Experiences with Marlin Crawler Transfer Cases Gearing Changes

[Azca]

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?

Toyota FIPG. Gear oil. Drain plug gasket. That's it. For the UD gears, IIRC, you need to modify the transfer case internals. A little cutting and grinding and you are done.

I was paranoid so I ran it 500 miles and changed the gear oil again.

 

[Outsane]

I also have done both gears.

Much more control in low range and technical driving. I have 35s and stock diffs so it helped with gearing.

No noise, only did the gears with a full rebuild kit on hand. I have done three cases now and have a spare case waint for any one else.

 

[DrDuc]

I also have done both gears.

Much more control in low range and technical driving. I have 35s and stock diffs so it helped with gearing.

No noise, only did the gears with a full rebuild kit on hand. I have done three cases now and have a spare case waint for any one else.

Are your stock diffs open, or factory lockers?

 

[Outsane]

Are your stock diffs open, or factory lockers?

Factory locked

 

[surfpig]

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?

Just seals AFAIK. My mechanic said that on nearly all these TCs (mine was at ~160,000k), everything still looks virtually new in there.

I'm at stock diffs, 35s. Rubicon trail #1 & 2 was with the stock gears, Rubicon #3 with new TC gears. Absolute game changer, on and off road.

 

[ajordan1975]

I did the MC crawler gear. I do wish it was lower from time to time (came from mini trucks w/ dual ultimate cases) but overall i'm very happy with them. I run 5.29's in the diffs w/ 37's and an LS swap.
the only thing i replaced in my Tcase was the bearing that's on the back of VC. I did a part time kit and put a new bearing on the spool. everything looked great inside with 200k+ miles.

 

[DrDuc]

Factory locked

Jealous.

 

[DrDuc]

Are your stock diffs open, or factory lockers?

So, if you had to add lockers, would you keep the stock ring and pinion and do both of the transfer case gearing changes, or would you do, say, 4.88s in the differentials and the low range in the transfer case?

 

[ajordan1975]

So, if you had to add lockers, would you keep the stock ring and pinion and do both of the transfer case gearing changes, or would you do, say, 4.88s in the differentials and the low range in the transfer case?

what size tire?
If you're in the case just do the both, low and high range gears and don't worry to much about the diffs. If adding lockers anyway i'd do the diffs too.

 

[DrDuc]

what size tire?
If you're in the case just do the both, low and high range gears and don't worry to much about the diffs. If adding lockers anyway i'd do the diffs too.

I will be running 35” tires. I want to end up with a high range that is close to stock gearing with the larger tires, and a significantly lower low range.

 

[ajordan1975]

I will be running 35” tires. I want to end up with a high range that is close to stock gearing with the larger tires, and a significantly lower low range.

Sorry if i missed it, but are you already running lockers? If so, just regear the Tcase and call it good. the underdrive puts you around 4.56. If not locked do 4.88's in the diffs and crawler gear in the case
Just my opinion, and i know others will chime in on this.

 

[DrDuc]

Sorry if i missed it, but are you already running lockers? If so, just regear the Tcase and call it good. the underdrive puts you around 4.56. If not locked do 4.88's in the diffs and crawler gear in the case
Just my opinion, and i know others will chime in on this.

I currently have open diffs and plan on adding lockers. Sounds like the 4.88s and crawler gear is the way to go for what I’m looking to do with my truck. Thanks for your input.

 

[Spdstr280Z]

Mine are Sumo, not Marlin. No reason not to go with Marlin, I honestly didn't even realize they were still selling them when I ordered. I did high range overdrive and low range. Other than a little time in a field testing everything, I have not been anywhere to use low range yet, but I can say just from testing that the low range gears are a significant difference. The high range under drive gears (the main reason I re-geared honestly) are less of a noticeable difference, but the truck feels better, less stressed. I'm on 35's (315's) with an Eaton aftermarket rear locker on stock axle gears. I did all the bearings and seals while I was in the transfer case. At 277K miles, there was nothing really bad in there, but I'm not sure the gear oil had been changed much if ever and I figured it couldn't hurt anything other than my bank account. The old bearings were obviously looser than the new ones, but the old ones were still all together and dong bearing things. I'm still getting everything sorted (the whole truck is essentially a fresh build) but no issues with the gears. I am listening for the whine, or any noise at all that might tell me something isn't right, and I'm not hearing it at this point in high range. Low range does sing. The only issue I am chasing in the drivetrain is likely TPS related, I can't find the right spot even with feeler gauges. I can either get my idle in the right spot, or I can have a relatively smooth shifting truck that isn't hunting for gears when trying to part throttle cruise at 50 - 60, but not both. Since I have been mostly driving a manual economy car for the last 3 years, some of it may be adjusting my expectations also.

