[directinjection]

Originally Posted by rider60

Skoda Rapid uses non-independent multi-link rear suspension. Where as its twin, VW Vento uses the independent rear suspension setup.

VW Vento does not have independent rear suspension. VW describes it as semi-independent trailing arm which is similar to what most cars in the segment use these days.

[lamborghini]

Originally Posted by rider60

I have a question.

Skoda Rapid uses non-independent multi-link rear suspension. Where as its twin, VW Vento uses the independent rear suspension setup.

This is actually news to me too! I always thought both the Rapid and Vento were identical, and the Rapid is actually marginally better.
Are you talking about the Jetta and Octavia, where the Jetta uses an independent suspension is marginally more comfortable and better handling?

[rider60]

Originally Posted by directinjection

VW Vento does not have independent rear suspension. VW describes it as semi-independent trailing arm which is similar to what most cars in the segment use these days.

So, this means they are marketing vento at a much higher cost even when they have this modern conventional dependent suspension?

And, in such a case why does rapid's cabin space and boot space take a marginal hit? approximately 50 litres of lesser boot space and slightly lesser cabin space.

Originally Posted by lamborghini

This is actually news to me too! I always thought both the Rapid and Vento were identical, and the Rapid is actually marginally better.
Are you talking about the Jetta and Octavia, where the Jetta uses an independent suspension is marginally more comfortable and better handling?

No, lamborghini, I am not talking about Jetta and Octavia. Its vento and rapid. That is how I understood from their websites.

[dark.knight]

Originally Posted by rider60

Can someone please elaborate on the following?

Like most cases it depends on type & preference, both of end user & manufacturer. There are some variables here, its a lot easier to design the suspension for the wheels that are not receiving the torque of the engine. In this case both Vento & Rapid are front wheel driven.

The 2 types of suspension as you've mentioned, are independent & dependent. Easiest explanation first, the dependent suspension is where there is a connection of both the rear wheels by a single axle based mostly from coil-springs though certain MUV's have leaf-spring. Now independent suspension is where the wheels are sprung independently. Most modern cars have the front setup as MacPherson strut with stabilizer bar, here there will be a slight camber variation when the tyres are stressed during turns/bad patches. There is a more expensive independent suspension called double wishbone used mostly in high end cars, they offer maximum handling advantage. I checked that Vento has a semi-independent trailing arm suspension which can to some degree deflect the disturbances from the other wheel but will still lead to more camber changes on vertical movement compared to double-wishbone.

Bottom-line is that semi-independent suspensions may cost a bit more to produce & assemble though nowhere to the tune of 60k. Most of it maybe for the VW brand which is clearly positioned as above Skoda. On Indian roads the difference in driving between these 2 models may be perceived but negligible. As far as boot capacity goes can you specify what the exact difference is? If its minor like 5-10 litres it may come down to something as simple as extra padding/cladding on any 6 sides of the boot or higher floor level to accommodate spare/tools. The difference cannot be any more than 5 litres since both are badge twins with identical shell. Purely independent link in most cases does liberate space.

[itwasntme]

Originally Posted by GTO

Excellent thread, directinjection! There isnt a doubt that IRS is superior to Non-IRS and all things alike, it offers better ride and handling behaviour.

But IRS comes at the price of packaging space and additional cost, at a time when value and space are fierce differentiators in this market segment. Also, the maintainence costs of IRS would be more than non-IRS?

Also factor in that IRS tends to need more 'maintenance' in terms of alignment and is more prone to damage on our terrible roads. Classic example is the stalwart Indica which launched with IRS and has/ had an excellent rear seat ride quality. However it's very common to see Indica cabs with totally messed up rear suspensions.

Net net non-IRS is a more robust technology for the third world.

[GTO]

Originally Posted by itwasntme

Also factor in that IRS tends to need more 'maintenance' in terms of alignment and is more prone to damage on our terrible roads. Classic example is the stalwart Indica which launched with IRS and has/ had an excellent rear seat ride quality. However it's very common to see Indica cabs with totally messed up rear suspensions.

Naah, I don't think the Indica is a good example. You see them with messed up suspensions because of the poor quality of components.

Independent rear suspensions are becoming increasingly commonplace today. Even if they cost a little more at the time of an overhaul, they're definitely worth the small $$$ premium. You just had to ride in a Duster AWD with an independent rear, or compare the Octavia independent vs non-independent back to back, to feel the difference.

[Sankar]

Originally Posted by GTO

Naah, I don't think the Indica is a good example. You see them with messed up suspensions because of the poor quality of components.

I wanted to say the same. Indica is not the ideal example even the early non-taxi private Indicas had messed up rear suspension.

