The Stovebolt Site Forums The Parking Lot Big Bolts 2 spd Rear end ?

I was wondering if 1 of U Knowledgable guys could tell me how innerchangable and avaiable are the gears in a 57 6500 2spd rear axle.
What I was wanting to know if possible is can you get 1gear around @3.00? (Decent city and Hiway gear) Then a even lower gear @ 2.00? (Like a overDrive) Thinking about making a car hauler with 396 4spd (Granny low)
Is this even possible? How about newwer 2 spd rearends?


Any help is appreciated.

you would have to have a lot of torque to pull a 2.00 gear(Haven't run across a gear that tall yet myself) otherwise you would likely have to downshift for a pebble in the road. Modern diesels are running in the low 3's but they have 1600 t0 1800 lbs of torque.

I quess what I'm asking are these 2 spd rear axles made where you could swap out the gears, to get a decent over drive atleast when your driving through the flats of Kansas.
or should you be doing the gear changing in the transmission.

Look up Mike B (Mike Boteler) here in the forums (do a search) and then ask him about his gear swap in his Task Force Fire Truck. I forget off hand what he did, but whatever gearing he swapped into his rear axle lowered his ratio to where he runs 65 -70 MPH (I couldn't outrun him on the 700 mile trip to Huntsville and back, that's for sure -- I was in a '95 Cummins Dodge and just over 18,000 lbs gross).

John

If it has an Eaton 2 speed, different rears that interchange, but there were no fast ratios in that period. If you are putting in a 396 you could pull faster gears. This can be accomplished by either using a 5 speed overdrive or a complete rear end out of a late model truck. Our over the road trucks have the high twos with a direct and the low threes with an od transmission. However their torque rating is at 1200 rpm and we have the governor set at 1700 rpm. These engines weigh 4000 pounds and simply won't work in your application. You can use this calculator to determine your road speed. http://www.free-online-calculator.c...d_calculator/road_speed_calculator.shtml

57ExtCab,

If you have the Corporate GM 15,000# 2-speed rear with vacuum shift (which I bet you do), than the "standard" rear ratio used in the TF trucks was 8.72/6.40:1. The parts book has a faster set of gears listed that are 8.39/6.17:1, but I've never seen this gear ratio...don't know what they came in.

How fast are you look'n to go? Any thing faster than about 65-70 and your out running you brakes if they are stock.

Installing a OD trans or by adding a OD unit like Gear Vendors or US Gear make might be easier to do.

Mike B