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Old 23rd November 2012, 14:49   #1
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Default Monocoque SUVs : Advantages and Disadvantages

The market dynamics are changing. Many are moving towards simpler SUVs which perform better than existing Hatches and Sedans. They have become the Hybrids of hatches.

Every manufacturer is trying to develop one such car.

Monocoque SUVs are selling like Hot cakes. Renault Duster, XUV500 had bookings since their launch. Rest of the manufacturers are trying to develop such SUVs. Many aspirants/prospective buyers are discussing about Ford Ecosport.

The old/traditional SUVs are on body on ladder frames. Yes the frame is built, and then the body is placed on the frame. They weigh heavier, which makes them difficult to turn in emergency maneuvers. They run like lazy cows (some say). They run like a Truck and are more balanced on straight roads. Braking is not up to the mark. Their heavy weight contributes towards their stability (If driven responsibly).

Monocoque SUVs are new to the Indian market. What would be the advantages and disadvantages of these vehicles?

They are more car like, simple, light weight and have more GC, but do they have enough balance in emergency situations?

What are the advantages and disadvantages of Monocoque SUVs?

Last edited by GTO : 23rd November 2012 at 17:22. Reason: Poorly composed post. Correcting language & formatting errors
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Old 23rd November 2012, 17:20   #2
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Default Re: Monocoque SUVs : Advantages and Disadvantages

Broadly, body on frame UVs are easier to design & cheaper to build (monocoques cost big $$$ in R&D). They are more robust and can handle abuse & rough roads better. Body on frame UVs are also more "overload" friendly. Offroaders generally prefer body on frames.

You could stretch / chop a body on frame UV far easier than a monocoque. Just ask Mahindra and its innumerable UVs based on the same platform.

Monocoque SUVs are significantly lighter and thus, all other things being equal, offer better performance & fuel efficiency. They also have superior ride comfort and road dynamics. They say that monocoque SUVs are safer because of more effective crumple zones (though there are always exceptions to the rule).

I personally think monocoque SUVs make the most sense for urban folk from India. You really need a body on frame only if you are a commercial operator / offroader / similar application. There are enough examples of 200,000 km Swifts, Logans, Citys etc. that prove the longevity of monocoques.
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Old 23rd November 2012, 17:46   #3
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Default Re: Monocoque SUVs : Advantages and Disadvantages

Another advantage could be easy sharing of the car platforms to create CUVs?Manufacturer's dont have to go for a new body on frame architecture. Honda used Civic for CRV initially and Accord for Odyssey, Pilot, MDX etc. Although they merged monocoque with body on frame for their truck !
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Old 23rd November 2012, 18:00   #4
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There are no advantages and disadvantages per se imho, just that they are built with two different applications in mind. Both are good in their own way.

That aside, I would say it also depends on the buyer's requirement. If one wants a serious off-roader, monocoque wont do any good. Conversely if its just for regular urban/occasional highway use with no offroading, monocoques (or soft-roaders as they're called) are the way forward. Comparing them at the outset is (not exactly, but a bit) like comparing apples to oranges. Both would cater to a different consumer set.

Last edited by Harshal.Bhosale : 23rd November 2012 at 18:01.
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Old 23rd November 2012, 18:45   #5
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Default Re: Monocoque SUVs : Advantages and Disadvantages

One advantage of monocoque SUVs is, there is no probability of the cabin getting separated from the chassis in the event of an accident
Monocoque SUVs have low floor height and thus easier to get in/out
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Old 23rd November 2012, 19:08   #6
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Default Re: Monocoque SUVs : Advantages and Disadvantages

So what happens in case of accidents? Are ladder and frame cars more easy to repair? Are monocoque cars written off as total loss given the same kind of damages?
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Old 23rd November 2012, 19:35   #7
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Default Re: Monocoque SUVs : Advantages and Disadvantages

I see some advantages in monocoque SUV's, however not sure whether i am correct or not. Please correct if required

=> Monocoque SUV's are basically SUV's and they are lighter, so this makes them more easy to control in some exceptional situations.
=> Lighter body implies better life of tires, suspension and other wear and tear parts. (Might not be completely true if the quality of spares is not good.)
=> The body is light, so the engine required would be smaller so more FE.
=> The body is light, so the engine would be small so should be easy for repairs and other tasks.
=> More space inside cabin and in bonnet so more DIY could be done.
=> Better visibility at night as the driver would be sitting a bit above.

When coming to negatives & doubts, I feel the following (Please correct if required)
=> Expensive spares as it is considered as an SUV.
=> Does monocoque chasis will be able to hold tight in case of an accident? (read low weight.)
=> Braking would be weak because of vehicle is big and not aerodynamic. so more load on pads and other areas.
=> Emergency maneuvers. again, i am not sure.

