Dual case install 1 of 2
“Minchworm” Dual Case Install
The first question people ask is why and the second question is how much did this cost.
Why? I am not big into rock crawling with my 4Runner but I do get into them from time to time and anyone who has tried to do technical work with a 5spd understands that trying to manage the clutch, gas pedal and brake pedal simultaneously is difficult. A reduction box “Tacobox” offers a significant increase in control by increasing your traction, torque, control and allows you to go very very slow! This results in less bouncing and less risk of breaking stuff. My final crawl ratio went from 48:1 (3.83*2.57*4.88) to 226:1 (3.83*2.57*4.7* 4.88). Torque (ft-lb) at idle is estimated to have increased from 439 to >2000. So the actual numbers are probably a little different but you get the idea….tons of low end torque and an improved crawl ratio. All of this to keep me safer in technical situations and less likely to break stuff. And yes…I can now tackle things that would have never before been possible. With this mod I don’t think you can stall the 4Runner in double low and 1st gear!
Cost? Well like most things I have done with my 4Runner I didn’t do it the low cost way…mainly because I didn’t know what I was doing and didn’t think it through but whatever….I have no complaints.
All said and done I spent a little over $4,200 on this modification.
I have heard people say it can be done for $2K but I would assume that means you are building your box from scratch and have all the extra parts/tools you need to get the job done. I tried to breakdown my costs below for a more practical understanding of what I got myself into.
Must have Parts/Cost
Marlin Crawler Tacobox w/Inchworm adapters w 4.7-- $2200
Drive shaft mod--$309
Transfer case mount for crawlbox (OEM)--$177
Crossmember/shifter mod-$100
The Right Stuff FIPG--$22
Redline 75W90 1 ga--$60
TOTAL: $2874
Extra Parts/Cost
Rad Design Triple Sticks--$300
HD detent springs--$8
Trail Gear TC shifter (better clearance than Marlin TC stick)--$110
Matching shifter knobs (Advanced Adapters)--$125
Spare TC to rebuild and use to minimize truck downtime--$200
New TC flange seals F/R, pinion nut--$45 (can’t remember…and can’t find all the receipts)
Big Red Torin Transmission Jack--$240
Custom shift boot--$200 (has not arrived yet)
90 degree hose barb for breather port on rear case--$9
OEM style Axle Vent-$7
TOTAL: $1244
GRAND TOTAL: A little over $4,200…I know I purchased some extra sockets (pinion nut), ratchet extensions, numerous cans of brake cleaner, wire wheels, acetone, shop towels, hose clamps, fuel line (breather hose) and some other odds and ends but whatever…I lost track.
Here is the watered down version of the step by step install. I am sure I have forgotten some details but hopefully this helps someone in the future. I had a lot of help from members on here. Big shout out to [MENTION=143526]theesotericone[/MENTION], [MENTION=135317]rkntoy[/MENTION], [MENTION=118207]midcoma[/MENTION]. Much appreciate the help.
Step 1: spare TC cleaning/rebuild
I replaced the F/R output shaft seals and companion flange seals and one of the pinion nuts…the other was in pretty good shape so I reused it. Timmy the Toolman was quite helpful for this part:
Transfer Case Output Shaft Seal Replacement - YouTube
Thanks [MENTION=120071]mtbtim[/MENTION] [MENTION=102606]infamousRNR[/MENTION]
Step 2: prep TC for Rad Design Triple sticks.
This required me to split the case open, remove the pin that locks the shift rails together and also cut/grind the foot off the driver side (L-N-H) shift rail. I did this without removing the shift rails and just stuffed a shop rag under the rails to catch the debris.
Step 3: Connect Minchworm to TC
The Inchworm adapters already had the alignment pins in place so rather than remove those I figured I should remove the 20 year old pins in the spare TC. Well…those things were in there good. I ended up using a torch, vice trip and filed down a bolt to the ID of the pin so I could clamp it easier. Also…I had to tighten some of the nuts on the adapters….though I bought a built unit…not everything was fully put together. The dry fit went well then I pulled everything apart added the FIPG and snugged down the bolts. This was my first horrifying experience. I wasn’t anywhere close to snug and 3 of the bolts starting spinning. On the first one I figured I was an idiot and just over torqued it…then the 2nd then the 3rd and I was being very careful. I am not sure what the problem was suffice to say the bolts were pretty short. Maybe the bolt holes were tapped sloppy…I don’t know. I ended up buying some longer bolts and they tightened down to what I would call a more normal feel and that was the end of that. I did a dry fit with the triple sticks and everything shifted as expected.
I had some extra parts including a set screw and a metal tab. Marlin assured me the set screw was not needed (more on that later) and neither was the metal tab as they already welded one on the shift rail in the Tacobox.
What I didn’t realize about the Inchworm adapters is that while the clockable aspect is great (if you need that…I did not)…it creates waaay more opportunity for leaks. And let me tell you…Marlin didn’t use near enough FIPG when they assembled it! Not only does it need sealed at the clockable ring…almost every single one of these holes needs sealed. This pic was after I just got done cleaning off all the FIPG I had placed and got the chance to do it again.
This next pic shows a leak at the clockable ring after install. I got lucky…I didn’t know that gear oil was fluorescent…and my UV light was super helpful to find the leaks.
I did my best to goober up a bunch of FIPG from the outside to almost stop it but it should really be taken apart and just resealed but that was NOT HAPPENING!
Step 4: Factory TC removal
…pretty straight forward…no pics of this. Only comment, the top two bolts are a #!@#$!@# to remove. In the end I was able to reach them easiest from the inside of the cab with a tiny ratchet. I have heard others could reach them with ratchet extensions but all of my extensions were for ½” and that was waaay to big and wouldn’t fit.
Step 5: Extend 2 wires on TC…no pics again…just cut them in the middle and added 12” of 18ga wire with soder/heat shrink and high temp loom.
Step 6: Install Transmission output shaft seal extension, spline coupler, oil seal
I used red Loctite on the back of the extension and RTV on the transmission side of the spline coupler. This was all pretty straight forward but I really had to beat both of them in place…they both seemed like “press-fit” parts. The oil seal was refreshingly easy to tap in.
Step 7: Install combined Crawlbox/TC
First issue…I’m an idiot. The combined unit on top of the transmission jack was about ½” too tall to clear the bottom of my sliders. I would have used my jack to just lift the truck up a little bit but I was using it to support the transmission as I had removed the crossmember. Thinking now I am pretty sure it would have been fine to let the transmission hang for just a little bit but I was frustrated and stopped thinking. I could have simply used my high lift but again I wasn’t thinking.
Rather in the most awkward fashion I pulled the combined unit on top of the transmission jack and secured it in place with two ratchet straps. Once this problem was solved I drank a beer! Everything seem to go together very smooth and I was almost there but the jack wouldn’t go up any higher.
I was so close…Looking around I found the bolt that you are supposed to hook the chain on that comes with the lift was catching on the exhaust pipe.
30 seconds with a cut off wheel and that problem was solved and the unit was in!
I pulled it back apart, sealed it up and bolted it to the transmission.
TO BE CONT in post 2 of 2
