[Leoshashi]

Originally Posted by PYSO

The Body panels of new ertiga are definitely thicker than the old one - they don't flex as easily as the Body panels of the old one.

Originally Posted by cyberwhizs

I concur with @pyso on the body panels part, while at the showroom , i tried to press it subtly on the fender and then the front door, it did not yield like i had expected it to.

Originally Posted by keshav1426

Was very happy to read your post regarding the body panels . The old Ertiga was more or less ok but it did dent easily. At that time , it was made much better than the Swift and desire. Now hearing that the new Ertiga felt stronger is definitely a plus point. More over , it will give the Maruti bashers something to ponder upon. Thanks for the information

Guys, concluding about body sheet metal thickness by testing the flex can be very misleading.

Today Auto Manufacturers are extensively using Structural patches to control excessive flexing of thinner sheet metal. The Marutis which we consider as well built, like the Ritz, SX4, S Cross etc all have such patches on the inside of panels.



Hence it might be possible that the metal is still thin, but it won't flex due to such patches.

More details here:

https://youtu.be/XejGfddwRUM

Blog link: http://henkeladhesivesna.com/blog/ve...tural-patches/

Regards,
Shashi

[GTO]

Thanks for sharing, Leoshashi! Learn something new everyday. Am copying your post to a new thread.

[saket77]

Nice observation. Actually, its an age old trick, at least I can confirm that my old Zen has this 'structural patch' on the inside of the rear hatch. This patch is mainly on the 'curved' area on the rear hatch. A picture that I had taken while installation of rear wipers where you can see that patch inside:

[ashis89]

Originally Posted by Leoshashi

Guys, concluding about body sheet metal thickness by testing the flex can be very misleading.

Today Auto Manufacturers are extensively using Structural patches to control excessive flexing of thinner sheet metal. The Marutis which we consider as well built, like the Ritz, SX4, S Cross etc all have such patches on the inside of panels.

Thanks for sharing. I have a few questions arising in my mind.

Will weight be the factor to decide if the body shell is strong enough?

Are the patches applied across the body? If not, we can try our thumb throughout the car to look for loopholes.

How effective are these patches and how much load can they take?

Are they glued onto the body? This can a potential upgrade items for existing Maruti owners like me who is afraid to lean on his car.

[Leoshashi]

Originally Posted by saket77

Nice observation. Actually, its an age old trick, at least I can confirm that my old Zen has this 'structural patch' on the inside of the rear hatch. This patch is mainly on the 'curved' area on the rear hatch. A picture that I had taken while installation of rear wipers where you can see that patch inside:

I remember seeing that on your Zen. My curiosity increased when I saw it on Sumit's Ritz too.

Originally Posted by ashis89

Will weight be the factor to decide if the body shell is strong enough?

No. Unless a car is crash tested in a lab, NOTHING ELSE can be a parameter for deciding structural integrity. With clever chassis design, you can eliminate the need of additional reinforcements. Most common example I'll give: Roof ribs and creases. Either put crossmembers and have a smooth looking roof on the outside, or eliminate the crossmembers and give ribbed pattern. If will give strength to the roof panel.

Want to experiment? Take two papers, fold one like this:



And the other sheet should be flat. Apply force in the direction shown. Which one will be easier to crumple?

Are the patches applied across the body?

No, mostly at the central point of any stretched panel. But compared to a panel without any such patches, it will still be resilient to flexing if you press elsewhere.

How effective are these patches and how much load can they take?

Very effective, again see the video and decide for yourself. Will resist flexing equivalent to a panel which is made of thicker gauge steel. But mind you, only flexing.

Are they glued onto the body? This can a potential upgrade items for existing Maruti owners like me who is afraid to lean on his car

Probably, but these things aren't available for end customers as of now. But I am sure it will be launched in future.

For the time being, you can stick damping sheets of same dimensions. Will give the same results, except the glue part which won't be so strong as the OEM ones. Damping sheets are in use in audio industry since ages to control the vibration of panels(again a flex).

I have done that on my car and the panels are noticeably resistant to flexing:
Link (The love of my life - A 2000 Maruti 800 DX 5-Speed. EDIT: Gets export model features on Pg 27)

Look at this video by 3M where they demonstrate the effect using a tiny sheet.

You don't need to cover the whole area, just a tiny sheet is enough to disrupt the free travel of the mechanical waves.

https://www.youtube.com/watch?v=STHgeZvbAIQ

Regards,
Shashi

PS: Another way of providing strength to panels is by providing creases. Try this, the panel won't flex where any crease is there. It will flex only where there is large area of smooth metal.

[the_skyliner]

Originally Posted by Leoshashi

I remember seeing that on your Zen. My curiosity increased when I saw it on Sumit's Ritz too.

Very useful and informative thread, thanks for sharing.

Originally Posted by Leoshashi

No. Unless a car is crash tested in a lab, NOTHING ELSE can be a parameter for deciding structural integrity.

FEA can also determine the structural integrity. However, for the purpose of validation and legality, a test is required.

[ashis89]

Originally Posted by Leoshashi

No. Unless a car is crash tested in a lab, NOTHING ELSE can be a parameter for deciding structural integrity. With clever chassis design, you can eliminate the need of additional reinforcements. Most common example I'll give: Roof ribs and creases. Either put crossmembers and have a smooth looking roof on the outside, or eliminate the crossmembers and give ribbed pattern. If will give strength to the roof panel.

