Reduction gear selection

Guys im torn between choosing either 43% or 85% Marks 4wd (Gearmaster) transfer case reduction gears for my GU.

I have well and truly found the lower limits of the standard low range gearing while climbing hills and being bogged in thick slop, often requiring heavy clutch riding just to keep the wheels turning.

I have always thought, if im doing a job I may as well do it properly and get the 85% gears!

But recently have been wondering if 43 will be enough? I do a bit of beach work during summer so 43 are generally more suited to this. But then I may upgrade to 35" tyres when the time comes to replace them so the 43% may not be enough? Then comes the turbo/cooler upgrades which may mean the 43 will be enough with the big tyres? But if im running bigger tyres, I may need to change to higher diff ratios anyway so if im running 83%, these may we too high with the 35's and turbo/cooler/diff upgrades?

Im not fussed about down hill's as the standard engine braking and manual box holds things pretty well. Its uphill control that im chasing! would love to idle up some pretty snotty hills.
Also thinking, 85% gives approx 30kmh top speed in 5th, if you are doing 20-30kmh in 4L surely it can be done in 4H or even 2H.

I generally run on the beach in 3rd now, so 43% will probably switch to 4th, 85% will require switching to 5th for the same stretch.
Dont plan on doing any simpson desert crossings so momentum for big sand hills isnt really a concers

I guess I can handle some time on the knobby lever as I dont like to run 4L when I dont need to anyway

So much has been running through my mind lately so Im hoping anyone that has ever driven a patrol with reduction gears to chip in about their experience :)

It also doesnt help that the 43 gears are $135 cheaper and dont require machining of the case to get the gears in!

ARRGH!

Want to buy them soon but its a big expense and would hate to regret buying the wrong set!

Cheers!

Mate, do you know anyone running the 43's and 85's. If you could go for a spin you could easily decide.

I would have thought 85's would be way too high for a manual trans. I've got and auto and was thinking 43's myself but it all depend on your application I suppose.

Good luck mate

I'm going 85% on Friday this week, but as Kris alluded to, I have an auto which runs away a lot more than a manual. If I had a manual (and diesel even more so) I would definitely only be going 43%. I do more hill work than mud and having to change in and out of 4 low to 4 high between attempts is a small price to pay for the added reduction to the auto.

Living in south east QLD I have been beach driving for 22 years and rarely use 4 Low. I've been bogged once and even then, it was my fault as I didn't deflate the tyres and it was on the first cutting onto the beach. That said, my previous rigs were diesel manuals (bar one of six).

43% would be ample and to be honest, I don't think you'd be driving in 4 low at all on the beach except for heavy going as even in 5th, you'd be doing about 25klms per hour maximum with 85% reduction!

Just my opinion mate for what it's worth - good luck with it - either way, you're going to notice a huge improvement for hill climbs and descents, etc!!!

Cheers guys, yeah thats what I have been thinking lately, wanted 85 at first for ages now thinking 43 will probably be best of both worlds! Mind changes almost hourly sometimes!

I dont know anyone personally with a set fitted so I will just have to go on opinions alone

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Originally Posted by GUte

Cheers guys, yeah thats what I have been thinking lately, wanted 85 at first for ages now thinking 43 will probably be best of both worlds! Mind changes almost hourly sometimes!

I dont know anyone personally with a set fitted so I will just have to go on opinions alone

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Talk to the guys at Marks Adapters mate - they are usually pretty willing to chat about the pros and cons of each and when I spoke to them, they weren't overly pushy on the sale factor, just which one would suit.

If you fit reduction gears you will more than likely try more slow technical stuff then you will want the lowest gear possible, when I can afford it I will be fitting the 85s for sure.

Im hearing ya gec

I know of a few local hills that I wont even attempt with the current gearing and not even sure if 43% will be low enough. I have much more fun climbing hills than playing in mud/sand. With tyres deflated, I dont have any dramas running on the beach in 4H, future 4.3 diff ratios will make it even easier.

Sent an email to Marks 4wd and there are a few distributors in Perth so I will contact them to see if they have some in stock and go from there.

Still thinking 85!! haha

I find the only time i wish I had reduction gears is declines, especially in the mud/wet. Everything else is no problem. Mine's an auto tho
I have been in a few situations in the wet where the auto tends to run away and you need to use brakes( bad move). There are other techniques you can use without dropping the gears...I'm still to master those

Toss a coin. lol

Seriously... It's a big decision so do your homework.

All the best.

Take care out there.

