I tried a search but didnt see what I was looking for so if there is a thread that will help id gladly like to be pointed in the right direction.

Im wondering if a 3.73 rear gear will work with what I want to do. I have a full weight 2001 ext cab silverado, its getting my spare ls1 with ported 241's, custom cam and a 200 shot, with a 4k converter. Im wondering if the 3.73 will help at the track and still be good for some highway pulls on the way home. I was told with 3.90's or bigger I might run out of gear with a 200 shot. So are 3.73's a good medium? Thanks in advance.

 

I'm guru here but I think 3.73's or the 3.90's will be good. The 3.90's would help more at the track.

4.10's or higher are awesome too but the draw backs are cruise rpms and less fuel mileage.

 

Tire size plays a big role in gear selection too.

smaller the tire diameter, the more effective your gear becomes.

http://www.grimmjeeper.com/gears.html go here to play around with tire size gears etc.

 

I have 3.73's in my truck and think it is a great gear. I have ran 275/55/20 tires that are 31.9" tall, and will be switching to 315/35/20's that are 28.7 tall. How tall are your tires?

 

My street tires are 265/65 17 im wanting to bump to a 275/60 17 in the summer. For the track I was thinking of running like a 28x12.5. Would a 3.90 be to low of a gear for a highway roll? I know it would be night and day from a dig but I just dont want to lose the option to run someone from a 60 on the way home from work haha.

My old camaro had 4.11's and I loved them. And I drove around on a 295/45 18 and did plenty of high speed rolls and topped 3rd at like 125 mph

 

with 28" tires and 3.73 you'll spin 2200rpm at 70mph in 4th

and you can get 134mph in 3rd under 6k rpm.

with 28" tires and 3.90 you'll spin 2300rpm at 70mph in 4th

and you can get 125mph in 3rd under 6k rpm.

with 28" tires and 4.10 you'll spin 2400 at 70mph in 4th

and get 120 out of 3rd at 6k rpm


You'll be fine with any of these options.


Even 28" tires and 4.88 you can go down the highway at 2900 rpm at 70

and get 100 mph out of 3rd gear at 6k rpm

This may be a bit of an aggressive option for the street, but awesome on the track.
Using your 30" street tires though you would spin 2700rpm and do 110 mph in 3rd gear.

Play with the calculator I posted and find a happy cruise rpm and gear ratio with both your tire sets.

 

Yea I like the idea of 3.90 or 4.10 gears but wont those kill and racing done from a roll?

 

Shifting of your trans will kill racing from a roll. You need it set up properly first to minimize shift times...tune, shift kit and servo pack etc.

So, you want gears large enough to not allow your trans to shift down, or small enough to get a few MPH out of 2nd.

Trans tuning will minimize it some what, but what can you do.

Depending on your rev limiter; I think stock is 6300;

3.73 will allow you to go to 90 ish in 2nd
4.10 will allow 85 ish
4.88 will allow about 70

If you go with 4.88 you will stay in 3rd gear and pull all the way to about 115, Just set up your trans to do what you want, like not shift into 2nd above 60MPH...

I would do 4.10 personally, if you haven't walked away from a guy by 85MPH, your done anyway. Also 4.10 gives you a good pull in 3rd and you don't tach over 2300 at highway speed (70MPH). Won't be fuel efficient...but if you wanted good fuel economy you would be driving a civic.

This will also allow 125 MPH in 3rd at the track with 28" tires...and when you start trapping over 125MPH, you'll have very few questions. (that equates to 700 Crank hp and a 10.9 ish second pass for a 4300lbs of truck and driver...just saying).

Also when you bust up your 4L60E and put in a 4L80E, 4.10's will still kick ***.


Anyway...that's my opinion...take it for what its worth.

 

gear that sucker, 456 and 488 have been done on spray and good mph

look up Skeet

373 isnt enough gear

 

i loved my 4.56, and 3600 converter. i wasn't a dd but i would drive it 60 miles a day when it was nice out to work and all 55mph to 70mph. changed from 3.73 and would do it again in a heart beat.

-Nate