[PaulKEsq]

Hi folks, new here - still haven't taken possession of our new 2013 Jimny.. BUT I have a very specific question someone may know the answer to.


Suzuki quote:

Approach angle is 34 degrees.
Departure angle is 46 degrees.
Ramp breakover angle is 31 degrees.

But no mention of:
1. Slant angle, or
2. maximum climb incline (assuming 100% traction).

Any clues?

Thanks in advance,
PaulK.

[31zook]

You will need to work the 'slant angle' your self

[303zuke]

Can you sit in the car and tell the difference between 29deg and 33 deg?

Having a "Magic Number" to tell you roll angle or climb incline will serve no purpose whatsoever, as the number will change with dynamics and inertia. A climb that would be impossible in dry conditions (100% traction?) in 1st low may quite well be acheivable in the wet in 2nd or 3rd low. Something that can't possibly be done with stock tyres might be easily done with a set of mud terrains. How can you simply quote a single meaningless number to describe that?

[BlueSuzy]

This ones about 110degrees

[PaulKEsq]

Thankyou for your inputs so far.

I would have thought the slant angle would be something that can be empiraclly stated as a angle on a slope where the centre of gravity does not exceed the outer edge of the supporting structure, being in this case, the outer edge of the tyres to which it is leaning where the vehicle is perpendicular to an even horizontal slope.

Of course it is not the same in "the rough" as other factors come into play as suggested.

As for "feeling the difference", that's what an inclinometer is for, to remove such guesswork.

Al I wanted to know is if anyone has any idea on this as the Suzuki Jimny would appear to have a higher base to height ratio than most other off-road vehicles therefore at first glance appears to be quite unstable laterally/vertically. The key to this question is the centre of gravity relative to base and height. If I knew what that was then this figure could easily be calculated. It could also be re-calculated for a single driver, driver and passenger and so on, as those factors change the centre of gravity.

Then, taken into all accounts a figure could be reached which provides a guaranteed non-tipping point relative to a 0 degree plane. The inclinometer could be set to those margins and if not exceeded would ensure that it would not overturn. I have ordered a couple of cheap inclinometers (as I would want them to be dampened, rather than a piece of string with a lead weight on a piece of cardboard) which include both lateral and longitudinal angles marked in degrees and do not require an electric power source..

FYI, these:
http://www.ebay.com.au/itm/221114226946 ... 1497.l2648
(One for each vehicle)


As to incline. Of course it depends on factors such as traction etc. 100% would mean that there is no slippage of the tyre / driven surface and again that is a calculation that can be delivered based on standard factory supplied tyres, driven force at the wheels, friction co-efficients and so on. I once wrote a program that calculated the speed of a vehicle based on the friction co-efficient of the road surface (type of surface /cement/ ashphalt/ice / loose gravel etc) and tyres (condition /surface contact areas etc), weight of vehicle and so on. All of these are data that can be utilised to determine the answer. (The police department use this or the modern updated program in accident investigation today - I wrote it about 30 years ago.)

So again this is a figure that can be determined relatively easily and the conditions for this to apply can be clearly stated and identified so as to provide a minimum and maximum. Once the tyre /surface friction co-efficient drops below 100% then you have reached the maximum incline.. (If the vehicle can actually move forward at that incline of course).

Obviously the friction co-efficient is a critical factor, eg, ice is extremely low whereas [clean] cement provides the highest, but it is not the only factor. As a manufacturer with R.A.M. analysis as part of their engineering and design process these things should be available.

I was merely asking if anyone knew those figures. I have asked Suzuki to provide the answer and will post the reply.

..and yes, you can suck it and see. That was how engineering was done up until about 1950..

[tanshi]

i think your over complicating it.

if your on a side angle and it "feels wrong" good chance your getting close to your angle.

driving offroand isnt about facts and figures. its 99% about "feel"

[SierraDan]

I agree that you're over complicating it.

A lot of the time there is a sudden change in "slant angle" which leads to a rollover. I doubt you'd have time to go "Hmm, better check the inclinometer to see if I'm about to roll."
And on a continuous "slant angle" your calculated degree measurement would go up and down several units with uneven ground.

