[DeTomaso] Taller 5th gear for cruise

Mad Dog Antenucci teampantera at yahoo.com
Thu Jun 17 23:18:05 EDT 2010


Good argument IF you have a wimpy engine ;-)> or don't or won't miss the 'hole-shot' that the 4.22 gear provides.  
 
Mad Dawg Antenucci 
Team Pantera Racing 
The 1st & still the only vintage race team in open road racing 
www.teampanteraracing.com




________________________________
From: P. Rimov <rimov at charter.net>
To: Will Demelo <wdemelo at cogeco.ca>; Daniel C Jones <daniel.c.jones2 at gmail.com>; Pantera REALBIG forum <detomaso at realbig.com>
Sent: Thu, June 17, 2010 3:37:20 PM
Subject: Re: [DeTomaso] Taller 5th gear for cruise

I would have to second Will's recommendation of sticking with the stock 
fifth and going with the 3.77:1. Granted I had a pretty wimpy C-engine, some 
guy I know  but it was just amazing the difference going from the 4.22:1 to 
the 3:77:1. I could run out first gear way farther, there was absolutely no 
gear noise and I found I could cruise in 4th or 5th at highway speeds. What 
ever speed I drove I always felt I had the right gear available.

Cheers

Paul
----- Original Message ----- 
From: "Will Demelo" <wdemelo at cogeco.ca>
To: "Daniel C Jones" <daniel.c.jones2 at gmail.com>; "Pantera REALBIG forum" 
<detomaso at realbig.com>
Sent: Thursday, June 17, 2010 2:10 PM
Subject: Re: [DeTomaso] Taller 5th gear for cruise


>I have the 3.77 and .655 fifth gear. I find it a little sluggish at 75mph
> with a 393 stroker. I don't recommend going any taller on the fifth. The
> 3.77 r&p is amazing.
> Will
>
> ----- Original Message ----- 
> From: "Daniel C Jones" <daniel.c.jones2 at gmail.com>
> To: "Pantera REALBIG forum" <detomaso at realbig.com>
> Sent: Thursday, June 17, 2010 3:41 PM
> Subject: [DeTomaso] Taller 5th gear for cruise
>
>
>> I've decide to have a taller 5th gear installed in the red Pantera's
>> transaxle.  The standard 5th gear is 0.705.  The optional 5th gear
>> ratios are:
>>
>>  0.655
>>  0.642
>>  0.620
>>
>> The tallest 5th gear with the standard ring and pinion is very similar
>> to the standard 5th gear with the 3.77:1 ring and pinion:
>>
>> 0.620 * 4.22 = 2.61640
>> 0.705 * 3.77 = 2.65785
>>
>> I ran some numbers assuming:
>>
>> 335/35/17 tires
>> 4.22:1 final drive ratio
>> current gear ratios
>>  1st 2.23
>>  2nd 1.47
>>  3rd 1.04
>>  4th .846
>>  5th .705, 0.655, 0.642, 0.620
>>
>> Speed  Ratio  RPM
>> 80 MPH  .705  3050
>> 80 MPH  .655  2834
>> 80 MPH  .642  2777
>> 80 MPH  .620  2682
>> 70 MPH  .620  2347
>> 60 MPH  .620  2011
>> 60 MPH  .642  2089
>> 60 MPH  .655  2125
>> 60 MPH  .846  2745
>>
>> Typical highway cruise speed is 75 to 80 MPH.  The engine is a 407
>> Fontana with C302B heads and IR EFI.  Looks like I should be able
>> pull the 0.620 gear at 80 MPH.  It might be sluggish at 60 MPH but
>> there's not much difference in RPM between the three gears at that
>> speed so I'm leaning towards the 0.620 gear.  I can always drop
>> back to 4th at 60 MPH which would be 2745 RPM.  Any thoughts?
>>
>> Dan Jones
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