Sent: Saturday, August 27, 2011 4:27 PM
To: chrysler300@xxxxxxxxxxxxxxx <mailto:chrysler300%40yahoogroups.com> ;
Thomas Cox
Subject: Re: [Chrysler300] Rear End 300F

I could be wrong here, but isn't the 300F rear end ratio 3:31 to 1 ?
And the 300G ratio 3:23 to 1?? 
I know , not a huge difference...and I agree with Don , 3000 rpm seems high
at just 60mph...
Jean-Yves

----- Original Message ----- 
From: Thomas Cox 
To: chrysler300@xxxxxxxxxxxxxxx <mailto:chrysler300%40yahoogroups.com>
<mailto:chrysler300%40yahoogroups.com> 
Sent: Thursday, August 25, 2011 8:48 PM
Subject: [Chrysler300] Rear End 300F

At 60 mph, I am running about 3,000 rpm. Is this to be expected with a 3.23
rear 
end? I wonder if I have the correct "chunk" in the F rear end.

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