RE: [Chrysler300] RE: Teck question 1960 300f

[Anthony Rinaldi <awrdoc@xxxxxxxxx>]

1960 service manual indicates 19 teeth for a 300-F. 

On Sun Dec 20th, 2009 8:44 PM EST Richard Barber wrote:

>Transmission Speedometer Pinion Charts show the proper driven gear as
>dependent on tire size and differential ratio.  It seems a common goal was
>to spin the speedo cable at 1,000 RPM at 60 MPH.  If these assumptions are
>accurate, driveshaft speed at 60 MPH can be calculated as follows: 
>RPM=(5,280 x 12 x R)/(Pi x D) where R is rear end ratio, Pi is 3.141592654,
>and D is the OD of the rear tires (inches).  Simplified, driveshaft RPM at
>60 MPH = (20,168 x R)/D.  
>
>Gil Cunningham's table of tires at our website indicates the proper tire for
>a 300 F is a 9.00 x 14.  The current Coker Tire catalog shows a 9.00 x 14
>tire diameter as 28.68".  With a 2.93 axle, this would give RPM at 60
>MPH=(20,168 x 2.93)/28.68=2,060 RPM.  This seems about right if Chrysler was
>aiming for 2,000 RPM driveshaft speed at 60 MPH.
>
>Now, the question is how many teeth are there on the driving gear (the worm
>gear on the transmission output shaft)?  My 1955-58 Chrysler Parts Manual
>has a table of Transmission Speedometer Pinions in section 21-85-0.
>Plugging and grinding with some catalog tire OD's, it appears the driving
>gear must have about 8 teeth.  If this is so, and if that nominal number
>carried forward to 1960, the number of teeth on the driven (pinion)
>speedometer gear of a 1960 300F is: 
>N=(8x 20.168 x R)/d, or N= 161.34 x R/ D.  For D=28.68 and R= 2.93, N=16.48
>or 16 teeth.  The Parts Manual specifies a 17-tooth pinion.
>
>Anyone have a 1960 Service manual to check out these calcs?
>
>BTW, there is a similar chart in the 1955 Chrysler Service Manual on page
>442 which shows the correct pinions to have two less teeth for all tire
>size/axle combo's.  Go figure.
>
>See this website for a speedo pinion gear calculator:
>http://www.bgsoflex.com/speedo1.html	 
>
>It is entirely possible that the 1,000 Revs/mile speedo head specification
>may vary and that the specification should be stamped or marked on each
>head.
>
>I hope you have as much fun with numbers as I have with this question.  As
>always, corrections and constructive criticism is always welcome.  Using
>this same math, and reviewing F engine specs showing HP peaks at 5,000-5,200
>RPM, it is calculated that an F would be doing 145.6 to 151.5 MPH at the
>peak HP RPM's.   How does that compare to actuals?  Pretty much uses up that
>150 MPH speedometer!
>
>Our 1955 C-300 with 29.08" OD 8.00 x 15's and  a 3.54 axle would be capable
>of 129.3 MPH at its max HP RPM of 5,200.  VERY close to the actual speeds
>achieved at Daytona.  I have no idea of what kind of torque converter
>slippage might be occurring in the old PowerFlites and TorqueFlites at those
>speeds.
>
>And, finally, tire OD's do not exactly translate to distance travel due to
>tread squirm and who-knows-what.  I have seen tables of revolutions per mile
>at a specified speed for some tires and they vary by tire construction.
>Also, that changing the driven speedometer gear by one tooth can change the
>speedo readout by about 7%, therefore the selection of pinion gear might
>result in 0-3.5% error, depending on how far off the computed number of
>teeth is from an integer.  i.e.--you can't create a 14.4 tooth driven gear.
>At 150 MPH, the basic error might be as much as 5 MPH!  Tell it to da judge.
>
>Part number 1636406 for a 17 tooth pinion or 1732113 for a 16 tooth pinion
>gear.  These part numbers may only be valid for the 1955-58 trannys, but I
>suspect they will work on TorqueFlites into the '60's.  They are found in
>section 21-85-0 Transmission Speedometer Pinion and come in 16-21 tooth
>versions.
>
>As a Christmas gift TO YOU , I have recreated the data in the Parts Manual
>below.
>
>Tire 		AXLE RATIOS
>Size		2.93	3.07	3.15/3.18	3.31/3.36	3.54	3.73
>3.90
>8.00x15		17			18		19	20	21
>8.20x15		17			18		19	20	21
>8.90x15		17			17		18
>7.50x14	17		19		20		21	21	21
>8.00x14	17		19		20		21	21	21
>
>8.50x14	17		18		19		20	21	21
>9.00x14	17		18		19		20	21	21
>
>9.50x14	16		18		19		20	21	21
>
>11.00x14	16		17		17		ILLEGIBLE
>
>Merry C-300'ly Christmas
>Rich Barber (16 teeth, each jaw)
>Brentwood, CA
>1955 Chrysler C-300 (17 tooth pinion according to the 1955 Chrysler Service
>Manual, 19-tooth according to 1955-58 Chrysler Parts Manual--ahh, Chrysler's
>inconsistencies)
> 
>-----Original Message-----
>From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On
>Behalf Of LOUISENYLA@xxxxxxx
>Sent: Saturday, December 19, 2009 7:44 AM
>To: Chrysler300@xxxxxxxxxxxxxxx
>Subject: [Chrysler300] RE: Teck question 1960 300f
>
>Good Morning to all the members:
> 
>I know somewhere out there in 300 land someone knows the answer to  this:
> 
>What is the proper tooth number for the driven Speedo  gear in a 1960  300 
>F  with a 2.93 rear?
> 
>I know someone out there has the answer thanks to all.
> 
>Teddy  
> 
>
>
>[Non-text portions of this message have been removed]
>
>
>
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>



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