Anyone regear HDJ80?

[Darije]

I have 1991 HDJ 4.2 12V turbo with 35" tires and 3.727 ratio. I tought it is 4.10. But axle code K305 said it is 3.727. With 5 speed manual H151F. Now I am thinking add ARB front&rear air lockers RD132 and RD142 and pair it with 4.88. Or I should regear to 4.56... dilema... I would like to gain torque but not add to much rpm. I am not into top speed... It is not my dd, I use it for trips. In my country is a lot of hills and ups and down. If someone did it, please let me know

 

[AussieHJCruza]

What tyre size are you running?

 

[Darije]

What tyre size are you running?

315/75/16 MT Toyo Open Country

 

[kevin in okinawa]

with that size tire, the best gears are probably the 4.56, especially if you have lots of hill to drive.

 

[Darije]

with that size tire, the best gears are probably the 4.56, especially if you have lots of hill to drive.

I saw that a lot of guys did 4.88. But most of them have petrol engine... I am not sure what is right for diesel

 

[Jorgito]

I am running 4.88 with 315 on 1hd-fte , RPM are around 2400 when doing 115 km/h ( around 71 mph ):

 

[Darije]

I am running 4.88 with 315 on 1hd-fte , RPM are around 2400 when doing 115 km/h ( around 71 mph ):
View attachment 3295965

Nice. Thanks for info

 

[AussieHJCruza]

In my opinion, 4.10 and a h150 or H152 with the shorter 1st are perfect. With the H151 id perhaps go to 4.56 but I'd say 4.88 might be too short

 

[AirheadNut]

I have found this calculator to be really handy for figuring out gear ratio, rpm, tire size and speed: Gearing Calculator | RPM and Tire Diameter to km/h - mph with Shift Tracer - https://www.blocklayer.com/rpm-gear

 

[mudgudgeon]

I have found this calculator to be really handy for figuring out gear ratio, rpm, tire size and speed: Gearing Calculator | RPM and Tire Diameter to km/h - mph with Shift Tracer - https://www.blocklayer.com/rpm-gear

That's a great tool.
Really interesting to do some comparisons.