Does anyone recognise the following phenominen. You are driving up a steep gnarly hill when you are confronted with an obstacle in your path forcing you to make a diversion to the left or right of that obstruction. Either way places your truck on a nasty compound angle. You first choose to go to the right but the left front of your truck rears up alarmingly and it feels as though you will overturn so you back off. You then attempt the same manouver to the left of the obstacle and your truck performs that feat with surprising ease and feeling of stability.
My question is, what is going on here? My own theory has something to do with one of Newtons Laws I think., "Where every action has an equal and opposite reaction". The vehicles chassis/body is reacting opposite to propshaft( US. driveshaft) torque and the tendency is to roll to the right.
When we attempted to go left this reaction worked to our advantage and the chassis/body was stabilised. The "equal part" I guess, is that the amount of force that is trying to overturn or stabilise your truck is directly proportional to the amount of force{ torque at the propshaft} that is required for the truck to move forward in that situation.
I don't mind if as I expect ,most of you tell me that I am full of shit, but I would also appreciate some input from a more scientific perspective.
Bill.
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Vehicle stability off road.
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is this called torque (twist and steer)
i know from drag racing the front passenger tyre lifts because upon launch the torque twists the chassis in rotation with the motor
i know the 4wd isn't doing the revs and doesn't have the power but in low range the actual torque passing through the axles might still be enough to effect the handling, especially when the vehicle is near a point of unbalance (can't think of how else to explain)
bill, how does the gear you made for under nigels hybrid work, does it counteract this problem??
david
i know from drag racing the front passenger tyre lifts because upon launch the torque twists the chassis in rotation with the motor
i know the 4wd isn't doing the revs and doesn't have the power but in low range the actual torque passing through the axles might still be enough to effect the handling, especially when the vehicle is near a point of unbalance (can't think of how else to explain)
bill, how does the gear you made for under nigels hybrid work, does it counteract this problem??
david
Gday modman and Nam Yes I posted this topic on the wrong forum.I was going to Tonka this thread in General tech but i got too busy for a while, and now I can't really be bothered. The fact that there were around 50 views and only 2 replies suggest there isn't too much knowledge or interest in the subject out there.
The forced articulation gearbox on Nigels vehicle does seem to counter this effect to a degree, but the backlash of three driveshaft slip joints allows around 15 degrees of interaxle articulation before there is any resistance. i should have used toyota slip joints as they are much tighter
Bill.
The forced articulation gearbox on Nigels vehicle does seem to counter this effect to a degree, but the backlash of three driveshaft slip joints allows around 15 degrees of interaxle articulation before there is any resistance. i should have used toyota slip joints as they are much tighter
Bill.
aaaaahhhh Newtons Laws of Motion.... are we getting a bit beyond the understanding of some of us here.... 
No offence to those who dont know......
The thought of the torsion wanting to overturn the vehicle has merit, and would be a concern once the angle of the vehicles reaches, i guess, a critical point, especially with high torque engines.
In specific competition vehicle design, it would be a factor i.e. lower CoG, weight distribution, etc. I guess that is why buggies are so good at the rockcrawling side of things, cause the vehicles are placed in positions that normal off-road vehicles are not normally subjected.
I dont know about other people, but I feel more comfortable being on an angle where I am on top (understand??), than on the bottom.
At the recent GC 4wd and camping show, our club set-up an exhibition track, with a mound in the middle to drive along. It was set-up with (I think) about 26 degrees that you drove along. One side your down low, the other side the driver is on the high side. So you get the feeling each way.
So in answer to your question, Bill, I think, the phenomenon 'ease and feeling of stability' is purely the feeling you, as the driver, are experiencing of the being on that angle on the lower side of the angle, rather than the vehicle being in a position where the torque will make it 'flop'.
No offence to those who dont know......
The thought of the torsion wanting to overturn the vehicle has merit, and would be a concern once the angle of the vehicles reaches, i guess, a critical point, especially with high torque engines.
In specific competition vehicle design, it would be a factor i.e. lower CoG, weight distribution, etc. I guess that is why buggies are so good at the rockcrawling side of things, cause the vehicles are placed in positions that normal off-road vehicles are not normally subjected.
I dont know about other people, but I feel more comfortable being on an angle where I am on top (understand??), than on the bottom.