Maruti 1000/Esteem (has IRS) has been on the roads for longer than the Indicas and have never seen one with Indica level messed up rear.

[anky]

I owned an indigo dicor for 6 years and the back seat ride was very comfortable , also I never had a problem with the rear suspension , but the front suspension gave up quite regularly on our roads .
Tata engineers at Concorde motors worli , were never interested in servicing my car properly in all the years I went to them . An excellent car let down by the casual and uninterested attitude of the service personnel .
Sorry for being slightly OT .

[rider60]

Originally Posted by dark.knight

Bottom-line is that semi-independent suspensions may cost a bit more to produce & assemble though nowhere to the tune of 60k. Most of it maybe for the VW brand which is clearly positioned as above Skoda. On Indian roads the difference in driving between these 2 models may be perceived but negligible. As far as boot capacity goes can you specify what the exact difference is? If its minor like 5-10 litres it may come down to something as simple as extra padding/cladding on any 6 sides of the boot or higher floor level to accommodate spare/tools. The difference cannot be any more than 5 litres since both are badge twins with identical shell. Purely independent link in most cases does liberate space.

the difference in boot space is approx 50Litres and rear part of the cabin is also slightly cramped compared to vento. Vento is more spacious in comparison both boot and cabin

[narendra.vw]

-With the rear Torsion beam Suspension, major advantage I can see is that, beam also acts as a Stabilizer rod for better rear road grip. VW has mastered it right from MK1.
-Less moving parts means less serviceable parts.

[dark.knight]

Originally Posted by rider60

the difference in boot space is approx 50Litres and rear part of the cabin is also slightly cramped compared to vento. Vento is more spacious in comparison both boot and cabin

Fifty seems to be way too much, has the recent Vento update resulted in any increase in cargo volume? I just checked a 2011 TBHP review of Rapid, & that shows a 20L difference. In any case I also made a miscalculation in the last post.. I assumed a semi-independent trailing arms due to its triangular layout might occupy more space than full-independent but that's not so. Irrelevant to the current topic however.

As far as your question is concerned & if the gap is indeed 20L + a slightly better rear space, its still a mystery nonetheless considering all other things remaining constant which in this case it is. Wheelbase is identical as well. Can I hint at the main reason of product positioning by making the Vento seem better in these 2 areas hence more luxurious? I'd assume lifting the trunk false-floor about 2 inches should do it (just speculation). I've even looked into tyre/spare sizes, overall width, length (Rapid is longer by 2mm!) and everything is same hence it doesn't make sense.

[aerohit]

According to wiki, manufacturer saves €100 per car by not installing multilink in the rear. Not sure if this is too much or too less.

It would have have been nice if they had incorporated independent suspension in the rear on cars like S-cross and Creta.

If you mentally picture the torsion movement it would feel that both side wheels will move when one wheel goes over a pot hole. But thats not the case because there is a flex, though very little.

Illustration below is exaggerated -

(didnt attach the image as it would break the animation)

[aerohit]

click here to view GIF animation

[keroo1099]

Originally Posted by mithun

Is the cost cutting the sole purpose ?

This great post got me doing a google search.

http://www.volkswagen.co.uk/technolo...ear-suspension

The torsion beam rear suspension has proved to be the most economical layout for non-driven rear axles. Two trailing arms are linked by means of a cross member, which also serves as an anti-roll bar. The advantages of this layout are good directional stability when cornering and a compact design, making for convenient use of space at the rear.

http://www.worldlibrary.org/articles...ear_suspension

ADVANTAGES

Low cost
Can be durable
Fewer bushes than multi-link suspension that are less stressed and less prone to wear
Simple
Neat package, reduces clutter under floor
Fairly light weight
Springs and shocks can be light and cheap
No need for a separate sway bar the axle itself performs that function

DISADVANTAGES

Basic toe vs lateral force characteristic is oversteer
Since toe characteristics may be unsuitable, adding toe-control bushings may be expensive.
Camber characteristics are very limited.
Not very easy to adjust roll stiffness
Welds see a lot of fatigue, may need a lot of development
Not much recession compliance - can be poor for impact harshness, and will cause unwelcome toe changes (steer effects)
Wheel moves forward as it rises, can also be poor for impact harshness (this can be negated by designing the beam with the mounts higher than the stub axles, which impacts on the floorpan height, and causes more roll oversteer)
Need to package room for exhaust and so on past the cross beam
Camber compliance may be high

[alpha1]

Originally Posted by aerohit

click here to view GIF animation

you have linked to the t-bhp attachment - there is no animated gif file.