MY85pontiac
im too old for this crap!
- Joined
- May 17, 2002
car: 1985 Grand Prix
engine: 231 C.I. N/A Buick V6
tranny: pre 81 TH-350
present gear: 2.41 one legger
ok so my daily driver has a very weak gear and since i put this tranny in its been even slower off the line (i previously had a th-200 metric POS) and i need a real gear, not this granny gear crap and i have come up with my own formula for gear selection.
now as a rule of thumb for a "street car" (very relative term here) if you multiply your trannys first gear by whatever gear you want it to be around 9:1. for a drag car it should be around 10:1. this does NOT take into consideration OD trannys like the 200-4r (which i dont have so lets not even discuss them at this point) however i feel for a daily driver (with an emphasis on daily driver first, performance second) the number should be around 8:1. now i'm using that number because while i want to increase performance it is STILL first and foremost a daily driver so gas milage is still a consideration i must keep in mind. now i have done some things already to improve gas milage: just replaced the carb with a holley remanned dual jet (runs much smoother and has made a big difference in performance anda little in gas milage), electric fan set up (runs cooler, has more power and gas milage has made a significant improvement) and i know the gear will off set what i have already done and then some but i'm tired of everyone getting the jump on me, i'm not slower than everyone but this gear makes for crappy take offs.
now my trannys first gear is 2.52 my gear is 2.41 multiply them and you get 6.07, pretty crappy huh? multiply my trannys first gear with 3.23 gear and you get a more respectable 8.13. thats a 2.06 difference and a difference i think i would feel immediately! 3.23 is the closest gear i can find and stay above 8:1, 3.08 lowers it close to mid 7's.
now ive done some calculations and driving around below 50 MPH i wont notice much of a difference in RPM levels at cruising speeds which is good. highway driving might suck but i rarely do that now so its no big deal to me.
so does anyone agree with me? anyone have anything they want to add? think my gear selection sucks? think its still too weak? thinks its too much gear? this is very important to me because gears are not cheap and not something i can do myself. gear selection is one of the most important things we can pick for our cars, it can mean the difference between a fun car and a car you absolutely hate now (whether the gear you chose is too steep or not steep enough).
to reiterate:
2.52 x 2.41 = 6.07 (what i have presently)
2.52 x 3.23 = 8.13 (what i want and what i think the car needs)
2.52 x 3.08 = 7.76 (i think this gear is too low)
2.52 x 3.42 = 8.61 (i think this is too much gear)
engine: 231 C.I. N/A Buick V6
tranny: pre 81 TH-350
present gear: 2.41 one legger
ok so my daily driver has a very weak gear and since i put this tranny in its been even slower off the line (i previously had a th-200 metric POS) and i need a real gear, not this granny gear crap and i have come up with my own formula for gear selection.
now as a rule of thumb for a "street car" (very relative term here) if you multiply your trannys first gear by whatever gear you want it to be around 9:1. for a drag car it should be around 10:1. this does NOT take into consideration OD trannys like the 200-4r (which i dont have so lets not even discuss them at this point) however i feel for a daily driver (with an emphasis on daily driver first, performance second) the number should be around 8:1. now i'm using that number because while i want to increase performance it is STILL first and foremost a daily driver so gas milage is still a consideration i must keep in mind. now i have done some things already to improve gas milage: just replaced the carb with a holley remanned dual jet (runs much smoother and has made a big difference in performance anda little in gas milage), electric fan set up (runs cooler, has more power and gas milage has made a significant improvement) and i know the gear will off set what i have already done and then some but i'm tired of everyone getting the jump on me, i'm not slower than everyone but this gear makes for crappy take offs.
now my trannys first gear is 2.52 my gear is 2.41 multiply them and you get 6.07, pretty crappy huh? multiply my trannys first gear with 3.23 gear and you get a more respectable 8.13. thats a 2.06 difference and a difference i think i would feel immediately! 3.23 is the closest gear i can find and stay above 8:1, 3.08 lowers it close to mid 7's.
now ive done some calculations and driving around below 50 MPH i wont notice much of a difference in RPM levels at cruising speeds which is good. highway driving might suck but i rarely do that now so its no big deal to me.
so does anyone agree with me? anyone have anything they want to add? think my gear selection sucks? think its still too weak? thinks its too much gear? this is very important to me because gears are not cheap and not something i can do myself. gear selection is one of the most important things we can pick for our cars, it can mean the difference between a fun car and a car you absolutely hate now (whether the gear you chose is too steep or not steep enough).
to reiterate:
2.52 x 2.41 = 6.07 (what i have presently)
2.52 x 3.23 = 8.13 (what i want and what i think the car needs)
2.52 x 3.08 = 7.76 (i think this gear is too low)
2.52 x 3.42 = 8.61 (i think this is too much gear)