Diff ratio in DC 79

[scalpel1]

I have a 79 V8 diesel double cab. I stay in South Africa. Driving at 110km/h the revs are at about 2500rpm. Going up to 120km/h revs picks up to 3000rpm. Speed limit is 120km/h in South Africa. Everything I read seems to indicate that the Cruiser has a 3.9 diff ratio in standard. Although some local Toyota guys suggest that ist is 3.7.

My question is. By changing the diff ratio to lets say 3.58 would the revs decrease? Or what ratio would be good to drop revs but not loose the drivability of the Cruiser. By how much would revs decrease? Would it be a worthwhile change. I run 265/70/16 tyres on the Cruiser. My normal driving speed is between 110-120km/h. It feels as if the engine is stressing unnecessary at these speeds.

All advise and suggestions would be appreciated.

 

[roscoFJ73]

Do you have a plate somewhere that has the diff code on it? I think they are a 3.9,same as the 6 cyl 79 series.
"driveabilty" is in the eyes of the beholder.
I do long trips in my HZJ75 with the 1HZ sitting on 2900 rpm for hours,doesnt seem to bother it.

There are some very good speed and rpm calculators on the net that will give you the answers,but you need the diff ratio.

 

[scalpel1]

According to thelate its 3.9 diff ratio. I dont mind the high revs. I just think it would be better for the engine in the long run to run at lower revs.

 

[gifu]

I think Marks Adapter in Australia makes a 5th gear replacement that will lower your revs.
Hmmmm now I only see that for Nissan Patrol. I swear they used to make it for the r151f. Hmmmm


...via a tiny telephony device and large thumbs.