at what rpms are you at when you are at 55, 65 ,75, 85, and 95.
do you run out of gear on the highway?
just curious, i like my 3.42 for the highway. can run all the way up to 140
but my bottom end sucks. lookin for something that will help gear wise. i would like 4.10s but i do alot of highway travlin.75 - 95mph. so im thinking 3.73 will alow me to do the highway thing and not lose to much top end. what do yall think?

 

55...2000rpm
65...2300rpm
75...2600rpm
85...2850rpm
95...3050rpm

even at 60mph I can still get a 4-2 downshift and 2nd runs out about 70ish...I DO have the 4L80E but the 3rd gear ratio is the same and the OD ratio is nearly identical (.75:1 vs. .70:1 for the 4L60)

I can hit the 120mph speed limiter LONG before I hit the 5600rpm rev limiter so I really don't think you will lose top-end...you WILL lose gas mileage

 

Gas mileage wont be hurt that bad. When i went from 3.73 to 4.56 I hardly saw a difference in gas mileage. And that is a much more drastic change than you are doing. I cruise at about 75 on the freeway and I still get 17 MPG.

The main reason is because you will find that your truck doesnt have to downshift as often on the freeway. 4.10s are a good gear for these trucks.

 

Since you got a 1500 truck, if you got the stock diameter tires like me, then at 60 it will run at 2000rpms, and at 80 it will run at 2700rpms! That is what mine does.

 

I love my 4.10's. 80 mph 2500 rpm with 30 in. tires. fuel milage off about 1.5 mpg on average. Rear tire life probably will be cut in half from 3.42's and hooking up gets harder, but driving gets a lot more fun. If the 4L60E trans would shift into 4th under throttle I would recommend 4.56's,but it will not and I hit the top of 3rd at 126 mph. with 4.10's.
You will be shifting into third in the 1/4 so you will really find that the long drop in the widely spaced 2nd. 3rd. shift will negate some of your et.improvement,it feels flat for a bit but then stay's strong to top. Jim

 

i am going to 4.10's next year with an eaton. right now i have 275/45/20 goodyears gt2's. next year i am also going to the 275/55/20;s which are 31.4 i believe and that should put me around 3.90. check me if i am wrong. but i think that will give me the grunt i want and still leave me some highway to.

 

In my opinion, I wish I would have stuck with the 3.73s. As far as gas mileage, My buddy and I lost at least 2mpg. I would give up the .05 of a second at the track.
I have thought about it long and hard and I believe that the taller gear might be better with nitrous. We were in the process of backing down the shift points in my buddy's truck, before he wrecked it. We did have it at 6,100 with the Z06 cam and backed it down to 5,500 and picked up 2 tenths and 1.5 mph. It seemed that the more I lugged the motor the more the juice pulled the truck. It felt like the truck was getting slower but, the numbers don't lie. The 3.73s might be better for nitrous than the 4.10s. I don't know until he gets another truck so we can continue the experiments.
A guy I work with says that is the most common mistake with juice, shift points. However, he and his friends don't shoot anything less than two stages of juice. both 400 shot. Pro-mod.

 

well i have 285-60-16 on stock 6.5 rims
trying to decide and i think im gonna go with the 3.73's
would theses help my launches better than the 3.42's?
i know the 4.10's would but like i said this is a daily driver and i do alot of highway driving. i love to be able to pass people. on the drop of a dime. dont wont to be left hangin by runnin out of gear.

 

If you decide on the 3.73's I've got the set I took out at about 10k miles.I needed the posi so I swapped to 4.10's while I was in there.I can bring them with me to the shoot-out this weekend.My main objective for the taller gear was towing,I pull a goose neck horse trailer with a half ton, but not offen enough to warrant a 3/4 ton.If you're intereasted I'll take $75. they are the stock GM ring and pinion. Jim

 

i have 373s and at 95mph im around 2700 rpms.