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Fitting Nissan Patrol GQ axles to a Discovery


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Well i finally got around to fitting the patrol axles to the Disco trayback after having them sit around for 12 months while I got my motivation together. Breaking a 3rd Rover diff in 4 outings was the final straw.

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One of the main reasons I made the change. Plus the fact that they come as 4.11 ratio and have a rear locker as standard.

Front alxe is straightforward. Cut off nissan spring mounts and weld on LR ones.

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Fabricate a new panhard rod by cutting the 2 and welding them together at correct length. Luckily the LR one is solid and fits (very) tightly inside the Nissan one which is hollow.

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Simply use the Nissan radius arms in the LR chassis mounts and its on.

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The TRE on the rover drag link fits the steering arm OK but the drag link is about 5 cms too short. Initially I wound out the 2 ends but then discovered that since my steering box has the swan-neck droparm like a defender the drag link is in fact 5 cms shorter that that fitted to later discos. A quick visit to town and a new drag link and its all OK now.

Other things you need to do on the front are put a run of weld into the pinion flange recess and then turn it down to accept the LR propshaft end. You can then drill 4 new holes. The front prop also need shortening by about 2-3 cms which can be down easily enough if you've got this far.

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Slit the prop just shy of the weld and knock the end off... it is a tight push fit.

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Then use a chopsaw or similar to remove however much you need to from the prop tube, then knock the end back on and reweld the thing back together. Don't forget to mark the position of the yoke before you cut it off.

All that remains is to connect the brakes but this is pretty straightforward as they are 10mm metric fine on both vehicles

Onto the rear. This is pretty easy too but a pain due to central diff. If I had taken more note at the outset I think I may have cut the axle tube and shortened one side by 5 cm and lengthened the other by the same amount. This is because although the diff pinion is dead central the diff is offset to the passenger side. This means that there is a long and a short halfshaft. As far as I could see there would be no reason that they could not be swapped over if the tube was cut and shut and that would bring the pinion flange much more into line with the transfer box thus reducing problems of propshaft vibration and alignment. Heres a pic from below to show how much angle there is. OK on 100" but would be a problem on a 90

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Note my helper!

To fit the axle I simply debracketed it and made up/transferred across the bracketry from the LR axle.

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Tricky bit was the ball joint bracket but a bit of HD fabrication and she was OK.

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I did end up cutting and sutting a recess into the top of the casing before I welded the ball joint bracket on so as to enable the use of a ring spanner on the bolt. I could have made the bracket taller but this would have made it weaker and would have adverse affects on the already altered geometry.

The rear pinion flange simply needed turning down a fraction to get the LR prop to fit and the new holes drilling. Rear prop also need shortening by 2-3 cms

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Brakes were not a problem, just a new hose and new pipes on axle.

The rear locker works on a vacuum and has a switch to operate a warning light in it. The switch was wired in and pipes run forward to the engine bay. There I sourced an electric 2 way vacuum solenoid thingy from a subaru Justy I had under the hedge. this is used to operated the 4WD on the Subaru by the same method as the Nissan difflock. Wired it all to a switch and warning light and T'd into the servo pipe to get the vacuum and it works just fine.

Taken here out for a few tests now. Am very happy with it. Some vibration at road speeds but she is not destined to spend any time there so not too bothered by that. Happy to have my gearing back too.

Anyway sorry this is long winded. Hopefully of help to someone out there. Any questions feel free to ask

Mark

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jsut a thought about the rear axle - could you not flip the axle and rotate the diff in the housing to get the short side on the drivers side?

cos from the piccie it looks like the diff would fit either way up in the casing.

unfortunately the pinion is offset from the diff so this is dead centre. By flipping the axle you will change the sides of the shafts but the propshaft attachment will be in exactly the same place!!

Going by what you described in the previous posts, I tend to agree with nicks90 and disagree with you on flipping the diff/axle housing and rotating the diff centre. If you think about it some more you should see it also.

I have not done this with nissan diffs, but have in the past with others.

It will be necessary to also rotate the rear cover and notch the mounting flange to suit the new position of the crown wheel.

I have on order a set of Marks portals for nissan gu diffs, so will be fitting these under my rangie in about 6 weeks.

Good write-up btw.

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Going by what you described in the previous posts, I tend to agree with nicks90 and disagree with you on flipping the diff/axle housing and rotating the diff centre. If you think about it some more you should see it also.

I have not done this with nissan diffs, but have in the past with others.

It will be necessary to also rotate the rear cover and notch the mounting flange to suit the new position of the crown wheel.

I have on order a set of Marks portals for nissan gu diffs, so will be fitting these under my rangie in about 6 weeks.

Good write-up btw.

I fully understand the principle of flipping the axle/diff and understand how it might work. But. On the GQ axle the diff pinion flange that bolts up to the propshaft is absolutely dead central. Any rotation of axle diff or otherwise will result in the flange still being dead centre and nothing will have been gained. Cutting and sutting the axle tube on the other hand and swapping the long and short halfshafts over WILL move the pinion flange 5cm to the right and thus more in line with a LR transfer box output. The more I look at it the easier i think it would be to do.

