Regearing Questions? READ THIS!

[MoparManiac]

yeah thats what i figured. i went to a mechanic today to ask him about it and he was certain that putting in a lower gear would actually lower my mpg

There is no definite answer as it is specific to one's setup. There are far too many variables to take into account to determine what gear ratio will improve performance / gas mileage for all setups:

- Tire diameter / width (increased rolling resistance)
- Tire / wheel weight
- Lift height (increased drag)

There is also how many miles are on the drivetrain, how smooth all your bearings are, etc.

The gear ratio calculators are a GUIDE and should be used as such.

 

[Just Differentials]

The answer is:
Go with the LOWEST gear ratio (highest numerical) you can and still retain Low enough RPM's for your highway use.

It is not often that people feel they went with gears that are too low, its hard to do with overdrive transmission and larger tires.

also try this calculator:
http://justdifferentials.com/index.php?main_page=page&id=2&chapter=0

 

[cal]

The answer is:
Go with the LOWEST gear ratio (highest numerical) you can and still retain Low enough RPM's for your highway use.

It is not often that people feel they went with gears that are too low, its hard to do with overdrive transmission and larger tires.

also try this calculator:
http://justdifferentials.com/index.php?main_page=page&id=2&chapter=0

This is the best advice I've heard yet.

 

[Just Differentials]

Its amazing what you learn from overseeing about 20,000 differential setups, and spend ten hours a day talking to people about gearing everyday!

This is the best advice I've heard yet.

 

[Mighty.Mighty_XJ]

Question for you: Do new gears tend to "whine" until broken in, or is it just that "cheap" gears are noisy?

 

[Phil]

Question for you: Do new gears tend to "whine" until broken in, or is it just that "cheap" gears are noisy?

My gears never whined.

 

[DougJ]

Never head a peep from my 4.56's...

 

[muduck18]

Question for you: Do new gears tend to "whine" until broken in, or is it just that "cheap" gears are noisy?

The only gears I ever heard whine where not setup correctly...:eyes:

 

[Mighty.Mighty_XJ]

Still waiting for JustDifferentials to respond ... since he's seen/done so many.

 

[89xj]

Still waiting for JustDifferentials to respond ... since he's seen/done so many.

PM him.

here is a thread on another forum that might give you some insight.

http://www.hotrodders.com/forum/i-didnt-break-my-new-ring-gear-pinion-157423.html


btw, when i regeared, i went with dana gears to avoid any problems with noisy gears and also did the break-in procedure. i had no noise at all. only problem i had was after about 4 years, a ring gear bolt backed out and got chewed up. luckily there was no damage to the ring/pinion so i replaced all the ring gear bolts(one at a time) with lock tight. on large axles with heavy loads and some race cars, the ring gear bolts have safety wires run through the heads.

 

[MoparManiac]

so i replaced all the ring gear bolts(one at a time) with lock tight.

You know you're supposed to put locktite on them the first time right?

 

[89xj]

You know you're supposed to put locktite on them the first time right?

yes. why do you ask?

 

[MoparManiac]

yes. why do you ask?

The way you wrote it sounded like you didn't put any on in the first place.

Carry on

 

[89xj]

The way you wrote it sounded like you didn't put any on in the first place.

Carry on

i didnt install the gears, but do see why you thought that by the way i wrote it.

there was locktite on the other bolts but since one let loose, i figured i redo all of them.

i also bought all new ring gear bolts becuase ive read that you should not reuse them.

 

[Just Differentials]

If your gears are noisy after install than it is not just going to go away. Gear whine is not part of the break-in period. If they are noisy then it is likely that they are setup incorrectly, happens all the time. That said, There are some gearsets that are just noisy, and will whine even when set properly.

Still waiting for JustDifferentials to respond ... since he's seen/done so many.

 

[Norwegian]

I actually read the whole thread.. no really, i did.

Any thoughts/experience on diesels? They have a different torque-range but are still a lot weaker than the 4.0, so i'm still not quite sure if gearing directly compares to the 4,0's.
The original gearing is the same as for the I6 so... 4.10 for 31's and 4.56 for 32/33's ?

 

[Darky]

How did this end up not a sticky? I could've sworn it was a sticky.

 

[Lincoln]

I actually read the whole thread.. no really, i did.

Any thoughts/experience on diesels? They have a different torque-range but are still a lot weaker than the 4.0, so i'm still not quite sure if gearing directly compares to the 4,0's.
The original gearing is the same as for the I6 so... 4.10 for 31's and 4.56 for 32/33's ?

If you are looking for mileage try for 10% to 20% below the peak torque RPM at cruising speed. 10% below should give you a little more power than the 20%.

 

[Norwegian]

Actually the diesel gets great mileage stock. 30-33 mpg is doable at highway cruising.
What i'm looking for is extra power so it won't struggle so hard uphill with bigger tires.
I'd be fine with topspeed at 65-70mph if i could cruise with ease at 55-60.

 

[jeeperjohn]

Actually the diesel gets great mileage stock. 30-33 mpg is doable at highway cruising.
What i'm looking for is extra power so it won't struggle so hard uphill with bigger tires.
I'd be fine with topspeed at 65-70mph if i could cruise with ease at 55-60.

What size tires are you running? It is generally accepted that 4:56 is a good ratio for 33's and 4:88 is a good ratio for 35's. Above that look at 5:xx.