I do not know whether the above mentioned points are correct or not. this is what i could get from net and other sources. please add/correct if required.
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Old 23rd November 2012, 21:16   #8
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Default Re: Monocoque SUVs : Advantages and Disadvantages

Quote:
Originally Posted by gemi_kk View Post
I see some advantages in monocoque SUV's, however not sure whether i am correct or not. Please correct if required

=> Monocoque SUV's are basically SUV's and they are lighter, so this makes them more easy to control in some exceptional situations.
=> Lighter body implies better life of tires, suspension and other wear and tear parts. (Might not be completely true if the quality of spares is not good.)
=> The body is light, so the engine required would be smaller so more FE.
=> The body is light, so the engine would be small so should be easy for repairs and other tasks.
=> More space inside cabin and in bonnet so more DIY could be done.
=> Better visibility at night as the driver would be sitting a bit above.
1. Yes.
2. No. The components are designed for loads and stresses that they will need to bear keeping in mind their application.
3. Yes.
4. Not always. Also, smaller engines can easily be more complex to repair than larger engines because they have more parts crammed in a smaller space.
When coming to negatives & doubts, I feel the following (Please correct if required)
5. Again, this depends on the vehicles being compared. Cannot be a thumb rule.
6. No. In fact, on a ladder frame vehicle, the driver sits higher. However, the driver height is a matter of engineering and doesn't depend completely on the body type.
Quote:
Originally Posted by gemi_kk View Post
=> Expensive spares as it is considered as an SUV.
=> Does monocoque chasis will be able to hold tight in case of an accident? (read low weight.)
=> Braking would be weak because of vehicle is big and not aerodynamic. so more load on pads and other areas.
=> Emergency maneuvers. again, i am not sure.

I do not know whether the above mentioned points are correct or not. this is what i could get from net and other sources. please add/correct if required.
1. No, in fact, many spares of SUVs are cheaper than the sedans of the same price range.
2. No. Body construction is done on the basis of uniform standards, be it a monocoque or a ladder frame.
3. Again, brake systems are designed keeping in mind the weight of the vehicle. I would not put the Alto's brakes on my Scorpio.
4. Emergency lane changes are better in a monocoque because it is more rigid.

Last edited by n.devdath : 23rd November 2012 at 21:17.
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Old 23rd November 2012, 22:12   #9
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Default Re: Monocoque SUVs : Advantages and Disadvantages

From my little experience, I think they are meant for different purposes. Like mentioned before. If one is going to do a lot of Urban and GQ (Sane high speeds) and a few kms on tough terrain best bet would be Monocoque.

Anything from carrying load, mostly rural, mostly offroad then its ladder frame.

If its 50:50 and you can control your right foot (drive sedately with no sense of hurry even on GQ), ladder frame.

If you need both qualities, then I guess one needs one of each and cannot exchange the roles of a horse and a mule.
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Old 23rd November 2012, 22:50   #10
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Quote:
Originally Posted by gemi_kk
=> Monocoque SUV's are basically SUV's and they are lighter, so this makes them more easy to control in some exceptional situations.
Agree. Monocoques by design are more stable, body roll is much lesser since the entire chassis is a rigid, single unit.

Quote:
Originally Posted by gemi_kk
=> Lighter body implies better life of tires, suspension and other wear and tear parts. (Might not be completely true if the quality of spares is not good.)
Agree. And as you say, depends upon the quality of spares as well as original parts.

Quote:
Originally Posted by gemi_kk
=> The body is light, so the engine required would be smaller so more FE.
Requirement is low, agree. But one could still have a big engine for insane power-to-weight figures! Kidding


Quote:
Originally Posted by gemi_kk
=> The body is light, so the engine would be small so should be easy for repairs and other tasks.
As mentioned above, depends on the engine complexity. Which in turns increases the smaller the engine gets.


Quote:
Originally Posted by gemi_kk
=> More space inside cabin and in bonnet so more DIY could be done.
If you meant for two cars with same external dimensions but one being mono and other being BoF, I guess that'd be true. Not sure.

Quote:
Originally Posted by gemi_kk
=> Better visibility at night as the driver would be sitting a bit above.
Again, depends on design. All SUVs are basically built to offer a higher seating position. The Skoda Yeti is touted as an SUV, yet the Tata Nano is taller than it at its highest point (had once seen a nose-to-tail pic in one of the threads on TBHP itself).


Quote:
Originally Posted by gemi_kk
=> Expensive spares as it is considered as an SUV.
Brand-dependant. Are you comparing mono vs BoF in this regard? If yes, I don't see any difference, since for a given manufacturer, mono will get the same/similar engine as the Body-on-Frame, so same/similarly priced spares. If you weren't comparing that way, well, Tata spares will always be cheaper than Range Rover. And with platform- and part-sharing nowadays, one may find many similar components in the sedan and SUV offerings of the same manufacturer.

Quote:
Originally Posted by gemi_kk
=> Does monocoque chasis will be able to hold tight in case of an accident? (read low weight.)
Did you mean emergency maneuvering or crash safety? Either way, I'd say mono is better than BoF.

