Towing using top gear

Even better still Greg, see what the owner's book says. Mine has an auto and the book says to tow in 3rd but not 4th/D.

So I do.

Haven't been on the forum for awhile so I don't know what the major opinions are. I will do a search but from what you say it would appear this issue has not been resolved. Transmission repairers are not necessarily the best source of reliable info re this matter. Has anyone had notice in writing from any auto manufacturer warning that they should not tow in top gear?

John R many thanks for info re owners manual. What make and type of vehicle are we talking about and is the manual implying damage will occur. Some underpowered vehicles won't tow in top gear and trying to do so may cause excessive strain on the engine and transmission.

Its like all things..if it doesn't feel good don't do it....

Willem,
Confirming the problem with 5th gear in the 85/86 pajeros.
Mine went at 95,000k, after only 2.5 years.
Mitsubishi admited to a design fault (after 3 years and a lot of complaints) and fixed the problem, they went from a 34 roller bearing to a 42 roller bearing. Most were lucky enough to get it done under warranty.

Like you I try not to lug in 5th. Any bearing with a high load works best with a reasonable number of revs. If in doubt change to 4th. Also helps to keep the EGT down too!
Wonder if diesels compound the problem by having max torque at lower revs (around 1800/2000) than a petrol?

I don't think all 5th gears sit to the side Willem, maybe the early GQ's but pretty sure the later GU's are on the main shaft, the earlier GU's were a main shaft set up with dodgy splines that had to much clearance between shaft & gear wich allowed to much movement & eventually stripped under load.

Cheers....Browny

I lost 5th gear in my 1990 Pajero, but it had made it to 267,000kms before I bought it, so who knows what it had done in that time?

I did get the spiel about it probably having towed in 5th gear too much. But I've since discovered that the trailer electrical connector in the tow bar isn't hooked up to anything on the vehicle side, so I've no idea what to think.

Sorry Greg, Pressed the wrong button.
What I was going to say was Land Rover are ok as they use a different system. Thought Nissan were ok to - it appears not according to reports.
TD5

I have read on here that doing as you do actually uses less fuel. Driving in 5th and staying on the speed limit uses more fuel and EGT's go up.

1500 kg, really. The tare is only 920 kg with a rated towball weight (wet) of 85 kg. So how does yours get all the way upto 1500 kg. Doesn't that mean you are overloading the suspension and bearings?

So your suggesting you carry over 1/2 a tonne of extra stuff...Hmmmm that's a lot of water, fuel and food.

My caravan used to have a GVM of 1450 kg, interesting how a CT can weigh more than a caravan.

Really Wizard.
My first reaction was to just ignore your post because of it's tone, but what the hell, life's too short to be bothered by such things. Frankly, I don't care much if you don't believe me (think I'm a liar?), but here's the facts:

Firstly, the 1,500 KG and 225 KG ball weight are as measured by a registered weigh bridge on the Gold Coast. I fully loaded, then did a weigh before a trip to Kimberley etc earlier this year.

The rated tare, when I bought the trailer was 930KG, though when I was going over the design and set up with Steve (owner of business that built it), he used 950 KG in his calculations. Not a lot of difference, but some.

From basic, we have added:
Large metal battery box in place of small plastic one. Adds about 7 KG
2 x 120 AH AGM batteries instead of 1 x smaller one. Adds about 40 KG
second water tank and guard approx 7 KG
2 extra gerry can holders and gerries approx 6 KG
Extended drawer bar approx 12 KG
Inner spring mattress instead of foam approx 10 KG
200 litres of water (in on board tanks) 200 KG
80 litres of fuel (in gerries on drawer bar) 80 KG
fill gas bottles (2 @4.5KG) 9 KG
1 KVA generator (in box on draw bar) approx 10 KG
Porta Pottie (in box on draw bar) approx 8 KG
2 x 100mm pipes on draw bar with tent poles, fishing rods etc approx 8KG
Food, cooking stuff, cutlery, crockery etc; I'm guessing but around 30KG
Camping stuff (annex, screen tent, chairs, and camping type gear, guess 30 KG
Clothes, towels, bedding, etc guess around 10KG.

That's about 470 KG of added weight of stuff I can think of, and I haven't included the wife's toiletries, books, art and craft stuff she likes to carry etc.

Now that all comes to about 1,450 KG or a bit more, which is a touch short of the weigh bridge measure. But since the calculation is very approximate, I'm inclined to trust the weigh bridge a bit more.

The suspension, bearings, trailer hitch etc are all rated well above 1,500KG. After all, a common option is to add a boat, motor, boat loader and folding trailer to these CTs. That adds about another 200KG (that I have not added).

Convinced yet? Doesn't matter either way. But I've been pretty meticulous with my planning and set up for both the CT and vehicle. The major part of the set up was done in conjunction with the trailer builder.
At least I know what they weigh. I suspect 90% of people on the road don't have a clue.

