Gearmaster
™Cruiser Crawler®
Rock crawling Transmission
For
Toyota Land Cruiser
Last Updated: 14/08/08
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The crawler transmission effectively converts your transfer case into a 3-speed
low range transmission. Normal low range is still available (2.02:1) or you can
select the crawler transmission (3.05:1) or you can select both at once giving a
total reduction of 6.16:1, effectively giving you a super low low range. This means the vehicle can be used
in normal low range for normal off road track conditions and when the going gets
tough or you feel like participating in some rock crawling you can simply select the crawler transmission
and low range. The above transfer case ratio is an example only and may not be specific to your vehicle, however I have picked a worst case ratio therefore the calculations for your vehicle will be equal to or lower than this. The unit may be operated in 2WD or 4WD. |
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| The Gearmaster rock crawling transmission is similar to the Gearmaster over drive in that it locates behind the transfer case in line with gearbox main output shaft. The new transfer case interface components transmit the power from the gearbox main output shaft into the Cruiser Crawler. The Cruiser Crawler transmission houses an input gear, idler gear, and an output gear. the drive from the gearbox main output shaft is directed either through the idler gear for a reduction drive or through the output gear for direct drive. The transmission requires compressed air to shift from direct drive to under drive. |
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No drive shaft alterations are required as the crawler transmission bolts up to
the back of the transfer case in line with the gearbox main output shaft.
This photo shows a crawler transmission casing fitted to a 80 series transfer case. Note: The transmission tunnel will need to be modified to clear the top of the crawler transmission or alternately a body lift can be fitted. The fuel tank will also require modification to clear the transmission. |
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| 100 Series The Crawler transmission will only fit the 100 Series live front axle models. The IFS models have a crossmember that supports the rear of the IFS torsion bars, this crossmember is directly behind the transfer case and does not allow enough room to fit the crawler box. The Crawler transmission has been designed to fit all model Toyota HF model transfer cases from 1990 on. this includes the following models. |
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| 78/79/80 series all models | Now available |
| 100 series (live front axle only) | Now available |
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The crawler transmission vastly enhances the vehicles off road performance
and safety.
Vehicles fitted with larger tyres to enhance their off road performance are at the same time are handicapped by this improvement as the increased tyre diameter reduces the engine braking on steep descents. The increased tyre diameter also increases the speed of the vehicle in all gears making steep ascents and rocky terrain difficult to traverse safely. If you intend fitting or have fitted a GM engine and automatic transmission to your vehicle you should also consider fitting the Gearmaster transfer case gears or the crawler transmission to improve your engine braking and general off road performance. |
| High Range Ratio | No Change remains 1:1 |
| Low Range Ratio | 2.488:1 = standard |
| Crawler Ratio | 3.05:1 = 23% reduction over standard |
| Low Range & Crawler Ratio Combined | 7.588:1 = 205% reduction over standard |
The following are some examples of gear ratios before and after fitting a Cruiser Crawler Transmission:
| 78, 80 and 100 series fitted with H151F 5-speed gearbox | 1st Gear Ratio | Final T/Case Ratio | Diff Ratio | Final Drive Ratio |
| 5-Speed with STD Low engaged |
4.081:1 |
2.488:1 |
4.10:1 |
41.63:1 |
| 5-Speed with Gearmaster Cruiser Crawler engaged |
4.081:1 |
3.05:1 |
4.10:1 |
51.03:1 |
| 5-Speed with STD Low & Gearmaster Cruiser Crawler engaged |
4.081:1 |
7.59:1 |
4.10:1 |
127:1 |
| 80 and 100 series fitted with A440F automatic transmission | ||||
| 4-Speed Auto (A440F) with STD Low engaged |
2.95:1 |
2.488:1 |
4.10:1 |
30.09:1 |
| 4-Speed Auto (A440F) with Gearmaster Cruiser Crawler engaged |
2.95:1 |
3.05:1 |
4.10:1 |
36.89:1 |
| 4-Speed Auto (A440F) with STD Low & Gearmaster Cruiser Crawler engaged |
2.95:1 |
7.59:1 |
4.10:1 |
91.80:1 |
| 80 and 100 series fitted with A750F automatic transmission | ||||
| 5-Speed Auto (A750F) with STD Low engaged |
3.52:1 |
2.488:1 |
4.10:1 |
35.91:1 |
| 5-Speed Auto (A750F) with Gearmaster Cruiser Crawler engaged |
3.52:1 |
3.05:1 |
4.10:1 |
44.02:1 |
| 5-Speed Auto (A750F) with STD Low & Gearmaster Cruiser Crawler engaged |
3.52:1 |
7.59:1 |
4.10:1 |
109.54:1 |
| 100 series fitted with A750F automatic transmission | ||||
| 5-Speed Auto (A750F) with STD Low engaged |
3.52:1 |
2.488:1 |
3.909:1 |
34.23:1 |
| 5-Speed Auto (A750F) with Gearmaster Cruiser Crawler engaged |
3.52:1 |
3.05:1 |
3.909:1 |
41.97:1 |
| 5-Speed Auto (A750F) with STD Low & Gearmaster Cruiser Crawler engaged |
3.52:1 |
7.59:1 |
3.909:1 |
104.44:1 |
| 100 series fitted with H151F 5-speed gearbox | ||||
| 5-Speed with STD Low engaged |
4.081:1 |
2.488:1 |
4.30:1 |
43.66:1 |
| 5-Speed with Gearmaster Cruiser Crawler engaged |
4.081:1 |
3.05:1 |
4.30:1 |
53.52:1 |
| 5-Speed with STD Low & Gearmaster Cruiser Crawler engaged |
4.081:1 |
7.59:1 |
4.30:1 |
133.19:1 |
| 78 and 100 series fitted with R151F 5-speed gearbox (split t/case) | ||||
| 5-Speed with STD Low engaged |
4.313:1 |
2.295:1 |
4.30:1 |
42.56:1 |
| 5-Speed with Gearmaster Cruiser Crawler engaged |
4.313:1 |
3.05:1 |
4.30:1 |
56.56:1 |
| 5-Speed with STD Low & Gearmaster Cruiser Crawler engaged |
4.313:1 |
7.0:1 |
4.30:1 |
129.82:1 |
| 78 series fitted with H150F 5-speed gearbox | ||||
| 5-Speed with STD Low engaged |
4.529:1 |
2.488:1 |
4.10:1 |
46.20:1 |
| 5-Speed with Gearmaster Cruiser Crawler engaged |
4.529:1 |
3.05:1 |
4.10:1 |
56.64 |
| 5-Speed with STD Low & Gearmaster Cruiser Crawler engaged |
4.529:1 |
7.59:1 |
4.10:1 |
140.94:1 |
Part Numbers is as follows:
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PART NO. MFK1550/80A
The Kit consists of: Crawler Transmission, Transfer case adaptors, and instructions. NOTE: The transmission will not fit 100 Series IFS models. |
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PART NO. MFK1550/80M
The Kit consists of: Crawler Transmission, Transfer case adaptors, and instructions. NOTE: The transmission will not fit 100 Series IFS models. |
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Copyright © 2006
Marks 4WD Adaptors 
Last modified:
August 14, 2008