tell me your opinion on my set up

[meatwagon83]

so im in the planning stages of my truck, heres my plan thus far, 8.1 4l80e 205 dana 60 front dana 70 rear, 3.73 gears 34x 9.50 tires,

do you think its going to be enough gear? or will it be a pig, motor in final form will have about 600 ft lbs, and its all going to be in my crew cab dually, (hence the skinny tires!)

[07XCSBZ71]

IMHO, I would go with 4.10s. I have an 01 3500HD with 8100/4L80e and 4.10s, It pulls really good and doesn't get bad mileage for what it is. It has 245/70r19.5s(33.7")

Had a 04 with 3.73s and like the 01 better.

[CherokeeC10]

Seems like too little gear for a 34'' tire to me. even w/ 4.11 gears you are still lookin at less than 2,000 RPM at 65MPH. If you want a lower gear than that I would put it in the transfer case in the form of a 4:1 low kit. That way you don't sacrifice driveability in 2x4.

[argonaut]

In an automatic with a motor with that much torque I wouldn't sweat the 3.73:1 ratio. Nice setup for the highway. But without a low first gear, if you plan on doing heavy hauling, or heavy hauling off road, then 4.11:1 would probably be more useful.

[meatwagon83]

i dont plan on hauling anything real heavy, taking my car to the track would be about the heaviest towing i would be doing, i do run the highway often for work and mild wheeling would about it, along with any amount of snow we would get

[argonaut]

I would get it all in and run the 3:73.1 gears. Since they are already in the D60 and D70 what have you got to lose? Then drive it for a while and see how it does.

My 96 Bronco has a 5.8L with small supercharger on it (6psi max), has an automatic overdrive trans, 3.55:1 axle gearsets and 33" tires. It did fine on the highway towing a 73 K20 on a dolly, and also did okay towing my 66 K20 on a flat bed trailer. If the little ford 5.8 liter can do that, then I think the mighty 8.1 liter ls motor can easily tow a racecar with the drivetrain setup you described.

I briefly owned an 83 K30 dually with those very same axles and I almost put them under my 66. Ended up selling it off and made double my money in the end. Good luck with your build!

[meatwagon83]

thanks, i will probably start in a couple of months, it will posted here when i begin!

[Hoods69BadBowTie]

Yea I don't think the 3.73s would be too bad either. Worse case try them out and go up to 4.10's if need be. Sounds like its gonna be a fun build. Can't wait to see some pics

[kwmech]

the 4L80 has a 25% overdrive so the 3.73s in OD makes a 2.797 final drive.
The 4.10s will equate to 3.08.
........Crew Cab 1 ton dually 4x4, that's a lot of truck ,..... I'd be on the edge of maybe considering even a 4.56 with the 34'' tires which will give you a 3.42 final drive

[argonaut]

But did you notice that he is using an 8.1 liter? It probably has 500 lb-ft torque at 1,000 rpm!

Leave the 3:73 gears in. If the towing gets tough, put it back into third gear...

[kwmech]

I did notice that, but given the weight of the vehicle and the tire size.... His cruising speed RPM at 65 with the 4.56s is gonna be about 22-2300 with the convertor lockup