what is your opinion on down ranging your 4wd gearbox to climb a steep sealed road without engaging the front hubs, i know not to engage 4wd on tar as it strains tyres and transmission, but what damage could be done using lower ranges with hubs freewheeling ?
Suspension one for the mechanics
- Thread starter poor but proud
- Start date
Is it because of a huge hill in mind or a "What If "scenario ?????
The old trick is for very big bluddy hills is you start at the bottom in a low gear so you hopefully don't have to change gear as you go up, you might be slow but it certainly works as you keep in the revs range, take it from me if you can't make it in 1st gear high then stopping and going to Low is not for the faint of heart, you have to select the right low gear to start off with, starting in 1st low means you will more than likely stay in it, trying to go up another gear for the novice can be scary, if done wrong you can stall or drop a tail shaft, hence one would start off in the middle of the LOW box and stay there ... Much the same as going down these big hills, same gear Down as Up......
With a van on the back stopped on a big hill, never ever get out of the drivers seat unless wheels chocked and blocked, hand brakes won't hold and van brakes backwards have less holding than forward same as most drum brakes..... never use sandstone rocks either and rocks should be as high as the rims...
Depends on the gearbox/TC set up, I used to pop mine into LOW to drag a trailer or van up my driveway, rough concrete about 60m, very, very steep, hub unlocked or fixed depending on vehicle Cruiser had hubs, Hi Lux was auto, Colorado fixed then hubs, Jeep were AWD and all did it just thrown into LOW ..... I think back in the dark ages (mid 70's) I threw the G60 into low range to clear a monster hill with the 23ft rig in back, hubs were disengaged at time luckily, a truck died in front so we had to stop, no way to get going in 1st so threw it into low and off we went at 3kph over the top ... I was more scared about the clutch than anything........
The old trick is for very big bluddy hills is you start at the bottom in a low gear so you hopefully don't have to change gear as you go up, you might be slow but it certainly works as you keep in the revs range, take it from me if you can't make it in 1st gear high then stopping and going to Low is not for the faint of heart, you have to select the right low gear to start off with, starting in 1st low means you will more than likely stay in it, trying to go up another gear for the novice can be scary, if done wrong you can stall or drop a tail shaft, hence one would start off in the middle of the LOW box and stay there ... Much the same as going down these big hills, same gear Down as Up......
With a van on the back stopped on a big hill, never ever get out of the drivers seat unless wheels chocked and blocked, hand brakes won't hold and van brakes backwards have less holding than forward same as most drum brakes..... never use sandstone rocks either and rocks should be as high as the rims...
Depends on the gearbox/TC set up, I used to pop mine into LOW to drag a trailer or van up my driveway, rough concrete about 60m, very, very steep, hub unlocked or fixed depending on vehicle Cruiser had hubs, Hi Lux was auto, Colorado fixed then hubs, Jeep were AWD and all did it just thrown into LOW ..... I think back in the dark ages (mid 70's) I threw the G60 into low range to clear a monster hill with the 23ft rig in back, hubs were disengaged at time luckily, a truck died in front so we had to stop, no way to get going in 1st so threw it into low and off we went at 3kph over the top ... I was more scared about the clutch than anything........
just over planning our trip to tassie the land of lots of hills, ranges like Cunningham Gap and the old Toowoomba range i always went with caution, because as you can be caught behind a loaded semi (up and down) not wanting to stress the clutch and motor (up) and the brakes (down) i would select 4wd but leave the hubs free wheel just to give the engine a little more grunt if i had to stop, my nissan is not really happy starting on a big hill when towing , i have seen too many vans coming down the range with smoke coming from the van brakes because the driver is oboviously using the brake controller to slow the van as they fly past you, i have always used this plan as the sign at the top of the ranges say trucks use low gear, and you are totally correct when you say dont change your mind half way,it does not end well
On main roads Low range is for those times when a Chinook with a sling coming towards you is a dream come true............. Cunningham and Toowoomba Range are just hills, many go for broke and hit a big hill at full speed, it doens't do a thing, best to hit the hill at a speed and revs that pulls, if you change gears at the right revs and start the hill in the right gear maybe one or two shifts all thats needed, change to revs/temp and your clutch is good and engine stays happy.... Tassie has some real doozies I am told, the thing many mistake is using the clutch they will ride it, in and out one movement done quickly, dragging only cooks thit and means you are going to be in the wrong gear, its even okay to jump a gear . each combination of gearbox/load requires a different method, so any suggestions as to what gear yoou should be in may not apply to your set up even if same tug.....
