Towing in 5th gear

Recently did some tests with my TD42T 99GU towing a 1600 trailer.

Economy travelling the same route over 300kms was better in 4th than in 5th....

Engine labured less and overhall it was more comfortable, but did change to 5th down hill...

Exactly. If the motor labours this will put more stress on the geatbox and more so if in 5th.

Leroy

Roachie - I'm with you. Used to use 5th until this issue was covered in great detail sometime last year. A search should find it. Had some excellent responses from the mechanically knowledgeable (which doesn't include me) explaining why towing in 5th is not advisable. Some people come up with crap for responses - the noise and fuel consumption are not horrific when comparing 4th to 5th - at least not for my petrol 80. Maybe if one towed at 100 plus but when off the blacktop I like to take it easy and I stay off the tar as much as possible. Interesting that you mentioned the temperature - I do recall something about that in the old post I referred to above. In it there was something about the gearbox running a lot hotter in 5th which apparently meant more stress.

Guys,

What it refers to is the fact that 5th is overdrive, as such it is a much smaller gear and has less surface area to get rid of the heat which contributes to the gear expanding and waring faster.
So regardless of any gearbox fault, 5th gear is not recommended for heavy loads, it was designed as a cruising gear.
This is technically and by design.

Roachie,

What is the build date of your 4.2?

Goona

Goona......May 2000 mate

G'day mate,
Depends on your vehicle. With the GU, I try to keep the revs around 2000 to 2400......... this is where the donk seems happiest to operate. In 4th gear, 2000rpm is around 85k/h and in 5th it's about 100k/h.

Roachie,
Are you talking 4.2 or 3.0? Our 2003 3.0 td sits on 2800 in 5 th for 100 kph.
Jon W

Robyn,

What was the build date on your 4.2.

Goona

Goona
The build date was April 2005 and car is 4.2td. Someone else from the forum had theres in the same workshop at the same time with the same problem. I have since heard of another one in our local area which has done 5th gear as well and made big waves about the problem and he got his done for around $1500. So for towing in 5th I dont think we will be doing it again.
Cheers
Robyn

Auto's are a different kettle of fish. When towing, try to keep your torque convertor locked up as this reduces the temperature of the trans fluid dramatically. I have a manual lock up switch installed on my GQ and the auto temps really drop when the torque convertor is locked up. I normally tow in 3rd gear with convertor locked as the overdrive in the GQ is ridiculous, it's only doing approx 1700rpm @ 100 kmh with the overdrive on.
Regards Andrew.

Your not exactly comparing apples with apples are you?

Of course a 3.0TD uses less fuel, it is a smaller engine!

In addition the ratios are probably worlds apart for your Nissan auto and the tojo manual for your 3rd and his 5th.

hl , I think these guys are having a go at you , normally only need to replace a gear and a shaft , took 2 days the first time , 1 day after the reco box let go . Why do you need the whole box ? What dealership ?

Glenn

Hi,
Yes, you are so right Glenn..
Won't say too much right now, just want my truck back!
Cheers

Hi again...
Got my truck back on monday. 2 days short of 4 weeks. They did fit a brand new box and I am very happy with that (don't think the shift pattern would have been the same if these guys had actually re-build the box!)
As it happened, they did manage to drag the job out over another weekend even though they got the new box on thursday.
In addition, they didn't replace the small plug on the bottom of the clutch housing so water could have got in on the next river crossing. And, they re-fitted the drive shaft back to front. I don't think it matters a lot but I have always thought it is best to put things back the way they came out. After all, there are paint marks on the drive flanges from the factory so it can be put back the same way without stressing the brain. All in all, not a real happy experience except for getting a brand new box. The dealer is on the Northern Beaches here in Sydney.....
I must say Nissan were quite supportive after the first week and apparently paid the dealer to provide a loan car (a KIA.. not a good replacement for a Patrol, believe me!)
Why they took nearly 4 weeks.. I don't know, but I did have a similar experience with the same dealer 3 years ago with my previous Patrol.
Maybe they just hate me......But when they lie to you (as they did then) it is very hard to regain confidence. Once again they have lived up to my expectations.

Cheers