BJ74 questions.

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BJ74Guy

BJ74Guy

10 Year
Joined
Dec 5, 2011
Threads
6
Messages
147
Location
Cle Elum, Washington State
Hello, Im looking at my first BJ74 purchase. I was originally looking for an auto, but a nice 5 speed is available. It has a full floating rear end and cable lockers that I really like. I was wondering, I was told the ausy version came with a very low first gear. Is this true of the Japan version as well? Second, Ive heard of people putting Marlin Toy boxes in these trucks. Does anyone know of this as well. Id really like to figure out a way to get an extreme low range if Im not going to benefit from the torque converter.

Anything else to consider Id appreciate it. Here is the truck.

https://forum.ih8mud.com/threads/1989-toyota-land-cruiser-bj74v-jdm-rhd-turbo-diesel.803950/
 
All H55's have the same ratio on 1st gear of 4.843:1, but, I recently learned that the Split Case that is mated to the H55's came with 2 different ratios for the low range, one was 1.959:1 and the other one is above 2:1 (can't remember the exact ratio).

This website has good information on gear ratios for Land Cruisers and other vehicles:

http://www.marks4wd.com/transmission-ratio-information
 
Thanks guys. Im trying to figure out what best ring and pinion ratio will work with the 37" tire I want to run after my SPOA. Funny thing is, staying with the stock 4.11 will give me 1903 RPM at 60mph with 37's?? I dont get it. What RPM's is the truck running stock then at 60mph?

60 x 4.11 x .85 x 336 / 37" = 1903rpm. That would seem to me to be a great highway rpm.

60 x 4.88 x .85 x 336 / 37" = 2260 rpm. Id like the lower gears but how is that RPM for highway use???
 
Trust me you will want the 4.88's to turn 37's. For comparison I run 4.56's with 33's in the winter and the speedometer reads very close to accurate. In the summer I run 35's and the speedo is about 5% out with a noticeable loss of power. Even when I recently switched from Mickey Thompson MTZ's with alloy rims to Interco Trxus M/T's with steel rims in the same 35x12.5 size their was again a noticeable loss of power (due to the added centrifical weight).
Another thing to consider is when working the engine at low RPM's the EGT's will rise very quickly. It's better to rev on the higher side when under load to keep the EGT's down. If your running 60mph at 1903rpm like you suggested you will be dropping a gear at the slightest hill or wind gust. 2200rpm is the minimum I run under heavy load and it makes good torque there.
As for lower T-case gears the Advance adapters 4 to 1 gears appear to be your lowest option at this time. They do also lower your high range by 10% as well though so take that into consideration when choosing your diff gearing
 
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Peak torque is at 2200rpm so thats the rpm you want to be cruising at or just over. With a 5spd, 35''s and 4.11 diffs I sit bang on 2200rpm at 100km/h which is great for cruising. I runs heaps of boost so cruising torque is no problem on inclines etc etc.
 
The US lucked out with fj60 t cases on the rotten 4 speeds. 2.29:1 and 2.27:1 are close to the original ratios for 81-85 then 85-87. The fj62's got 1.99:1 as did all 5speed and international automatics through the end of production for the split case behind the h55/h41. These days finding a set with under 200,000 miles is a pipe dream. If you want that gearset, order new (NOW) from a dealer before they go obsolete.

As a former 13bt driver, be warned you won't go very fast with the factory 4.11's in the diffs. The engine does not have the power band to pull very hard. Absolute Max realistic speed with 32" tires in AZ on flat ground was 75mph. (HDT I have done 92mph, same tires same ratio)

There are no land cruiser "H55's" with any other first gear than the 4.8:1. Only one gear for the entire run 1983-1998

giant tires on a truck may help you be a wheeling machine but once you drive a 74 you will understand why it is so much more than a 40 series. I can go drive from Tucson to 4 corners (350 miles) at highway speed, tool around the desert with confidence I am not going to get stuck and return home. I'd have no teeth or kidneys in a 40 series. Please drive it before you decide on 4.88's and 37" swampers.
 
I'd have no teeth or kidneys in a 40 series. Please drive it before you decide on 4.88's and 37" swampers.

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Excellent advice......
 
Thank you guys. Ive a lot of wheeling time under my belt. I wont be putting swampers on her. Radial BFG's. This is going to be a trial rig most of the time with very little highway time.
 
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