gu patrol 3.0 and 4.2

There's some real good stuff in there, nice work.

Do you do write ups on any other vehicles?

That link is very informative, but it doesn't really touch on the post 2002 engine problems after the "Nissan fix".

Does this mean Nissan got it right, or isn't any one talking about post 2002 blowups?

Cheers.

Thanks V8Diesel
I have done Commodores and Prados so far. As time permits I will put more pages together slowly on other vehicles.
P.G I can't comment on post 2002 as most of my customers still have very low km's. My Nissan dealer tells me they are much better but time will tell.

Hi Muzzgit,

I had my 1990 1HZ 80 series for 300,000kms and always towed in 5th gear. While I have no doubt that your experience has resulted in a buggered gearbox, my experience has been different, never had a problem.

I find towing in 5th gear at 100km/hr more appropriate for engine revs (but obviously select gear choice based on terrain).

Cheers

Captain

I'm with Captain on this one. My GQ did a lot of towing on and off road for about 7 years that I had it I always use 5th.

It had 385,000km on when I sold it and never had a gearbox problem.

Couple of other things got a little exciting but not the gearbox.

The prob with the GU 5th gear was rectified, it was specific to a known period and a vehicle can be checked by comparing the Vin Chassis number to the list at your local dealer.

Duncs

I have been given the same advice as you muzzgit, by a mechanic who has worked on many 4wd's. 5th gear is not designed for towing. If you are worried about revs slow down a bit, the fuel saving will be worth it any way.

To Captain and Dunc's,

You can then get the other side of the story and replace three (3) lots of 5th gears on a 100 cruiser in 18 months and 13000km by towing in 5th just ask me.

All work done under warranty and all done because the dealer kept telling me if your at the right revs/speed 5th is ok. Well I'm here to tell you experience tells me NOT to tow in 5th.

My 2 bobs worth.

Hi Trevor,

A bit hard to know what to do isn't it!!! Some have had no problems, others like yourself have had a heap of issues. Maybe I would have a different opinion if I had some of your problems.

My thoughts on the issue is that my vehicle is rated for 3200kgs tow weight yet I only tow ~1600kg. Nowhere in the manual does it state to only tow in 4th gear, but is does state a recommended speed range for each gear and 5th gear is fine for 100 km/hr.

But if you want to be conservative then arguably a good idea to tow in 4th. And to be even more conservative why not tow in 3rd, or 2nd... Me, well I reckon if the vehicle has 5 gears, I'll use them all ;)

Cheers mate

Captain

transmission repairer/specialists know if you're full of crap? I doubt that, how could they all know.......?

If you are having launch problems with 265/75, you will have worse launch problems with 285/75.

To then change diff ratio to ease the launch problem back to close to 265/70 status, would seem a lot of money spent to go nowhere in particular except gain a little more ground clearance and possibly lose your roadworthy status for Insurance and RTA.

For getting off the line you would be better off going back to standard size tyres, although this may preclude using LT tyres which are usually why you go to the /75 from the /70.

Hi Roachie,

I reckon the 285/75's (~33") are the way to go. I had a direct back-to-back comparison in my 80 series when I went from 10.5x31R15 to 10.5x33R15 and the offroad improvement was astonishing. The old 1HZ diesel never used to like beach work, it was always a big effort even at low psi but after going to the 33" tyres, beach tracks that needed say 20 psi could be done at road pressures and 15 psi tracks were now ~20 psi. And when ypu got down to 12 psi, the old girl was unstoppable compared to before. Was enough difference to convince me to change to 285/75's on my brand new GU on the day I picked it up.

When towing in the 80, i never really noticed any difference. The 80 already had a good first gear and the 7% increase did not seem to make a noticeable difference. But as you have already gone from 265/70 (31") to 265/75 (32") and have an issue, the 285/75 (33") will add another 3.5% to your problem. But is it enough to change diff ratios???

Personally, I would fit the 285/75's just for the improvement in off-road performance and then see how it performs on-road with your van. If you find it OK, great, but if not then do the diff ratio change IMHO.

Cheers

Captain

Roachie, I was looking into putting a 6.5V8 into my GU ST4500 and the bloke at Brunswick said that GU's do have different gearboxes and diffs depending on what one you get.

Aparently the petrol 4.5 / 4.8's and the 4.2D's are bulletproof. The 3.0 and 2.8 less so. I think the 2.8 had a cra gearbox in it. Diffs ratios vary too. They swap them out anyway as a matter of course.

Don't quote me, but that was what I was told. The reason I looked into all variations was resale value of the motor to offset the cost of conversion.

Hi V8Diesel,

The 3.0TD has the same gearbox and diffs(but different ratio) as the 4.2/4.5/4.8's. The 2.8 GU has the skyline gearbox and not the trucklike ones in the higher Nm output motors.

Cheers

Captain

Roachie, I'm with Captain on this one. I went from 31x10.5R15 to 33x10.5R15 on my FJ62 and found the difference off road well worth the effort.

That's right Cap'n, it's all coming back to me. It's the 3.0 auto transmission that was different (the 4.8 is out of the US Titan) the 3.0 manual is the 'truck' number as you say and the 2.8 is the wee one.

Drive train is not all the same for starters you get two different size back diffs 3.0 has a small back diff.

Hi ACDC,

Depends what you mean by "small" back diffs. They have different diff ratios but can be interchanged i.e. fit bigger tyres to the 4.2TD and you can change the 3.9 ratio to the 4.3(?) from the 3.0TD. But as far as the diff casing and axles go, they are the same.

Cheers

Captain

Check the ARB air locker listing there's two size back diffs most 3.0l have the smaller back diff about the same size as the front diff with a curved bottom centre housing and then the larger diff with a flat section at the bottom of centre housing.

ACDC is almost right.

The 4.8 petrol and 3.0TDi manuals have the larger 260mm rear diff, all of the others have the 233mm rear diff. Thois ruleis not absolute as someARB fitters have randomly foung 260 rear diffs in vehicles that shouldnt have them.

Roachie - you"should" have the 233 rear diff so make sure you get the right size centres if you are going to swap.

BTW - 33s are FINE ya big sook 8-))

Thanks everbody for your ideas and responses.
I sort of feel guilty that I stole the thread....sorry...
Andrew, the old girl does already suffer at getting off the line with the trailer on if the road has even a slight incline. I never drove it with the 265/70s on.....had the 265/75s placed on before I picked it up brand new in 2000.
So I can only imagine that the 285/75 (or 305/70 like yours), would make it just that much worse.
Does anyone know how much effort is involved in changing the diff ratios and where would a bloke be likely to get onto a set? Come to think of it, I met a bloke at Peake on the weekend with a 4.8 petrol who was wanting to get his rig revving less.....he has 315/75s on and it still does 2600rpm @ 100k/h....it was doing 2900rpm when he had the standard rubber on it. Maybe I could do a swap with him??? hhmmmm
Cheers

Roachie

I did say most 3.ol have small back diff as i have found some with big diffs as you say they should'nt have them!

ACDC - 3.0TDi manuals should have the 260 diff, 3.0TDi autos should have the 233. In reality it seems a bit of a lottery.

Roachie - The only way you will be able to get the diff ratio from the 4.8 would be to do a rear axle swap. Try and get him to swap the front as well, then you can have the 4.8s big brakes. LOL. Worth a try. hehehe

Roachie, speak to engine conversion places. I know that the Chev V8 diesel swap requires the standard gearing to be changed, so there must be about 10,000 sets of standard gears for every configuration of GU lying around somewhere gathering dust (well they don't break do they!).