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Old 23rd January 2017, 14:29   #16
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Default Re: Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!

Ah... one of those whodunit mysteries! Thanks GTO & SDP for drawing my attention to it.

Can't figure out the direction/manner in which the car spun, whether it be due to tyre failure or rear left suspension breakage. There are no skid marks on the road visible in the pictures, nor the site on the divider where the impact happened. Such evidence is essential for a crash sequence investigation, but it's probably too late to get that now.

From what I can gather:

Scenario 1 (as described by the owner): The rear left suspension/axle collapsed as a primary incident, the vehicle went out of control at ~100 kmph and spun out due to the primary incident. Tyre deflation and rim damage are secondary to impact with kerb / divider.

Scenario 2 (as speculated by the Mahindra workshop): The left rear tyre (presumably erronously labelled as the right rear tyre - which appears to have been intact) deflated completely as a primary incident, the vehicle went out of control at ~100 kmph and spun out due to the primary incident. Suspension and rim damage are secondary to impact with kerb / divider.

I would like to draw attention to one picture, suitably cropped and marked:
Name:  wheel.jpg
Views: 1609
Size:  39.4 KB

In case of complete tyre deflation followed by spin/fishtail, where the tyre is completely unseated from the rim (as seen in the picture), the rim will roll directly on tarmac and show abrasion marks along the entire circumference of the rim lip, at least on the side from which the tyre bead came unseated. The picture shows intact paint and no damage over a majority of the rim lip, apart from the impact point, which is typical of a sideways impact with a kerb / divider while a vehicle is spinning/fishtailing. The tyre would therefore have been intact at the moment of impact, and deflated due to rim distortion.

Prima facie, it therefore appears that the primary incident that caused the vehicle to go out of control was not tyre deflation. Scenario 2 therefore cannot be said to have caused the crash.

As to why or how the suspension breakage occurred, would be impossible to pinpoint without inspecting the components closely, and even subjecting them to metallurgical and other laboratory tests.

Last edited by SS-Traveller : 23rd January 2017 at 14:36.
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Old 23rd January 2017, 14:50   #17
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Default Re: Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!

Quote:
Originally Posted by abirnale View Post
Looking at these two pics, looks like the owner is telling the truth. The initial pic shows the bumper without a scratch and even the rear bumper guard to be in place but look at the second pic and we can make out it has been damaged later.
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Old 23rd January 2017, 15:11   #18
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Default Re: Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!

Quote:
Originally Posted by abirnale View Post
7. Is it necessary to have an independent authority to investigate such accidents impartially & competently?
Yes, and there are baby steps being taken towards setting up vehicle crash investigation infrastructure in various states. The links would give you more information:
https://thewire.in/60995/why-india-n...gation-agency/
http://www.ircobi.org/wordpress/down...f_files/13.pdf
http://www.irte.com/crash-investigation/

However, we as a country are a century away from actually taking this up seriously.
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Old 27th January 2017, 10:49   #19
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Default Re: Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!

SS-T has done a good analysis, moment i saw the pics it was either as suspension failure resulting in collusion and tyre damage or the other way around. With the limited pics available that is the best one can do. A burst tyre or even a slow puncture driven tyre will have lot of scarring to reveal the fact. This seems to be abrupt failure and that too on impact.

EDIT:
Quote:
either as suspension failure resulting in collusion and tyre damage or the other way around.
What i meant that tyre has taken an impact and suspension failed, when i meant the other way around.

Last edited by Jaggu : 27th January 2017 at 11:11.
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Old 27th January 2017, 13:55   #20
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Default Re: Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!

Quote:
Originally Posted by GrammarNazi View Post
IIRC from the post in the Facebook forum, this is a pre-owned car. Not that it takes away from the seemingly defective axle, but just clarifying.

.
Given that this is a pre-owned car, Im wondering if the car met with an accident with the previous owner/or was an abused vehicle. This doubt crops up in my mind since the first owner sold off the car within a few months of ownership.

The current owner may be giving an accurate picture of the events, but perhaps eh genesis of the issue lies elsewhere.

Either ways, M&M need to do proper investigation.
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Old 27th January 2017, 14:43   #21
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Default Re: Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!

Quote:
Originally Posted by GrammarNazi View Post
IIRC from the post in the Facebook forum, this is a pre-owned car. ....
Quote:
Originally Posted by himanshugoswami View Post
Given that this is a pre-owned car, ...
Pretty sure this is not a pre-owned car.
Car bought in Oct-2016. Accident happened in Nov-2016. In fact the owner has mentioned "still paying EMI on it".
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Old 27th January 2017, 20:37   #22
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Default Re: Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!

