GU Patrol 5trh gear

Submitted: Tuesday, Nov 25, 2003 at 13:01
ThreadID: 8735 Views:1629 Replies:4 FollowUps:6
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I have read with interest the problems with the failure of 5th gear on a few GU Patrols and the comments with relation to driving at 6o to 7o km in 5th gear being a big no no due to stressing out 5th gear.

My question is if the 4.2 turbo Patrol makes its peak torque at 2000 rpm and in 5th gear relates to a speed of approx 100km then my thoughts would be this would have a bigger and more demanding effect on the gear box than just loping around at say 60km/h at 1300rpms and what it appears to do easily and with a hell of a lot less torque. Also at 100kph there is more friction with wind resistance due to the higher speed and also tyre friction. This in turn would it or would it not put even more stress on the 5th gear.

I totally agree with the towing side of things as depending on weight this would definately put more stress on things.

Your thoughts would be appreciated
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Reply By: GUPatrol - Tuesday, Nov 25, 2003 at 15:13

Tuesday, Nov 25, 2003 at 15:13
Goona,
5th gear problem only affects vehicles built from 2000 to 2001but not all.

With regards to the usage....

5th in all cars is made to be quiet and as such is smaller and with fine teeth, the problem loading it at lower speeds is that for each stroke there is more preassure on the gear than at higher speeds, that is the reason why it fails sooner on the 3.0L than on the 4.2, the three litre engine (being only 4cyl) produces more kw and torque per stroke than the 4.2. That is also the reason why Nissan reviewed the g'box with the introduction of the 3.0L engine and the gear manufacturer stuffed up the splines tolerances.
To have an understanding of the forces involved vs the speed, grab a bicycle with gears and put it in first, if you apply lots of force on the pedal you are likely to spin the wheel right?
Now set the gear to the last (smallest) apply lots of force to the pedal and you are not likelly to spin the wheel but more likelly to brake the chain (if you apply lots of sudden force).

AnswerID: 38388

Follow Up By: Michael - Tuesday, Nov 25, 2003 at 16:28

Tuesday, Nov 25, 2003 at 16:28
Hi there, I cant believe that you believe that the extra power and torque from the 3.0L engine is the cause of the extra failures, its a piddly few kw's. If thats the case, then there is an awful lot of 4.2 owners that are running on the edge. The 3.0L has a much lower diff ratio than the 4.2L, so the bike chain theory goes out the window. Hey i could be wrong, my thoughts only. Best regards Michael
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FollowupID: 27894

Follow Up By: GUPatrol - Tuesday, Nov 25, 2003 at 16:43

Tuesday, Nov 25, 2003 at 16:43
Michael,
That is not what I said....
Chek reply below from patrol list.
4.2 and 3.0L use the same box, 3.0l however are failing earlier than the 4.2s for that reason, I have driven both and it is much easier to load the 3.0L box than the 4.2 because of the lower ratio...
Just call Nissan Customer service and you will get it first hand from them.
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FollowupID: 27895

Reply By: rors101 - Tuesday, Nov 25, 2003 at 15:58

Tuesday, Nov 25, 2003 at 15:58
From the Patrol list:

The problem vehicles are series 2 from 2000 to 2001, there is a
tolerance fault in manufacturing and it does not matter if you tow or
not.

Nissan will fix them even if no longer under warranty.

Series 1 and series 3 are unaffected.

Check with Nissan if you have any doubts
AnswerID: 38394

Follow Up By: pathfinder - Tuesday, Nov 25, 2003 at 17:05

Tuesday, Nov 25, 2003 at 17:05
Basically buy a Series 3 to avoid the engine problems in Series 1s and G/box problems in Series 2s...then you'll just have EGR and other high-tech things to worry about... Makes a low-tech mechanically controlled early 90s TD seem appealing for remote work...
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FollowupID: 27899

Follow Up By: rors101 - Wednesday, Nov 26, 2003 at 11:37

Wednesday, Nov 26, 2003 at 11:37
Pathfinder,- Better still get a horse and cart and only worry about hay and water who needs A/C, radio, fridge, electric lights etc anyway.
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FollowupID: 27989

Follow Up By: pathfinder - Thursday, Nov 27, 2003 at 08:58

Thursday, Nov 27, 2003 at 08:58
rors101 - my fourby has all those things...and power windows...but power windows won't leave me stranded in the Simpson if they bleep up. The second major reason for Simpson Desert vehicle recoveries from Birdsville (at >$2K for the pleasure) is electronic engine management failure, behind suspension failure. Regardless of what manufacturers say, many high-tech electrics in new fourbys will not sustain years of moisture, dust and vibrations...imagine the reliability of all the electronic componentry of these vehicles (particularly in something like the BMW X5) in 10-20 years time... Until electronically controlled TDs have a simple, easily accessible, affordable plug-in control module, which can be replaced by the driver if it goes belly-up somewhere remote, I won't be venturing anywhere remote with one...

For around town or highway towing, as many seem to be used, they're more than fine and gruntier/more efficient than my mechanically-controlled TD.
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FollowupID: 28615

Reply By: Member - Richard- Tuesday, Nov 25, 2003 at 21:51

Tuesday, Nov 25, 2003 at 21:51
Same question appeared in Dec 4X4 Magazine, letters to the editor. It was answered by Outback 4WD and basically said that 5th is an overdrive only made for light loads and if subjected to heavy stress can break.Richard and Leonie, The grey nomads.
AnswerID: 38451

Reply By: David N. - Wednesday, Nov 26, 2003 at 12:59

Wednesday, Nov 26, 2003 at 12:59
I've been working my 5th gear HARD in my 13 year old TD42 GQ since day one.
Always use it around town at 60km/h. (revs too much in 4th)
Always tow with it, both a big boat and a 2 tonne caravan. (Having said that I don't "lug" it in any gear.)
Gearbox is as good as the day I got it- never get any metal off the magnetic plug. It's quiet, changes well, and the only thing I don't like much is the gap from 2nd to 3rd ratios. ie: if engineered properly you can use 5th as much as any other gear. The Patrol 4.2 gearbox is normally bulletproof but there was unfortunately a stuff up for a short time- which ruined the reputation of the best gearbox in the business.
Cheers
AnswerID: 38537

Follow Up By: Flash - Wednesday, Nov 26, 2003 at 16:09

Wednesday, Nov 26, 2003 at 16:09
Agree
There aint a better gearbox than the Nissan. I work on them all and it's the only one I'd trust with my super. 5th gear is no problem except for the few dud ones they made for a short time.

I see eight or ten of the other make for every Nissan one and the Nissan one's usually been abused beyond belief before they give a hint of trouble. eg:run out of oil.
I'd say if you have a GU not affected by the dud build dates then don't get grey hairs about using 5th gear- you won't have a problem.
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FollowupID: 28539

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