Reduction gears for the mighty 2.8

[Outrage]

The reduction is the transfer case gearing, so 85% means 85% more teeth, as seen in Macca's pdf, original ratio of 2.02, 85% reduction gives 3.743 ratio. It ends up around 54% of original speed. From the pdf, standard, 35.4 rotations from the motor gives 1 at the wheels, with 85% reduction, it now takes 65.6 (1.85 times more) rotations to make 1 turn of the wheels. You're close to doubling (1.85 times) how many rotations it takes, thus you're close to halving the speed.

That's my understanding, correct me if I'm wrong.

Same process, 43% reduction leads to 70.6% of original speed. 24% reduction leads to 81.3% of original speed.

[macca]

Something else to consider is the final drive ratio in reverse as that changes in low range as well.

Backing out of a bog might get a whole lot more interesting!!!

Macca

[Winnie]

Same process, 43% reduction leads to 70.6% slower at the wheels. 24% reduction leads to 81.3% slower.

Think you mean 70.6% and 81.3% of the original speed, not that percentage slower.

[Outrage]

definately misworded that, thanks kristoffa, edited my post.

[patrol2.8]

Thanks Macca and thanks outrage for explaining it gives mr more to think about

[gu4500]

I have the 3.743 ratio in my GU - one of the first batch Marks ever made for Patrols, back in Oct/Nov 2002. Awesome if you want to go slow, and rock crawl, but most normal offroad use requires 3rd gear takeoffs, even on 35" Centipedes.

Was funny seeing my boss trying to drive it when I left it in L4 though....

[buderimlad]

I have 85% with 33's. Wouldnt go the 43% because it still wouldnt be low enough to crawl. If you want to go faster user a higher gear.

[Outrage]

I done an excel spread sheet comparing different transmission/dif/transfer combinations, will try and find it and post it up. I do remember my 4.5 petrol auto was shocking compared to the manual, manual runs at 65% of original speed (of the auto) in first (no reduction gears), 85% gears in the auto bring it to the 54% of original making it a bit slower than the manual.

Ended up, 24% reduction in the manual was equivalent to 85% reduction in the auto...

[Outrage]

Delayed response, finally remembered it. Couldn't actually put the spreadsheet up, but gives an idea of some engine/transmission combos (only some of them).

[mfw]

I have the 43% in a gu td with 33, Made it a really nice 4WD go down the steepest hill in first full control with no brakes, crawl up in 1st or 2nd and will still do 40-50 in low 5th, withy the 80% you will have to change between high and low range more often