If a slow truck in front you change down, Ive even been in 1st but you must remmeber once in 1st you won't want to try to change up a gear unless the incline has dropped, the load on the running gear could be too much... If you are forced to stop then Low may be required to get going again but only about mid box.... Never drag the clutch or drive with a foot resting on it...
The smoky brakes is often because the driver is just a steerer or hasn't been shown......... Downhill you select the gear for the hill, be it an auto or a manual, bigger the hill the lower you go in the box, you can always go up a gear but never go down a gear once your over the crest, thats how runaways happen, you disconnect the major brake from the wheels, the engine.
Brakes get tapped to keep off top revs, if you have to keep foot on brake then stop select a lower gear and roll away again, on really steep down grades like Black Mtn down down Bega way, drop it right down, again tapping the brake alternating between van and tug braking also works allowing at least tug to drop temp a little bit....... If your brakes do smoke at the bottom of the hill don't stop, pull up when the smoke seems to have gone, they have then cooled down enough, stopping right at the bottom they may ignite and thats it all over red rover............ at night you may see them glow, don't use water, the drums could explode... and dry powder just dries out and become a combustable source.
When I'm at top off TWB Range I would roll over the top in 2 or 3rd in my 6 speed Colorado, 3rd or 4th in the Jeep (8 speed) and wishing I had a Jake Brake, just like my Truck with exhaust brakes, 40kph going down, I find 40 is a nice downhill speed on moderate hills, bigger mongrels I'll be 20Kph so if it tries to run I can pull it back... Time has shown to me 40k at most, really big ones 20 or less, you need to be able to stop dead with one good stab of the brake, more than 2 and you may not have any brakes.... Having had the odd runaway with gears poping out or Jake fails Ive tested the theory.... even one foot on gear shift other on brake, laugh now but not at the time.
Ideally I like to go down a hill towing not using the brakes and if I do only a few times .... Cooyar Range I rarely use the brakes and its a short sharp bendy drop, a great spot to keep the skill honed.....
If a slow truck in front you change down, Ive even been in 1st but you must remmeber once in 1st you won't want to try to change up a gear unless the incline has dropped, the load on the running gear could be too much... If you are forced to stop then Low may be required to get going again but only about mid box.... Never drag the clutch or drive with a foot resting on it...
The smoky brakes is often because the driver is just a steerer or hasn't been shown......... Downhill you select the gear for the hill, be it an auto or a manual, bigger the hill the lower you go in the box, you can always go up a gear but never go down a gear once your over the crest, thats how runaways happen, you disconnect the major brake from the wheels, the engine.
Brakes get tapped to keep off top revs, if you have to keep foot on brake then stop select a lower gear and roll away again, on really steep down grades like Black Mtn down down Bega way, drop it right down, again tapping the brake alternating between van and tug braking also works allowing at least tug to drop temp a little bit....... If your brakes do smoke at the bottom of the hill don't stop, pull up when the smoke seems to have gone, they have then cooled down enough, stopping right at the bottom they may ignite and thats it all over red rover............ at night you may see them glow, don't use water, the drums could explode... and dry powder just dries out and become a combustable source.
When I'm at top off TWB Range I would roll over the top in 2 or 3rd in my 6 speed Colorado, 3rd or 4th in the Jeep (8 speed) and wishing I had a Jake Brake, just like my Truck with exhaust brakes, 40kph going down, I find 40 is a nice downhill speed on moderate hills, bigger mongrels I'll be 20Kph so if it tries to run I can pull it back... Time has shown to me 40k at most, really big ones 20 or less, you need to be able to stop dead with one good stab of the brake, more than 2 and you may not have any brakes.... Having had the odd runaway with gears poping out or Jake fails Ive tested the theory.... even one foot on gear shift other on brake, laugh now but not at the time.
