Marlin T-Case Gear Install (1 Viewer)

[akarilo]

So I decided to dive into an install on the Marlin gears. There are online instructions but some have stated that they leave a little to the imagination, I agree. For starters, I recommend removing the entire t-case (6 bolts). Marlin says no, Slee says yes, I say hell yes. So much easier to do the work on the bench. I did initially disassemble it on the truck but later removed the front case for reassembly. On the second truck I pulled the entire case as one piece.

Back of tranny, (6 bolt locations).

Rigged up a "cradle" by spot welding some channel iron to the jack. I highly recommend something similar as this is a beast of a t-case.

The main problem I had issues with was the actuator motor (on top of the case). Even with the case hanging down lower than normal, it is really difficult to break the seal after removing the four bolts; thought I was going to break it.

The torx screw (at the top) is 40mm. This is the screw that has to be removed to get to the spring and detent ball bearing that is used to "index" the gears when shifting the t-case. Try removing them for the first time laying on your back. Royal PITA and can really only be accomplished with a mirror. Take the whole case off!

Here's the case completely disassembled. I don't have a splitter or press so I had a local installer "set up" the gears.

One other thing that was missing from the online Instructions is the shift fork clearance. When I put the gears back in and shifted back and forth from high to low, there was only the slightest clearance on the curved casting where the fork bolts to the shaft. I feel like if the outer case/ plate would have been cinched down, there would have been contact. The other clearance instructions (provided by Marlin) are comprehensive enough.

Here is a link to the MC online instructions.

http://board.marlincrawler.com/index.php?topic=88536.0

If you decide to install a set and have problems in the process, I will be more than happy to try and help; no matter how many questions one might have.

The gears are pretty impressive BTW.

 

[Wilson]

So how is the "seat of the pants feel?" Mathematically,my jump from 4.10's to 37's was larger... This is the last step if I stay Toyota on the power train. I can honestly say I noticed a difference after my gear swap, but it was not impressive. I'm looking for DEEP gearing for snow. I rarely rock crawl my 80.

 

[OGBeno]

So how is the "seat of the pants feel?" Mathematically,my jump from 4.10's to 37's was larger... This is the last step if I stay Toyota on the power train. I can honestly say I noticed a difference after my gear swap, but it was not impressive. I'm looking for DEEP gearing for snow. I rarely rock crawl my 80.

5.29s and the Ozzie gears (aka: Marlin gear) make the 80 into a decent rock crawler.... Decent ... Not great... But enough to where you could walk fast next to your rig with no one in the driver seat on flat surface....

 

[Wilson]

5.29s and the Ozzie gears (aka: Marlin gear) make the 80 into a decent rock crawler.... Decent ... Not great... But enough to where you could walk fast next to your rig with no one in the driver seat on flat surface....

After many rigs, that is about the picture that I have in my mind, which is not enough for the snow wheeling that I like to do. In many cases you can walk (At a normal pace) faster than the vehicle, given the conditions. For rocks, I do think the Marlin gears would begin to approach the threshold of decent for a rock crawler with an automatic transmission, at least for what something as large as an 80 series would be tackling.

 

[akarilo]

So how is the "seat of the pants feel?" Mathematically,my jump from 4.10's to 37's was larger... This is the last step if I stay Toyota on the power train. I can honestly say I noticed a difference after my gear swap, but it was not impressive. I'm looking for DEEP gearing for snow. I rarely rock crawl my 80.

It's definitely a nice step. Not as impressive as the 4.7 box I had in the 4runner, but with the combo of the 5.29's at least I know I've taken it as far as you can (reasonably) with this platform. I'm happy with the total package. With an auto, the reduction "varies" depending on what the torque converter in the tranny is doing. It is pretty impressive for what "25%" reduction offers. No brainer if you need to go lower than you already are.

 

[AuburnFJsexy]

I just installed my tcase gears a couple weeks ago and I couldn't imagine installing them on my back under the truck. I was lucky enough to have a lift and it made it A LOT easier! That actuator was the hardest part and impossible without a mirror. As for first impressions of the gears, I think they helped a lot (i still have stock 4.10 diff gears)

 

[akarilo]

not enough for the snow wheeling that I like to do.

Sounds like you need a different truck.

 

[Wilson]

Sounds like you need a different truck.

Nope, it's the only one I've kept. Your opinion may represent the purists, but I am not.

 

[Delancy]

Nice work, KR.

I'm a firm believer in the advantages of the MC gears, coupled with 5.29s, if nothing else, defraying some potential axle carnage by minimizing wheel spin, on the rocks.

May not be the the absolute best, but it's the only option, and not a bad one, in my opinion.

 

[bugsnbikes]

Personally these gears open up a wider versatility for those running 4.88s /37s who drive longer distances (hwy) in more expedition oriented rigs. Im still pulling 19mpg hwy avg with 4.88/37 and the addition of the gears gives it that much more versatility.

 

[devildogcruiser25]

Personally these gears open up a wider versatility for those running 4.88s /37s who drive longer distances (hwy) in more expedition oriented rigs. Im still pulling 19mpg hwy avg with 4.88/37 and the addition of the gears gives it that much more versatility.

This is my plan when I eventually re gear. 4.88's/37"s with t case gears. I drive too much long highway to do 5.29's.

 

[Delancy]

No you don't.

Ain't that big a deal, I swear.

 

[devildogcruiser25]

No you don't.

Ain't that big a deal, I swear.

Lol.. Ok busted. I'm just imagining my upcoming drive from San Diego to salt lake to San Antonio...to Oklahoma

 

[Delancy]

to Oklahoma

Gonna piss aikirilo off, but Lawton?

 

[devildogcruiser25]

Gonna piss aikirilo off, but Lawton?

No idea where Lawton is. Figured I'd swing by your house to meet the man, the myth, the legend, owner of the pp80.

 

[Delancy]

No idea where Lawton is. Figured I'd swing by your house to meet the man, the myth, the legend, owner of the pp80.

Bahahahaha.

Prepare to be sorely disappointed, but more than welcome.

 

[devildogcruiser25]

Bahahahaha.

Prepare to be sorely disappointed, but more than welcome.

Plus I need to actually ride in a rig with 5.29's and TC gears before I do it.

 

[akarilo]

Plus I need to actually ride in a rig with 5.29's and TC gears before I do it.

Several here to choose from in Tulsa.

 

[Delancy]

Several here to choose from in Tulsa.

Mines cooler.

 

[akarilo]

I did the second case today. A few more notes on clearancing. For the oil guide/ tin metal piece, you cut the entire upper lip off. The easiest way to do it it is lay the cut off wheel flat on the flat edge of this piece and just go around until you get it all. Both cases need to be done the same. Be careful not to cut into the aluminum case. On the other guide (tail piece) you have to go at it from an angle because the output shaft is in the way. Same concept, just a bit of an angle.

The case clearance requires slightly more grinding than you might initially think. The first case I did the gear made slight contact despite looking like it should clear. The second one I ground enough off the first time.