manual v auto transmission

Submitted: Sunday, Jun 15, 2003 at 16:49
ThreadID: 5463 Views:1543 Replies:4 FollowUps:3
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A friend of mine is in the market for a late model petrol 4wd(2000/2002). He is looking at Pajero, Prado and Jackaroo.

He has recently purchased a large fishing boat that I guess would
weigh around 1500 - 1800kg, thus the reason for looking at purchasing a 4wd.

His question is....should he be looking at purchasing a 4wd with manual
or auto transmission.

Any input is much appreciated and I will pass on all posts to him.

Thanks in advance
Jason
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Reply By: Member - John- Sunday, Jun 15, 2003 at 19:24

Sunday, Jun 15, 2003 at 19:24
Virtually all modern automatic fourbies are superior for towing (and off road).

The ONLY weakness with auto's is poor engine braking in low range for down hill work.

You can get around this one with a driving technique called "driving through the brakes". Many 4WD training instructors endorse this method but some don't. I used it to great effect with a 2002 V6 petrol auto Nissan Pathfinder and easily did some very difficult downhill rock crawling. Without it, things can get dicey especially if you allow the speed to build up.

I strongly recommend auto's for first time 4WD owners BUT also strongly urge them to complete a 4WD training course and better still, join a 4WD club.

JohnS
AnswerID: 22583

Follow Up By: Derek - Sunday, Jun 15, 2003 at 22:40

Sunday, Jun 15, 2003 at 22:40
John, what is 'driving through the brakes'? Please explain.
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FollowupID: 14924

Follow Up By: Truckster (Vic) - Monday, Jun 16, 2003 at 00:03

Monday, Jun 16, 2003 at 00:03
Driving thru brakes,

Accelerating while braking, its used to keep your car going straight, as well as other things.

If you drive an Auto, greasy downhills are your enemy, you have FA engine braking, and this can help a little

AS said driver training courses are well worth the investment.
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FollowupID: 14931

Reply By: Member - John- Monday, Jun 16, 2003 at 11:00

Monday, Jun 16, 2003 at 11:00
Derek,
Here is the text out of a post I put on another chat board some time back. I think it contains most of what you need. Go practice it (on a gentle slope!!)
JohnS

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There is another very effective method for taking auto fourbies down steep hills (slippery or rock hopping), often referred to as "driving through the brakes". My Pathy had a lovely auto box that had very good engine braking in low first but it would still tend to go too fast especially if you were crawling over some rocks down hill.

Here's the gist of it, see if you can get the hang of it after a bit of practice.

Basically you select low first (or reverse) and apply modest, steady pressure to the brake with your LEFT foot. Enough to hold the car with the handbrake off,
then gently apply power and the car will move slowly in a very controlled way, in fact dead slow if you want.
If you lift off the gas and it gently stops then you have about the right brake pressure.
On muddy slopes you will need to keep on enough power to keep all the wheels turning slowly and steadily whilst keeping absolutely constant pressure on the brakes.

A few of things happen when you use this technique,
1. you tend to fool the open diffs into seeing very similar torque across the axle so you get a very even drive across axles, particularly true on the front axle where your brakes become the dominant load on the axles, not the tyre grip (or lack of it)
2. you get all four wheels receiving very close to the same drive torque and nice and slow. You can suddenly feel the car biting on all four wheels insead of slipping and sliding as it will do if you attempt to roll down the hill on brakes alone.
3. your torque converter is slipping heaps (you are forcing it to) but your engine rpm will be somewhere around 1000-1500 (not at idle) and that usually means the torque converter will be trying hard to connect engine & tranny .. this is one you would have to ask an expert about, but I have heard claims that this is one of the reasons this technique works so well.

I have crawled down slopes and rock ledges where I have got on three wheels momentarily but despite a little bit of slip the car quickly regains composure as you still have all four wheels (restrained by the brakes) being driven nice and steadily. The same piece of track tackled on brakes alone would have been pretty dicey.

I have found this technique very valuable whenever you want to crawl an auto fourbie through a hard bit and you can easily go as slow as a Tojo or Land Rover diesel in Low first. In fact using this technique I could often get through better than manual diesels with open diffs

My guess is that your ATF fluid heats up doing this but you are only doing it a couple of minutes here and there, plus your front discs may makes some weird squealing and rattling noises as the calipers move about under the combined forces of braking and drive. Nothing too alarming though as they are still working

Some 4WD training instructors teach this technique.

Go out and practice it and soon you will be using it often in the hard stuff. When you are good at it, you just apply a bit of brakes with the left foot whilst maintaining or slightly increasing the power anytime you look like losing momentum UPHILL because it helps even out the cross axle torque (poor man's LSD).

There is a variation on this used by some experienced drivers with either manual or automatics where short stabs with the left foot on the brakes are used to try to get a stuck (or nearly stick) vehicle moving. They are usually trying to momentarily split the drive torque more evenly across axles with open diffs.

BTW, don't forget the key factor of tyre pressures. Let them down to about 25psi and that alone will make a big difference.
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AnswerID: 22641

Follow Up By: Member - Bill- Monday, Jun 16, 2003 at 18:45

Monday, Jun 16, 2003 at 18:45
John, thank you for one of the most exellent posts I've read in a very long time..real value add stuff for us growing multitude of auto owners wanting to minimise the few shortcomings.Regds

Bill
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FollowupID: 14971

Reply By: Member - Bill- Monday, Jun 16, 2003 at 17:56

Monday, Jun 16, 2003 at 17:56
Jason,

I compared Petrol Paj, Prado and Jack for this purpose a few years back. Went Auto Jack. Reasons, more power, fuel economy, less saggy arse towing and value for money. Auto worked well for towing, but change fluid at 40K intervals. Auto Diesel Jack would be worth a look too.Regds

Bill
AnswerID: 22675

Reply By: Member - John- Monday, Jun 16, 2003 at 22:17

Monday, Jun 16, 2003 at 22:17
Bill is right. The auto mates particularly well with the new Jackaroo diesel. Other brands with the new high tech diesel and auto combinations are all excellent tow vehicles.

In my auto Pathy which did quite a lot of hard off road stuff, the rear diff and transfer case oil changes were brought forward to 30,000 intervals. Auto tranny isn't too bothered by low range work because it gets a pretty gentle life in low range.

Have fun!
JohnS

AnswerID: 22722

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