Experiences with Marlin Crawler Transfer Cases Gearing Changes (1 Viewer)

[DrDuc]

I found some threads in which folks mentioned making the transfer case gearing changes to their rigs, but I wasn’t able to find posts in which people talked about their experience driving their trucks after making the change. I’m thinking of having the modifications made to my transfer case, but before I do, I would love to hear from those that have the Marlin Crawler gears in their rigs.

 

[jfz80]

There are a pretty good number of comments on here but perhaps no dedicated threads. Most mention a noticeable increase in gear noise, I believe esp when changing the high side gears (probably because majority of time spent there and highway speeds at that). I don’t recall if underdrive and overdrive gears both lend to the comments. The other repeated comment is harsh shift from 1-2 in low range and accelerated wear on old motor mounts. Folks have recommended using 2nd start option (95-97) when in low off-road to reduce this and prevent wheel spin during shift.

Which are you considering. Low range? High range? Both?

I have had the low range set on the shelf for 3-4 years lol. Now I’m considering the high range under drive gears as well since I haven’t opened up the case yet. 10% underdrive on the High range should net similar results to the 4.56 ratio at the ring n pinion.

 

[MMaxim]

I have 3.11 transfer case gears in mine with 4.88s front/rear. Do not have any regrets and it made noticable difference. It crawles much better it snow with 39" tires. Do not notice any negatives mentioned above. They are a must offroad in my opinion.

 

[OffRoadScott]

I do not know personally but have heard that the low range gears are nice for descending obstacles or mountain passes while off-roading, less use of brakes with the lower range gear when in 4L.

The high range gears will essentially change your power band without having to re-gear the 3rd members.

It was mentioned earlier that the high range gears would essentially give you a 4.56 ratio. But if you do decide in the future to re-gear consider using a 4.56 ring/pinon set, with the high range gears and 4.56 you would be looking at nearly 5.016 gear ratio (4.56x1.10=5.016) essentially putting you at 2150 RPMs with 37s/2360 RPMs with 35 both at 70 MPH in overdrive.

People will say that 4.88 or 5.29 are ideal for 37s as it will get you back into the factory power band. Also, people have posted about shearing the ring gear due to the lack of metal, but beating on the gears could be a factor (bouncing the axle while trying to climb at obstacle).

 

[DrDuc]

There are a pretty good number of comments on here but perhaps no dedicated threads. Most mention a noticeable increase in gear noise, I believe esp when changing the high side gears (probably because majority of time spent there and highway speeds at that). I don’t recall if underdrive and overdrive gears both lend to the comments. The other repeated comment is harsh shift from 1-2 in low range and accelerated wear on old motor mounts. Folks have recommended using 2nd start option (95-97) when in low off-road to reduce this and prevent wheel spin during shift.

Which are you considering. Low range? High range? Both?

I have had the low range set on the shelf for 3-4 years lol. Now I’m considering the high range under drive gears as well since I haven’t opened up the case yet. 10% underdrive on the High range should net similar results to the 4.56 ratio at the ring n pinion.

Thank you for your input. I’m considering doing both and foregoing gear changes in the differentials. I’d love people’s thoughts on that option.

 

[OffRoadScott]

Thank you for your input. I’m considering doing both and foregoing gear changes in the differentials. I’d love people’s thoughts on that option.

Great idea of just re-gearing the transfer case. If you buy both gear sets (high/low) it will be cheaper then re-gearing the 3rds.

If you can source a transfer case pick it up, do the re-gear and then you will have a 2nd transfer case if things go sideways.

 

[DrDuc]

I have 3.11 transfer case gears in mine with 4.88s front/rear. Do not have any regrets and it made noticable difference. It crawles much better it snow with 39" tires. Do not notice any negatives mentioned above. They are a must offroad in my opinion.

Thank you. Very helpful.

 

[DrDuc]

Great idea of just re-gearing the transfer case. If you buy both gear sets (high/low) it will be cheaper then re-gearing the 3rds.

If you can source a transfer case pick it up, do the re-gear and then you will have a 2nd transfer case if things go sideways.

Thank you. I was thinking of doing just as you suggest.

 

[RoaringFork]

This thread by @nukegoat explains how the reduction is possible w/o changing all 3 gears… it also explains the additional noise some have reported, especially in high range.

If the hf2av uses 3 gears to drive the output shaft in high range, how does the underdrive kit work?

Since you have 3 gears in a row like oOo then it would seem you have to replace all 3, right? Or does the old idler shaft gear just mesh kinda poorly with the new high range output and input?

forum.ih8mud.com

 

[DrDuc]

This thread by @nukegoat explains how the reduction is possible w/o changing all 3 gears… it also explains the additional noise some have reported, especially in high range.

If the hf2av uses 3 gears to drive the output shaft in high range, how does the underdrive kit work?

Since you have 3 gears in a row like oOo then it would seem you have to replace all 3, right? Or does the old idler shaft gear just mesh kinda poorly with the new high range output and input?

forum.ih8mud.com

Thank you for pointing me in the right direction.

