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Old 23rd October 2008, 23:32   #1
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Default ABS/TCS and Offroading

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Originally Posted by star_aqua View Post
This is the disadvantage in ECU driven vehicles. Hrishi, never try engine braking on your vehicle without using brakes. you will still experience the braking effect but the response would be very slow. this is because its a comfort feature we have in our newer generation diesel engines called as surge dampers to avoid jerks when the vehicle drives the engine. The ECU matches the engine speed to what the vehicle is driving it and ramps it down slowly. this will take few seconds. Due to this the trucks and offroad vehicles are equiped with a engine brake switch which will be manually operated by the driver when going down hill to command the ECU to stop the fuel injection until the engine rpm reaches the idling point.
What do you guys think about an ABS in this situation? I think it make sense. Whenever it locks the wheel, ABS will come in to action. Hrishi, Think about it. Safari is an awesome Off-Roader with little more GC and track width. I think it can be easily modified to meet both of this. Some tall tyres for GC (Suspension lift will not work since there is no change in GC) and spacers for track width. Having said that, There is a definite down side when it comes to power to Weight ratio, and Rear and Front overhangs.

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Originally Posted by khan_sultan View Post
With all these rains in past few days, I anm sure Sakleshpur would be a heave for Off-Roading. Am very much tempted to ask Chandan on what is the scene there and if we can have another OTR session there soon :-)
Cheers,
Khan Bhai, i am game now itself, Chandan are you litening? . Now, that will be one of the most challenging terrain with all these rain. @Star_Aqua
Get yourself a soft top. We are heading Shakhleshpur next weekend cheers:

Thanks
--Sree--
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Old 23rd October 2008, 23:50   #2
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Originally Posted by sreerajunnithan
What do you guys think about an ABS in this situation? I think it make sense. Whenever it locks the wheel, ABS will come in to action.
No Sree, ABS works only in the panic braking and it will see that your vehicle will come to standstill. there are two sensors wheel speed sensor and the vehicle speed sensor used. if the vehicle speed sensor shows some value and wheel speed sensor shows zero, then it is interpreted as the vehicle is sliding. now the brakes are released and applied within a fraction of second. this process repeats until the vehicle comes to standstill. The ABS is based on the simple concept "the sliding wheel produces less friction than a moving wheel". but here this is not what Safari require on OTR.

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Originally Posted by sreerajunnithan
@Star_Aqua
Get yourself a soft top. We are heading Shakhleshpur next weekend
Wow! then i should use this weekend completely to get the work done. I should also come with NDMS tires then .
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Old 24th October 2008, 00:18   #3
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Originally Posted by sreerajunnithan View Post
What do you guys think about an ABS in this situation? I think it make sense. Whenever it locks the wheel, ABS will come in to action.
No, no, ABS is a bad thing to have in offroading. First of all you are not supposed to be using brakes. Secondly, have you seen ABS activated in low speeds, it is scary. It practically kicks back at your foot even when you lightly tap the brakes. Easy to experience while driving on fresh snow. Hmm, that reminds me. One has to use the same no brakes principle in snow/ice driving, which I have done a lot. While driving on snow or ice, even a light tap on the brakes can result in total steering loss.

After a snow fall, it is very common to see cars/suvs crashed out of the highways. Why, people try to brake. Mostly it is the SUVs, because the drivers of SUVs think they are invincible and drive fast.

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Old 24th October 2008, 00:55   #4
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Hmmm... I understand now. But any insight about traction control? Especially in a struck situation where your wheels are spinning away to glory?

PS: Man, i learn a lot of Mechanical engineering being a arts graduate!!! Thanks to Mighty Jeep.

Thanks
--Sree--
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Old 24th October 2008, 07:30   #5
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Originally Posted by star_aqua View Post
Hey Mahesh, i had posted a mini report on this. wel it went lost with no clue in the floods of your wonderful report . here you can check out http://www.team-bhp.com/forum/1023133-post45.html
Oops. I missed this may be bcs it was last in the page Thanks for pointing.
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Old 24th October 2008, 08:32   #6
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Originally Posted by sreerajunnithan View Post
But any insight about traction control? Especially in a struck situation where your wheels are spinning away to glory?
Traction control is more useful in offroading I suppose, since it is like LSD on steroids to put it crudely. Time for experts to jump in here.
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Old 24th October 2008, 09:08   #7
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Originally Posted by star_aqua View Post
Yeah sure. It is mahindra cj500d 4wd which is a stock vehicle with no mods in engine, power train and the body. It has International aka B275(tractor) aka MD2350 engine. 3 speed gearbox. and it is 26 years old now . this kinda jeep served the police and forest dept for several years. infact my jeep has served the police dept till 1991.
is it 26 yrs old???
i thought it was 36!!

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Originally Posted by Samurai View Post
Secondly, have you seen ABS activated in low speeds, it is scary. It practically kicks back at your foot even when you lightly tap the brakes. Easy to experience while driving on fresh snow. Hmm, that reminds me. One has to use the same no brakes principle in snow/ice driving, which I have done a lot. While driving on snow or ice, even a light tap on the brakes can result in total steering loss.

After a snow fall, it is very common to see cars/suvs crashed out of the highways. Why, people try to brake. Mostly it is the SUVs, because the drivers of SUVs think they are invincible and drive fast.

ABS at low speeds??? how is that done now?? by jamming on the brakes real hard at low speeds??

oh yeah!! driving on snow is quite tricky if one does not have a snow chain.
sleet is trickier. and its a whole lot of fun as well.
had more fun driving on sleet than on sand.

Last edited by Rehaan : 25th October 2008 at 14:49. Reason: Posts merged. Please use the MULTIQUOTE button instead of making multiple consecutive posts.
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Old 24th October 2008, 09:37   #8
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traction control would ensure that there is limited tire slip in acceleration on slippery surfaces.
one does not have to feather the "A" to get out of the rut as traction control would take care of that.

@sree
it would definately be of use in situations that you are talking of.


but, on the flipside. you can really have fun doing a wheel spin on tarmac when TC is present.
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Old 24th October 2008, 11:17   #9
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Originally Posted by star_aqua View Post
No Sree, ABS works only in the panic braking and it will see that your vehicle will come to standstill.
Just to add to it, ABS comes in to play when the wheels are getting jammed due to heavy breaking, which results in skidding of the vehicle. ABS ensures that wheels are still rolling (instead of skidding) while coming to a halt and the vehicle remains steerable.

Last edited by Guna : 24th October 2008 at 11:20.
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Old 24th October 2008, 12:45   #10
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ABS at low speeds??? how is that done now?? by jamming on the brakes real hard at low speeds??
Even light braking on fresh snow or black-ice activate ABS. Try it on a deserted road with fresh snow or black ice, there is a risk of losing control. Do it carefully.
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Old 24th October 2008, 14:20   #11
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back home in INDIA now.

how do i do this on tarmac?
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Old 24th October 2008, 14:30   #12
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back home in INDIA now.

how do i do this on tarmac?
It can't be done on dry tarmac. However, if you visit Himachal during snow, you can find similar conditions.
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