1st Generation Dodge Cummins 89-93 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with Rotary Injection Pumps

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Old Mar 31, 2010 | 10:40 PM
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Default Getrag

hey guys im still learning all this getrag stuff, and iv been trying to get my mileage up. it turns out that my tranny is a 4spd with granny, i was wondering if they put od in em. bc im averaging 15mpg empty runnin 30 miles to school and driving in town and then driving back and going to work. on long drives where i get to level it out i get about 17mpg. thats with the cruise. and 2 days ago i counted my differential gears and it turns out that i have 3.54. so anybody have a good but kinda cheap idea? and would 75hp injectors help my mpg at all?
 
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Old Mar 31, 2010 | 10:43 PM
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Unless someone swapped in another tranny (unlikely) your getrag is an OD tranny...

The gears are....

1st: 5.531
2nd: 3.017
3rd: 1.60
4th: 1.0
5th: 0.77
Reverse: 5.029

Bump your timing 1/8" and you should pick up a mpg or two.
 
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Old Mar 31, 2010 | 10:44 PM
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so your a 5 speed getrag or an auto?
 
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Old Mar 31, 2010 | 10:54 PM
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its a 5 speed. and it only runs like 12 or 15 mph in first, is hat normal?
 
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Old Mar 31, 2010 | 11:08 PM
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mine only does like 4 or 5 mph in 1st. 2nd gear will do 12 or 15. if you count first gear as granny and 2nd as 1st, thats normal. but these arent known as a granny transmission, just a 5 speed OD manual
 
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Old Mar 31, 2010 | 11:26 PM
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Originally Posted by BIGREDGOAT
its a 5 speed. and it only runs like 12 or 15 mph in first, is hat normal?
crawl under that sucker and look the trany should say GETRAG casted in the case
should look something like this
 

Last edited by big bad diesel 416; Mar 31, 2010 at 11:29 PM.
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Old Apr 1, 2010 | 08:01 AM
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since it has od then it should be able to get over 80mph. thats my top speed.
 
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Old Apr 1, 2010 | 08:29 AM
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91.7mph!!

haha I have the same setup. I would suggest a 366 governor spring, it will be a HUGE help on the highway.

does anyone use first? I did once towing when I started on a steep hill but that was the only time.
 
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Old Apr 1, 2010 | 09:38 AM
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im trying to find out how to lower my rpm's, is the nv4500 differently geared?
 
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Old Apr 1, 2010 | 03:30 PM
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it would be easier to change the rear end ratio
 
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