GEARMASTER - transfer case reduction gears 85%

Submitted: Wednesday, May 07, 2008 at 20:16
ThreadID: 57364 Views:8682 Replies:5 FollowUps:3
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Has anyone fitted the Marks4wd gearmaster transfer reduction gears 85% to a 3.0lt GU patrol?

If so what issues did you face with the install? I belive that you have to 'modify' the transfer case a little bit to enable the gears to go in (they are bigger than the stock gears)

What differences did you find after install?

Was there any 'downsides' to the install

Marks4wd gearmaster reduction gears

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Reply By: Member - Roachie (SA) - Wednesday, May 07, 2008 at 22:20

Wednesday, May 07, 2008 at 22:20
I think Trevor R has got the 85% ones in his 4.2TD and he loves them.

I have the 43% reduction in my 6.5 and I reckon that any lower (ie: the 85%) would be just too low unless you do a lot of rock-hopping. Even the 43% units are pretty low and a lot of the time I find I have to go back up to high range 1st or 2nd, cos even 4th low is pretty low and top speed is about 30k/h without it screaming.....

Great bit of kit......

Roachie
AnswerID: 302591

Follow Up By: KiwiAngler - Wednesday, May 07, 2008 at 23:06

Wednesday, May 07, 2008 at 23:06
Roachie

Thanks for the feedback.

How do u reckon a 85% would go in the 3.0lt though.

Its interesting when you look at the Marks website and compare the 3.0 and the 4.2 turbo diesel ratios
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Follow Up By: Member - Roachie (SA) - Thursday, May 08, 2008 at 08:28

Thursday, May 08, 2008 at 08:28
Kiwi,
Not sure about the 3 litre.... I know they have a different final drive ratio (4.1 or 4.3??), but this would be only a marginal difference to the 3.9 diffs in the 4.2TD.

If you have larger tyres (like 285/75 or 315/75), then the Gearmaster would be great.....also if yours is an automatic gearbox, excellent choice.

The BIG decision is whether to go for the 85% or the 43%..... Personally (and it IS only MY opinion), I can't see why 99% of owners would need them as low as the 85%......to me it;s just way too low.......

Roachie
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Reply By: Grungle - Thursday, May 08, 2008 at 07:05

Thursday, May 08, 2008 at 07:05
Hi KiwiAngler,

I have those exact gears in my 2.8/4.2T GU Patrol. I installed the gears myself but I was lucky in that I had a second transfer case that I fit the gears without disabling the Patrol.

I read the instructions several times before doing anything and then planned what I needed to do and when. Stripping the transfer case is easy as was grinding out a small section of housing on the inside (used a small 4" grinder). I had then made arrangements to go to a bearing place and remove and fit new bearings and seals to the new gears and case with their press as I have very limited hand tools.

Next was reassembling where I made sure that I used a good quality gaskey sealer on all surfaces so I had no leaks when filled with oil.

To remove and refit the transfer case you will need 2 blokes and a pit/hoist. I am not sure ablout the 3.0L patrols but the 2.8 has gearbox oil lapping the transfer case housing so we were coated in oil when we broke the seal. The 4.2 has the gearbox oil contained in the gearbox.

There was 2 reasons I went for the 85% reduction. One was the 2.8 had 35" tyres and just didn't have enough low down torque offroad. Second was we tow an Aussie Swag Camper and trying to maneaver in tight spots meant either riding the clutch or too higher speed.

Things are slightly different now since converting the 2.8 over to a 4.2T but I still appreciate the fact that I have so much more control with revs, torque and speed whilst doing steep (up or down) climbs or tight maneuvers. There has only been a couple of instances where first gear is used now (and that has been for really difficult offroad work) so most low range work is 3rd gear or 2nd whilst towing. Engine braking down hills is done mostly in 2nd to 3rd low as babies crawl faster than 1st low.

The only downside is that top speed in low range is 25km/hr at around 3000rpm so there is a lot more cog swapping between low and high range.

I am very impressed with the gears and will have them in pretty much any touring/offroad 4wd that I will ever own.

Regards
David
AnswerID: 302612

Reply By: Trevor R (QLD) - Thursday, May 08, 2008 at 09:05

Thursday, May 08, 2008 at 09:05
Kiwi,

Grungle has summed it up beautifully. I love the control the crawler gear gives me on my 4.2. It is true that low 1st is very rarely used or needed but if you do need it, it is better to have it. I reckon, if you are changing the low range gear you may as well go lowest available to give you the most options and gears from the work you are doing to the rig. I think it adds so much to my GU that I don't feel the need for a locker at this stage.

Last years national gathering saw a lot of blokes back in first low for one of the climbs to the summit of one big hill (all sorts of vehicles) but the lowest I got was 3rd low and second low to start off again when I was stopped by the nanny driver of the vehicle in front hehehe (Hi Ross H LOL!!).

Get it and enjoy, best money you will spend on the truck.
Regards, Trevor.
AnswerID: 302632

Reply By: KiwiAngler - Thursday, May 08, 2008 at 18:22

Thursday, May 08, 2008 at 18:22
Thanks all for your replies - I have read and considered them all

I have made the decision to go with the 85% mainly because I have a LOT of weight in my 3.0lt (weighs about 3,500kg all up) and I have 285 tyres so I like the notion of being able to 'crawl' both up and down hills without the need for a lot of momentum. Less momentum means less crashing and bashing which means a better ride and less damage to vehicle, contents and passengers

I will wait until I get back from the CSR trip (12th July - 11th August) as I wont need it for then.

But will definitely appreciate them when I am in the Victorian High Country

Once again thanks
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Follow Up By: Trevor R (QLD) - Thursday, May 08, 2008 at 20:19

Thursday, May 08, 2008 at 20:19
Yep, better to have them (lower gears) and not need them, as opposed to needing them and not having them.

They work well in sand, in my rig pics there is a photo of my GU and Van up at Inskip point after 4 or 5 days parked up and the sand was choking the bottom of the rims of both vehicle and caravan (which weighs 3 tonne). I hooked the snatch strap up and was going to just get a tug start but thought, why not see if I can drive out first.... 1st low, digging in, reverse till it dug in a bit more, then 1st low again and away she went, I thought ohhh no it is bogging down but then I realised I had just hit the top of the rev range and was running out of puff, into second and it kept pulling and pulling, into third and out we went (all the while, my B_I_L was walking beside the car carrying the snatch strap I had hooked up to the front recovery hook, 3rd low a little over walking pace). Same stretch of sand caught many solo vehicles out and they had to be snatched to recovery. Had many an onlooker that day, with a few coming up and asking what I did to get out unaided.

Cheers, Trevor.
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Reply By: KiwiAngler - Thursday, May 08, 2008 at 20:41

Thursday, May 08, 2008 at 20:41
Trevor

Thanks for that review it has just confirmed what I had already decided is right for me

I just don't have time, unfortunately, to get it done b4 I go to the Canning.

I am not too fussed about that really as I believe (for me anyway) the true value will be in places like Victorian High Country

I will report back here once I get the work done and done a couple of VHC trips

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