Quote:
Originally Posted by SDP View Post
...
Any further information / action from Mahindra yet?
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Old 31st January 2017, 05:19   #23
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Default Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!

We have an update from owner -
Quote:
This is a brand new car. Bought it in October 2016 and just the following month this happened.

After tweeting about it and posting on fb, they have sent me an investigation report. But it talks about the puncture. I don't think they will change their statement. They sent me a few pictures and a few bullet points on what they think caused the accident and damages.

I have filed a case in consumer forum last week. It should get processed by end of this week. Also wrote to the VRDE grievance officer.

Thank you all for your support. I will keep you updated on developments.
Below are screen grabs from the report mentioned above -

Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!-imageuploadedbyteambhp1485820124.964733.jpg
Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!-imageuploadedbyteambhp1485820186.216600.jpg
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Old 31st January 2017, 10:01   #24
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Default Re: Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!

Slow air loss from the rear tyre causes vehicle to spin.

The guy who did the analysis deserves an Einstein award, which is given for stupidity.
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Old 31st January 2017, 13:06   #25
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Default Re: Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!

Quote:
Originally Posted by abirnale View Post
We have an update from owner -

Below are screen grabs from the report mentioned above...
Awesome! No report about damage/abrasion to RH rear tyre carcass / sidewalls, which is inevitable if a tyre is run in deflated condition at 120 kmph.

There is report of severe damage to the inner side of LH rear tyre, which would happen if the tie rod broke while the wheel & tyre were spinning at high speed when suspension components came in contact with it.

Last edited by SS-Traveller : 31st January 2017 at 13:13.
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Old 31st January 2017, 13:37   #26
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Default Re: Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!

Interesting development!
1. Looks like both rear wheels got impacted. From initial report, it seemed like only the rear-Left rim was damaged. This also clears why the original explanation given to the owner mentioned both LH and RH.

2. ABS was activated. I can't imagine why, unless the driver panic-braked AFTER something broke.

3. Parking brakes got activated. Again, surprised by this observation.
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Old 31st January 2017, 21:57   #27
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Default Re: Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!

Quote:
Originally Posted by SDP View Post
3. Parking brakes got activated. Again, surprised by this observation.
Cable actuated parking brake actuation was dependent on cable being pulled through outer sleeve as the suspension broke and wheel dislocsted. Try removing the wheel of a motorcycle with cable-actuated brake system, and you'll figure out how the brake jams if the brake cable isn't disconnected before removing the wheel.
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Old 8th February 2017, 05:01   #28
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The latest update from Lovette is -
Quote:
Filed a case in Consumer Forum. Current Complaint Status is "In Process". Should get processed and registered soon.
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Old 8th February 2017, 09:25   #29
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Also an effort by others to seek attention from higher-ups:

Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!-imageuploadedbyteambhp1486526071.549517.jpg

Lets hope we get a proper outcome!
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Old 16th February 2017, 12:27   #30
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Default Re: Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!

Going by M&M statement,
Rear Tire (Non driving or not connected to power train) losing air pressure or completely flat --> Vehicle goes out of control (what???) --> Jumps over the median --> hitting all possible corner module parts --> Damaging them

Does this explanation satisfactory? Definitely not, at least to me.

My assumption of what could have gone wrong, seeing the failed parts (Toe control Rod & one of the link rod)

- Vehicle losing control or spinning needs one (or both) of the wheel(s) to deviate from the geometry. In simple words, go far out of alignment under dynamic condition.
- This can happen when one of the connecting link fails (may be due to the excess load put on them as result of flat tire)
- In specific to the subject vehicle, weakest link on the rear suspension is Toe Control Rod or the rear Tie-Rod
- Failure sequence : Flat Tire (may or may not be) --> Toe Control Rod --> Upper Link Rod bush --> Vehicle Goes out of control / spinning

When can Toe-Control Rod fail?
- Manufacturing Defect
- Accident / Physical damage or Hit (on the part itself)
- When the adjustment nut is not tightened or loosening as a effect of so many reasons

Last option is more likely to happen IF the statement of both M&M and Customer is true.

Any information when was the vehicle last serviced or wheel alignment done?

1. Toe-Control Rod
2. Upper Link Rod (This bush is designed to take articulation only to the level of suspension link geometry change (suspension / wheel travel) and adjustment range of Toe control rod. Anything beyond that will make the bush to dislocate)
Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!-1485002700609_rev.jpg

Reference image of 2WD XUV rear suspension link. Toe control rod marked in Red (both ends are Aluminium, and they are the weakest structure in entire rear suspension)
Mahindra XUV500 - Broken Axle is diagnosed to low tyre pressure!-ref.jpg
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