New gears
12-25-2018, 02:08 PM
#1
TECH Fanatic
Thread Starter
New gears
Looking at picking up a set of 4.56 gears but I’ve got a couple of questions. Will I need to get a new driveshaft with a higher critical speed? I should have the 8.5” axle, correct? Any suggestions on an LSD while I’m in there? It’ll be over geared with stock tires but once they wear out I’m swapping from the stock 18’s to 20’s with 33” tires. I prefer having more gear than I need to help offset the bigger wheels and tires and still get an increase in performance.
12-25-2018, 08:05 PM
#2
My stock 20's are 32" and it blows the tires of with ease with a 5.3 and 6L80
That being said yes the drive shaft is going to turn a lot more RPM with the 4.56 gears. I have 3.42, and from what I understand my shaft pops around 120 mph or so. Yours with 4.56 will be quite a bit lower.
Easiest thing to do is buy a 2 piece shaft kit. They are about $700. Or you can have a custom shaft built for 700 or so and up.
Do you not already have a limited slip? People have a lot of opinions there. If you want to go aftermarket Auburn, Eaton, and Yukon are pretty popular. Auburn is a cone type and eaton/yukon clutch type. Look into the and read and see what you want.
That being said yes the drive shaft is going to turn a lot more RPM with the 4.56 gears. I have 3.42, and from what I understand my shaft pops around 120 mph or so. Yours with 4.56 will be quite a bit lower.
Easiest thing to do is buy a 2 piece shaft kit. They are about $700. Or you can have a custom shaft built for 700 or so and up.
Do you not already have a limited slip? People have a lot of opinions there. If you want to go aftermarket Auburn, Eaton, and Yukon are pretty popular. Auburn is a cone type and eaton/yukon clutch type. Look into the and read and see what you want.
Last edited by 00pooterSS; 12-27-2018 at 11:14 AM.
12-25-2018, 08:38 PM
#3
TECH Fanatic
Thread Starter
It’s the 5.3 with 3.42’s according to the window sticker. I’ll have to double check the tow package because I know it’s got an optional something having to do with towing but can’t remember right now. Without the tune it wouldn’t chirp the tires. With the tune it’ll bark them off the line but that’s it. Just finished a tune up on it as it’s got a 120k miles. Gears are one of my favorite mods and I’ve always preferred to have a little to more than what I need. I need to see if there are 4.30’s available. That would be ideal.
I’ve got an LSD currently but always interested in upgrading. Seems most folks hate the factory ones but it hasn’t let me down yet.
I’ve got an LSD currently but always interested in upgrading. Seems most folks hate the factory ones but it hasn’t let me down yet.
12-25-2018, 09:05 PM
#4
100% Redneck
The 8.5 carrier was upgraded to 8.6 quite a few years ago. IIRC the difference between the two is in the carrier bearing size. This matters when ordering the bearing/shim kit but the ring & pinion gears are identical between the two. Ron's machine is probably the most "go to" when buying gears and carriers when it comes to price and customer service. I actually saved about $15 buying through Ron's e-bay store instead of buying from his www with my 4.10's and Yukon LSD. He dose carry the 4.30's as I was on the fence between the those and the 4.10's. I'm happy I passed on the 4.30's because the 4.10's are a little annoying on the hwy going 75 with my 29.7 tires. It will smoke the tires from a stop through 2nd gear without using the brakes making it fun to drive.
Last edited by RedXray; 12-25-2018 at 09:12 PM. Reason: spellin
12-25-2018, 09:24 PM
#5
TECH Junkie
Have to agree I was really happy with 4.10's and 32's in town and the highway...4l60.
12-26-2018, 09:05 PM
#7
The 8.5 carrier was upgraded to 8.6 quite a few years ago. IIRC the difference between the two is in the carrier bearing size. This matters when ordering the bearing/shim kit but the ring & pinion gears are identical between the two. Ron's machine is probably the most "go to" when buying gears and carriers when it comes to price and customer service. I actually saved about $15 buying through Ron's e-bay store instead of buying from his www with my 4.10's and Yukon LSD. He dose carry the 4.30's as I was on the fence between the those and the 4.10's. I'm happy I passed on the 4.30's because the 4.10's are a little annoying on the hwy going 75 with my 29.7 tires. It will smoke the tires from a stop through 2nd gear without using the brakes making it fun to drive.
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12-27-2018, 11:14 AM
#8
According to AAM you are spot on. I even read this a couple of months ago... facepalm fail.
Marsh also notes changes to the 2014 powertrain application information so technicians can identify the axle they are working on. The 8.6” axle is used with the 1500 series 4.3L V6 pickup (carry-over), the 9.5” axle is used with the 1500 series 5.3L V8 pickup and SUV, and the 9.76” axle is used with the 1500 series 6.2L V8 pickup and SUV. The 9.5” and 9.76” axles share the same 12 bolt cover plan. The 9.5” and 9.76” axle size is cast into the passenger side top portion of the carrier web.
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