Does A 2speed axle give the truck more low end pull, or does it lower rpms at road speed like an OD, or a little of both. Thinking of finding one for my 61 500, especially if it help it cruise at lower rpms.

 

A 2speed will only help lower your cruise rpms if the axle ratio is higher than the single speed axle ratio you have now. ... I went from a 6.8 ratio single speed to a 6.33-8.81 2speed ... no real gain on the top end (driveshaft turns 1/2 revolution less to make 1 complete rotation of the tire) but I gained alot of low end power. For your truck the highest 2speed ratio made was a 5.83-8.11.... what size tires are you running?

 

Tire size yet to be a problem, restoration in progress. Any recommendations?

 

Actually a little of both usually.

I have a 6.80:1 single speed axle in mine right now. I found a 5.83:1 2 speed (low range is 8.11:1) so it WILL give me lower RPM on the highway.

I also have an E4OD automatic that's going in and that will give me a pretty tall OD.

I also went with 9.00-20 tires which are a little taller than the original 8.25-20's.

 

In my opinion 2spds are horrible. You might be better off finding a brownie box with a overdrive gear. As for tire size I'am really surprised you can find any 20 inch rubber especially 8.25-20 around here you have to find used tires.

 

There's a lot of 2 speeds out there. I don't plan on shifting it while running. I don't think that'll work well with an automatic.

As for the tires. I bought them from Les Schwab. The fronts are new Toyo tube-type radials and the duals are goodyear recaped radials.

They didn't indicate that they're hard to find etc.....

 

Tire shops I deal with just laugh when you want 9.00 or 10.00 rubber trying to get 8.25 they would be really laughing.

The other option would be is retrofit a newer rear axle into the truck something you can get taller gears for. The only problem is you won't beable to retain the old style wheels if you want to keep the stock look.

 

I used a dana 80 out of a 99 freightliner mt45 (step van) It had the 6 lug wheels that you want to keep the stock look (1800rpm @ 62mph) 9r22.5 tires

 

I wish I had done what you did!!

 

if you will be pulling anything realy heavy the two speed rear is a good option, mine worls great and when hauling hay I need all eight gears it gives me. I just installed a 5531 brown lipe this weekend and hope to have my driveshafts made this week. As far as using them with an auto GMC used a two speed Brown lipe under/direct with there Hydromatic in the early fiftys.

 

I know this is an olde post, i read 60 pages to find my answer, Thank you, thank you thanks. my personal is a 85 f600 370 2v stick shift split shift service truck as i work i the oilfield and its a cheap rollaway toolbox. My cruising speed is 50-55 and it kills me. I have found so many ideas and ways to make my truck better. This by far is the best, solves the hydraulic brake issues. a Mico brake for a e brake and walla, a truck that works for me. Thanks FTE Big Truck Forum