3.91 gears w/ 3.23 speedo

-
onehellofadart

onehellofadart

Well-Known Member
Joined
May 23, 2004
Messages
3,588
Reaction score
5
Location
Moonachie, N.J.
after my trip to a bodies only car b que the total mile on my new set up,(engine, trans, and rear) reached 1024 miles. i have 3.91 gears and my speedo is set up for 3.23 gears. does anyone know the conversion to find out my true mileage. also at 3k and 4k rpms what would my true mph be? also when can i start useing a synthetic oil, or oil additive like lucas in my motor? i plan on doing an oil change this comming weekend.
 
why don't you just get the right spedo gear... they are cheap and really easy to install....
 
Yeah thats what I would do, or should do :D

I would find out wich gear you need for 3.91 gears and G60-15s. They should be the same hieght tire so it should work perfect.
 
Whats the right speedon gear for a 8 3/4 with 4.56's i hav now a stock open 7 1/4 with 2.73's :scratch:
 
you are good for synthetic oil now. My builder said after 300 or 400 miles your good for a synthetic.
 
i had my dart out last night.. it has 245/60/14 tires on it and i was doing about 50mph at just under 3000 rpm. the spedo seems pretty damn close. not sure how accurate the tach is though....

here is a couple charts. the link goes by how tall your tire is and the pic. is tire sizes...

http://www.moparts.org/moparts/tech/pages/speedo.html







spedo%20gear%20chart.jpg


spedo%20gear%20chart.jpg
 
Zombie the right gear depends on tire size and gearing.
Becuase 4.56 werent factory offered you"ll need to do some math and figure out what tire size and gear combo will rev like your 4.56s and your gear size.
 
zombie, if you are going to use those gears on the street you better buy a gas station. it would be cheaper. i get 6 mpg with 3.91's :shock: and if you plan on driveing that to the next car-b que next year from where you live you better leave tomorrow. :D
 
there is a single bolt that holds it in... be prepared . fluid will come gushing out if you don't drain the trans.
 
im most likey going to run a 255/60x15 for her set up or a 245 im not sure yet,my dad had the same set up with the same rear end in the garage he said on high way he was at around 4800-5000 :cheers: :scratch: :salut:
 
i know this much about my mph

2k in second around the neighborhood
2500 on the highway around my house
and 3000 on the interstate

that seems to get the job done
 
You must log in or register to reply here.
-

Back
Top