[a4anurag]

Originally Posted by GTO

It is the front brakes that do 70% of the stopping work. This is one of the reasons you see economy cars with superior disc brakes at the front only.

Agreed!

If that's the case then why choose Rear-ABS instead of 4-wheel ABS?

I am not able to understand the need of the Rear-ABS for the Bolero?! If the brake bias is around 70% to the front.

Anurag.

[audioholic]

Originally Posted by a4anurag

Agreed!

If that's the case then why choose Rear-ABS instead of 4-wheel ABS?

I am not able to understand the need of the Rear-ABS for the Bolero?! If the brake bias is around 70% to the front.

Anurag.

That is because its much simpler to implement compared to a full fledged ABS system.

[a4anurag]

Originally Posted by audioholic

That is because its much simpler to implement compared to a full fledged ABS system.

Agreed!

When majority of the braking is done by the front wheels why add ABS only to the rear where the bias is on the lower side. I would have understood a 'Front ABS' would have been better.

Anurag.

[audioholic]

Originally Posted by a4anurag

Agreed!

When majority of the braking is done by the front wheels why add ABS only to the rear where the bias is on the lower side. I would have understood a 'Front ABS' would have been better.

Anurag.

Not exactly if you see how much weight is on each axle. Consider an unloaded bolero where majority of the braking is done by the front wheels. Now the rear wheels arent under much weight. During braking, most of the work is done by the front brakes. The rear brake OTOH may not perform a serious role in braking, but at the same time it shouldnt lock up. If there is no brake, no problem. But if there is a brake that can lock up the wheels, then the car will be out of control.

Thats the reason we have valves that control brake pressure to the rear wheels. In the same way, the Rear ABS will prevent the rear wheels from skidding. Maybe the front wheels arent prone to skidding in the case of the Bolero?

[a4anurag]

Originally Posted by audioholic

Maybe the front wheels arent prone to skidding in the case of the Bolero?

So you mean to say that the Rear-ABS is more of a preventive measure to keep braking in control under load or no load.

The engine weight must be heavy enough to prevent wheels from skidding may be.

Anurag.

[YaeJay]

Is it like something like the micro hybrid as they called it? Load sensing pressure valve, is a component of the mordern ABS. Maybe ABS is a broad term. I think even a V2 Tata indica has been having it for a few years. If its just a LSPV MM has let me down. Only experts know the answer.

@black_rider : Yes, the front wheels will lock up under heavy braking. It is natural. As GTO mentioned earlier, when we brake the weight gets shifted to the front of the contraption you are riding or driving, When weight moves up front, the rear wheels lock up first( because it gets lighter). The Load sensing pressure valve, prevents that. That is what they have done. They can call that ABS. I woudn't. At this point of time.

[veyron_head]

I just checked with a dealer here in Bangalore and they don't seem to know the price. But he did tell me that it is only available in one color - Pearl White. He was guessing the price would be around 30k more than the regular ZLX (which is now at 9.25 lacs on road in Bangalore).

[Herbie98]

The rear ABS is a welcome addition to the Bolero. Having owned a Bolero for close to 150K kms, i can say that rear wheels do get locked up under hard braking. Till date I have never come across a situation where in the front wheels locked up.

Anyday a complete ABS would be a nice to have. But may be Mahindra wants to always differentiate Bolero to a Scorpio by omitting basic features :( For example the foldable rear bench exists in Scorpio but not even an option in any Bolero variant.

My wishlist in next generation Bolero:
- A more powerful engine, the one in Thar CRDe is great to have. I like the silent smooth surging power in Thar, always dream to have this in Bolero.
- Better brakes with ABS
- 4WD as an option across variants. (with a mechanical shift please)
- Foldable rear seats (2nd row) to increase on utility.

The rest of existing things in Bolero is great for a basic no nonsense, super durable vehicle.

[.anshuman]

The most important function of the ABS is to avoid locking the wheels, which keeps the vehicle steerable. If Bolero in this case just has ABS on rear wheels, the steering control under hard braking will be lost. Its the front brakes which do most of the stopping work in straight line.

I can understand huge trucks having rear ABS but its for the first time i have heard about rear wheel only ABS on a passenger car.

The last time i heard about a strange ABS version for the first time was when Scorpio VLX came out. Scorpio had/has 3 channel ABS, while the front wheels had independent channels, the rear wheels on rear axle shared a common channel. This system also lacked/lacks EBD(a function we expect to be standard on any ABS system) and i am not sure if it had/has emergency Brake Assist function. Though in the real world the stability improvement under hard braking was noticable, the non ABS Scorpio was a scary vehicle to drive at speed.

[hubolt]

A very smart move to market a feature without really offering it.

