3.0 ltr Auto Patrol - Towing : why only 2.5tonnes

Submitted: Wednesday, Mar 09, 2005 at 12:26
ThreadID: 21083 Views:3627 Replies:7 FollowUps:13
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I have a 3.0ltr 2000 Patrol TD and need to two up to 3.5tonnes (large boat etc.). The specs show that the auto can only two 2.5 tonnes. Why is this and what can I do to allow the car to tow up to the 3.5 tonnes that the manual version can? Note.. I have a DTRONIC chip installed.
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Reply By: Member - Beatit (QLD) - Wednesday, Mar 09, 2005 at 13:17

Wednesday, Mar 09, 2005 at 13:17
Hi Zil,

Even if you could tweak the beast, how would you stand with your insurance? They may look dimly at towing something over the manufacturers limit.

Kind regards

Theo
AnswerID: 101732

Reply By: pjchris - Wednesday, Mar 09, 2005 at 13:21

Wednesday, Mar 09, 2005 at 13:21
I would suggest that Nissan has decided that the Auto gearbox won't take the strain involved with towing more than 2500 kg.
So the only thng you can do to tow 3500kg is swap the Auto for a Manual gearbox.

Is it worth risking a gearbox rebuild and the legal issues by towing 3500kg? Personally I wouldn't do it.

Peter
AnswerID: 101733

Follow Up By: Member - Jeff M (WA) - Thursday, Mar 10, 2005 at 12:12

Thursday, Mar 10, 2005 at 12:12
I would say it has nothing to do with the auto being able to handle it, but the fact that you are relying soley on the vehicle's brakes with no engine braking. Tow rating quite often having nothing to do with the power of the vehicle, but the ability of it to stop.
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Follow Up By: pjchris - Thursday, Mar 10, 2005 at 16:27

Thursday, Mar 10, 2005 at 16:27
Then why do they de-tune the engine so it produces less torque when teamed with the auto?

Peter
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Follow Up By: pjchris - Thursday, Mar 10, 2005 at 16:29

Thursday, Mar 10, 2005 at 16:29
Also all trailers where GVM of the trailer exceeds 750kg have to have their own brakes by law. Once over 750kg the braking argument is not relevant.

Peter
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Follow Up By: Member - Jeff M (WA) - Thursday, Mar 10, 2005 at 17:49

Thursday, Mar 10, 2005 at 17:49
pjchris, I will happily stand corrected. However why do vehicles with the same power outputs have different towing capacities? Is it weight? my surf only has a 1500kg towing capacity which is rediculous as it can two a disabled pajero along a sand track without even working and that's a damn site more than a 1.5t boat. My Rocky had less power and a higher tow capacity? I had always assumed it had somthing to do with the brakes as my surf only has rear drums not discs...

Wadya reckon?

BTW What difference in power is there between the Auto Patrol and the Manual Patrol, I'd never heard of them detuning before? That seems a bit bleep weak if you have to de-tune the engine perhaps a better designed gearbox is in order. Mind you in saying all this out work 3.0L TD auto patrol is terrible to drive, the auto box is always slipping and it's jumps around all over the place with bad lag and pretty heafty turbo lag. The beauty about Auto's and Turbos is that when configured correctly you can almost take all the turbo lag away, what were Nissan thinking??
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Follow Up By: pjchris - Friday, Mar 11, 2005 at 00:25

Friday, Mar 11, 2005 at 00:25
According to the Nissan Website the 2005 Patrol 3.0TD manual produces 118KW/380nM and the 3.0TD Auto is listed as 118kW/354nM. I believe he difference is less now than in the 2004 model.

As I understand it towing capacity calculations are a black art combining chassis strength, rear suspension spring and damper rates, axle loadings, weight transfer caused by ball weight and strength of the drivetrain.

The fact that a vehicle will pull another along (apparently effortlessly) does not mean that you are unlikely to damage something.

I mean LR and Rangies supposedly can tow 4500kg in some models of the old TD engines but they only have about 90kw. To say that towing would be pedestrian would be an understatement.

In the case of the PAtrol, since everything about the vehicle is the same except for the gearbox means that the limiting factor must be the gearbox or gearbox related. Maybe the tailshaft from the transfer case to rear diff is longer/shorter than on the manual which maeks it weaker or makes the angles through the universal joints more extreme and therefore unable to take as much strain.

Only Nissan now for sure....

Peter
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Follow Up By: Member - Jeff M (WA) - Friday, Mar 11, 2005 at 12:21

Friday, Mar 11, 2005 at 12:21
"(apparently effortlessly)" - Nice way of saying you don't belive me...

Perhaps it's the stock springs on the surf/4runner that limits their towing capacity as the stock springs can barley hold the weight of the vehicle un laden, they are crap.

With heavy duty springs and poly air bags it's a new vehicle.

Oh well, I guess it clears that up, how would you change the NM without changing the kw on an engine electronically? Is that measured from the rear wheels on those specs, if so it the slush box taking some of the power out of the specs?
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Follow Up By: pjchris - Friday, Mar 11, 2005 at 13:57

Friday, Mar 11, 2005 at 13:57
No Jeff, I believe you...I've done similar things myself.