Ross

I dunno ... Hate to be the voice of reason, but 85% reduction in a manual means that is about all he'll be doing in low range - extreme climbs and descents ... worthless for most beach work, worthless for most bush work and truth be told, not much chop for mud either as you can't build any real momentum ... may as well turn it into a comp truck!! lol

Example - my missus' jeep has standard overall low range ratio (as an auto) of 2.6:1 ... mine is 2.02:1 ... hers absolutely crawls downhill compared to mine running away (she'd be doing 4-5kph when I would be doing 18-20). A 43% reduction takes me to around 2.85:1 which would be plenty, but as said, I only use low range for the hill work I like to do, hence going 85% which will sit it around 3.45:1 - which is awesome. That's starting from 2.02:1 but what is the manual starting at? If you end up with reduction ratio of somewhere near 3.8-4.0:1, you will be crawling in low range even in fifth gear - and I mean crawling ... someone correct me and happy to be wrong, but even though you can use 3rd, 4th and 5th gear to start off with in Low range for ascents and mud etc, it's not what your transmission (not transfer case) was intended for and you end up stripping (potentially) gears that are smaller and not meant for the stress and abuse the shorter gears are meant to handle ...

Just my pickled view though ... I'll shut up now and go back to my box ...

Very helpful comments bigrig, I like your experience with the jeep also. My mate has a new 2010 Wrangler rubicon and that thing crawls everywhere, I will have to find out what the final drive ratio of that is and something like that would be sweet. I was wheeling today, had to slip the clutch twice but I rekon it would of been fine If it was 1 gear lower which I assume would be around 43%, not 2 gears lower like 81%

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Originally Posted by GUte

Very helpful comments bigrig, I like your experience with the jeep also. My mate has a new 2010 Wrangler rubicon and that thing crawls everywhere, I will have to find out what the final drive ratio of that is and something like that would be sweet. I was wheeling today, had to slip the clutch twice but I rekon it would of been fine If it was 1 gear lower which I assume would be around 43%, not 2 gears lower like 81%

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Too easy mate - ours is a Rubicon also - 2.66:1 low range ratio - as you said, it dead set crawls!! Good luck with it either way mate.

Cheers bigrig, that really puts things into perspective for me.
Last time I was wheeling with him he was cruising in 5th for most of the low range work that we did where I was using 3rd (flat water crossings/some mud)

His is a white 2 door, apparently only one, or one of a couple in Australia. Had to wait a fair while to get it, love the factory diff locks on them!

http://a5.sphotos.ak.fbcdn.net/hphot..._7887119_n.jpg
http://a7.sphotos.ak.fbcdn.net/hphot..._4394194_n.jpg

Anyway thats enough jeep!! haha

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Originally Posted by GUte

Cheers bigrig, that really puts things into perspective for me.
Last time I was wheeling with him he was cruising in 5th for most of the low range work that we did where I was using 3rd (flat water crossings/some mud)

His is a white 2 door, apparently only one, or one of a couple in Australia. Had to wait a fair while to get it, love the factory diff locks on them!

http://www.nissanpatrol.com.au/forums/
http://www.nissanpatrol.com.au/forums/

Anyway thats enough jeep!! haha

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They need the difflocks to cater for the lack of height and lack of wheel travel (standard) !!! Without them, they'd be taking the chicken track more often than not!! LOL

Your not wrong haha! He wants to spend 10 k on it before the rains start over here, lift, rims and 35's, diff gears. Thats an expensive way to have fun offroad!

Looking at the Wrangler manual, it seems the low range ratio is 4:1! With a final drive ratio of 73:1, where my patrol with 85% reduction fitted will be 3.743:1 and a final drive of 65.56:1
Factory ratios are 2.02:1 and 35.38:1

http://www.offroaders.com/tech/jeep/...ew-Offroad.htm

May have to ask him to take me for a drive in it and go from there

Well, after bulk research and constant mind changing I just placed an order for the 43% reduction gears.

Went wheeling yesterday and there were only 2 times I needed to ride the clutch to get things moving .
Received some advice from Elliot (marks 4wd) and also read a post from a gq comp truck owner who installed 85% reduction and runs 42" tyre. Perfect for his current setup but the first few gears were pretty much useless when running 37's.

Getting install quotes now as Im not confident in doing the whole thing myself, I can take the case out though so that should work out cheaper, ill just weigh it all up.

If anybody knows someone in perth that they recommend, please do so!

Quote:

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Originally Posted by GUte

Well, after bulk research and constant mind changing I just placed an order for the 43% reduction gears.

Went wheeling yesterday and there were only 2 times I needed to ride the clutch to get things moving .
Received some advice from Elliot (marks 4wd) and also read a post from a gq comp truck owner who installed 85% reduction and runs 42" tyre. Perfect for his current setup but the first few gears were pretty much useless when running 37's.

Getting install quotes now as Im not confident in doing the whole thing myself, I can take the case out though so that should work out cheaper, ill just weigh it all up.

If anybody knows someone in perth that they recommend, please do so!

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Look forward to hearing how she goes after the reduction gears are fitted, been thinkin of all options as you have!

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Originally Posted by growlers71gq

Look forward to hearing how she goes after the reduction gears are fitted, been thinkin of all options as you have!

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Will do growler!

If i had an automatic I would have chosen the 85% reduction as the manuals first gear is lower and autos suffer from running away downhill a lot more than manuals.

Will keep this thread updated

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Originally Posted by GUte

Will do growler!

If i had an automatic I would have chosen the 85% reduction as the manuals first gear is lower and autos suffer from running away downhill a lot more than manuals.

