Gearing question

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wagon77

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New here, and I’m looking to regear my 2018 power wagon. I’m running 35’s with 37’s possible in the distant future. I’m looking to add either 4.88 or 5.13 gears. I do tow often, that’s the main reason for the regear. Either my rzr on a 20ft deck over or my 30 ft toy hauler, or a trailer full of horses!! I’m needing more power for mountain passes! What would be the recommendation? I also drive interstate almost every weekend to see my son! I have an upgraded exhaust, and an s&b cold air on order, and just ordered a ported throttle body from moes! Thanks for any help
 

SeppW

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A lot of discussions here and on other PW forum about gearing. My only advice is whatever you go with, find a axle specialist that knows what they are doing. Despite the job being relatively easy, it can be FUBARed just as easily. Otherwise, there will be issues if it isn't shimmed right, gear lash is spot on, and the pinon/yoke is set up correctly. Unless you know your dealer's tech is on top of his/her game, the dealer would be my last choice.
 
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wagon77

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A lot of discussions here and on other PW forum about gearing. My only advice is whatever you go with, find a axle specialist that knows what they are doing. Despite the job being relatively easy, it can be FUBARed just as easily. Otherwise, there will be issues if it isn't shimmed right, gear lash is spot on, and the pinon/yoke is set up correctly. Unless you know your dealer's tech is on top of his/her game, the dealer would be my last choice.
My only trusted mechanic is doing the job! He’s the only one I trust with my diesel or anything! He definitely knows his ****! Thank you!
 

olyelr

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Yea, I understand your frustration in picking the gears. I have been pondering it for years now. Same thing...5.13’s or 4.88’s. If you are indeed considering 37’s in the future I personally would go 5.13’s. The 4.88’s would probably be just fine too. But the gearing in the final drive is so damn high I think 5.13’s would be just fine even with 35’s and on the freeway.
 

62Blazer

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For the possible future 37s and the big trailers I would definitely recommend 5.13's. 37's and 5.13 is only a 200 rpm increase at 65 mph as compared to the stock 33's and 4.10s.
 
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wagon77

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For the possible future 37s and the big trailers I would definitely recommend 5.13's. 37's and 5.13 is only a 200 rpm increase at 65 mph as compared to the stock 33's and 4.10s.
So do you think 5.13 gears would be to low with 35’s? I do drive more interstate than I want to! Like every weekend! And I just put these 35’s on. So it’ll be when they wear out that I step up bigger! Also, how’s the acceleration with this type of gearing? I’m imagining a lot more grunt off the line!
 

WY-Dave

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Here is the formula when changing tires to get the equivalent ratio.
Get the new ratio and find the nearest one avail. Then bump it up one
to give a lil umph for towing.

Since you didn't say what gears you have now, 3.73 for example
(new tire size/old tire size) X old tire ratio = new gear ration

(35/33) X 3.73 = 3.95
(37/33) X 3.73 = 4.18

Here is an website with it
https://www.4lo.com/calc/geartire.php

Here is a rpm calc. I don't know the overdrive ratio but jsut use 1:1 for comparison
https://www.crawlpedia.com/rpm_gear_calculator.htm
 

olyelr

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Here is the formula when changing tires to get the equivalent ratio.
Get the new ratio and find the nearest one avail. Then bump it up one
to give a lil umph for towing.

Since you didn't say what gears you have now, 3.73 for example
(new tire size/old tire size) X old tire ratio = new gear ration

(35/33) X 3.73 = 3.95
(37/33) X 3.73 = 4.18

Here is an website with it
https://www.4lo.com/calc/geartire.php

Here is a rpm calc. I don't know the overdrive ratio but jsut use 1:1 for comparison
https://www.crawlpedia.com/rpm_gear_calculator.htm



its a power wagon, so 4.10 only.

here is the setup for a power wagon switching from stock to 37’s...


2C1D4CB1-420A-4493-98AE-7E610DC9F749.png
 

olyelr

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Here is the rpm difference between stock gears/tires and 5.13’s and 35’s...basically 300 rpm. Thats totally doable in my opinion. A lot of the time I drive around in 5th instead of 6th (I have the 6 speed) because it is much better geared that way for 55-60 mph driving. Doing that raises the rpms roughly by 200, so would not be much more different then switching to 5.13’s for me.

027CE61E-7238-4AF8-8362-22B103CAED5D.png

15541EA7-CF8C-4FF9-8B63-64280908C443.jpeg
 

62Blazer

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The RPM difference between 4.88 and 5.13 gears at 65 mph is right at 100 RPM. From my personal experience it is very hard to notice the difference in one step between gears.......for example 3.73 vs. 4.10 is generally one stop up, then 4.10 to 4.56 is one step, 4.56 to 4.88 is one step, etc.... It's not worth the time and money to go "one step" up in gears in my opinion and I always recommend at least 2 or 3 steps. Personally I think 35's and 5.13 gears would be fine.
 

hbleconey

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so if you have the 19+ with 37s, given it has an 8 speed tranny, would you regear at all? and if so 4.88 or 5.13?
 

Down the Tubes

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I had a 4" lift and 37's on my 18 PW when I got it.
I hated the way it drove. Too sluggish and it never wanted to downshift unless I was in Tow/Haul.
I wound up having the lift removed (changed to Carli Backcountry System) and went with 35's.
I like the truck much better now! I don't do enough off roading in my current situation to need the lift or larger tires.

When the 35's wear out, I might go with 37's, but I would definitely regear!
5.13 sounds pretty interesting. There is a thread on here that shows the RPM's at different speeds with 37's.
Both with the 4.10 and with 5.13 gearing.