What I meant (need to put on clear speaking hat here) is that when you pull something along often the car will feel like it could pull something twice as heavy even when you know damn well that what you have on now is technically too heavy. Probaly means in your case that, as you said, it's not the drivetrain that's the limiting factor on the Surf.

As far as manufacturer specs are concerned they would take them wherever they can get the highest figures wouldn't they?....It would be at the flywheel with no accessories attached I'm betting. And I'm fairly sure that the torque difference would be due to a computer change in the vehicle. Ford did this with the original BA XR6 Turbo I'm told. They had to reprogramme the engine managment to limit the torque produced by the engine or destroy driveline components. Hence the unbelievably ruler straight flat torque 'curve'.

Peter
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Reply By: flappa - Wednesday, Mar 09, 2005 at 13:24

Wednesday, Mar 09, 2005 at 13:24
Its not the ability of the motor to tow it , but the ability of the auto to withstand it.

Nothing you can do to change it.

the Auto with the 4.8 can tow 3500kg's.
AnswerID: 101735

Follow Up By: zilbert_man - Wednesday, Mar 09, 2005 at 17:53

Wednesday, Mar 09, 2005 at 17:53
Flappa... to your knowledge, can the auto gearbox I have be replaced with the auto gearbox from the 4.8?
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Follow Up By: flappa - Thursday, Mar 10, 2005 at 16:48

Thursday, Mar 10, 2005 at 16:48
Nup
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Reply By: Truckster (Vic) - Wednesday, Mar 09, 2005 at 15:07

Wednesday, Mar 09, 2005 at 15:07
You sell it and buy a different car, or sell the boat, and buy another.
AnswerID: 101755

Follow Up By: Michael ( Moss Vale NSW) - Thursday, Mar 10, 2005 at 22:30

Thursday, Mar 10, 2005 at 22:30
OR, He could sell both and buy a humungous Plasma TV and a pile of DVD's and stay at home!!!!!
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Reply By: Baz (NSW) - Wednesday, Mar 09, 2005 at 15:21

Wednesday, Mar 09, 2005 at 15:21
I was told the auto was supposed to be the best for towing most car makers have a higher towing capacity on the auto, so why has Nissan done this and gone the other way don't make sense to me.

Baz.
AnswerID: 101760

Follow Up By: Member - Geoff M (NSW) - Wednesday, Mar 09, 2005 at 16:04

Wednesday, Mar 09, 2005 at 16:04
Must have a lighter gearbox in the 3.0l auto than the 4.2l auto.

Geoff.
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Follow Up By: floyd - Wednesday, Mar 09, 2005 at 17:41

Wednesday, Mar 09, 2005 at 17:41
Oh what a feeling. The Auto in the 3 litre is about as good as a LandRover. Not
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FollowupID: 359616

Reply By: Chaz - Thursday, Mar 10, 2005 at 11:33

Thursday, Mar 10, 2005 at 11:33
zilbert_man,

There is nothing wrong with the auto box in your patrol. In fact the auto is probably physically stronger than a manual. The problem is that the Jatco box that you have has been designed to be used in overdrive, which is a big no-no in my book. When towing heavy loads it will overheat very quickly. If you were to drive it manually and keep it out of fourth gear, you would have no problem towing for reasonably short distances in moderate weather. The best thing you could do is to fit a shift kit and torque converter lockup over-ride switch. These modifications will help keep the trans cooler while towing. The Jatco box has been designed to give very smooth operation, which it does very well, but in the process it destroys itself. Taking some of the slip out will decrease the heat that is generated, especially while towing, and it makes much better to drive under normal conditions as well as extending the life of the box. In my view this is why Nissan have down rated the auto models towing capacity, because other than the transmission, there is no difference in the cars. The 5 speed Trans used in the 4.8 is a much heavier duty unit that has been designed for manual use already and is more efficient and the 4.2 GQ auto's have the same Trans as yours.
Good Luck

Chaz
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AnswerID: 101911

Reply By: motherhen - Friday, Mar 11, 2005 at 00:24

Friday, Mar 11, 2005 at 00:24
Having been asking the same question for some months, best answer was that park gear wasn't designed to take great weights - let's use the handbrake! We generally tow with overdrive off even though it uses more fuel. We are getting a trans temp guage and exhaust gas temp guages fitted. Do you guys with the DTronic fitted use more fuel?
AnswerID: 102023

Follow Up By: Chaz - Friday, Mar 11, 2005 at 00:56

Friday, Mar 11, 2005 at 00:56
motherhen,

Not really, although I would say I probably do because It's easy to use the extra power and therefor more fuel, but having said that, if you drive it like you do now, you shouldn't notice any difference in fuel consumption. I find around town, I'm still getting under 11 Lt/100Km if I drive it easy, but on the open road when towing, I tend to use the power climbing hills without slowing down and that tends to use a bit more than I would without the dtronic. Short answer is that it depends on how you drive.

Chaz
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