But also, losing rear traction could be more of a problem than losing front traction.

[a4anurag]

Originally Posted by .anshuman

The most important function of the ABS is to avoid locking the wheels, which keeps the vehicle steerable. If Bolero in this case just has ABS on rear wheels, the steering control under hard braking will be lost. Its the front brakes which do most of the stopping work in straight line.

I can understand huge trucks having rear ABS but its for the first time i have heard about rear wheel only ABS on a passenger car.

Still keeps me in splits as to why M&M has chosen such a safety system for its car rather than going for a 4-wheel ABS that is more helpful that this creation of theirs.

When the front wheels do the braking, steering why give a feature to wheels that do it very less when compared to the ones that need it.

I hope this is NOT some marketing gimmick by M&M to boost the sales and attracting the customer by saying 'Only 500 units would be manufactured, H.U.R.R.Y!'

Originally Posted by hubolt

A very smart move to market a feature without really offering it.

But also, losing rear traction could be more of a problem than losing front traction.

Why do you say so?

I thought the front wheel needs more traction that the rear ones as the front wheels do the steering and need more traction so on a lock-up of the front wheels the life is more in danger than a rear-wheel lock up.

Anurag

[Sutripta]

Originally Posted by a4anurag

When the front wheels do the braking, steering why give a feature to wheels that do it very less when compared to the ones that need it.

Hi,
If the rear wheels lock, the vehicle has a tendency for the back to overtake the front. Extreme and spectacular case is that of tractor-trailer rigs jackknifing.

It is not possible to set up a brake balance for a load carrier which is suitable for no load, fully loaded, and (in the Indian context) fully overloaded. Thus the cheap (and semi effective) solution of a rear LSPV. Which ceases to function once juggadis go about recambering springs, and adding helper springs to carry even more load. If it is a real active ABS. it is to be welcomed, even if only on the rear wheels.

But given MMs love for 'engineering by copywriters' (remember micro hybrid) I would like confirmation on the ABS part.

Regards
Sutripta

[hubolt]

Sutripta - "If the rear wheels lock, the vehicle has a tendency for the back to overtake the front. Extreme and spectacular case is that of tractor-trailer rigs jackknifing." also to add .. which makes fighting this phenomenon by counter steering more difficult (that is - regaining control of the rear and coming back to straight position).


Also for taller vehicles like jeeps , in a rear traction loss condition overturning tendancy is higher.

[audioholic]

Originally Posted by a4anurag

When the front wheels do the braking, steering why give a feature to wheels that do it very less when compared to the ones that need it


Why do you say so?

I thought the front wheel needs more traction that the rear ones as the front wheels do the steering and need more traction so on a lock-up of the front wheels the life is more in danger than a rear-wheel lock up.

As Sutripta has explained, it would be a better situation to have a jammed front wheel and loss of steering compared to having a jammed rear wheel whoch throws the car all over the road. Also as I told before, the loaded front wheel has very less chances of skidding compared to the rear wheel with lesser load, especially when the car is not fully occupied.

[rahul4321]

Some more investigation and reading up on it revealed this

"The new Special Edition Mahindra Bolero also claims to offer ABS, a feature that has never before been offered on the Bolero as a part of the package. The system offered though is only on the drum brake equipped rear wheels and not on the front. On further enquiry, we found out that the ABS system that Mahindra claims is in fact not a full fledged conventional ABS setup but a low cost sensor that releases the brakes if the wheel Rpm drops below a certain value. This system, either developed by Brakes India Limited or Bosch is in fact a temporary substitute for a full fledged independent ABS unit which is conventionally active on the front wheels since they do more than 90 percent of the braking. That said, Mahindra’s initiative to make the high selling Bolero a little safer for the Indian audiences is quite welcome"


Source: http://overdrive.in/news/mahindra-bo...ched-in-india/


So this is what I derive from the above paragraph

1- It is a temporary stop-gap measure before the arrival of a full fledged normal ABS
2- According to the paragraph; It releases the wheels if the wheel rpm drops 'under a specified limit'. Just to clarify; the words are probably poorly chosen- it shouldnt be the 'limit' that should act as the deciding factor but the 'speed of decline' in reaching the limit which should act as a deciding factor.

Example: Say the wheel RPM is 20 for the ABS to kick in- any braking; however slow and gradual it may be is going to make the wheel go down from 40 to 30 to 20 to 10 and then to 0. So that 20 wont be the deciding factor. But 40-20 in 2 seconds may be the deciding factor and will make the ABS sensor active and get it to release the brakes but 40-20 in 3 seconds may not be enough for the sensor to make the ABS Sensor active and get it to release the brake. (Rough figures just picked out of the air to elaborate)