Jason

 

[DrDuc]

Mine are Sumo, not Marlin. No reason not to go with Marlin, I honestly didn't even realize they were still selling them when I ordered. I did high range overdrive and low range. Other than a little time in a field testing everything, I have not been anywhere to use low range yet, but I can say just from testing that the low range gears are a significant difference. The high range under drive gears (the main reason I re-geared honestly) are less of a noticeable difference, but the truck feels better, less stressed. I'm on 35's (315's) with an Eaton aftermarket rear locker on stock axle gears. I did all the bearings and seals while I was in the transfer case. At 277K miles, there was nothing really bad in there, but I'm not sure the gear oil had been changed much if ever and I figured it couldn't hurt anything other than my bank account. The old bearings were obviously looser than the new ones, but the old ones were still all together and dong bearing things. I'm still getting everything sorted (the whole truck is essentially a fresh build) but no issues with the gears. I am listening for the whine, or any noise at all that might tell me something isn't right, and I'm not hearing it at this point in high range. Low range does sing. The only issue I am chasing in the drivetrain is likely TPS related, I can't find the right spot even with feeler gauges. I can either get my idle in the right spot, or I can have a relatively smooth shifting truck that isn't hunting for gears when trying to part throttle cruise at 50 - 60, but not both. Since I have been mostly driving a manual economy car for the last 3 years, some of it may be adjusting my expectations also.

Jason

I love the feedback I’m receiving. It’s helping a lot.

 

[MMaxim]

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?

My bearings were in good shape and tools is all I needed. Hydraulic press, bearing splitter and a puller, etc. RTV, gear oil, break cleaner...
I did mine with the case still in the truck like in the writeup on Marlin Crawler forum. There is also a great video on youtube by OTRAMM with t-case out on the bench.

 

[Stylo07]

What causes the whining in the high range gears over the stock gears?

 

[QuackAxel]

What causes the whining in the high range gears over the stock gears?

From my understanding, gained by reading this thread and the one referenced on the first page, it's the difference in tolerances between the new gears and the remaining idler gear in the tcase.

 

[1jzhilux]

I have both under drive and low range gears (Sumo and Trail Gear) with 5.29s. I didn't really notice a change in gear noise, but big muddies would drown that out anyway. On the rocks it's incredible. On the highway, the RPMs are a little high, but it's right in the power band and great. I still want a manual with a doubler though...

 

[Spdstr280Z]

I have a little over 600 miles on the transfer case gears now. I have also quieted down a few other things (when you leave body plugs out, you get a little bit of noise it seems).... I CAN hear the gears now, mostly when cold. Now that I hear it, others have described it perfectly, it sounds like an old car radio with a bad cap, picking up ignition whine. Other than when cold (coldest external temp I have seen is probably 27), it isn't very noticeable. First mile or so, especially in cold weather it is noticeable enough my kids asked if the truck was about to explode. To put that in perspective though, before the 80 was back on the road, both cars they rode in daily were 18's, a Mazda and a GX, so they are used to modern and stock. Any other time, it's no big deal. It is there if you listen for it, but I can't see it being an issue for anyone who is going to lift their truck and put it on 35's. I'll probably change transfer case oil over to Red Line this weekend, we'll see if that makes any difference.

Jason

 

[890man]

I have both under drive and low range gears (Sumo and Trail Gear) with 5.29s. I didn't really notice a change in gear noise, but big muddies would drown that out anyway. On the rocks it's incredible. On the highway, the RPMs are a little high, but it's right in the power band and great. I still want a manual with a doubler though...

Just to clarify, you installed the 10% underdrive on the high range and the low on the low range with your 5.29 and your happy with it. I am in the process of a engine rebuild and have the tranny out so plan to do the lower low range gears but was contemplating the under drive high range. I am on 37's and stock gears at this time. With the rebuild, money is tight so I cant do the ring gears right now but plan to in the future. I just want to make sure I dont have to go back into the transfer case.