2 speed rears

an 18 spd with 3.73 or hight 4.11, 4.33 etc should do OK,,about the only time a 2spd rear helps is getting under the goose neck of a mechanical rgn when goss exceeds 120,000#..I hauled upto 140,000# with just an 18spd and 3.73 rears on tall 24.5 rubber, if you are going to gross over 250,000# might want to look at 2spd rears,,

 

With that weight arnt you limited to 40-45mph anyways?

 

In the oilfield you need them. We had a V12 CAT, 13 over, 4 speed Brownie and 2 speed rears. You could put it in low and walk around it at full throttle.

 

Hi DMH, I think what you mean is, at what weight do you need a 2 speed rear axle. Back in the day, when smaller straight trucks had gas motors or small diesels, anything with dual wheels ( 10x20 or 11x22.5) on the rear usually had a 2 speed rear axle (red button on shifter). Nowadays, with more powerful diesels and automatics or straight 6 or 7 speed transmissions, you don't see 2 speed rear axles as much. As far as weight, I'd say anything over 25,000 lbs. or 30,000 gross, would have a 2 speed.

 

I'm not really sure that there is ever a "need" for them, I can see where they could be really nice though. I know a guy that has them, he had one of the rears go out on him, and the other wasn't far behind. Cost him $19K just to have them rebuilt.

I would like to have them so I could have a little longer legs when I am empty, and keep my 4.10's or maybe even 4.33's for when I am loaded.

 

ol boy I run with has two speed rears. always braging about how handy they are. I go into the same mud holes as he does with my 4:11's I don't see a need for them running around at 150000 lbs some times. would I have them, probably. but haven't seen a need for them yet for what I do.

 

I talked to the head mechanic for a huge heavy haul company in the mountains centered around the WV area, mostly their own construction equipment. Ran about 40 trucks vintage 1995-2003, all cat 550's, 18 spd, 2 spd 46k rears with lift axles on tall rubber. Told me two speed rear ends were absolute junk, they were complex to repair and don't last nearly as long as they should, and that the trucks they ran with an auxiliary tranny were more reliable. They were set up with 4.10/5.87's or 4.30/6.33's

 

Well when being stalked by a bear, my rear has 2 speeds,,,, Fast and Oh #####!

Other than that I have not needed them.