At the recent GC 4wd and camping show, our club set-up an exhibition track, with a mound in the middle to drive along. It was set-up with (I think) about 26 degrees that you drove along. One side your down low, the other side the driver is on the high side. So you get the feeling each way.
So in answer to your question, Bill, I think, the phenomenon 'ease and feeling of stability' is purely the feeling you, as the driver, are experiencing of the being on that angle on the lower side of the angle, rather than the vehicle being in a position where the torque will make it 'flop'.
Heath & Melissa - 93 GQ LWB.
HeathGQ wrote:aaaaahhhh Newtons Laws of Motion.... are we getting a bit beyond the understanding of some of us here....
The thought of the torsion wanting to overturn the vehicle has merit, and would be a concern once the angle of the vehicles reaches, i guess, a critical point, especially with high torque engines.
In specific competition vehicle design, it would be a factor i.e. lower CoG, weight distribution, etc. I guess that is why buggies are so good at the rockcrawling side of things, cause the vehicles are placed in positions that normal off-road vehicles are not normally subjected.
I dont know about other people, but I feel more comfortable being on an angle where I am on top (understand??), than on the bottom.
At the recent GC 4wd and camping show, our club set-up an exhibition track, with a mound in the middle to drive along. It was set-up with (I think) about 26 degrees that you drove along. One side your down low, the other side the driver is on the high side. So you get the feeling each way.
So in answer to your question, Bill, I think, the phenomenon 'ease and feeling of stability' is purely the feeling you, as the driver, are experiencing of the being on that angle on the lower side of the angle, rather than the vehicle being in a position where the torque will make it 'flop'.
i agree heath, i think everyone prefers to be on the 'high side' of a side angle
knowing bills driving skill level and vehicle knowledge i'm suggesting he does find the critical tip over point or knows just before it.
with duel lockers and 200(plus) to 1 gearing i reckon he gets it
i'll try to get this thread moved to general. i reckon it will generate some traffic
david.
bill, can you post pics of the hybrid?? also any bush shots or ramp queen shots of your trucks?? i like to watck
with duel lockers and 200(plus) to 1 gearing i reckon he gets it
i'll try to get this thread moved to general. i reckon it will generate some traffic
david.
bill, can you post pics of the hybrid?? also any bush shots or ramp queen shots of your trucks?? i like to watck
I agree that being on top is a naturally more comfortable position on side slopes in potentially dangerous situations, but in an effort to remove this psychological factor from the equation I did some tests last week in conditions that were safe and non damaging and have proven this phemominen to my own satisfaction with an old narrow track series 2 LandRover with a rear locker. I drove along a drainage ditch(narrow ravine) with banks on either side of around 30 degrees steepness. When i tried to exit the ditch by turning the wheels hard right and articulating out, the truck did it easily. When I tried to exit the ditch by turning the wheels hard left the truck wound it self up and fell over on its right side. I then turned the truck in the opposite direction to compensate for any differences in the steepness of each bank and repeated the test 3 times with the same result each time. These tests can be replicated by many of you out there without incurring any real damage to your trucks, and if your results concur with mine this knowledge should probably be passed on to others, perhaps when undergoing 4wd club driver training for example.
Unfortunately I do not possess a digital camera, so I am unable to post any photos as requested, but about 3 months ago Aus 4wd monthly did a photoshoot of the hybrid and a write up was prepared. I believe the article
will appear in their September edition,and it explains the forced articulation in some detail including line drawings I think. Bill.
Unfortunately I do not possess a digital camera, so I am unable to post any photos as requested, but about 3 months ago Aus 4wd monthly did a photoshoot of the hybrid and a write up was prepared. I believe the article
will appear in their September edition,and it explains the forced articulation in some detail including line drawings I think. Bill.
daddylonglegs wrote:I agree that being on top is a naturally more comfortable position on side slopes in potentially dangerous situations, but in an effort to remove this psychological factor from the equation I did some tests last week in conditions that were safe and non damaging and have proven this phemominen to my own satisfaction with an old narrow track series 2 LandRover with a rear locker. I drove along a drainage ditch(narrow ravine) with banks on either side of around 30 degrees steepness. When i tried to exit the ditch by turning the wheels hard right and articulating out, the truck did it easily. When I tried to exit the ditch by turning the wheels hard left the truck wound it self up and fell over on its right side. I then turned the truck in the opposite direction to compensate for any differences in the steepness of each bank and repeated the test 3 times with the same result each time. These tests can be replicated by many of you out there without incurring any real damage to your trucks, and if your results concur with mine this knowledge should probably be passed on to others, perhaps when undergoing 4wd club driver training for example.
