low range gears

Transmissions, Transfer Boxes, Axles, Drive Shafts
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Peter Connan
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Re: low range gears

Post by Peter Connan » 07 Jan 2018 14:13

Just to keep everything in the same place:
I recently managed to acquire a transfer case in which somebody had fitted a set of Marks 2.86:1 low range gears (let's not go into what it cost, and just say both Dawid's cars are now considerably heavier). My brother and I fitted it last week and the first outing with the new gears was Hennops yesterday.

For starters, I can say that it makes a HUGE difference. It feels like I have much more time to make decisions and manuevre in an obstacle and engine braking on downhills is much better.

The most telling though is that second-last obstacle, the steep climb one climbs when turning left just before the big mud-hole. Previously, the slowest I could get up here was about 5km/h (1200rpm in first low). I needed to lock everything up to do this and there was a fair amount of bouncing happening.
I have plenty of photos of Patrols coming up there one two or even just one wheel to prove that I am not alone.

Now, I crawl up at just about idle speed (600-800rpm, or about 2.0km/h), and even managed it once with the rear diff open. No bouncing, no nerves, just an easy climb.

The point is, because I was going slow enough to keep all four tires in firm contact with the terrain, I needed far less momentum. This is exactly what I was hoping for, and I hope it also translates as such on Koos se klip...

I also had a dice with Tijmen. First gear, low range, as slow as possible but without touching the clutch. Result: Tijmen took 30 seconds to cover the distance, I took 1minute and 12 seconds. Of course, there are several contributing factors. He has 35" wheels, my current wheels are probably no bigger than 30". Also, I think his idle speed is set higher, and lastly I was holding mine back with some gentle braking, going down to around 500rpm...

Of course, this is not conclusive proof that 2.86 is the ratio to get if one has the choice. It will be a good long while before I can find out how it performs on dune sand, and of course each obstacle and engine/tire/diff ratio combination will probably have a different ideal ratio...
Gut feel tells me I would still have preferred the 3.73, but that the 2.86 is probably a big enough improvement. And there may be issues with the 3.73 that I am unaware of.

The one unfortunate is that since I got the gears already fitted to a transfer case, I did not dismantle in order to measure and draw them up... And there's just no way I'm taking them out again.
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Re: low range gears

Post by hugejp » 07 Jan 2018 14:30

Thank you for the update!

I would love the 85% gears.

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Re: low range gears

Post by davidvdm » 08 Jan 2018 08:56

Makes me feel optimistic about my 4.2 gearing..
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1997 Nissan Sani MK3 2.7TD - Hillbilly (SAFANI)
MQ Patrol C200 SFA
MQ Patrol H260 LSD Rear
MQ Patrol Transfer as second low range
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