how much gear is too much gear?

[G_Body_Enthusiast]

Well I just installed the 2004r transmission and I love it!!! I have the GN 10 bolt posi with 3.42's and man my car screams! It's great off the line and even better on the highway with the lockup converter from the GN also. So my vote would be for 3.42 with the 2004r it makes a great combo. I can easily get 2nd gear chirps and still cruise on the highway going 75-80mph with the tach at around 2,000rpm!! This is also my fisrt O.D transmission in my GP and I love it!! I should have done the swap loooooong ago!

every time i read a post like this i get more and more impatient to get this swap done. i havent seen a person complain about this type of swap and that tells me its a winning decision.

i wish i had gone with this swap instead of the th-350 when i got rid of the 200c. oh well, live and learn!

i guess i will stick with a 3.42 or 3.73 gear and leave the 4.10 and 4.56 gears for another car in the future.

 

[dogsht]

You gear it like you would a three speed with the goal of maximum acceleration in the quarter mile.

OD is just for sustained speed travel, motor saving lowered rpms, and gas mileage. Not used in calculations other than to see what your cruising rpms would be at a given speed and maybe to see if this is after the torque ban has come on but below peak torque for near optimum economy. This should also be where vacuum in highest. IMO this is a distant secondary goal.

For the online calculators such as the ones at; http://www.wallaceracing.com/Calculators.htm

1. You can estimate or get your actual car with driver weight. There are various places to find truck scales.
2. You can estimate, dyno, or if stock use factory ratings for maximum HP and at what rpm. Your goal is going to be going thru the eyes at or slightly past peak horsepower. Drag racers generally find this to be the best gearing for quarter mile times. And with the 200-4R I have found it to make the best most enjoyable driver gearing.

Example
300 flywheel HP @ 5200 rpms (275ish RWHP)
3,800 lbs with driver fuel spare tire tools etc.

You put in your weight and try different MPH examples until it matches your HP on the bottom line. ie 3800lbs at 100mph took 304HP with optimal gearing lol and traction. http://www.wallaceracing.com/hpcalculatorquarter.php

Now use; http://www.wallaceracing.com/calcmph.php to see that a 4.10 gear with a 1 to 1 transmission ratio ie 3rd gear and a 26.0" tire in this example (235/60/15) would reach 100 mph by 5,300 rpms ie just past your maximum horsepower. 8)

BTW you can use that same calculator to see that the .67 (overdrive) trans gear ratio with the 4.10 gear and 26" tire would have you turning 2300 rpms at 65 mph. This in most near stock motors is in the lower end of the torque range and should provide the best economy and cruising. 😀

fwiw 100mph in the quarter with good traction should net you a 13.9 slip.

 

[dogsht]

OK your last two posts must have posted before my post as I did not see them.

Buick 3.8 was
140HP at 4400 rpms I think thats net or closest to RWHP
200TQ at 2000 rpms

The V6 is lighter and assuming your are not a big fellow with tools in the trunk lets use 3,600lbs.

Calculator says that with optimum gearing ye ole carberated smog v6 could push her to 81 or 82 mph in the quarter. 🙁

Calculator says that a 4.10 gear with 26" tires (215/70/14) could push this car to 81mph at 4,300 rpms. This would be my pick if I was staying with that motor and buying a gear to go with the 200-4R and 3.8. Really IMO often its an ideal gear with this transmission until you get to turbo or big cubic inch motors then usually 3.73 or 3.42s become ideal.

At 65 mph with a 26" she would be turning 2,300 rpms a lil over peak torque. You would probably get a little better mpg in town and a little less on the highway as to what you get now at that speed. Opps that would be with the 2.41 & 200-4R it should be a lot better than what you get now. Plus it would feel like it gained 100HP lol.

Optimally thats about a mid to high 16 in the quarter. Three speeds should be kept for race setups or go the way of the hand crank starter and the wood spoke wheel.

 

[G_Body_Enthusiast]

i've decided to get a 3.73:1 gear series 3 with a detroit locker truetrac. just under 547 bucks total with shipping included from summit.