Unfortunately I do not possess a digital camera, so I am unable to post any photos as requested, but about 3 months ago Aus 4wd monthly did a photoshoot of the hybrid and a write up was prepared. I believe the article
will appear in their September edition,and it explains the forced articulation in some detail including line drawings I think. Bill.
Bill, your experiment seems fairly conclusive, but did you control the experiment for driver's weight on the RHS of the vehicle? Turning to the right the driver's weight will act within the track of the vehicle, helping to stabilise it. Turning to the left the driver's weight will soon act outside the vehicle's track, adding to the (over)turning moment. You would need a weight equivalent to the driver (i.e. similar size and weight passenger?) in the front passenger's seat to correct for this.
I hope 4WD Monthly will print the line drawings - if the editor doesn't understand them they may get omitted as irrelevant/too detailed. They never provide enough tech detail in their stories.
Cheers,
Scott
The truck I used for the experiment is an old unregistered series 2 petrol LandRover of very little value, and the conditions were safe with soft grassy banks to fall on. I did not have a passenger but the left hand side fuel tank was almost full, whereas the right hand tank was empty. This was deliberate as I did not want to lose fuel and risk a fire while the truck was on its side. and I wanted the weight distribution left to right to be fairly even. Anyway i only weigh 85kg and I dont think that would have had as much influence as the 1000lb ft of torque that the front and rear propshafts were transmitting with the vehicle in low range 1st gear.
I think 4WD monthly would print the line drawings of the forced articulation system on Nigels hybrid. They sent a rough draught of the article for us to check , and I got the impression that they are intrigued by it. I had almost come to the conclusion that the foced articulation system wasn't worth while, but Nigel told me that one of the drive shafts had popped off at the slip joint on an off road trip a few weeks ago, and the truck wasn't anywhere as capable without it. Anyway I don't have enough room under my own LandRover to do the same to it. Bill.
I think 4WD monthly would print the line drawings of the forced articulation system on Nigels hybrid. They sent a rough draught of the article for us to check , and I got the impression that they are intrigued by it. I had almost come to the conclusion that the foced articulation system wasn't worth while, but Nigel told me that one of the drive shafts had popped off at the slip joint on an off road trip a few weeks ago, and the truck wasn't anywhere as capable without it. Anyway I don't have enough room under my own LandRover to do the same to it. Bill.
i recon the twist comes from the tailshaft. not the engine.
i noticed this while watching the 2002 tuff truck video with sams overkill buggy. everytime the rear would get too much traction and the body would roll around the diff.
also 2 of my mates can wheel lift going around left hand corners and tramping it. the right rear gets pushed into the guard and the left front lifts as a result. (body roll helps here)
as a result i think its the tailshaft not the engine. if you were sitting there reving the engine your front left wheel would not lift.
this same torque is why most rear right tyres start spinning before the left.
the tailshaft pushes the right hand side up and the left hand side down. putting more weight on the left than the right.
MaccA
i noticed this while watching the 2002 tuff truck video with sams overkill buggy. everytime the rear would get too much traction and the body would roll around the diff.
also 2 of my mates can wheel lift going around left hand corners and tramping it. the right rear gets pushed into the guard and the left front lifts as a result. (body roll helps here)
as a result i think its the tailshaft not the engine. if you were sitting there reving the engine your front left wheel would not lift.
this same torque is why most rear right tyres start spinning before the left.
the tailshaft pushes the right hand side up and the left hand side down. putting more weight on the left than the right.
MaccA
Interesting experiment.
Maybe as a thought experiment imagine this: you've parked on some wet concrete, then it set, and by the time you go to drive off all four tyres are stuck fast to the ground. No way they can turn.
You let the clutch out.
What happens?
Torque makes its way down from the flyweel through the gearbox through the transfer case and down the propellor shaft, and then... can't turn the diff.