THIS is a realistic inclinometer:

[Matthew]

^^ x2

Way over complicating it.

Just get out there and drive with competent people and gain experience.

You will find situations where the vehicle will slide off a slope long before it reaches it's tip point. Likewise you find tracks where you will unload a spring if you tap the brakes causing the car to roll, whereas keeping a constant speed would cause no issues whatsoever.

PS ill give you $400 for your arb voucher

[alien]

^^ what they said...

go drive the jimny, you'll get a feel for it very fast, and i'll bet what you're thinking is near its rolling point when you first start is WAY less than the angles you'll put yourself on intentionally later down the track... especially once you learn the dynamics of your own car.

Good example: using the tyre sidewalls in a rut to stop you rolling - so you can be well past your "rolling point" but the sidewalls are on the side of the rut stopping the body touching or going any further over... its unnerving at first, but once you get used to it you'll do it all the time and use it to get places you otherwise wouldnt have tried.

[Mike57]

I understand where you are coming from but I can suggest that you will start to feel very uncomfortable way before you get any where near to the angle that will roll the car. There are dynamic forces as well which I am not sure you addressed.

I know I have driven up slopes that I could not walk down but again if it looks scary don't do it.

Finally until PC's were invented and became common place in the 1980's we still did a lot of suck it and see engineering. You just could not run the complex calculations you needed with a slide rule in some areas of engineering. They did however, design the Sydney harbour bridge with a big room full of engineers with slide rules - and seemed to get it right.

[kenn]

Suzuki probably don't want to put a number on it so as not to open themselves up to litigation when some numpty rolls their car in a car park. " but I was on flat ground".

[Rhinoman]

When you get close to the tipping point you won't be looking at the inclinometer. Some say that when the going gets tricky then you should always walk the route first but the Zuk will climb slopes you won't be able to climb up. Take it easy at first and learn the car, ignore anyone that encourages you to push it harder than you feel comfortable with.

[SierraDan]

I reckon if you roll a stock 2013 Jimny you either deserved it or have horrid luck...

[atari4x4]

just drive the bloody thing.

[bakerboy]

The only time they are useful are for gimicky photos, just drive it and get a feel, you'll be moving around in your seat/passanger will be up in your ear long before you reach that point. Also you can go past that magical number and not roll just due to the nature of what you're doing at the time.

[Gwagensteve]

I think I understand that you're trying to work out what the maximum "safe" angle is, that, under no circumstances, could lead to a roll/flop.

I'm going to try and avoid rehashing what's already been said - it's all correct.

You will almost never find those figures published for any vehicle these days, because they are meaningless. Stationary cars don't roll over or flip backwards, only moving cars do.

It's posible to take a car well, well, beyond it's "safe" slant angle if there is ant sort of lip that's retaining the low side tyre, like this:



It's possible to greatly reduce the maximum slant angle if the suspension is articulated, the car is in motion, being steered up the hill, has a wheel in the air, or any other number of variables. A little bounce, and it's not hard to turn a "safe" angle into this:



In fact, the last time my car fell over, it actually felt OK until the passenger moved in their seat, and then it went.

If you are looking for comparative figures to determine if you've bought an unstable car, too late. you've already bought a (comparatively) unstable car. It's actually less stable than an empirical "slant angle" figure would convey for two reasons. It's light, so as a % of the vehicles dry weight, the weight of passengers and equipment (normally carried above the cars "dry" COG has a much larger effect.

The second reason is the effect of radius arm suspension front and rear. As someone who has flopped my car on its side quite a bit (ten times I think) and seen countless others, they flop when the suspension unloads. (i.e transitions from articulated to straight) Radius arms have inherently high roll stiffness, so they're trying to "straighten out" all the time. This effect can take a car that's sitting lightly articulated and on an OK angle into car that's on its way over with a very small change in angle or with the application of drive load (torque), because applying drive load to a radius arm rear suspension causes it to "jack" or lift and therefore this can push the car off the obstacle, quickly exceeding the "slant angle" obviously this effect is exacerbated because the car is in motion so you have to consider the effects of inertia.

