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Old 16th January 2010, 09:52   #481
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thanx for all the comments and replies on the matter of rear and front tracks being of smaller and bigger size, respectively.

but are there any drawbacks or flaws of this kind of set up on a vehicle?
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Old 16th January 2010, 10:38   #482
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In a rear wheel drive car it seems to make sense to have a wider front track for steering stability. Imagine you pushing a wheel barrow with a wider front track. Now imagine you pushing a wheel barrow with a track narrower than your feet, chances are it will be all over the place and a nighmare to steer effectively.

Same way in a front wheel drive car it may make sense to have a wider rear track, so the rear tracks more efficiently (like a man pulling a kart)

I am just visualising a wheel barrow/man powered kart scenario. I wouldn't know more technically but logically it seems to make sense

Last edited by DKG : 16th January 2010 at 10:39.
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Old 16th January 2010, 11:08   #483
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Default Front track width vs rear

I have a book on automotive engineering. Quoting from there:

At basic level:

Wide track decreases load transfer which is generally good for getting grip on that end of the car.
One disadvantage is that you increase usually weight, because of longer A-arms, push- or pullrods, tierods and driveshafts. Also the moment of inertia in yaw is increased a lot, because it is dependent on the lever arm of your wheels.

At the rear of the car:
A narrow track can be an issue with the drive shaft. You need more angle for the same vertical movement of the wheel you would like to allow.

A shorter track at the rear is also helpful as during turning there will be lesser difference between the radius of curvature between the wheels, not causing the differential to lock to often.

Rear wheels closer tgether aids in traction, for example dragster rear tires are very close. Having the front track width wider than the rears also helps with being able to change direction more quickly. Why? Because: The front wheels will have to absorb all the load transfer... that means the outside front tyre will be much more heavily loaded (twice as much load transfer to the outside front tyre than an equivalent car with equal front and rear track).... and that will promote understeer.

Source: RaceCar Engineering


EDIT: infact we have a thread on teambhp on this which never came to any conclusion. Maybe we can continue discussion about this there.
http://www.team-bhp.com/forum/techni...-v-s-rear.html (the difference in track width- front v/s rear)

Last edited by Tejas@perioimpl : 16th January 2010 at 11:09. Reason: see edit
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Old 16th January 2010, 13:51   #484
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Hi guys,
Even i had problem initially with difference in the track of Bolero range of vehicles except for Invader.

The wider front track as Trammway said was to accomodate tighter turning circle. The rear was left just like that because-
If you put wider track rear axle, it may foul with body work due to articulation. This may require further investments to cut the body and the door line which is expensive. Invader was newly developed and has a wider and higher body. Plus due to inverted leaf over axle type suspension and commonality of parts i think the Maxx festerra rear axle was adopted.

Plus what ever tejas said holds good for handling purposes.

However this is a big draw extreme back off road specifically for competitions. Imagine if you have to cross a stream on log of wood. How would you accomodate 100+mm difference on a just two wood logs running parallely? Thats why which ever vehicle was developed purely for off road duty like LC, defender and Jeep warangler to name few will not have such wide difference in track.

Now the question is why cant invaders wider axle be adapted to thar? The reason is wider the axle the wider should be the spring points, i.e nearer to the ends of axle. Else there would be tremendous body roll if the springs are not stiff. (1985 to 1989 MM540 and first generation Maxx festerra's)

Thar according to me is developed under tremendous constraints considering market is very small. Expect all the revisions to happen (including MLD/LSD etc) as and when both export and domestic markets pick up. Demand of suitable rear axle width has to come from abroad. Till then who ever is doing logwood crossing and competition specific terrain have to satisfy with spacers.

Last edited by vinod_nookala : 16th January 2010 at 13:57.
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Old 16th January 2010, 16:11   #485
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@vinod: It shouldn't be a BIG problem since the difference of approx 100 mm is shared between 2 sides, so one side will go in by 50 mm which is negligible right?
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Old 16th January 2010, 16:35   #486
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Quote:
Originally Posted by Tejas@perioimpl View Post
I have a book on automotive engineering. Quoting from there:.....

At the rear of the car:
A narrow track can be an issue with the drive shaft. You need more angle for the same vertical movement of the wheel you would like to allow.

