lowering diff ratios.

[bigbear]

hi all,

i'm planning on put some taller tyres on my nl. 3.5L
at the moment i tow a camper (850/950 loaded) and when on the high way sitting on 100 klm i'm constantly droping out of over drive at moderate inclines in the road.this seems to make the car rev fairly hard (in my opinion) and as i understand it if i put taller tyres on this will become worse, so my ? to anyone that can help would be is it possible to lower diff ratio to combat this? i also would like the car to run alittle lower in low range as i find the auto is geared quite high even in low/ low range
at present i'm running standard size kumo a/t on the alloy 16" rim and i'm hoping to use the same rims with a 33" a/t tyres.
THANKS ALL

[mrbitchi]

WHat's the reasoning behind the taller tyres? Is it purely cosmetic or are you after more clearance? If more clearance is the goal then a suspension lift will achieve the same thing without mucking around with gear ratios.

Forcing the car to run lower in the rev range (with taller tyres or a lower diff ratio) is going to make the lockup problem worse, not better.

AFAIK there is no other diff ratio available for the NL

[Monterorider]

WHat's the reasoning behind the taller tyres? Is it purely cosmetic or are you after more clearance? If more clearance is the goal then a suspension lift will achieve the same thing without mucking around with gear ratios.

Forcing the car to run lower in the rev range (with taller tyres or a lower diff ratio) is going to make the lockup problem worse, not better.

AFAIK there is no other diff ratio available for the NL

I'm guessing he wanted to make lower ie going slower ratio of course is going up. (just like It's said use low range while ratio in t-case is actually higher numerically)
Anyway. On contrary there are plenty of ratios available for NL diffs with lowest being 4.9 out of 2.8TD. Standard ratio for NL 3.5L is 4.272. So it's quite a change. Nice if you plan to run 35" tires or towing (I've got them on my NM and it's pulls 800kg camper relatively easily even on 33" tires). There is also 4.636 which was used on NK 3.5L - exact same diff just different ratio.

[bigbear]

sorry guys,
as Monterorider said, think i ment higher not low (when traveling up the high way i'd like the car to be reving a little higher in the rev range so it doesn't slip out of over drive at every little incline).
so if these diff centres are availible does any body now a rough price or availibility of the centres out of the nk model? (don't want to be reving it's arse of with the 2.8lt gears as i'll only run 31" tyres)
would there be any side affects other than feul costs / e.g. any problem with transfer gearing ?
thanks!!!

[Monterorider]

(don't want to be reving it's arse of with the 2.8lt gears as i'll only run 31" tyres)

You won't my NM came with 4.9 stock and with 31" tires obviously. Runs just fine.

[TX Montero]

I'm guessing he wanted to make lower ie going slower ratio of course is going up. (just like It's said use low range while ratio in t-case is actually higher numerically)
Anyway. On contrary there are plenty of ratios available for NL diffs with lowest being 4.9 out of 2.8TD. Standard ratio for NL 3.5L is 4.272. So it's quite a change. Nice if you plan to run 35" tires or towing (I've got them on my NM and it's pulls 800kg camper relatively easily even on 33" tires). There is also 4.636 which was used on NK 3.5L - exact same diff just different ratio.

I have a 2001 NM and I also have 33" tires (BFG 285/75/16). I am pulling a 2300lb (1045.45kg) trailer and I cannot keep it in 5th gear. On hills I have to put it in 3rd and sometimes 2nd. I would like to explore changing the drive ratio in my diffs.

Could you tell me more about where you sourced the gears?

Also, who did the work for you or did you do it yourself?

[Monterorider]

Like I stated above. I didn't do any work. It's stock gearing. You must have the Limited version. Similarly equipped to rest of the wold Gen 3 Pajeros. on contrary, stateside 2001-2002 Montero XLS came with 4.9 Gears but only 4 speed auto and part-time t-case. Easiest for you would be to source second hand front and rear diffs off junk yard. Only problem is that you have Hybrid LSD rear diff and most of XLS came without. It was part of Touring package for XLS. You can either try to find one or swap one off your current diff.
You can find more Montero owners stateside over here http://www.4x4wire.com/forums/postli...t=&Board=UBB69

[TX Montero]

Like I stated above. I didn't do any work. It's stock gearing. You must have the Limited version. Similarly equipped to rest of the wold Gen 3 Pajeros. on contrary, stateside 2001-2002 Montero XLS came with 4.9 Gears but only 4 speed auto and part-time t-case. Easiest for you would be to source second hand front and rear diffs off junk yard. Only problem is that you have Hybrid LSD rear diff and most of XLS came without. It was part of Touring package for XLS. You can either try to find one or swap one off your current diff.
You can find more Montero owners stateside over here http://www.4x4wire.com/forums/postli...t=&Board=UBB69

Thanks so much for the quick response. I am still trying to figure out what ratio my differentials actually have. I have the OEM service manual (4 books) for my year model and it's a bit cryptic. For the rear, it states that I have a 4.3 ratio in the rear one (with no mention of different options for different transmissions).

For the front, it give two options: 4 speed A/T=4.3 and 5 speed A/T= 4.9

I have the 5 speed and I figured I had 4.9 in both based on the spec for the front and assuming that both diffs would have the same ratio. Either way, either it's a misprint for the front diff or they left out the different offerings for the rear.

Monterorider, if you're running 33" tires and you have the 4.9 and you say that you can pull a trailer just fine, then either I have 4.3's in both of my diffs or the 4 speed transmission that you have is a better match and assists in pulling your trailer better than my 5 speed.

Thanks,

Tony