Norm, you need to take some weight off that drawbar, our CT sounds fairly similar in weight and add ons, but i only have 120kg over the hitch.

I'm assuming you know that weight over the ball is part of your load carrying capacity too and looking at your rig pic the boat would also be apart of that load as well, you must be pretty close to the max load capacity of your 4WD or even over.

With that amount over the ball do you have any stability problems and a bit of feel in the front end.

Baz.

Well Norm, I for one would also agree that camper trailers have become very heavy and seemingly by the inclusion of lots of small items. Ours went 1.4 tonnes fully laden. I would also agree that a lot of people (90% may be conservative) have no idea about the weights and tolerances they are dealing with. This is often evidenced by comments such as I have a 7 leaf spring etc rather than I have a 1500Kg spring. This is an issue close to my heart and I am appaled that manufacturers are not required to be clearer on this etc.

At least your guy was interested enough to make sure that the trailer was set up for the weight.

Kind regards

Baz,

Thanks for your interest. Yes, I know that ball weight is part of the vehicle load. The Hilux has a kerb weight of about 1850 KG (it varies between 1815 and 1865 depending on options fitted). It has a max GVM of 2780 KG. This gives a load capacity of about 930 KG. Before I added the boat and motor, I had a GVM of 2,740 KG when fully loaded for a trip (including the trailer ball weight - measured at weigh bridge). Between boat, motor and accessories and rack for boat, I've added about 135 KG. So without making any other changes, we would have a GVM of about 2875 KG, which is 95 KG or 3.4% over weight. But we have reduced the stuff we carry somewhat since our last big trip.

I couldn't convince Kathryn (SWMBO) to leave a lot of stuff at home before the trip. But on returning after 16 weeks and a fair bit of stuff not being used, she has agreed to a reduction. My estimate of the reduction is around 50KG, but not yet measured. If I'm right I will be about 45 KG or 1.6% over weight.

If I travel at that weight, we won't be over loaded for long. Remember this weight includes 220 litres of water (200 in trailer tanks and 20 litres in back of Hilux), 200 litres of fuel (140 in Hilux LRT and 80 litres on trailer). We only carry full capacity when needed. Even when fully loaded, these volumes come down pretty quickly.

At least I know my weights. In fact I know them backwards; having spent a lot of time on vehicle set up. Even if I do travel 50 KG overweight, we are heaps better off than thousands of 4WDs (particularly wagons which have less load carrying capacity), many of which are 500KG or more overloaded.

In terms of stability, I have Firestone airbags on the rear leaf springs. At about 35 to 40 PSI, the vehicle is level when fully loaded.

The recommended ball weight for a trailer is 10 to 15% of the total weigh of the trailer (depending on which expert you listen to). At 225KG, I'm right on 15%. As I use fuel from gerries and water from front tonk on CT (always used first), it quickly comes down to around 160 to 170 KG. With all gerries and front tank on trailer empty, ball weight is around 140 to 145KG.

We never go off bitumen with the trailer ball fully loaded. I'd estimate our maximum ball weight when off bitumen is around 190 KG, more commonly 170 KG. Still high, but quite managable.

And finally, the rated GCM for the Hilux and trailer is 4,600 KG. Before adding the boat, our GCM was around 4,240 KG. With boat and adjusted load, it will be around 4,300 or a bit less. Well within specs.

As you can see, I'm happy to discuss all this in a reasonable way as it is handy to have my reasoning tested on such an important issue. But I'd hazard a guess that few people have done the level of work on weights and distribution that I have. Certainly some on this forum will have, but far from the majority I would think.

Most Autos’ will have notes like don’t tow in O/D or don’t tow in Power mode, this is to keep the Transmission Fluid temperature at acceptable levels.

Towing in a Auto in top gear may make the Toque converter stay unlocked due to the extra strain form the weight on the back this may cause the Fluid to overheat or because the Box needs to constantly kick down gears to maintain speed the fluid once agene overheats.

Basically the way I see it is with any gearbox if the engine has the Power/ Toque to hold Top gear with ease then there is no problem towing in top gear. But if you have 2000Kg on the back and on a slight incline need to have the accelerator flat on the Boards and you are still watching the speed dropping off then you are just straining all drive line components as well as the engine and are going to damage something.

You don’t try to do a hill start in 3rd do you? So why try and lug something up a hill in 5th.

If a manufacturer recommends in a handbook not to tow in top gear, is he saying don't lug at low speeds or is he warning there might be a failure? I don't know.> he means don't tow in top gear as the Box isn't built for it.

Also I was taught not to change down gears when slowing down, as the newer gearboxes are not built for it. Perhaps this is one reason behind a lot of gearbox failures, I know how you oldies like to gear down LOL.

I was also taught this when I did my truck license basically if you are coming up to a set of light’s knock it back down to 5th or 6th and just roll up using the brakes then clutch in just as the RPM starts to dip and back to 3rd. Obviously with load on the back you would gear down a bit more.