Quote:
Originally Posted by gemi_kk
=> Braking would be weak because of vehicle is big and not aerodynamic. so more load on pads and other areas.
Didn't quite catch you. How would aerodynamics affect braking? In fact, weaker aero would mean greater air resistance, in turn helping the vehicle to stop better. But that's in theory. Due to the relatively soft tune of SUV suspension systems, there's a lot of wallowing and pitching involved. But here I'd say monocoques get my vote. More stable by design.

Quote:
Originally Posted by gemi_kk
=> Emergency maneuvers. again, i am not sure.
Monocoque all the way.




PS: As I said earlier, it all depends on customer requirements. You have mostly mentioned high speed runs in your considerations. That's not what Body-on-Frames are built for. They're for low-speed, high-fun, go-anywhere capabilities.

Its the capabilities that differ, so a disadvantage for Monocoques is and advantage for BoF's, and vice versa. I suggest the thread title should rather be just "Monocoque vs Body-on-Frame" or something similar.

Last edited by Harshal.Bhosale : 23rd November 2012 at 22:58.
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Old 23rd November 2012, 22:52   #11
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Default Re: Monocoque SUVs : Advantages and Disadvantages

One point which is not mentioned in this thread is that the Body on Frame construction is easier to repair. When offroading, damage might be done to either body or chassis or both. The Body on Frame construction has a very distinct advantage here as they wont require relatively expensive process of laser welding. Not all repair shops will have proper welding facilities which are required in case of damage to a monocoque construction. A Body on Frame construction will have easier time getting repaired and reaching back to civilization as compared to monocoque SUV.

This is one reason why Toyota has till date not shifted into monocoque SUV for LC series. LC series is very popular for rough use in Africa, Middle East and in deserts. A lot of rough use and overload is being done in remote regions where having even a repair shop is rare. So Body on Frame construction will hold much better than monocoque.

EDIT:
A few things must be very clear for buyer when he is purchasing the car. Either its real offroad deal or a good on road car which can handle some slush or occasional drive to farmhouse. This should solve all confusion for prospective buyers. Scorpio is more suitable for offroading than XUV. XUV is a huge improvement over Scorpio/Xylo/Safari even Fortuner when it comes to on road manners.
Hence the concept of softroaders ( CRV is best example ). The biggest advantage of softroader is that they are in a better position to handle rougher roads than equivalent ( price-wise ) sedans and also handle some very light offroad scenarios better. AWD is icing on the cake in softroader segment for majority of the buyers. The best example of a car being used the way its supposed to use is TSK. He has actually done a lot of exploring ( if not offroading ). SUV will fit the bill there rather than a typical softroader. Another example where a monocoque SUV has fared good is GV ( of Samurai and Sudev IIRC ).

Last edited by aaggoswami : 23rd November 2012 at 23:00.
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Old 24th November 2012, 07:34   #12
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Default Re: Monocoque SUVs : Advantages and Disadvantages

After reading all the posts above, it seems like Monocoque is possibly the way to go in future, but i am wondering.

Why is it that most Monocoque SUV (Captiva, CRV, Outlander, XUV) are always softroaders and most Ladder-on-frame SUV are proper off-roaders (like Safari, Fortuner, Pajero). Why dont the manufacturers make proper off-road SUV on Monocoque platform (technically speaking what stops them from doing so)?
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Old 24th November 2012, 10:47   #13
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Default Re: Monocoque SUVs : Advantages and Disadvantages

Quote:
Originally Posted by mayankjha1806 View Post
After reading all the posts above, it seems like Monocoque is possibly the way to go in future, but i am wondering.
Body on frame SUVs are also referred as old school SUVs . Probably the future is a hybrid chassis like the Grand Vitara has.
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Old 24th November 2012, 11:33   #14
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Default Re: Monocoque SUVs : Advantages and Disadvantages

The Mitsubishi Pajero/Montero/Shogun (Not to be confused with Indian market Pajero) is a monocoque construction since 1999 & has finished in many cross-country rallies including Dakar.

Of course there would be many modifications done to such vehicles but i believe a stock Pajero/Montero/Shogun can off-road much better that most SUV's with body-on-chassis construction (sparing LC series, Jeep & LR/RRs).

4X4 experts please confirm if Montero has any serious handicap considering a similar powered chassis mounted SUV.
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Old 24th November 2012, 15:05   #15
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Default Re: Monocoque SUVs : Advantages and Disadvantages

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Originally Posted by Skyline GT-R View Post
4X4 experts please confirm if Montero has any serious handicap considering a similar powered chassis mounted SUV.
There is an OTR report somewhere on the forum, in which the thread owner was skeptical about heavy SUVs like Montero as it might get stuck and hinder other participants. Later the Montero turned out be mother of breakdowns and had to retire early on. I am not sure how Pajero SFX or Fortuner would have performed in those conditions (being body of frame chassis).
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