Rear-End Gear Ratios

[marek4792]

So I just got the new differential put in and it rides like a dream at 55 bobtail ended up with a total cost of about 2800 including the core return. This involved taking out the wheel bearings and cleaning them along with the axle inside. Bearings were ok as the magnets caught most of the debris which ended up coming from the input shaft bearing and planetary gear bearings.

I wonder if it failed early at 1.2 million miles due to what the truck used to do as it was a former mega fleet truck from the Northwest pulling rocky mountain doubles and/or quad axle trailers before I got my hands on it and finished it off?

[the missing link]

I am actually thinking of regearing my truck from 3.70 to 4.30 . I have been talking to a few pretty smart people on the subject .
Here is the facts
I pull 63,500 kgs or 140,000 lbs
A lot of off-road work
It always seems there is a headwind or a soft road , hill , a duck farting , something all the time
I don't care if I ever go more then 110 Km/hr again , I like that 90- 100 km/ hr
Same old argument, you'll lose fuel millage , you can't run a hill, blah ,blah,blah

Fuel millage
Maybe with the n14, old cats and s 60s . But even then I don't agree

Running a hill
Who cares if I can only run the hill at the speed limit , I still shift half as much going up the other side . That and our roads are rougher than f@ck up here .

I am 110% sold on regearing my truck , even with the 9,000$ price tag
Just my ridiculous opinion
Now would somebody like to invest 9,000$ ? Lol

[Rawze]

(08-30-2017 )the missing link Wrote:  ...
I don't care if I ever go more then 110 Km/hr again , I like that 90- 100 km/ hr
Same old argument,
...

90 - 100 km/hr is roughly 58 - 62 mph. Read the article and take a look at these charts ...

http://rawze.com/forums/showthread.php?t...3#pid17353

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4.30 would be the low side,.. 4.11's would likely suit it better at those speed ranges.

Just my own opinions anyways.

[Brock]

(08-30-2017 )the missing link Wrote:  I am actually thinking of regearing my truck from 3.70 to 4.30 . I have been talking to a few pretty smart people on the subject .
Here is the facts
I pull 63,500 kgs or 140,000 lbs
A lot of off-road work
It always seems there is a headwind or a soft road , hill , a duck farting , something all the time
I don't care if I ever go more then 110 Km/hr again , I like that 90- 100 km/ hr
Same old argument, you'll lose fuel millage , you can't run a hill, blah ,blah,blah

Fuel millage
Maybe with the n14, old cats and s 60s . But even then I don't agree

Running a hill
Who cares if I can only run the hill at the speed limit , I still shift half as much going up the other side . That and our roads are rougher than f@ck up here .

I am 110% sold on regearing my truck , even with the 9,000$ price tag
Just my ridiculous opinion
Now would somebody like to invest 9,000$ ? Lol

I'm assuming your rocking 11r24.5 right? My prostar has 4:11 on 11r22.5 and I run 1600 rpm at 105km hauling 63, 500. My fuel mileage is good, pulls hills awesome and has lasted forever. I've thought about dropping down to 3.70 so I could get better fuel mileage but my engines lasted 1.75 million so obviously something is working here and it's not my amazing maintenance plan lol.

Do you have 46 rears or 40, s40? If straight 40, you won't be able to re gear that low. 3.90 will probably be the lowest you can go without new pumpkins.... depending on what type of pumpkins you have.

[Rig Wrench]

My own personal experience, my truck has 3:90s and 11r24.5 tires, I've often thought of putting 4:10s in it, or even 4:33s cause I'm consistently 100k+ in the Catskills and Adirondack mountains. About 65% 2 lane, 35% hi way. I just pull it back a few gears in the mountains and keep it 1700-1800. I do think the lower gears would take strain off the engine though. I believe on the big road it would be revving more, but not necessarily using more fuel because it wouldn't be working as hard??

[Hammerhead]

Yes, missing link is running 24.5's which is why we've figured the 4.30's. That is an equivelant of 4.10 on 22.5's

edit: you edited or I missed it Brock, yeah they told him he could go 4.10 without any Mod's, but might have to mod for 4.30's. I've never done that in 40k rears, could you tell me why? I haven't Thad time to research it myself yet...

[Rawze]

(08-30-2017 )Hammerhead Wrote:  Yes, missing link is running 24.5's which is why we've figured the 4.30's. That is an equivelant of 4.10 on 22.5's

Now that makes more sense.

[the missing link]

Yes I am running 24.5 and they are super 40 rearends .bear with me I ain't to bright ,but I was told to go to 4.30 I have the change where the axel comes in slightly . If that makes any sense , to those who know a lot more then me . I would love to put 46 under it , but damm that's pricey . I am also going to a 4 way locker instead of my 3 way now , so I have to change the one punkin housing regardless . It's a extra 1000$ bucks at most . I have to change one axle also for the diff lock . The upgrade to 4:30 instead of 410 is about a grand also .
I have been told the super 40 will not take what I do , but I never had a problem with them in my last truck. Not saying there as tough as 46 . I believe you can break anything if you want to. I do know there a lot cheaper to fix though .
Just my own thoughts
Oh and the speed is on the top end of what I want .

[Brock]

On the peterbilt, the super 40 is the exact same as a 46. The ring gears and all are the same size and from my understanding, the pumpkin housing thickness is the only difference.

Call the gear centre/ pats driveline in edmonton. They are usually pretty good with all that stuff.