Patrol 5th Gear : change in ratio

G'day mate,
I'd better do it sooner rather than later, cos I'm gunna soon be putting the trucks (the old 4.2TD and the Chev) into the workshop to get the gearbox, transfer case and front diff changed over. Why? The gearbox in the old 4.2 DEFINITELY has had the new shaft and 5th gear installed; but I don't know the history of the Chev's box. The 4.2's Transfer Case contains a set of Marks Adaptors 2.8:1 ratio gears, whereas the Chev still has the standard 2.02:1 ratios. The front diff of the 4.2 has a ARB Air Locker, the Chev doesn't.
So, while they're doing all that, it would be the ideal time to do the 5th gear job too.

BTW, do you know what the symptoms of a buggared thrust bearing are and what's involved with changing it? The Chev is sometimes prone to mild "surging" at around 60k/h in 4th or 5th gear.

Cheers

Roachie

G'Day Roachie,

Thrust or spiggot bearing problems usually show themselves by a noise when the clutch is fully depressed, noise goes away when clutch released.

Either way have to pull the box out to fix.

If you have nay doubt, do it at the same time as gearbox change as mechanics can see $$$$ when they have to remove a Patrol box.

If need a new clutch then heavy duty Exeddy, depending on what they have fitted to the chev, you can also ask if it has the original flywheel or an adapted one.

Hope this helps

Rolande

Thanks Rolande.....it has the HD Chev clutch etc, so I'm hoping that will last a while longer yet.

Cheers mate

Roachie,

If it's the clutch thrust bearing, the noise will appear when you've got yer foot on the clutch and disappear when you've not got yer foot on the clutch.

If it's the first motion (primary shaft) bearing, the noise will be there when yer foot is off the clutch and will disappear when yer foot is on the clutch. i.e vice-versa to the thrust bearing.

The surging would have nothing to do with either of the above. I would guess it's the LPG injection that's causing it. Mine is as steady as rock (- got no LPG injection - I wish!!). But it's far easier to maintain a 60 kmh (or any other) speed limit than the TD Cruiser - which wandered all over the place by plus or minus 5kmh at 60 to 90 kmh! The only place that "Cruiser was really happy was on cruise control at 110kmh! It was after all a thoroughbred stallion of a car!

Bilbo

Roachie,

Why would ya want to change the transfer ratios? You can go up the side of a tall house with it now!,,,,,,,,

In 3rd high,,,,,,,,,,,,

Bilbo

G'Day Bilbo,

Its about low speed control rather than power.

I have a 2.8, the antithesis of the chev - I should know!

:))

Rolande

Must be nice to have money.

PC = Bilbo - The Eagle has landed.. will repay somehow sometime.

Truckster,

Sheesh, that WAS quick!! It only left my place yesterday afternoon!!

Hope it works for ya!

I hate throwing stuff out if someone can use it.

Have a good 'un,

Bilbo

g'day Bilbo,

Rolande hit the nail on the head......it's all about slow speed control, especially steep downhill decents etc.

Trucky, Yes it WOULD be nice to have money; I meet a lot of people that fit that category in my job. Unfortunately, I am but a simple salary-earner (one income family) with a wife, 4 kids, 2 Patrols, One Feroza, one camper trailer and a box trailer to support. One of these days I hope to get the deposit together so I can buy/build a house....But what the hell, I'm only 52; too young to be burdening myself with such frivolous non-essentials!!!!! ;-))

I suppose it's OK if you've bought the gears already and the box is being stripped anyway. But personally, I wouldn't go to the trouble. I've never had a problem with the Chev or any of the Nissan Diesels with going downhill and engine braking.

I do know that when I was in my mates 2.8 Nissan out the back of Meekatharra, I was amazed at how often he changed up and down that box!!! He was in low range a lot where I would have not even bothered switching to low range. But it was still a good little truck, just not my style.

Bilbo

On the Mark's website, it says that the new cog can be installed without the need to strip the gearbox, but that transfer case would obviously need to come off the back.

Bilbo, I 1st realised I needed the lowrange reduction gearing when I tried to do a stall recovery during a Club training assessment a year or so ago. I was pointing uphill and had to stop the truck (too hard to stall the old 4.2, let alone the 6.5!!!) by switching the key off. Then had to select reverse and let the truck (all 3.2 tonne of it) hang of the gearbox alone. Too my surprise (astonishment really) the LowRange reverse wouldn't hold it.....mind you, this was a BLOODY steep hill too.

That was when I decided to get the low range gears from Marks; they'd just released the 2.8 ratio.....I always thought the 3.? were just TOO low for my driving style. But I think that is what Trevor R settled on in the end......howya finding them Trevor?

Cheers

Roachie

Lookin at it today, spittin twin of the 4.2 in everyway.

You dont have the mounting brackers from front ot back do u? :) Need to hack them for the core we are going to use, rather keep mine in good cond... :(

Truckster,

If you mean the bracket that goes from the front of the radiator panel to the firewall,,,,,,,,,,,,,,and supports the whole assembly,,,,,,,,,shaped like a letter "H",,,,,,,,,,YES, I do have it.

It looked such a "handy" piece of steel, I thought,"Hmmmmm,,,,,that'll be handy if I want one 'n I haven't got one". It looked so handy that I thought to meself," That would be handy even if I NEVER used it!"

Do you want that as well?

Bilbo

Would love it :) make life easier

Monday OK?

With the same freight arrangements?

This one's gonna be a real bitch to wrap!!

What about I cut it into 4 inch pieces and put all the bits in a little square box?

;)

Bilbo

Isn't the toughest gearbox around out of the GQ. I thought that was what they put in all the Chev conversions???

Yeh, should do mate. The bloke from Brunswicks has got a GU that he repowered with turbo etc and it can light the tyres up, no worries.

Mine is n/a with LPG injection, so doesn't have anywhere near the grunt of the turbo'd jobbie. It's just a more usable torque band right from idle. So I don't think the gearbox or transfer case will have any issues coping with the engine's output.

G'day Brew, (BTW, I love the new one wheel drive tow vehicle you've got the trailer hooked up to, mate!!!!)
The GQ box apparently does not fit straight in where the GU box sits (otherwise lots of blokes would be using a GQ auto box in their GU's), so, no, they don't use the GQ boxes in the V8 conversions to GUs.
Cheers mate

She struggles on the hills mate.

Bilbo has one (the manual) link text

Roachie,

Mine's a GU and it's definitely got a GQ box in it. It's tight squeeze though - had to bash the firewall and transmission tunnel around a bit,,,,,,,,,,

I just don't wanna be the one that has to take it out!

But when you figure that I only use 3 gearchanges to get to 5th then that should increase the clutch plate life by about 30% ;)

Bilbo

Hey Bilbo, you still haven't told me what size tyres you're using? Mine will take off in 2nd okay and could go from 2nd to 4th and 5th, but I always choose to use all the gears (most of the time); it's just that once it's in 5th I tend to drive it like a slush box.....lazy b@stard, aren't I????

Roachie,

I sent all the tyre details in a PM to you on 7/1/07. I have a copy of it, I'll PM it to you again.

Bilbo

Yeh, but is doesn't growl at ya every morning!!!!!!!!

Bravo!
My sentiments exactly.

Yup, auto is the way to go, just finished swapping the T400 for a 4L80E (basically a T400 with 4th gear and lock up torque converter) in the Humvee, made a huge difference to engine rpm on the road, now it is sitting at 2,000 rpm at 95kph, right on max torque.
The T700 won't handle the torque 'backload' from the truck when in low range, they go boom in a Humvee, might be ok in a higher geared vehicle like a cruiser or patrol though.