Marlin Crawler 4.7 gears for Toyota

   As we all know, in the world of rock crawling control is what it's all about. Spinning tires and beating your rig against the rocks is rarely a good thing. Big tires only add to gearing issues and reduce the ability to 'crawl' on the trail. Enter aftermarket transfer case gears.

A stock 5speed Toyota truck with 4:10 gears has an average crawl ratio of 37:1. That means the for every 47 times the crankshaft turns, the rear tires turn once. Seems decent at first, but if you think about it, that means at idle (assuming 800rpm), your tires turn 21 times a minute. Now, if you actually have to give it gas to keep the engine from stalling, that goes up considerably. With 35" tires, you can move quite a ways in 21 turns! This is also very tough on your clutch as it fights to keep grip on your flywheel.

The stock Toyota gear drive transfer cases have a gear reduction of 2.28:1 in low range. In high range it's 1:1. The introduction of aftermarket case gears has made it possible to change the low range to 4-5:1 without affecting the high range like gearing axles does. This increases the crawl ratio to 76:1. Another advantage is, when you double the crawl ratio, you also effectively double the torque to the wheels making it harder to stall. It's like changing to gears on a bicycle that allows your legs to spin faster, you feel less resistance. Gear reduction rocks! This means you can still really crawl, and keep your highway ability.

Lately, I have been hitting tougher and tougher trails and it had become quite obvious that I needed to do something different. My poor clutch was smoking and making me quite nervous. I already had 4.88 gears, and the change to 5.29's was not going to make that much of a difference. I decided then to go ahead and get case gears.

     I decided to go with the 4.7 gears from Marlin Crawler based on price and reputation. I placed the order and a few short days later, I got the gears. I was happy to get the package as you might imagine, but upon opening the box, I was a little bummed. The main gear had some pretty big nicks in it, and I was a bit worried. I called Marlin back, and they decided the should be replaced. The customer service seemed friendly, and I went ahead and ordered my crossover steering at the same time. I'll cover that in another review. Well, the steering and new gears showed up along with a call tag for the old one. This little delay had set me back a few days This was a bit frustrating, but hey, things happen right?

   The items arrived packed well (again) and are quite heavy. You get several new gears with the bearing pre-pressed on, a Marlin 'Turtle Knob' for the shifter, and little aluminum carabineer with "Marlin Crawler' engraved, a sales sheet with other items they have for sale and a big yellow Marlin sticker

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   We started the install using a spare case I had, so we wouldn't have to mess with downing the truck in case there were problems. I purchased a lock ring plier at the local Sears, but I have seen them at Pep Boys now. This tool is essential for your sanity! Spend the $10! No, really! The instructions that came with the gears were, well... non-existing so we had to go to the internet ( http://www.rcrc4x4.com/ProductReviews/Marlin4_7_install/howto.htm ) for the instructions. These were for a forward shift case and mine was a top shift, but the minor differences weren't a big deal. During the install, we discovered that the bearing had been pressed on upside down. *sigh* This time a comment on their BBS went absolutely unanswered and ignored. I had to hunt down a shop to press it off and back on correctly. Pep Boys ended up being open, and kind enough to do it for me. Other than that other little setback, the assembly went well.

   Well, I started by taking it around the block a few times with no noticeable noises or other issues. I did notice right away how much easier it was to shift the case. I used to have to mess with it a bit to shift from 2-4wd, but this just worked smooth as silk!

   Our first wheeling test was out in Florence Junction. I met up with some of the guys to run Woodpecker and Ajax. The difference the gears made was incredible! The clutch never even hinted at slipping and it was very tough to stall! In top of that, I had control like I had never experienced before. I could just let the clutch out, let the tires spin slowly and work the steering back and forth until I was able to gain traction, and up I went! The difference was astounding.

Contact Info

 

Marlin Crawler

1543 B North Maple
Fresno, CA 93703

Orders & Technical Help : (559) 252-7295
Fax: (559) 252-7294

http://www.marlincrawler.com