Thanks for the input

Mark

PS fitting drop boxes to the axle may not be a daft idea. I think it may be the way to go!! :lol::ph34r:

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I fully understand the principle of flipping the axle/diff and understand how it might work. But. On the GQ axle the diff pinion flange that bolts up to the propshaft is absolutely dead central. Any rotation of axle diff or otherwise will result in the flange still being dead centre and nothing will have been gained. Cutting and sutting the axle tube on the other hand and swapping the long and short halfshafts over WILL move the pinion flange 5cm to the right and thus more in line with a LR transfer box output. The more I look at it the easier i think it would be to do.

Thanks for the input

Mark

PS fitting drop boxes to the axle may not be a daft idea. I think it may be the way to go!! :lol::ph34r:

I don't have a rear diff here to look at at the moment, but I do have a front, that I just went and checked. I can't imagine that the rear diff centre is much different as far as crosswise offset goes (I know there are other differences such as low pinion).

The proof that clinches it for me is in your own statements that one half shaft is shorter than the other.

So if the diff pinion flange is central between the wheels, the diff centre, must be offset (where it bolts into the axle housing), which is why the half shafts are different lengths. Therefore if you flip the axle housing, then spin the diff center so that is no longer upside down (as I may not have described well enough), you will achieve the same result as cutting and shutting the housing as you described.

If you can't see that, then you are missing something logical and we will have to agree to disagree.

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Ok OK John I concede :lol: I was being over logical!

Just spent 20 mins with the back of an envelope and it could be done as you describe. Of course it would still involve having to relocate the drain/fill plugs and the rear difflock mechanism as well as redrilling/tapping out the studs, all of which in my mind would be more involved than cutting and shutting the tube. If you added strengthening bracing to the axle tube when adding the A Frame mount then any worries about weakening the tube could be easily overcome.

Its good to discuss.....

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  • 9 months later...
Ok OK John I concede :lol: I was being over logical!

Just spent 20 mins with the back of an envelope and it could be done as you describe. Of course it would still involve having to relocate the drain/fill plugs and the rear difflock mechanism as well as redrilling/tapping out the studs, all of which in my mind would be more involved than cutting and shutting the tube. If you added strengthening bracing to the axle tube when adding the A Frame mount then any worries about weakening the tube could be easily overcome.

Its good to discuss.....

This may sound dumb but how about using the top 2 Nissan arm brackets on the diff, using 2 short arms back to the front A-Frame mounts and doing away with the A-Frame and it's bracket on the diff? It should achieve the same outcome though it may need a panhard rod if the arms aren't sufficiently angled.

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GQ is (I think) about 1989 to about 1997. They are the coil sprung square faced monsters! Get them from a 4.2 diesel and it should be 4.11 ratio which willl match the yota 80 series rear.

Good write up,

Just checking though, am i correct in thinking you used a Nissan GQ front axle and a Toyota landcruiser (80 Series) rear, or did you use the rear axle off the GQ?

Cheers

Mark

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Mark is away at the moment but I know he used a Nissan front and rear.

Cheers Steve,

Makes life a little easier to get a pair of axles from one donor truck, rather than 2.

Am i correct in assuming the Land Cruiser axles is offset and more suited to the LR driveline?

ATB

Mark

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Am i correct in assuming the Land Cruiser axles is offset and more suited to the LR driveline?

Yep! The rear anyways, the front Nissan diff offset is fine, and almost a bolt on replacement.

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Cheers Steve,

Makes life a little easier to get a pair of axles from one donor truck, rather than 2.

Am i correct in assuming the Land Cruiser axles is offset and more suited to the LR driveline?

ATB

Mark

The rear landcruiser does have a offset diff but it's not as much a landrover, enough to give no vibes with a lt230 though.

The internals in the gq axles absolutly dwarf 80 series cruisers as well

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I own a 4.2LWB 1997 and it's commonly known a Y60, great big ugly mother, pulls like Brad Pitt, I use it for towing my challenge motor up and down.

When I did a front halfshaft seal I thought I'd treat the front axle to an oil change, 5 litres of EP90 it took, kept looking to see if I'd done something wrong, but they are seriously big diff 'n' halfshafts and CV's look very robust compared to Landy stuff.

Keep yer fingers of my axles when its parked upon the Howlin Wolfs please, especially you Dirty Diesel. :P

Cheers lads

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  • 1 year later...
  • 1 year later...

It's been a while since this topic was opened, but been reading and re reading.

Just bought a pair of Y61 GU axles which will replace RR axles. Wheelbase is at 103".

Took out the measuring tape and measured the rear axle from diff centre to each side, and difference is of a couple of cm, about 4cm if I recall.

Will those few cm make any difference in reducing vibration?

Am asking before taking the plunge and start cutting down.

thanks,

bob

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