Ideally I like to go down a hill towing not using the brakes and if I do only a few times .... Cooyar Range I rarely use the brakes and its a short sharp bendy drop, a great spot to keep the skill honed.....
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@poor but proud , all that @Drover has said is true and he has had a lot of experience in driving heavy vehicles including 40 foot coaches with passengers on board , so heed what he says. I too have driven many a 4WD vehicle but only up to 10 tons (Mack truck) in the Army. Some massive changes have been made since I first learnt to drive second world war GMC and Studebaker 6 X 6s with all crash gearboxes.
The basic and safe rule is: whatever gear you need to climb a hill is the same gear you should use to travel down in. And select the right gear BEFORE you start to climb and no stopping!!. And still applies today even with the modern manual and auto gearboxes.
Firstly, it is quite okay to travel in 4 wheel drive on tar or good surfaces if you have to. It DOES cause unnecessary noise and extra wear as well as poor fuel economy . But why be in that situation when not required unless extra traction required.? You have an extra gearbox, differential and axle and tyres involved. If the front wheels are not engaged, then there is no load on those areas, just turning for no reason! Personally, I have no experience with hubs as my 2011 Colorado has "shift on the fly system" except if I wish to go from 4WH to 4WL when I have to stop and move through neutral before engaging 4WL.
However, your earlier comment does have some truth in it, and this applies to a system called "diff lock" which causes ALL the driving wheels on both axles to rotate at the SAME speed. Some modern 4WD tugs have this function I believe, but under another name. Okay in EXTREME circumstances and only on SOFT surfaces for short sections. Because on hard surfaces, when you turn, the inside wheel rotates less than the outside wheel and causes all sorts of problems such as tail shaft windup and wheel lockup too. Have heard of drivers in the Army on exercise forgetting to dis-engage this function and having to drive in reverse for some distance to unwind tail shaft before being able to drive forward again!!!
For @Drover, I too am familiar with the Cooyar range and know what you are talking about. I have had my Colorado climb up the range to the Bunya Mountains from Maidenwell. Although sign warns that climb not suitable for trucks, buses and caravan, I have travelled that way on 3 occasions towing my Penguin (probably only 1.3 tonnes), starting off in 2nd gear (out out he only 4 I have!!!) with the Power switch on without hassles or overheating. Did have to go back to 1st on the very last section when revs dropped off before auto did it for me! Coming down same way in 2nd and keeping revs under 3000 with the occasional and infrequent taps on the brake. Similar thing for the decent from Maleny to Landsborough.
At any time if in doubt, select a lower gear and keep speed down. Hot brakes do not work well at all!!
I have taken a Coach up Bunya the other way and that was a lot of fun, revs and gears running out fast trying to keep the old Gemmy on full noise........ and coming back down wasn't fun either , only 5 gears and bugger all Jake..... we were smoking at the bottom and low flying to Oakey....
The basic rules haven't changed even in these new trucks with all the gimmicks, though before I hung up the keys I did a run in a new Globetrotter, slowed at top of range set cruise to 40kph, downhill mode or something, Jake On and let it go, put feet back on peddles at bottom, did try same thing on earlier truck, not good idea at all, cruise croaked half way and we nearly went into free fall. such is life............
If you can drive a Army Studebaker, GMC or Mack you can drive anything, @Boots in Action, you learn to drive properly in one of them, then the Inter with a Joey box comes along...lol,lol...... modern vehicles just require steerers............ At 13 I learnt on an Army SII Landy then graduated up to the Studebaker 6x6 wrecker, I could drive it as long as my Brother in Law moved the gear stick as I could do the foot dance and steer but couldn't reach the lever, since I learnt to drive on a bomb dump he made sure I could before I left the section confines .... later on bit like S Line, would kick the lever into gear as it was too far away........ Now I sit back D for drag and steer, the shame of it all says my son, .............................
