gears

chazman · November 20, 2004

a while back I asked if when ordering my 2005 2500HD w/ duramax/allison, If I should woory about the gears when putting 35's on. Someone said the deisel would have no problem. Now ordering it I find that it has a 373 or something like that. Doing alot of readin and alot of you have told others to get a 410 minimum or better a 456. So with that I try to change the rear end when ordering and it says I can't with the 8' bed style. what is that ? Shoulden't I be able to order it with the rearend I want? sorry but this is my first time ordering a truck and want to get it right, the salesmen just keep screwin me around so I'm tryin to do this myself, with your help of course

your opinions are appreciated.............chaz

vhato · November 20, 2004

Well,

First off, whomever mentioned the Durmax had enough to turn 35's doesn't really understand why you need lower gears. You need the lower gear ratio so the larger tire size doesn't strain the transmission. You also need the lower gear ratio to maintain your towing capacity. Stock ratio and larger tires can/may reduce your overall towing capacity by several thousand pounds.

Next, when you asked for the Duramax Option you are upgraded to an Extreme Duty 14-bolt axle with an 11.50" Ring Gear Size without C-Clips. Trucks with the 6.0 V-8 only get the Heavy Duty 14-Bolt axle with a 10.50" ring gear and C-Clips to hold the axle shafts on.

Finally, when going to a lower ratio (ie 4.10 or 4.56) the Pinion is reduced in size which reduces strength. As of right now GM does not feel the Extreme Duty Axle included with the Duramax is strong enough to support the weight of the truck, a 16,000 pound trailer and 605 lbft of Diesel Torque. So they limited the axle to 3.73 ONLY. GM feels in order to pull heavier loads a 4.10 or 4.56 option is better suited, but the reduced pinion size weakens it, so there is no benefit with the lower 4.10/4.56 ratio. Ford does not agree and as of 2005 allows for lower ratios to be purchased for increased towing capacity. I agree with Ford. GM should get on the bandwagon soon because I feel many Duramax's would be sold with 4.10's.

So, if you want the Duramax you have no choice but to purchase the truck with 3.73's. Sure the Diesel has MORE than enough power to turn 35" tires, but the transmission will bear the load by heating up and....well....you know...

chazman · November 20, 2004

do ya think I can have the gears changed after I buy the truck without a warranty issue. Or should I just live with the 373 gears. What would you guys do?

vhato · November 20, 2004

do ya think I can have the gears changed after I buy the truck without a warranty issue. Or should I just live with the 373 gears. What would you guys do?

<{POST_SNAPBACK}>

Many people roll 35's with 3.73's. Just remember, if yo do you no longer have the strength and towing capacity of 2500/3500 truck unless you do an upgrade. I do gear swaps pretty often at my home so I would change them. If I didn't know how to do gear swaps myself AND I didn't tow anything then I would stick with the 3.73's.

asilverblazer · November 22, 2004

Original Post

As I stated the Diesel would help but I suggested at least a 4.10, but as reading earlier posts in this thread doesn't help your situation any being stcuck with 3.73's, perhaps aftermarket is your best solution.

LiftedHDRado · November 23, 2004

When I bought my 05 duramax, I was wondering the same thing about the gears. After doing weeks of research, I found out that all duramax come onlyl with 3:73 gears. Now, I am going with a 12" lift on my diesel. I've been to 4 lift shops and they all tell me I do not need to re-gear. I'm not one to know much about the gears but I keep getting the same thing from all shops..its a diesel you dont need to re-gear. Diesel's have a lot of torque and blah blah blah blah. Now I am getting the Rolling Big Power Exhaust Stage II kit. I'll be at 470 hp and over 895 lbs of torque.