I understand that proper crash tests can give an insight into how safe a car is when involved in an accident. However my question was slightly different. Crash safety aside, I am also interested to know how a car can handle minor shunts - say a bump by a biker or cyclist or even a dash by a arrogant buffalo on the road.

Will the patch help in such cases? I am assuming it will help.

Another area where these patches won't help is minor and yet sharp dents such as from a stone, a cricket ball or a hit with a stick. These create small dings or imperfections on the body panel but are difficult to fix. A stronger panel will be more resilient in such scenarios. I know it sounds weird but these are some of the damages they we may face in our day to day lives.

PS: Another way of providing strength to panels is by providing creases. Try this, the panel won't flex where any crease is there. It will flex only where there is large area of smooth metal.

I also understand the advantages of the ribbed roof and creases. Out of curiosity, won't it better if there are ribs in the inner side of the body panels and smooth on the outside. It might add to the weight but shouldn't it improve strength as well?

[the_skyliner]

Originally Posted by ashis89

I also understand the advantages of the ribbed roof and creases. Out of curiosity, won't it better if there are ribs in the inner side of the body panels and smooth on the outside. It might add to the weight but shouldn't it improve strength as well?

The location of ribs (inner or outer side) will change the strength characteristics of the roof. Outer ribs will provide more rigidity against forces acting in case of toppling.

Having creases as well as smooth surface is contradictory and won't be feasible/logical. Better to put inner ribs instead of creases to achieve smooth outer surface (more weight plus cost).

[R2D2]

This is a great thread!

Originally Posted by ashis89

I am also interested to know how a car can handle minor shunts - say a bump by a biker or cyclist or even a dash by a arrogant buffalo on the road. Will the patch help in such cases? I am assuming it will help.

Actually IIRC patches are to prevent flexing and provide a level of structural integrity to the panel itself. It cannot prevent damage from external impacts. A buffalo swinging its heavy head and the animal's horn contacting the metal will probably put a nice noticeable ding patch or no patch. Ditto for a bike rider's crash guard having an unintended meeting with your car's sheet metal. It all comes down to the force applied to that spot. A patch may absorb some of that force and minimise inward deflection but it cannot prevent the ding.

[the_skyliner]

Originally Posted by R2D2

This is a great thread!
A patch may absorb some of that force and minimise inward deflection but it cannot prevent the ding.

True that.

In fact, in some cases these patches will do more harm than good. For example, in case of rubber ball dent on car, these patches will make it hard to repair due to reduced flexibility. Without the patch, one can simply repair the dent with opposite force at right place (some mechanics are expert in knowing the right spot to hit).

[Nav-i-gator]

If applied only in patches here and there, it would not enhance structural integrity. At best, it will reduce sheet metal flex, when pressed. Only if the patch is end to end, would it affect the structural rigidity/integrity. Like a heavy rod piece, if welded to the middle of the door, it would only increase the weight of door panel, while end to end welding of a long rod (like a beam), will increase the structural integrity.

[Blow Horn Ok]

Curious to know the material of the reinforcement. Is it hard rubber? Or bitumin sheet kind of thing?

Guess the oem ones are more harder material than that of the usual damping material.

[GTO]

Originally Posted by Leoshashi

For the time being, you can stick damping sheets of same dimensions. Will give the same results, except the glue part which won't be so strong as the OEM ones. Damping sheets are in use in audio industry since ages to control the vibration of panels(again a flex).

After I got my Civic's doors professionally damped, they became noticeably heavier and felt as sturdy as the ones on my C220. They wouldn't flex as easily either.

[Sankar]

Originally Posted by Leoshashi

Guys, concluding about body sheet metal thickness by testing the flex can be very misleading.

Shashi, is this piece the same as the one usually found stuck to the car floor below carpet? Any information regarding the base material these are made of?

I was thinking whether there is an advantage of sticking this liberally on the outer skin of the doors and whether to purchase the OE ones sold my MGP or go for dynamat or similar aluminium backed sheet.

[Leoshashi]

Originally Posted by Blow Horn Ok

Curious to know the material of the reinforcement. Is it hard rubber? Or bitumin sheet kind of thing?

What Maruti uses is some kind of reinforced fabric type of stuff, sorry I am not aware of the material and I am trying to find out more about the vendors, details etc. For the time being, I can send you closeups of the material:







These things are super hard to pry out, and will probably need even heating, such was their bond strength.

On a lighter note, Our dear friend Sumit is clueless what all mischief I keep doing with his cars.

The patches shown in Video by Henkel is more like the stuff which Tufclad/Dynamat uses.

Originally Posted by Sankar

Shashi, is this piece the same as the one usually found stuck to the car floor below carpet? Any information regarding the base material these are made of?

The ones stuck below the carpet is known as Melt sheet. It won't be very effective on vertical surfaces unless its properly heated(which may damage the paint) and applied as its done at factory level. Add to that, its very heavy.

My experience with SGP Melt sheets: https://www.team-bhp.com/forum/long-...ml#post3989444 (The love of my life - A 2000 Maruti 800 DX 5-Speed. EDIT: Gets export model features on Pg 27)

Don't Miss Behram Dhabar Sir's comment on that page.

I was thinking whether there is an advantage of sticking this liberally on the outer skin of the doors and whether to purchase the OE ones sold my MGP or go for dynamat or similar aluminium backed sheet.

Dynamat or Tufclad stick better if applied nicely. I won't recommend Melt sheets for door outer skins.

Regards,
Shashi