Nissan Patrol 4x4 (Africa)

Even on 35's it looks like the standard Patrol TC Ratio achieves what you are saying Peter. Looking at an engine RPM of 2000 it falls right between 2nd and 3rd gears in low range compared to the speed at 2000 RPM in 1st High, at around 18km/h.

I don't mean to be a stick in the mud here, but why does want to lower the ratios even with 33" tyres?

In my opinion sand or dune driving is just that... driving. On the river trip I was mostly in 4H and was fully loaded. Juice (Greg) found that 4L worked better for him. The difference was mine is a 4.2 diesel ( turbo ), and Juice has the 3.0 diesel. Ok, the diesels do have a very different feel to the petrol motor in the sand, that we know as petrol loves sand.

In my mind the real benefit in changing the T/C ratio will be when one is at an obstacle and a rocky one at that. Many petrol patrols go up obstacles in 2nd 4L, which gives you a certain speed at which you climb out of an obstacle. In my 4.2 diesel I love to put it in 1st 4L and literally idle up out of an obstacle with my revs at between 900 and 1300 rpm. This is a very slow speed, as i'm sure a few of you guys have seen when I go through an obstacle. If I changed the T/C ratios I would probably still use 1st 4L and same rev range but I could probably get out of the Patrol and walk next to it to check my line while the vehicle is still moving.....hahaha.... it will just be even slower, which in turn gives you more control.

There will be times that you need more momentum to get up an obstacle. More momentum = more speed. to me this negates the need for different T/C ratios, as you don't need the wheels to turn slower, but rather faster.

This is how I see it for a diesel motor based on the diesel motor characteristics. I do understand that the petrol motor may behave differently, and if with an auto g/box the will also be significant behavior differences.

Its a LOT of money for something that could rather go towards something else on a vehicle..... unless you are building an extreme 5+ rated obstacle eater, in which case I would probably just get a front difflock and an extra inch suspension lift and body lift.

Cedric, i think something has gotten lost in translation here.

I want lower T/C ratios to be able to go slower in extreme rock crawling. Just as you say, idling in first gear. Slow enough to get out and check my line.

If you saw the two jeeps going up Koos se Klim this weekend, you will understand just why. Lower speed means less loss of traction due to the wheels keeping a steadier pressure on the ground.

But i want approximately the same ratio as i currently have in 2l for dune driving.
So that i can retain the same torque/speed relationship, as the current over-all ratio in 2l is just about ideal for that. I don't mind what gear that is, whether it's 3rd, 4th or 5th, that's immaterial.

I have also done things as slow as possible.. Basically just keep the revs high enough so I don't stall the little 2.7td. Then when you go from 29" up to 35" tyres, things get faster than you would like. So crawler gears is something I have always wanted. But you have to be realistic and see what you are going to need for sand. I will end up with the perfect setup, with two low ranges, giving me 10 low range gears and 5 high range.

Whats the cost comparison to rather add a second TC and replace two proshafts to the Patrol?

I am inclined to agree with David and Cedric but still being mindful of Peter’s needs.
The above comments tie in with my gut feel.
Peter’s standard ratios are so good already.

I also have looked at it from just above idle RPM to see what one would get in that scenario.

The 4.2 Petrol Patrol standard trf box provides the same ratio in 1st gear LR as the 4.8 were it fitted with a 2.86 reduction box.
In looking at the calculations its easy to see that the 4.2 standard ratios are the best of the lot for serious off-road and the 4.5 Auto ratios are the worst.
(Which makes me question the need for such a large reduction – Peter specifically)

It further showed me that the ratio options from Marks 4WD have little to do with application but are rather very much vehicle specific.

After doing the calculations in the attached spread-sheet it again confirms my feeling that the 2.86 reduction would be the better choice all round

From a technical aspect, reduction and longevity are inversely proportional.
The smallest of gears in trf case will be working that much harder.
Something to think about?

Finally the difference between the 3.743 reduction ratio and the 2.86 reduction ratio is less than 300mm travelled distance per second in 1st gear on any vehicle configuration.
Im not sure that for less than 300mm/second travel distance its woth going to the extreme end of the scale.

Personally it makes no difference what your choice is.
My objective is too see if one could establish a one size fits all and I believe the 2.86 comes closest to that.
The objective being to have as many sets as possible to make them as cheaply as possible.
My thinking is still between 15 to 20 k for 10 sets, but it could actually be way less once I do an actual costing. Which I will upon receipt of Transfer box.

But I’m not going down the road for anything less than 10 sets.
Far too many manufacturing processes involved.
But I would manufacture 10 sets even if I received confirmation for only 8.
If those who are interested could reach consensus as to what it is they want one can take this further.

But if not its been interesting to look at nevertheless.

Thank you for all the effort guys!!!

Dear Peter

I have been back and looked and looked at your calculated total ratio and when one looks at that I understand why you feel the 3.743 (or 3.5 which is an unknown), is what is going to work for you.

However, based on your statement earlier as quoted below any ratio above 2nd High but lower than 1st High should work for you

‘’Now in these cars, 2nd low is the only gear that works for sand. 1st high is too low, and 2nd high is too high.

I attempt in the attached table then to show why a ratio of 2.86 would be more beneficial to you within those very same parameters.
The same table will then also show why 3.743 would be a step backwards for you.

In conclusion, the 2.86 ratio will improve your progress in that you will go slightly faster on the same RPM in a higher gear and still keep within Torque parameters that the vehicle is capable of.

The 3.743 Ratio, for all intent will mean at a one up higher gear, you will now go slower than what you used to be able too, standard.

Cheers

Ek het nou lekker gespeel mat daardie spreadsheet en omdat ek 35" op het sal die 3.743 ratio tog die beste vir my werk. Op die duine trip het Michael met sy diesel die lang duine in 3de begin en dan af gegear as ek reg ontou. So ek sou graag daardie as my maximum wil hê. Op 3.743 is 5de gelykstaande aan standaard lowrange 3de op 33". 4de Rat sal dan gelykstaande wees aan my huidige 1ste high range. Ek glo nie ek wil graag n vinniger ratio wil hê nie. Indien ek 33" op gehad het sou ek die selfde ingevoer het en sekerlik die 2.86 ratio gekies het. Ongelukkig gaan ek nie commit vir n vinniger een nie.

Does anyone on the forum have the imported low range gears in their vehicle?

I would be keen to hear first hand accounts of how well they work.

hugejp wrote: ↑13 Dec 2017 15:09 Does anyone on the forum have the imported low range gears in their vehicle?

I would be keen to hear first hand accounts of how well they work.

Anybody with the Marks4wd gears???