Like money in my pocket my recently purchased 3.15:1 Transfer Case Gears were proverbially burning a hole in my room. <img src="/forums/images/graemlins/lol.gif" alt="" />

So with Carlos' (CAP510) help we began the swap this past Saturday. Fortunately he still had a spare transfer case from when we swapped his gears a few years ago.


In addition to cleaning it up as best we could (a shop vac and heavy brush are great for doing this) we also found a plug separating the housings had a strange non-uniform hole it in.


After carefully reviewing the pictures I took of Carlos' swap, we were able to determine his also had this same opening so I suspect although not a uniform/straight cut it is this way from the factory.

We then proceeded to disassemble the necessary parts. Below I'm taking pics of the servo's/position senders for the 4WD system so I can put them back properly after the install. You can also see that I've already taken the end cap off so the shifter shaft/linkage can be pushed out to allow the shift forks to be removed so we can remove the gears.


Below I've pushed out the cotter pin that holds the shift fork in place, removed the 4 position senders and pushed the shift rod out the back of the transfer case so I could remove the shift fork so that the gears on the other side can be removed.

(Note: The 2 senders that are farthest away in the pic the left side did not need to be removed. We forgot and removed them anyway.

Below you can see the 1 shift linkage and the rod for the 2nd shift linkage pushed to the left into the housing so that the shift linkage that was attached to it could be removed.

You can also see the large opening just above the gearset that you'll need to grind down so that the new gears will clear it.


Below is another view of the area from the Transmission side point of view with the hole that needs to be ground down at the 12 O'Clock position to the gear. Also notice the Dremel Buffing Wheel and Carlos' spare radio antenna that we inserted into that hole to prevent aluminum shavings from falling into the back gear compartment. The plan was that the Antenna would allow us to pull the buffing wheel back out. We just had to be careful while grinding the opening down that we didn't accidentally cut the antenna.

Now all those bearings will also need to be taped up to prevent aluminum shavings from entering.


Another pic below of the holes & bearings now taped up and the shop vac in place prevent contamination from the aluminum shavings.


And below the are the results from the 1st cut. <img src="/forums/images/graemlins/shiner.gif" alt="" /> We used a 1/16" thick cutting wheel on a 4" die grinder.


Below you can see we've now switched to the Dremel with a standard cutting wheel. Some of you may not realize this but aluminum can easily be cut with standard wood working tools which for this mod is a really good thing. <img src="/forums/images/graemlins/cyclops.gif" alt="" />


Actually that cutting wheel is also good for cutting steel as you can see in the antenna below.


Since we now only needed to refine the bottom half of the hole, we switched to using baling wire instead of that antenna.
[img]http://inlinethumb33.webshots.com/48928/2650138930104986527S600x600Q85.jpg[/img]

And below is the finished result showing the clearance with the new larger gear in place.
[img]http://inlinethumb61.webshots.com/50748/2431240590104986527S600x600Q85.jpg[/img]

Stay tuned for part II (coming to your screen in June <img src="/forums/images/graemlins/lol.gif" alt="" />) when we transfer the OE bearings from the original gears to the replacement gears and install them into the housing.
[img]http://inlinethumb22.webshots.com/45205/2624667740104986527S600x600Q85.jpg[/img]

Are those 3.15's. Just got back an email from Paul (works at Marks) just informed me that they aren't producing the 3.15's anymore, they switched to 2.7's. They were having too much modifications issues with the 3.15's to make them work. Are 2.7's still a decent crawl?

Yes, they're supposed to be a set of 3.15's. Never told me they weren't making them any more when I bought them though. That's weird... <img src="/forums/images/graemlins/confused.gif" alt="" />

I hope he misinformed you.

The mod is pretty easy to do especially since the transfer case is made with aluminum and can be cut using basic woodworking tools/blades.

Guys, thats very interesting , I had a conversation with Mark Hardman last year I think it was (it could have even been the year before, my how time flies) to ask him if they could go any lower than 3.15, he said no 3.15 was the limit & he also said that in hindsight he would not have gone 3.15 but taller. So thay may have decided to pull the plug on 3.15's for future releases & drop to 2.70.

BTW this represents a 16% drop in reduction, bringing you back to 35:1 instead of 40.1 ! Not nearly as good.

Wow that makes dual boxes look even more attractive IMO.
Would be good if someone like Frank could confirm that they are dropping the 3.15's.

Just to confirm can you work out the ratio on your new gears by counting the teeth on both sets & coming up with the ratio.

I have had my gears in now for 6 years (wow) & they have performed flawlessly.

cheers

I still can't see having to mod the xcase as a valid reason for dropping it. Was a very simple mod in fact.

Sounds like its already been done

That sucks then and will just push most to consider a dual xcase setup. Eventually we'll figure the easiest dual case setup and their mitsu gear business will suffer because of it.

agreed 100%

maybe Frank can explain the decision, he talks to Mark. Maybe they are just covering their asses in case someone trashes a box whilst doing the grinding etc.

So a 2.7 ratio isn't a decent crawl?

Hopefully we can get more insight into the decision. In reality you need to grind maybe 1/4"x1/2"x1" off the bottom of that part of the housing. Not much really.

I suspect customers were complaining and asking for a smaller ratio instead which spoils it for the rest of us. <img src="/forums/images/graemlins/angry.gif" alt="" />