Take all of that into account and a maximum safe "slant angle" limit might have to be set far too conservatively to be useful. I think even 20˚ might be excessive if the car was articulated, under power, and required steering input (and to take into account variations in payload)

The short answer is you're going to feel very anxious before the car falls over, as others have said. Nobody ever feels comfortable on big side angles. I have experience with damped inclinometers in Toyota 4Runners where the manufacturer stated "Do not exceed 30˚" and even with a lifted car with a roof basket and no increase in track width, it was quite possible to safely exceed 30˚ in both directions simultaneously

Unfortunately, there's no substitute for experience.

As for the "100% traction" gradability, I cant think of any reason that number would be at all helpful. It's just impossible to achieve, yet even a surface with well under 100% traction can exceed the 100% traction gradability # with a touch of momentum.

Just out of interest, are you seeking this information because you don't have any off road experience, or you don't have any experience with a Jimny?

It's quite good fun to get a car into a spooky angle, and then with a whole bunch of people standing around the car to steady it, to start rocking it to get a sense of how "light" it will start to feel once the suspension unloads. quite safe, but very educational.

Steve.

[Ace]

atari4x4 wrote:

just drive the bloody thing.

THIS - and that's me past my "tech" slant angle... you will poo when you get close

[alien]

Gwagensteve wrote:

It's quite good fun to get a car into a spooky angle, and then with a whole bunch of people standing around the car to steady it, to start rocking it to get a sense of how "light" it will start to feel once the suspension unloads. quite safe, but very educational.

I do that almost every time i flex mine up for a pose... just to see how stable it really is with a wheel off the ground... Havent made it fall over yet. lol

What Steve said about it being fun is 100% true... talking about that time you "almost rolled it" but found a way out of doing so is part of what we do =)

EDIT: just remembered a really good example... see pics below:




i was on a HUGE side slope with shithouse tyres for the job of driving on a gravel cross slope... as i drove straight i was sliding sideways into a big rut, which if i went abotu 300mm further i'd have rolled for sure. I stopped, attached a recovery strap to my rear tow point and a nearby tree and wrenched it tight... then i dumped the clutch with the rear locker turned off, which slid the front around to a 45 degree angle facing down the rut... with man power we rocked it side to side until it faced directly down, then i drove straight down and back out of the rut i was trying to avoid at the beginning... point being - i was on a scary, uncontrolled angle and found a way to rectify it... those pics are from 2010 and it feels like yesterday =) lol

[BlueSuzy]

For that angle to roll it, There isn't even a wheel in the air..

I have come close numerous times, but never full roll. That's in a modded sierra. Would never take a new jimny in these places.

(no grip to drive further here)

[alien]

the angle wasnt what was going to roll me, it was that it was sliding sideways down the cross-slope and was going to come to a sudden stop at the bottom in that "V" in the track, which would have sent me over... its a case where the pics don't really do it justice. Either way, it was an unnerving situation, so i stopped and found a way around it rather than risking it... which applies to the OP's question and the direct replies given to driving by feel rather than figures.

[SierraDan]

Is this now a post your angles thread?

[atari4x4]

L <- that's a 90 degree angle

[SierraDan]

V <- that's an acute angle

[alien]

[SierraDan]

[31zook]

Did anyone else open this thread thinking it was going to be about 'your opinion on Asians'?

[atari4x4]

hahahahhaahahahahaha maybe


or shitty old 4k toyota motors.

[steve]

It's great that there's no abuse in this thread, great effort... but... hey... stop it

less piss take and more help

I know some people have said in the past that they can tell the exact moment the car will tip, but i dispute that. I've been on angles and you think it's going to tip over and it doesn't., and then you think you're ok and without notice you're on your roof.

[got_bar_work]

BlueSuzy wrote:

:? For that angle to roll it, There isn't even a wheel in the air..

I have come close numerous times, but never full roll. That's in a modded sierra. Would never take a new jimny in these places.

(no grip to drive further here)

It that the bottom of daniels point rd

[SierraDan]

Yes .