Would swaping axles help my low gear situation?

[benbloom]

I am exploring options for making my 4x4 more drivable, its a 4 speed with granny gear, and low gears in the axles. i believe they are 410s or 411s. So, my question is: would swaping out my axles for higher geared ones ( like a 3.08 or whatever that would be) make the 1st gear like a regular first gear? how much better would my highway driving become? is this at all plausible, or am i just better off getting a new truck or getting an OD tranny instead?
thanks!

[benbloom]

also, would this cause problems on hills and such with the wide range in between 2nd and 3rd? would i see a dramatic difference with new axles or would it be subtle.

[Andy4639]

To not sound harsh but do you mean rear gears instead of axles? The axles will not help you at all on the gearing.
You have several ways to do what you want. Change the rear end gears to a better highway gear set which in turn will knock some toque out of the truck which is what you need for off roading climbing hills.
You could go with a over drive transmission also to help. This will let you have pretty good gas milage and torque both.
Changing both would be ideal.

[benbloom]

yeah i meant the gear ratio. i know i would loose torque but ive got the low gear range so i will never lack the necessary torque. would changing the gear ratio make a dramatic difference? would first gear be able to get me up to 10 mph if it gets me to 3 now?

[cdowns]

your grannie gear is going to b a grannie gear no matter what you change

[Mike C]

Yes, swapping axles would help. BUT...

Some more info would help. To begin, what year is your truck? Is it a K10 or K20? Verify for sure gear ratio (will be on tag between cover bolts on front diff if a Dana). If it's a drum brake front axle swapping starts to make even more sense because you can do a brake upgrade. If a half ton are you going to run bigger tires and use it hard? Upgrading to 3/4 ton axles makes sense.

What size tires are on the truck? Do you plan on keeping that tire size? Is the truck lifted?

Sure fix for a high geared truck is bigger tires. 35's knock the revs down significantly over a 30" tire.

35's on a 3.73 geared setup would be a cruiser on the highway at 70 mph and 2800 rpm or so.

[hugger6933]

Be aware that if you change gears in the rear you need to change gears in the front as well. This could get expensive if changing just the Ring gear and pinion and have some shop do it. If you don't match the ring and pinion front and rear the truck will bind up when locked in four wheel drive. this binding will basically lock up the whole truck from the binding until either the front or rear wheels are jacked up off the ground and the truck taken out of 4X4 mode. that normally happens at a point where you can't jack up half the truck like a muddy or sandy spot thus leaving you stranded. Jim

[jocko]

Your best option, no matter how you slice it, is to put in an O/D trans and or larger tires. Both axles would be expensive... If you don't use the granny, which 99% don't there's no reason to have it. O/D trans will give you a deeper 1st than a traditional automatic (not as deep as the granny though, and that's probably a good thing) and much higher 4th. If you can share tire size, confirm axle ratio you have now, we can give you a much better idea.

[k29349]

You do know that you're not supposed to use first gear in normal driving, don't you?

[jocko]

To answer your original question, if your trans is an SM465, 1st gear ratio 6.55:1, so with a 4.10 rear, that's the equivalent of 26.8 combined ratio (what really matters). Switching to a 3.08 (not that I'd recommend that), would yield an overall ratio for 1st of 20.2 ratio. To give you a comparison, a 4.10 in a TH400 would be a 10.2, i.e. about half. So, no, the 3.08 does not make your granny low more drivable. And as k29349 so eloquently pointed out, 1st gear in a granny is not for normal driving use. You really have a 3-speed manual unless you're doing some major heavy duty work with the truck. Even 2nd in an SM465 is deeper than 1st in a 700R4 (or most any other automatic)

SM465 ratios:
1st- 6.55
2nd- 3.58
3rd- 1.57
4th- 1.0

One other option is adding a G/V over/underdrive. Not something I'd recommend, because I'd be the first one to screw the pooch and engage it accidentally in 4WD, but I have heard of it being used on a 4x4 and engaged only when in 2WD. That option retains your original 4-speed, your granny low should you ever need it, and gives you gear splitting all the way up. So, essentially an 8-speed with one o/d gear above 4th. Not cheap, expect to spend around $2500 in parts.

[Mike C]

His issues seem to be too many RPM's on the road at speed not in 1st gear from what I'm reading.

Overdrive WAY more expensive than a set of used axles. It also requires driveshafts front and rear.

Would really help to know what kind/style truck this is and what tires he is currently running and what he plans for the future.

33"-35" tires solves a lot of highway gearing woes if that's his problem.