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Old 2nd February 2011, 15:12   #91
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Default Assumption

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Originally Posted by SPIKE ARRESTOR View Post
my query was "What is the basis for all these assumptions", if that means offending someone then so be it.
Spike
Hi Spike,

For Reference - http://www.team-bhp.com/forum/offici...review-52.html (Mahindra Thar : Test Drive & Review)

Question 1 - Why was the Thar Lifting Wheels.

Answer is IFS and RTI Score, even though Thar CRDe has better Rear-Axle Articulation compared to most regular JEEPs.

Question 2 - What has IFS to do with Rear Lifting.

Post#43 -- http://www.team-bhp.com/forum/4x4-te...ulation-3.html (Articulating on Articulation)

Sharath, went further to make a graph using Lifting a Tyre (on a ramp/obstacle) vs Shifting of CG.

On a Ramp/Obstacle the Rear Wheels/Type of Suspension/Chassis will determine the Articulation.

If you include these factors, the Shifting of CG in non-linear on a Ramp/Obstacle.

The basis of assumption is observation, maybe we cannot explain it in scientific terms but that does not mean it cannot happen or has not happened, and this is not a one off phenomenon.

You have explained the Shift in CG on a Bank (Side-Slope), and we are talking about in a RTI Ramp/Obstacle.

Regards,

Arka

PS - I don't even get offended by sarcasm.

Last edited by ex670c : 2nd February 2011 at 15:37.
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Old 2nd February 2011, 17:33   #92
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Default Re: Articulating on Articulation

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Originally Posted by svsantosh View Post
And drop the 'sir' Vikram, not after we got aquainted face-face...
Nevermind Santhosh - There are some here who are pleased by that word!!

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Originally Posted by SPIKE ARRESTOR View Post
I am not an expert when it comes to offroading parlance (I am still learning), but with whatever little I know, your reasoning fails to convince me i.e. why should CG shift non linearly?
Spike, If CG shifts linearly, then all topples - I mean the rate of topple will also be linear. This somehow is not the case in real life.

There is a threshold point during the topple until which it appears slow [linear?] after which you just fall [well non linear!!!]


I have toppled twice to tell you this !
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Old 2nd February 2011, 17:48   #93
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Default Re: Articulating on Articulation

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Nevermind Santhosh - There are some here who are pleased by that word!!

Spike, If CG shifts linearly, then all topples - I mean the rate of topple will also be linear. This somehow is not the case in real life.

There is a threshold point during the topple until which it appears slow [linear?] after which you just fall [well non linear!!!]


I have toppled twice to tell you this !
Hi Vikram,

Stop UNCL-ing.

And describe the conditions for your Topple/s.
1) Were they on road or off-road
2) How many wheels were in the air before you toppled?
3) Was the topple caused by pronounced/sudden acceleration.
4) Please describe the vehicles and necessary mods (mechanical).

Regards,

Arka

PS - Stop taking the BE & MS in UK bit seriously, go easy with the threshold
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Old 2nd February 2011, 18:07   #94
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Default Re: Articulating on Articulation

Body Tilt/Vehicle lift could be non-linear depending on the suspension setup (shown in the modified graph of Samurai that I posted). The shifting of CG with respect to the vehicle lift/body tilt should be linear.

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Originally Posted by headers View Post
...
Spike, If CG shifts linearly, then all topples - I mean the rate of topple will also be linear. This somehow is not the case in real life.

There is a threshold point during the topple until which it appears slow [linear?] after which you just fall [well non linear!!!]
...
That is gravity

In a real life off-roading situation you have other forces at play like centrifugal foces, force (obstruction) offered by obstacles etc. The same vehicle that is able to put one wheel up by 3 feet on a ramp without toppling could topple in a trail by climbing onto a 2 feet obstacle, because of the other forces at play.
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Old 2nd February 2011, 22:06   #95
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Default Re: Articulating on Articulation

Bumping a thread which has gone dead for all of 4 hours!