Will keep this thread updated

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Cheers mate, its a way off for me yet need lockers, turbo wait for my near new 33's to wear out and replace with 35's and on and on and on but good to fill the grey matter up with as much info as it will handle till then

I kept saying that too but ive only had it for 5 months now and doing them already!
I would defiantly get the locker first, makes a HUGE difference and no amount of low range can really help a open front diff! Also, I never really noticed the low range gearing issue till the locker went in, the vastly greater traction the vehicle has once they go in really plays havoc with the low down torque when climbing hills etc. You just think its fine with open diffs and they just spin, you go nowhere while not noticing the lack of low gearing

I'd reckon the 43% would be enough for most normal use, 85% would really only be required for rockhopping etc in most cases.

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Originally Posted by Oka374

I'd reckon the 43% would be enough for most normal use, 85% would really only be required for rockhopping etc in most cases.

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85% for autos either way - overcomes the lack of engine compression for steep descents.

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Originally Posted by Bigrig

85% for autos either way - overcomes the lack of engine compression for steep descents.

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Further to this - what are you driving? Manual or auto? I figure either way, why not go the larger reduction for the minimum price differential anyway - we are only talking low range when the gears are active, and even on the beach (if you have a manual) you can still run in 4th or 5th gear with the lower reduction - an auto would struggle here a bit, but only due to speed - I never use low range on the beach, but am there rarely compared to off road (tracks, parks etc), so my opinion is based directly on your use - if you're predominantly beach use then maybe the 43% gears - if not, 85 all the way.

I have 85% in my auto by the way.

Quote:

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Originally Posted by GUte

I kept saying that too but ive only had it for 5 months now and doing them already!
I would defiantly get the locker first, makes a HUGE difference and no amount of low range can really help a open front diff! Also, I never really noticed the low range gearing issue till the locker went in, the vastly greater traction the vehicle has once they go in really plays havoc with the low down torque when climbing hills etc. You just think its fine with open diffs and they just spin, you go nowhere while not noticing the lack of low gearing

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Hi GUte!

How did u go with the reduction?
I'm doing the same, but don't do a lot o rock climbing, but the odd steep accent and a lot of soft sand driving. Planning a trip across the Simpson Desert next year with a 1 ton off road trailer in tow, thought the gear reduction might help a bit.

Cheers mate!

Was there ever an update on the 43% gears?

Quote:

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Originally Posted by GUte

Will do growler!

If i had an automatic I would have chosen the 85% reduction as the manuals first gear is lower and autos suffer from running away downhill a lot more than manuals.

Will keep this thread updated

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Very happy with the 43% glad I didnt get the 85% would not use L1 or possibly L2 with the stuff I do. If you are into rocks and steps well then the 85's are the way to go.

Quote:

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Originally Posted by GUte

Cheers guys, yeah thats what I have been thinking lately, wanted 85 at first for ages now thinking 43 will probably be best of both worlds! Mind changes almost hourly sometimes!

I dont know anyone personally with a set fitted so I will just have to go on opinions alone

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Looks like 2 wheel drive to me.

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Originally Posted by Rustyboner81

Looks like 2 wheel drive to me.

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Another MC misquote by any chance?

Well it's time to start this thread up again. I am in the process of doing this but my application is a little different. I've got a heavy GU camper combination. It quite often drops under turbo influence and stalls in 2nd low climbing and I'm on the brakes even in 1st descending. The idea of backing it down a hill with the current gearing doesn't bare considering. I originally thought something around 2.5:1 would be sufficient but then (like everyone else) am now stuck between 2.86 and 3.74. If I was confident the 50.1:1 1st and similar reverse with the 2.86 gearing would allow both controlled descents and rock stepping on steep ascents without stalling it appears to be the best of both worlds. 2nd gear in the ratio looks handy and 3rd is closer than currently. The guys at Marks have sent me a speed calculator but in reality what is the difference between 3.7 and 5.2 kph when descending a steep hill? And what is the effect on engine braking? l see the original thread came from Macca with a gu ute. Have you got any more experience relevant to mine since the last thread? Much appreciate any input

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Originally Posted by paps01

Well it's time to start this thread up again. ........... l see the original thread came from Macca with a gu ute. Have you got any more experience relevant to mine since the last thread? Much appreciate any input

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Still feel the same, suits my usage

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Originally Posted by macca

Very happy with the 43% glad I didnt get the 85% would not use L1 or possibly L2 with the stuff I do. If you are into rocks and steps well then the 85's are the way to go.

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Quote:

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Originally Posted by macca

Still feel the same, suits my usage

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Thanks, Cheers!

Ive got the 43%'s with an Auto and for general 4wdriving it has been great. Everything from the Cape to the Beaches. With the exception of maybe one or two rare occasions I have not found the need for a lower gear and have been able to make do.

Compared to a mate's standard Auto, it is way better. During some recent steep downhill stuff when we pulled up at the bottom in a creek, his brakes were nearly red hot. Mine were perfectly fine as they were hardly touched.

Maybe try hitting up LoveKey70 who was doing those sets of 66% reduction gears. Just an option.