Marlin Crawler: Cheap Tricks

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Here are some cheap tricks and tips I've found with my Marlin Crawler transfer case:


The Facts:

A Marlin Ultimate Crawler (#263) consists of a dual transfer case in which a 4.70:1 gear is installed in the rear transfer case. The front transfer case reduction unit (or crawl box) retains the stock 2.28:1 low ratio. The front crawl box is sandwiched between the transmission and the actual transfer case and it is 6.5" long. Only the high-low gear range is retained in the crawl box, the front drive part is removed. With the dual case, the front drive shaft is lengthened 6.5", which allows for longer wheel travel. In the rear, the shaft is shortened by the same amount. With a dual transfer case, you effectively have a 4-speed transfer case (see table below) and you gain a 2-Lo range (without having to unlock the front hubs) by putting the crawler box into low and shifting the transfer case between 4H and 2H.

With a Marlin Ultimate Crawler (dual transfer case), 5.29:1 R&P gears, overall crawl ratios work out to:

Final Drive Ratios (lower-than-stock)
Front Rear 1st 2nd 3rd 4th 5th
1.00:1 1.00:1 20.9 11.3 7.3 5.3 4.5
2.28:1 1.00:1 47.7 25.8 16.7 12.1 10.2
1.00:1 4.70:1 98.3 53.2 34.4 24.9 21.1
2.28:1 4.70:1 224.1 121.4 78.5 56.7 48.1

To put this in perspective, take a typical engine idle speed of 800 RPM and using 33" tires with the above gearing, your speed is about 29 feet/minute, or less than 1/3 MPH!separator

Driving Experiences:

A few things I've noticed about driving with a Marlin Crawler:



With such extreme low gearing, a few cautions must be exercised:


Gear Oil Change:

After about a 5000 mile break-in period, I decided it was time to change the lube to the Marlin cases. I opted to use 75-90W Mobil-1 synthetic gear oil. Those dual cases seems to really heat up with the mineral oil, the slicker oil seems to help out some. Also, with the added friction of the second case, I found that I picked up 1 MPG or so after changing to the synthetic oil.

So, upon close examination of a Marlin Crawler dual transfer case, I noticed there are two drain plugs but only one fill plug, (on the stock transfer case). It turns out the crawl box shares the same gear oil with the transfer case. To change the gear oil in this setup involves the following steps:


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Last updated: 04.MAR.1999