So instead of gears in the diff turning, the motor turns itself in the opposite direction, and takes the chassis and the body with it. Thus the body lifts away from the ground on one side.
I think what you've got is a less extreme version of this. It's not inertia, it's the resistance from the tyres fighting back against the motor.
Or, to put it another way, it's that the resistance in the diff (caused by traction) causes the axles to turn one way, and the body to turn the other.
Maybe I've just restated what you said, I'm not sure.
Jason
ps I have a weird, weird idea that I read somewhere of a vehicle that had two tailshafts, each rotating in opposite directions to prevent this, but it might have just been a hypothetical vehicle to illustrate the concept... Hmm.
Maybe as a thought experiment imagine this: you've parked on some wet concrete, then it set, and by the time you go to drive off all four tyres are stuck fast to the ground. No way they can turn.
You let the clutch out.
What happens?
Torque makes its way down from the flyweel through the gearbox through the transfer case and down the propellor shaft, and then... can't turn the diff.
So instead of gears in the diff turning, the motor turns itself in the opposite direction, and takes the chassis and the body with it. Thus the body lifts away from the ground on one side.
I think what you've got is a less extreme version of this. It's not inertia, it's the resistance from the tyres fighting back against the motor.
Or, to put it another way, it's that the resistance in the diff (caused by traction) causes the axles to turn one way, and the body to turn the other.
Maybe I've just restated what you said, I'm not sure.
Jason
ps I have a weird, weird idea that I read somewhere of a vehicle that had two tailshafts, each rotating in opposite directions to prevent this, but it might have just been a hypothetical vehicle to illustrate the concept... Hmm.
This is not legal advice.
The Mercedes G wagon's front propshaft rotates in the opposite direction to the rear one, and they just turn the front diff upside down so that the front wheel rotate in the same direction as the rears. I wonder if G wagons are affected by the same phenomena as our more conventional 4wd's?. The Germans (Borgward-Porsche} and the French(Latil} built 4wd Artillery tractors before and during World war 2 with twin propshafts front and rear. I used to wonder why? but now I think I am beginning to understand. Bill.
I was running 2 standard duty ome springs on the rear, I tried running 1 heavy duty rear spring on the right, and 1 standard duty on the left. Loved it, could feel the improvement. Now I running heavy on both, but will be going back to left standard, right heavy. In a stock zook, not only the driver, but the fuel tank and spare are on the right, add to that the torque twist, too. christover
4WD SUZUKI CLUB VICTORIA
http://www.vic.suzuki4wd.com/forum/
http://www.vic.suzuki4wd.com/forum/
Ive had similar experience to christover1. 45 series cruiser also has driver and tank on the same side and you can notice the effect of this even going through "S" type bends on road - one side rolls more than the other.
Im aware that some brands of suspension have designated Left and Right springs to counter this - you fit them the wrong way round and your 4b sags to one side - and will roll more to one side than the other.
Perception . . . torque . . . wieght distribution . . . all of them seem plausable to me.
Im aware that some brands of suspension have designated Left and Right springs to counter this - you fit them the wrong way round and your 4b sags to one side - and will roll more to one side than the other.
Perception . . . torque . . . wieght distribution . . . all of them seem plausable to me.
daddylonglegs wrote:The Mercedes G wagon's front propshaft rotates in the opposite direction to the rear one, and they just turn the front diff upside down so that the front wheel rotate in the same direction as the rears. I wonder if G wagons are affected by the same phenomena as our more conventional 4wd's?. The Germans (Borgward-Porsche} and the French(Latil} built 4wd Artillery tractors before and during World war 2 with twin propshafts front and rear. I used to wonder why? but now I think I am beginning to understand. Bill.
The short answer to this from Steve G (has an orange\red Gwagen pres of the Vic Zuk club) is yes .. it still suffers from the phenomon.
" If governments are involved in the covering up the knowledge of aliens, Then they are doing a much better job of it than they do of everything else "
.
most hard core rock buggies in the US are running sway bars to help combat this problem. Shorties Deisel GQs are good at whanting to flip from passenger front wheel over, mine does it all the time and is exagerated by engine torque. need to keep rear sway bar on to help reduce it.
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