 

[ChaseTruck]

We have the low range gears in the LX, for maybe 5 years now; otherwise stock axle gears, 315s, S/C. Same for the ‘93 ( although those are not Marlin).
Excellent mod for the trails, with improved control. No issues with gear noise. Mr. T should have made them like that in the first place.

 

[DrDuc]

We have the low range gears in the LX, for maybe 5 years now; otherwise stock axle gears, 315s, S/C. Same for the ‘93 ( although those are not Marlin).
Excellent mod for the trails, with improved control. No issues with gear noise. Mr. T should have made them like that in the first place.

The feedback I am receiving has been very helpful.

 

[Azca]

I have both the low range gear and the underdrive gear. Off road, the difference is very noticeable. You have to get used to driving in low again as it definitely wakes up the rig. I use lock out 1st using the console buttons unless navigating obstacles. Yes, you do get a good jump from 1st to 2nd otherwise. That same jump is there from 1st to 2nd without the gear change but now it is just more noticeable. The low range makes navigating easier as well, you definitely have more control.

On the road the underdrive gears help with the 35" tires. There is a whine, it is not noticeable to others who ride in the truck but I have gotten used to how she sounds. It is kind of like a high frequency hum from a radio but is not loud. After I first installed the gears, it took me a while to pick up on it. It is less noticeable than when I cut off my resonator for my 4x labs bumper and akin to the wind noise created by my snorkel. Bottom line, the extra "noise" is worth it.

Unless you get irritated over vehicle noises, just do it. For the investment, big bang for the buck!

 

[mudgudgeon]

It was mentioned earlier that the high range gears would essentially give you a 4.56 ratio. But if you do decide in the future to re-gear consider using a 4.56 ring/pinon set, with the high range gears and 4.56 you would be looking at nearly 5.016 gear ratio (4.56x1.10=5.016) essentially putting you at 2150 RPMs with 37s/2360 RPMs with 35 both at 70 MPH in overdrive.

Are you talking underdrive or overdrive high range gears?
Underdrive gears increase your final drive ratio ( lower hearing), and increase RPM at a given speed.

You seem to be suggesting underdrive gears 4.56*1.1= 5.016 is lower geared. And would increase RPM.

4.56 diff gears with 10% transfer case overdrive gears gives a final drive of approx 4.1, and will reduce RPM.

 

[OffRoadScott]

Are you talking underdrive or overdrive high range gears?
Underdrive gears increase your final drive ratio ( lower hearing), and increase RPM at a given speed.

You seem to be suggesting underdrive gears 4.56*1.1= 5.016 is lower geared. And would increase RPM.

4.56 diff gears with 10% transfer case overdrive gears gives a final drive of approx 4.1, and will reduce RPM.

The tire size is the difference in RPM.

This is where I was getting the RPMs based off FD and tire sizes.

RPM Calculator

 

[fresnoLC]

Originally I re-geared to 5.29s with 315s which was great for the trails but gave me pretty high rpm’s around 3k at 70mph. Re-geared the t-case with 3.11 low range gears and an overdrive on the high range. 80mph at 2900/3k and low range is awesome, saves the brakes on trails and crawls great. Definitely a little noisier in high range but nothing the radio doesn’t cover up.

 

[mudgudgeon]

The tire size is the difference in RPM.

This is where I was getting the RPMs based off FD and tire sizes.

RPM Calculator

It was your quoted RPM at 70mph that looks way off, and back to front.
Your adjustments for final drive gearing is ambiguous (you know, they/them) which is why I asked if your talking underdrive high range gears, or overdrive high range gears.

Haven't checked all your calcs.


Point being for @DrDuc , verify calcs for yourself

 

[DrDuc]

It was your quoted RPM at 70mph that looks way off, and back to front.
Your adjustments for final drive gearing is ambiguous (you know, they/them) which is why I asked if your talking underdrive high range gears, or overdrive high range gears.

Haven't checked all your calcs.


Point being for @DrDuc , verify calcs for yourself

I used to teach stats. I think I may be incapable of not verifying calls for myself.

 

[jfz80]

For those that have installed gears but not done a full rebuild on the case what are the must have pieces that have been found necessary save any damages to bearings/races/shafts found once inside.

Or what pieces should be replaced to effectively open up and reseal the case. Seals, gaskets, one time use items, etc?

 

[CrabCake]

PO on mine did the Marlin low range and 4.56's as well...running 285's. He was in AZ and said that he had very steep inclines to get to a remote cabin that could be very tricky with ice. I bumped up to 315's and in my opinion, the truck does great both on and off road, but I cannot compare to stock. Acceleration is very reasonable up to 50 or so, then there's a flat spot if you are trying to accelerate 50-60's, but cruises well and easy keeps up with traffic once up to 65-75. I don't have any excessive gear whine/noise that I would complain about.