Last Call

iTrader: (4)

What is the height of the wheels you run at the track? 4.10's and a smaller track tire may be a better solution since the tire size does effect the overall drive ratio.

Mr. Sandog

When I had the Radix in my Avalanche, I saw a significant increase in performance going from 3.73's to 4.10's. Given that experience I would say it is certainly worthwhile to consider it. If performance was my only consideration I would do it again in a heartbeat.

Regarding 4.56's, keep in mind the inherent weakness of a 4.56 pinion gear in a 10-bolt application. With the kind of power you are making I'm sure you would break the gears in one hard 2WD launch.

Also, I will second the sentiment of going with OEM (AAM) gears. People will try and convince you that other gears are just as good, but once you start digging deeper you will find that they just mean less expensive. You can't get stronger and quieter than OEM/AAM gears.

KySilverado

iTrader: (7)

I am seriously considering 4.56's. The truck really isn't a daily driver now so the loss in highway driving wouldn't be an issue. Some even saying an increase in mileage around town with gears, anyway its not about gas mileage at this point.

Looking at about the same money in gears just going 4.10's. If I do the installs myself. Might save a little money with 4.10's, if I found a front diff out of an SS and were paying someone to do the installs.

4.56's would actually put the truck a little bit more in its power band looking at 1/4 mile. Peak HP at 5800 rpm, or was at my last dyno run. 4.56's would put me through the traps at about 5200 rpm. With 3.73's I'm at about 4200.

Course this all depends on traction. Will I be able to hook on on street tires in 4wd... keeping similar or improved 60' times.

KySilverado

iTrader: (7)

Posted my 4.56 thoughts before reading pinion gear weakness.... I do not want anything breaking. I am easy on the equipment really. Consider this, I have run the stock G80 for 2 years with the SC and it is still going strong. I very seldom do hard 2wd launches and the occasion I have its been just a smoke show.

If I do the gear swap and 4.10's they will be OEM.

KySilverado

iTrader: (7)

True and good point but so far I've refrained from modifying from street trim at the track. The track is just a measure of street performance for me.

TIM Z

iTrader: (12)

Time to do a "4.10 ratio truck search" and see who likes that ratio in their truck and why. Personally i'd go with factory 4.10's if your going through the trouble. besides, if you ever want a stronger rear a 4.10 rear should be easy to find.

1Bear

iTrader: (1)

I'm have had 4.56's in my C3 for about a year, without issue. Rolling on 20's my highway rpm at a little over 65 mph is about 2300. At the track though due to wheel spin off the line I'm crossing the line about 6000 rpm, with a 1.78 60'. I'm also contemplating going with caltrac's due to the wheel spin off the line. Every time the front end lifts, it unloads the front tires. Engine combo is basically the same as what everyone else is running, 6.0L, Radix with 2.9 pulley, Dynatech's, Yank TT3000, so on and so on.

blake2kz71

iTrader: (17)

i have 4.10's in mine with 32.?? tires. i came from 3.73's and i could tell a pretty big difference. i need to get some 4.10's up front so i can have 4wd again. im just too cheap to do it.
oh btw i also had a trutrac installed at the same time. it sucks offroad in case anybody was wondering.

04BlackGmc

iTrader: (18)

never heard this 4.56 issue since most the of th 4wd guys have them.

Mr. Sandog

How many 4WD guys have the mods (and put out the power) that KY does?