All of the manufacturers say it is OK to tow in 5th, overdrive gear, but, if you want true longevity in the box if you are doing a lot of towing according to RAC in WA don't tow in a manual Overdrive. Autos are different to some extent but if the torque converter is not locking up then you may overheat the trans fluid with the slippage going on in the torque converter.

I am with Exploder on that one ..
No 4WD or Ute or Sedan for that matter is really made for towing, unless they come with a transmission oil cooler, firmer clutch packs, towing mode etc.
All standard 4WD are not suitable to tow anything more than 1500Kg despite the specs of the towbar etc. You want a certain amount of revs and you don't want gear hunting, this is why automatic transmissions have tow/haul mode. If you do not have that and tow heavier watch EGT and transmission oil temp. Put an external oil cooler in. It has nothing to do with weakness of OD or such, it has only to do with temperature and slippage when the tranny is not capable of holding the torque of a high powered diesel in a low gear.. My new truck has a 6 speed and will tow fine in high gear unless I use the high power tunes.The tranny is smarter than me anyway .. it will pick the right gear for me ...
have fun
gmd

Hmmm,,,,,,,,,,Trev,

Most overdrive gears (5th) give approximately a 25% reduction in RPM for a given road speed. Well mine does anyway.

So if a truck does say 12 litres per 100 kms, then 25% of 12 litres is damn sight larger than 0.3 litres! I think yer decimal point's out somewhere mate,

Say - 3 litres per 100 kms extra economy?

I tow in 5th all the time. My old GQ did it fer 1000's of Kms and more than likely this GQ box in my Chevissan will do the same.

Perhaps some of us need towing lessons?

Get the revs up and then go into 5th. If the load starts labouring the engine, drop it back a cog and give another bootful.

If it still doesn't work drop another cog and go with another bootful.

If, by the time you get down to 1st gear low range, it's still labouring then check that you have removed yer foot from the brake pedal ;)

Bilbo

How can you claim a 25% fuel economy difference just by using/not using 5th???????

That's right Shane, there is no way you will get a 25% reduction in fuel usage by slotting it into 5th.

I will agree with Bilbo that it could be my driving that is most of my problems regarding 5th gear but then there is a lot of other people having the same dramas so could we all be driving so wrong?
Bilbo, I have an uncle that, like you towed in 5th with his GQ and MQ before that, without drama. This is the same guy that has only last year required a gearbox rebuild in Norseman in his GU 4.2 turbo Patrol. He like so many have been warned and did not take the warning seriously and is now lighter in his hip pocket for it. He now tows in 4th with negligible difference in fuel economy. Possibly some makes are just not as tough as the GQ??? I will not try to find the weaker ones by towing in 5th, but that is my choice and it is yours and everyone else's choice to tow in 5th if you wish.

Regards, Trevor.

Shayne 'n Trev,

Hmmm,,,,,,,now where in my statement did I emphatically claim a a 25% fuel economy difference just by using/not using 5th??????" - as you say.

Read it again.

I was simply pointing out that using 5th gear reduces engine RPM by about 25% in most gearboxes - as it does on mine. Therefore, Trev's maths must be wrong somewhere.

Whether improved fuel economy is actually gained from that reduction in RPM depends on many other aspects. One of many aspects would be if that reduction in RPM drops the engine below it's maximum torque output.

I have a GQ box in a GU Chevy. I don't have a problem towing in 5th at 80 kmh and above.

Bilbo

we have a 96 GQ patrol ute aftermarket turbo and tow a 17' caravan,around oz last year,around tas year before several trips up to gulf and back all using 5th gear sensibly i.e over 2100 revs not a problem and still not a problem 269000k's on the dial

Bilbo,
I read it,
lines 3 & 4
"so if a truck does say 12 litres per then 25% of 12 litres is damn sight larger than 0.3"
no it doesn't say it emphatically but you certainly insinuated that there was a 25%(your number) difference in fuel economy between 5th/not 5th.
Oh by the way Bilbo my name is not Shayne
please read it again!

Geez Gronk,
Better be careful mate, the brainwashed do-gooding speed police of this site will be on your case for such 'dangerous' speeds whislt towing, don't you know that once you hook something up to the towball you're supposed to automatically become a mobile roadblock at a supposedly 'safe' 80kph :-))

Avagoodn
Pezza

Gronk,

you and I would make good travel partners, that's the speed I like to sit on as well but I will still be in 4th.

Cheers Trevor.

Yeh Trevor, but you have the advantage of a few less revs at that speed !!

I only usually sit "just" above the speed limit, but I still like to hear the motor purring instead of growling. !!!!

But I do occasionally sit on the speed limit, just can't remember the last time ????

And Pezza, yes its a shame that a lot of older people still think you have to stick to 80k's if you are towing ?? Not that I'm saying they HAVE to go as fast as me ? And after seeing some of their driving maybe they should stick to 80 ( or get off the road altogether ) But they probably say the same about me when they see me whizzing past at a "lunatic" 110k's.. he he !!!