3.07 axles

[Daniel John]

I have a pair of 3. 07 alxles and transfer case for sale. You can check out the details in the classifieds.

 

[Don in Missouri]

Does anyone have expereince running 3. 07 gears with overdrive? Do you get any fuel mileage gains? Do you you need your motor tuned up to pull those tall gears?



I know I get over 20 mpg if I drive 65, but get 15 or less if I drive 75mph. Some of that loss may be high RPMs, but a lot of it is wind resistance.



I've heard people say they only get about 1 mpg improvement with the Gear Vendor overdrive. I wonder if 3. 07 gears would do better than the overdrive, since you are not adding the friction of the moving parts in the auxilliary overdrive.

 

["Mad Max"]

Hi Don - (got the box, thanks!)



I think it's personal preferance. I don't think you'd need to turn up a pump to run a GV on back of a set of 3. 07's. For me, I like the engine to hum along in the high teens on the tach while cruising at ~75 mph - just my preferance. When my rig is done it'll turn 3000 rpm but I'm saving that potential for serious pulling power/sprinting and not cruising speed.

My rig is going to have 4. 10's, a '98 47 re w/ lock-up, a factory overdrive, and a GV overdrive. That should net me very flexible gear selection and really great pulling power, especially at slow speeds or with BIG weight like I'm expecting.



With the 3. 07's, when you're cruising along empty the engine will love a GV. When loaded you can just turn it off when more rpm's are needed. It's pricey but it gives you lots of flexibility. For the same money you may look into a 2nd gen trans and doing the swap to the lock-up converter and the o/d. I think you'd get the same results but not sure what the $$$ difference would be in the end.



- S

 

[Greenleaf]

you have a pm



gl

 

[bgilbert]

Don, I know Philip has a 518 and 3. 07's. I think it'd be a great combo. I think he said something like 1500 or 1600rpm at 65, not sure though. I think the max torque starts at 1500 or 1600? So you'd be fine holding that speed at cruise, loaded maybe not as well.

 

[Philip]

Someone mention my name. LOL



I do have the 518 with the 3:07's. At 60 MPH I turn around 1550 RPM. On a 4 lane limited access road. I run around 1900 RPM for my cruse speed. That comes in around 80 MPH or so.



I don't like anything over 8k loads. I have towed a 10k load before a couple of times. It takes a while to get to speed with the 3:07's. But it can handle the load allright. With a 10k load on a trailer I get around 13 MPG.



At 80 MPH with a set of bad injectors I am getting 16 right now. At 60 MPH its getting 18 MPG. Before my injectors started dieing. I was getting 20 MPG at 60 MPH.



Greenleaf has driven my truck. So he can tell you a little about how it handles with the 3:07's. Case500D has driven it even more. He might step in and say a few words. LOL



For my normal type of driving the 3:07's are a good gear. If I towed heavy and a lot I would want the 3:54's.



Now my thoughts on a GV setup. I have driven a truck with one in it. It worked allright. But if your thinking about fuel milage only. How long would it take to recover the purchase price and install if it only helps a couple of MPG? The payback time would be high unless you drive a lot of miles.



The same payback question apply's to swapping out from your current gearing to the 3:07's also.

 

[Case500D]

Yup, I have driven the 3. 07 truck. Don't tell Philip, but it will lay a lot of rubber with the stock engine, LOL (just kidding). All joking aside, the 3. 07s are nice for daily driving. I would just stay away from towing with them too much. If you have to, you can kick OD out and run like a 727. The only bad thing is that parts for a 3. 07 are getting hard to find and are expensive. Hope this helps.



Jeremy