Guys,
What will be the behaviour of a vehicle with Independent Suspension compared to a solid axle one if it has the same suspension travel and the same spring rates?

Regards
Sutripta
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Old 2nd February 2011, 23:05   #96
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Default Re: Articulating on Articulation

A very amateur try, i feel vehicle can be more unstable in an offroad terrain. Reason being the IFS is attached to the vehicle which will result in high CoG compared to a low slung solid axle displacing the weight at less height.
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Old 3rd February 2011, 00:55   #97
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Thumbs up Re: Articulating on Articulation

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Originally Posted by Jaggu View Post
A very amateur try, i feel vehicle can be more unstable in an offroad terrain. Reason being the IFS is attached to the vehicle which will result in high CoG compared to a low slung solid axle displacing the weight at less height.
Quote:
Originally Posted by Sutripta View Post
What will be the behaviour of a vehicle with Independent Suspension compared to a solid axle one if it has the same suspension travel and the same spring rates?
The FAW difference in IFS and solid axle is not significant. The majority of weight is in the differential housing and the drive shafts/ drive rods so the only difference comes from the weight of tubing of solid axle. Also, this difference is somewhat off-setted by the additional weight of CV joints. Therefore the CoG of the vehicle does not change significantly.

A definite benefit that is derived from the solid axle comes from the leverage effect. For the same spring and damper travels, the wheel travel is more in solid axle as compared to IFS. This results in higher cross articulation.

Quote:
Originally Posted by pjbiju View Post
In a real life off-roading situation you have other forces at play like centrifugal foces, force (obstruction) offered by obstacles etc. The same vehicle that is able to put one wheel up by 3 feet on a ramp without toppling could topple in a trail by climbing onto a 2 feet obstacle, because of the other forces at play.
Therefore speed of vehicle while approaching an obstacle plays a crucial role in safely over-coming it. This is supported many times by off-roading experts in the Off-Roading forum.
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Old 3rd February 2011, 10:35   #98
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Default Re: Articulating on Articulation

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Originally Posted by AutoNoob View Post
The FAW difference in IFS and solid axle is not significant. The majority of weight is in the differential housing and the drive shafts/ drive rods so the only difference comes from the weight of tubing of solid axle. Also, this difference is somewhat off-setted by the additional weight of CV joints. Therefore the CoG of the vehicle does not change significantly
What is FAW?

And if what you say is true, the majority of weight part, then CoG is definitely lower in a solid axle right?
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Old 3rd February 2011, 10:47   #99
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Default Re: Articulating on Articulation

FAW - Front Axle Weight
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Old 3rd February 2011, 10:48   #100
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Default Re: Articulating on Articulation

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Originally Posted by Jaggu View Post
What is FAW?

And if what you say is true, the majority of weight part, then CoG is definitely lower in a solid axle right?
Full Articulation at Wheel? (too..).
Thanks Biju.

Last edited by starter : 3rd February 2011 at 10:51.
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Old 3rd February 2011, 11:26   #101
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Default Re: Articulating on Articulation

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Originally Posted by Sutripta View Post
Bumping a thread which has gone dead for all of 4 hours!

Guys,
What will be the behaviour of a vehicle with Independent Suspension compared to a solid axle one if it has the same suspension travel and the same spring rates?

Regards
Sutripta
In a sold axle suspension setup, when one side is pushed up, it automatically tries to push the other side down (which would be less pronounced if the suspension is very stiff). This I think is a major adavantage of solid axle setup. In the IFS setup, if one side is pushed up, the other side will get pushed down only by its own weight mostly. So for cross articulation, solid axle setup will do better even if the IFS setup has the same suspension travel and spring rates. This is what I feel. I could be wrong though.
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Old 3rd February 2011, 11:40   #102
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Default Re: Articulating on Articulation

Quote:
Originally Posted by Sutripta View Post
Bumping a thread which has gone dead for all of 4 hours!

