100 series Landcruiser towing in 5th gear

Submitted: Sunday, Jul 24, 2011 at 22:16
ThreadID: 87768 Views:11241 Replies:7 FollowUps:5
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Hi all, I have a 100 series standard 4.2 L diesel Landcruiser built 1999 (the type with the barn doors) and have recently put a turbo into it. A few months ago I purchased a camper trailer 1400 kg gross wt and 140 kg at the tow ball. The cruiser pulls it well. I have now been advised that towing in 5th could damage the gear box. I have read some of the archived blogs and they have raised a similar concern but with heavier payloads (ie around 3000 kg). One solution was to drop down to 4th on hills. Others had written never to tow in 5th. My question is, has anyone had any experience of gear box damage when towing a pay load around 1400kg or am I being over cautious. My vehicle has only done 140 000 km.
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Reply By: olcoolone - Sunday, Jul 24, 2011 at 22:28

Sunday, Jul 24, 2011 at 22:28
From memory the non turbo 100 series had the same gearbox as the Hilux from the same year and the factory turbo 100 series had a stronger upgraded gear box.

With our previous Hilux D4D we towed in 5 gear a lot and sold it at 100000k with no problems.

There is merit as to why you shouldn't tow in 5 gear but how many gearboxes fail because of it is unknown and may be a bit of an urban myth.

Most have heard of it happening but not to themselves.
AnswerID: 460829

Follow Up By: Member - nick b - Monday, Jul 25, 2011 at 12:33

Monday, Jul 25, 2011 at 12:33
When you tow in 4th gear thats the gentlest on the box (& not the vehicle) as its 1:1 straight through line in your box . But 1st 2nd 3rd 5th use the cluster gears shaft , so that uses the all box , but thats not to say it cant handle it , in a cruiser /patrol big tough boxes !!!!!
5th gear towing caravans was a major problem with smaller type car 4wd on long trips , but thats not to say it cant be dun , its just be aware of it .

cheers nick
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Follow Up By: olcoolone - Monday, Jul 25, 2011 at 18:35

Monday, Jul 25, 2011 at 18:35
5th gear is smaller and tends to be hung of the back of the shaft putting more strain on bearings.
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Reply By: The Rambler( W.A.) - Sunday, Jul 24, 2011 at 22:31

Sunday, Jul 24, 2011 at 22:31
Iown a standard 4.2 diesel 2001 Troopy and have towed my camper 1200kg loaded for many thousands of kilometers over tha past 4 years in 5th gear with not a problem with the gear box.Surely if you are driving you will know when to drop dpown to 4th or stay in 5th as the response in the engine will tell you when to change gear. In my opinion and the opinion of some of my mechanic friends as regards a blanket "do not tow in fifth gear " is a load of rubish.
AnswerID: 460830

Follow Up By: aussiedingo. (River Rina) - Monday, Jul 25, 2011 at 09:07

Monday, Jul 25, 2011 at 09:07
Hear hear!! you just need to keep the rev's above 2000 to keep the engine breathing freely, under that can cause overheating - as you know the engine will tell you when to change gear, you need to change before that. hoo roo
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Reply By: Member - Andrew L (QLD) - Monday, Jul 25, 2011 at 08:07

Monday, Jul 25, 2011 at 08:07
Nobby, yours would be a 105 series Landcruiser. If you have a turbo bolted on, whack on an Exhaust Gas Temperature guage as well, preferably measure pre turbo.

That will also show you how efficently the thing is going, and deciding on 4th or 5th gear when loaded, travelling an incline.

When I had the 1HZ in my 105 series, and towing a van etc, any sort of incline and generally it was better to drop to 4th gear. I still maintained my road speed, but with less or static EGT's....ie..less fuel being burn't and ending up as heat and not torque.

4th gear is also 1:1 ratio, so no torque loss/division of the engine torque from the flywheel thru the gearbox, as compared to using overdrive/5th gear.

Remember that as you go down your gears you actually multiply the engine torque, hence your vehicle has more punch in it in 2nd than 5th gear...right..?
AnswerID: 460842

Follow Up By: sheps - Monday, Jul 25, 2011 at 21:13

Monday, Jul 25, 2011 at 21:13
If you have an instant fuel usage readout on your dash it will also equate to load on the transmission...... the more litres/100 you are using, the higher the load.
So Nobby, go for a run in 5th without the camper and see what the typical readout is at say 110-120kph on the flat. Then don't exceed that figure when towing; you'll probably get a similar readout sitting on 80kph or so.
FollowupID: 734606

Reply By: Gnomey - Monday, Jul 25, 2011 at 09:38

Monday, Jul 25, 2011 at 09:38
Nobby I have a 2002 Troopy which now has, at considerable expense, the stronger H!50 (turbo) gearbox instead of the original R151 box.

The reason for this is that 5th gear in the old box started to stick a couple of times and that is a standard message of imminent failure. You can read about it on LCOOL.

Without knowing for sure I'd tend to assume your gearbox is the same as my old one which had done 250k of mostly bitumen kms.

Overdrive gears are weaker than 1:1 gears. The R151 is known for its relative weakness. You've just significantly increased the output of the engine and with 1400kg extra mass to pull, everything in the drive train has to work harder.

If I were you I'd be very discriminating about when and how I used 5th if towing.

AnswerID: 460850

Reply By: Member - Rob D (NSW) - Monday, Jul 25, 2011 at 10:15

Monday, Jul 25, 2011 at 10:15
A few years ago I completely stripped 5th gear on my Patrol when towing my camper trailer to Adelaide. There was a strong headwind that day to make matters worse.
It was after this that I was advised that the 5th gear was only an overdrive and was not as robust as the other gears and further that I should only tow in 4th gear.
I have also been told that this problem had been fixed in later gearboxes by using more robust gears. I do not know if this is a fact or not.
I would definitely seek professional advice before I would risk stripping the gears.
I now have a LC100 auto.
If you relax at a faster pace you can get more relaxation in for a given time.
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AnswerID: 460856

Reply By: Member - Barry B (WA) - Monday, Jul 25, 2011 at 11:19

Monday, Jul 25, 2011 at 11:19
Totally agree with Gnomey,2002 Troopy,250,000 kms,now has,at considerable expense,a stronger gearbox .Only ever towed a camper trailer.Barry
AnswerID: 460860

Reply By: VistaMax - Monday, Jul 25, 2011 at 12:53

Monday, Jul 25, 2011 at 12:53
Why go into 5th. We found we get better fuel economy towing in 4th at all speeds up to 110. And eliminate the possible trouble 5th could do to the gearbox.
AnswerID: 460869

Follow Up By: Nobby - Monday, Aug 01, 2011 at 23:13

Monday, Aug 01, 2011 at 23:13
To Vistamax and those above who so kindly replied to my question, thank you very much for the feedback. The additional information provided was also very helpful.

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