Referring to IRS, I think.

...

Rear wheels closer tgether aids in traction, for example dragster rear tires are very close. Having the front track width wider than the rears also helps with being able to change direction more quickly. Why? Because: The front wheels will have to absorb all the load transfer... that means the outside front tyre will be much more heavily loaded (twice as much load transfer to the outside front tyre than an equivalent car with equal front and rear track).... and that will promote understeer.
Unclear as to what will promote understeer. Doesn't an understeering car not want to change direction?


Quote:
Originally Posted by vinod_nookala View Post
Hi guys,
However this is a big draw extreme back off road specifically for competitions. Imagine if you have to cross a stream on log of wood. How would you accomodate 100+mm difference on a just two wood logs running parallely? Thats why which ever vehicle was developed purely for off road duty like LC, defender and Jeep warangler to name few will not have such wide difference in track.

Agreed. Even in non extreme situations, the ability to make two tracks rather than four is a great advantage.

Now the question is why cant invaders wider axle be adapted to thar? The reason is wider the axle the wider should be the spring points, i.e nearer to the ends of axle. Else there would be tremendous body roll if the springs are not stiff. (1985 to 1989 MM540 and first generation Maxx festerra's)
AFAIK, for a solid axle, roll stiffness is independent of track. Other things being equal, it will vary as the distance**2 between the spring mounting points.

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Old 16th January 2010, 16:49   #487
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Quote:
Originally Posted by vinod_nookala View Post
Expect all the revisions to happen (including MLD/LSD etc) as and when both export and domestic markets pick up. Demand of suitable rear axle width has to come from abroad. Till then who ever is doing logwood crossing and competition specific terrain have to satisfy with spacers.
A suggestion, have a properly rated winch as a dealer option to cross the log bridges.
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Old 16th January 2010, 17:50   #488
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Default difference in track matters

Quote:
Originally Posted by Jaggu View Post
@vinod: It shouldn't be a BIG problem since the difference of approx 100 mm is shared between 2 sides, so one side will go in by 50 mm which is negligible right?

It matters in such cases!
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Old 16th January 2010, 17:55   #489
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We did such a log crossing in Kakkabe (Coorg) OTR, Gypsy to Telcoline did cross the bridge, although it looked very narrow, just enough for a Jeep.

Vinod, aren't you supposed to be on vacation now?
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Old 16th January 2010, 17:59   #490
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Yes thats what i meant, the tyre width itself will take care of such variation unless its those thin NDMS thingies?
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Old 16th January 2010, 18:29   #491
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If I take this ' Done up ' Thar for a OTR.I need Arka's 1 ton just to pick up the plastics/lights/air intakes/some I don't know things etc etc I leave behind.
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Old 17th January 2010, 00:10   #492
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so this discusion about the front and the rear track measurments concludes that THAR will be getting bolero's front and rear tracks, to enable MM to keep the costs down!

so does that mean the export version of THAR also has a similar set up of the front and rear tracks as the Desi Thar or its different?

Could any one please comment on the front and rear tracks in the following photos i have attached?
Attached Thumbnails
Mahindra Thar revealed at Autoexpo 2010-jeepster201.jpg  

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Old 17th January 2010, 01:08   #493
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Quote:
Originally Posted by Parm View Post
so this discusion about the front and the rear track measurments concludes that THAR will be getting bolero's front and rear tracks, to enable MM to keep the costs down!

so does that mean the export version of THAR also has a similar set up of the front and rear tracks as the Desi Thar or its different?

Could any one please comment on the front and rear tracks in the following photos i have attached?
What comments are you looking for buddy. Let the car be launched. The first & fourth pic are of the now old generation THAR, live axle.These too had the Track difference.
Why would M&M develop two different chassis, when it knows that THAR will be sold in very small number compared to other vehicles in the portfolio.

Last edited by dinar : 17th January 2010 at 01:26.
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Old 17th January 2010, 09:45   #494
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Quote:
Originally Posted by dinar View Post
What comments are you looking for buddy. Let the car be launched.
, he's just trying to keep this thread alive & kicking
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Old 17th January 2010, 10:23   #495
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There is a nice report / article in the Indian Express today. Here's the link.

The desert rider
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