Guys,
What will be the behaviour of a vehicle with Independent Suspension compared to a solid axle one if it has the same suspension travel and the same spring rates?

Regards
Sutripta

Again, no scientific proofs and formulae , but given the same suspension travel and spring rates I think a vehicle with independent suspension will be less likely to topple than a vehicle with solid axles.

This opinion is largely influenced by having watched Baja style buggies and Tatra (and other european military vehicle manufacturers) type trucks going over boulders as if they don't exist (because it is Independent, only a single wheel is lifted while the rest of the wheels and the chassis itself hardly even tilts).
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Old 3rd February 2011, 11:43   #103
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Default Re: Articulating on Articulation

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Originally Posted by pjbiju View Post
In a sold axle suspension setup, when one side is pushed up, it automatically tries to push the other side down (which would be less pronounced if the suspension is very stiff). This I think is a major adavantage of solid axle setup. In the IFS setup, if one side is pushed up, the other side will get pushed down only by its own weight mostly. So for cross articulation, solid axle setup will do better even if the IFS setup has the same suspension travel and spring rates. This is what I feel. I could be wrong though.
think what will happen if the Thar's ,anti roll / stabiliser bar is removed .

I had asked this before ,

IMHO , at the cost of some high road speed,(specially cornering & above 100 kmh) this will give wonderful articulation at front & the wheels will hold good for more traction .

Sudarshan

@ 72 Bullet I feel similar,

Last edited by Sudarshan : 3rd February 2011 at 11:45.
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Old 3rd February 2011, 11:45   #104
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Default

Quote:
Originally Posted by pjbiju View Post
In a sold axle suspension setup, when one side is pushed up, it automatically tries to push the other side down (which would be less pronounced if the suspension is very stiff). This I think is a major advantage of solid axle setup. In the IFS setup, if one side is pushed up, the other side will get pushed down only by its own weight mostly. So for cross articulation, solid axle setup will do better even if the IFS setup has the same suspension travel and spring rates. This is what I feel. I could be wrong though.
Hi Pjbiju,

I would like to add a diagram.

Hilux 4x4 Off-road Forum - View topic - SFA vs IFS

Stock vs. IFS Lift vs. Live-Axle Conversion - Technical Articles - Four Wheeler Magazine

Regards,

Arka

Quote:
Originally Posted by Sudarshan View Post
think what will happen if the Thar's ,anti roll / stabiliser bar is removed .

I had asked this before ,

IMHO , at the cost of some high road speed,(specially cornering & above 100 kmh) this will give wonderful articulation at front & the wheels will hold good for more traction .

Sudarshan

@ 72 Bullet I feel similar,
Hi Sudarshan,

The Stabilizer Bar has secondary feature of maintaining the Wheel Track.

This will be important especially under Articulation (RTI Ramp).

How much more wheel travel will you get by removing the stabilizer bars?

Don't you think they will add more strain/load on the Lower Arms and Rack & Pinion Steering?

Regards,

Arka
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Last edited by ex670c : 3rd February 2011 at 11:55. Reason: back-to-back post
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Old 3rd February 2011, 12:09   #105
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Default Re: Articulating on Articulation

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Originally Posted by ex670c View Post



Hi Sudarshan,
Thanks ( at last, I am less a JEE )

Quote:
The Stabilizer Bar has secondary feature of maintaining the Wheel Track.
how ? can you be Thar specific


Quote:
How much more wheel travel will you get by removing the stabilizer bars?

Regards,

Arka
my feeling is ,if that bar is removed both sides will be acting independently .So if one wheel goes over a rock ,it will move upward in the wheel well & the opposite will still hold the ground .

As there will be no connection bet the two( the anti roll bar) it will be really an IFS

need to think deeper here , will be beneficial

Sudarshan

P.S. your IFS picture , third frame

Last edited by Sudarshan : 3rd February 2011 at 12:10.
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