The basic rules haven't changed even in these new trucks with all the gimmicks, though before I hung up the keys I did a run in a new Globetrotter, slowed at top of range set cruise to 40kph, downhill mode or something, Jake On and let it go, put feet back on peddles at bottom, did try same thing on earlier truck, not good idea at all, cruise croaked half way and we nearly went into free fall. such is life............
If you can drive a Army Studebaker, GMC or Mack you can drive anything, @Boots in Action, you learn to drive properly in one of them, then the Inter with a Joey box comes along...lol,lol...... modern vehicles just require steerers............ At 13 I learnt on an Army SII Landy then graduated up to the Studebaker 6x6 wrecker, I could drive it as long as my Brother in Law moved the gear stick as I could do the foot dance and steer but couldn't reach the lever, since I learnt to drive on a bomb dump he made sure I could before I left the section confines .... later on bit like S Line, would kick the lever into gear as it was too far away........ Now I sit back D for drag and steer, the shame of it all says my son, .............................
we seem to be getting away from my actual mechanical question , will driving a vehicle in 4wd range damage a vehicle if hubs are not engaged? i also have driven crash box trucks, full size crash box coaches , road ranger 13,15 speeds semis , tip trucks, 8 ton pantechs, and actually been the instructor for specalist vehicles at a large driving school, just an opinion needed about mechanical issues when not engaging the hubs if in 4wd (btw its sunday afternoon and i,ve just had a couple of glasses of cheap red)
No,.........but you will have to stop to do it and speed restricted in Low ... Sorry we wandered off.
As I see it, there is no advantage to using 4WH or 4WL if the hubs are not engaged. There is no traction from the front wheels and you are just engaging the gears of the low range box for no purpose.
thats the whole question , just trying to get the engine into a lower gear range , no point in 4wd as on tar, just more grunt to pull up and roll down hills but will it do things like snapping axels if hubs are not engaged????
no wandering read, all points are correct as written, yes you are correct all actions to be taken before you start the climb or decent
Nah your right I did wander a bit, so long as you have manual hubs it should be good, fixed, auto or AWD not good, just as I said pick correct gear not first as a hill climb you may not be able to change gears due to revs and loading, it can be a how long is a piece of string but if you have wrestled a Road Ranger on a hill then you know what I mean... Vehicles like my Jeep or Rangies not a good idea TC would be a pretzel as they lock up.
@poor but proud, sorry I led @Drover off the point. Not having any experience with vehicles with hubs on wheels to engage , I am no help. With my Colorado, I can only have 2WD high ratio, 4WD high ratio or 4WD low ratio. No way to use low ratio gear box without 4WD, unless I break one of the front axles or disconnect forward drive shaft to stop drive to front wheels..
The answer is no - using 4wd low with hubs disengaged is fine. You just can't go much over 30kmh in most vehicles because of the revs
FWH were pretty much invented for early 4wds where the front diff and transfer case where being passively rotated by the front wheels all the time, regardless of 4wd being engaged. Mordern setups use actuators to disconnect enough to minimise what has to spin. So FWHs are designed to allow free rotation without issue - except in the case of my mate who got bogged and we discovered (eventually) he had forgotten to lock them....
FWH were pretty much invented for early 4wds where the front diff and transfer case where being passively rotated by the front wheels all the time, regardless of 4wd being engaged. Mordern setups use actuators to disconnect enough to minimise what has to spin. So FWHs are designed to allow free rotation without issue - except in the case of my mate who got bogged and we discovered (eventually) he had forgotten to lock them....
Re the OP I have a hilux and it has issues starting on a steep hill with the van. I have wired up a switch on the dash to disconnect the front diff when in 4wd. It works well, you need to be stopped to engage low range but when you are up and running with momentum and time i can put back to high range on the fly around 40-50. So far as damage goes i think the transfer case is the weakest point so try and take of as gental as possible