I'm a new member and have not figured out yet where I should post my messages. But anyway I am sure if it's not the right place someone will straighten me out.
I have a 1966 C60 with a 750 Holmes wrecker mounted on it, 35,000 GVW
6.50 Rear end
I believe it's a New Process 540C Tranny
409 engine
At 60 MPH it is revving 3000 RPM
Question, should I change the rear end gears and loose some power, or install a auxiliary transmission? If it's the auxiliary, what size would it need to be to lower the RPM on the highway but still be tough when hauling a heavy load?

Thank you in advance
AC

 

Customarily it's the other way around.
Get some lower Ratio Gears in it, then, use what we call down here a "Transfer Case", which provides you with a lot of power when you need it.

For instance...
I run 3.73 rear end gears, and have a Transfer Case which multiplies that ratio by 2.72. So, when I shift into Lo Range, that gives me a ratio of 10.14, which will almost let you climb a Tree if you wanted.

You could look around and see what's available, maybe find a Case which isn't as drastic as the one I use.

 

SW,
Thank you,
We call a transfer case the one used In a 4x4. I think your idea is the best way to go. Now, I bought the truck 2500 miles from my home. Will it hurt the engine to travel at 3000 rpm for that distance?
Allan

 

SW,
I forgot to ask, are you using a 5 speed like mine with a 4speed transfer case?
Regards
Allan

 

Allen,

No, I don't think it will hurt it to drive it that far. It was set up that way originally, and you should expect it to ride out for many thousands of miles. HA, just keep in mind, the faster your drive that thing, the harder it's going to kick you in your hip pocket !

I have a 4L60E (a 4 speed Tranny) + a NP246 Transfer Case (2 speed "direct 1/1 or 2.73/1 in Lo").

But you do/may have another option...
Many of the heavier rigs have a two speed Differential/Rear End.
I don't know if that applies to your ride, but, it may be worth checking out. It would be a lot easier switch if you could do it that way, if you could find a REnd that was made for/fit your ride.

 

I don't work for these guys, I just thought it would be a good site for you to browse in.

Take a look at...
Ring and Pinions

 

No, I don't think it will harm it to generate it that far. It was set up that way initially, and you should anticipate it to drive out for many a large number of kilometers. HA, just keep in thoughts, the quicker your generate that factor, the better it's going to punch you in your hip wallet !

 

Sw,

My truck has the two speed rear end, it runs 60 MPH at 3000 RPM in fifth gear, Hi range.
I will drive it home, take it as easy as possible, then see if I can find a transfer case that will bring the RPM down while on the highway, but still give me some grunt when hauling.

Thank you.
Allan

 

Dave,

Thanks for the advise, the truck only has 30,000 original miles so it should be OK. I will change the oil to synthetic, change all belts and hoses, give it a tune up and hit the road. If there is something else besides getting a few Gerry cans as well, let me know.

Thanks for everything
Allan

 

You're asking for an Overdrive.
I'm not sure that's available.