I believe the guy's response to the new gears was F*** YEAH!
 

Breaker Alex

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so if you have the 19+ with 37s, given it has an 8 speed tranny, would you regear at all? and if so 4.88 or 5.13?

I have about 35 000 KM on 37s 4.10 gears on my 2019 PowerWagon.

I did rock crawling, sand pits, lots of snow ( and sometimes more then 24" deep ).
The 4 low is low enough.

The truck pulls a 5000 Lbs trailer all week for work and a 3000 camper or 3500 trailer with side by side on week ends.
Pull like a sofisticated champ.
( I leave it in 7th gear on highway and 6th on montain roads )

I have no trouble staying in 8th gear not pulling something.

I will never regear.
 

mtnrider

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You are in a tough situation as you want the best of both worlds here. Low gears for the mountain pass towing and a taller gear for interstate driving every weekend.
You are going to have to compromise on one or the other. Go lower gears and tow better (but suffer at highway speeds) or live with struggling to tow and have better highway manners.

Honestly, for what you are doing with the truck you would be better off leaving it stock but I get it.

.
 

62Blazer

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The 8 speed only has an advantage over the 6 speed in the lowest gears, so take off and slow going off-road. In the upper gears while cruising on the highway the 8 speed has the same basic gearing as the 6 speed so both transmissions have the same issues with larger tires. Overall the biggest advantage to changing axle gears is for road driving and towing on the freeway. Also, if you regear in proportion to the tire size increase all you are doing is brining the operating RPM range back to what it was with the stock tires (or ideally a slightly higher RPM to help compensate for the increased weight and rolling resistance).........changing axle gears doesn't mean you are somehow compromising between low speed and highway driving.
In my years of off-road experience I've never felt the need to go to lower axle gears for slow off-road trail driving as low range 4wd generally offers plenty of gearing. Keep in mind that 4 low adds 264% gearing reduction. Going from 4.10 to 5.13 is only a 25% reduction......so 4 low adds 10 times as much gearing reduction as 4.10 to 5.13 to put axle gearing in perspective.
 

hbleconey

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The 8 speed only has an advantage over the 6 speed in the lowest gears, so take off and slow going off-road. In the upper gears while cruising on the highway the 8 speed has the same basic gearing as the 6 speed so both transmissions have the same issues with larger tires. Overall the biggest advantage to changing axle gears is for road driving and towing on the freeway. Also, if you regear in proportion to the tire size increase all you are doing is brining the operating RPM range back to what it was with the stock tires (or ideally a slightly higher RPM to help compensate for the increased weight and rolling resistance).........changing axle gears doesn't mean you are somehow compromising between low speed and highway driving.
In my years of off-road experience I've never felt the need to go to lower axle gears for slow off-road trail driving as low range 4wd generally offers plenty of gearing. Keep in mind that 4 low adds 264% gearing reduction. Going from 4.10 to 5.13 is only a 25% reduction......so 4 low adds 10 times as much gearing reduction as 4.10 to 5.13 to put axle gearing in perspective.

so for a 19 with 37s if you regeared to 5.13 the performance difference would be at higher speeds on the highway? and a lower mpg? slower off road speeds would stay the same given the 8 speed tranny?
 

62Blazer

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so for a 19 with 37s if you regeared to 5.13 the performance difference would be at higher speeds on the highway? and a lower mpg? slower off road speeds would stay the same given the 8 speed tranny?
Going from 4.10's to 5.13's will obviously make a difference in all situations to some extent. You would just notice the difference on the highway and towing more than you would when tooling around in 4 low. You also need to remember that lower axle gears don't automatically equal lower MPG as there are a lot of other variables going on. Just because the engine is running a slightly higher RPM does not always mean it's using more fuel....RPM and fuel use rate are not 100% correlated to each other. For example you can have your foot to the floor trying to tow a trailer up a mountain pass with the engine lugging at 2,500 rpm in which case you are at a 100% fuel use rate, or you could be running an empty truck down a flat road and manually shift into lower gear that lets the engine spin at 3,500 rpm....but that only requires being at 1/4 throttle. When comparing those situations you are using way more fuel towing the trailer up a mountain pass even though the engine is running at a lower RPM.
 

hbleconey

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Going from 4.10's to 5.13's will obviously make a difference in all situations to some extent. You would just notice the difference on the highway and towing more than you would when tooling around in 4 low. You also need to remember that lower axle gears don't automatically equal lower MPG as there are a lot of other variables going on. Just because the engine is running a slightly higher RPM does not always mean it's using more fuel....RPM and fuel use rate are not 100% correlated to each other. For example you can have your foot to the floor trying to tow a trailer up a mountain pass with the engine lugging at 2,500 rpm in which case you are at a 100% fuel use rate, or you could be running an empty truck down a flat road and manually shift into lower gear that lets the engine spin at 3,500 rpm....but that only requires being at 1/4 throttle. When comparing those situations you are using way more fuel towing the trailer up a mountain pass even though the engine is running at a lower RPM.

thanks, very helpful. I don't tow at all, but i carry a fair amount of gear in the bed on baja surf trip down in mexico. I put a carli pintop system in and just put stiffer carli springs in the rear as it was rolling like a boat in heavy swell on the highway when not even fully loaded. It sounds like its a nice to have but not entirely necessary for me given my activities. I'm really hesitant to swap out the gears due to two separate major failures in my old 2012 power wagon in the front diff. both instances would not be covered if i had changed the gears and the first time it happened they replaced the entire front axle (it came in at 8k total). luckily i had the extended warranty both times.

the truck drives fine but i never drove it with stock tires as i swapped it out immediately
 
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