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Old 23rd September 2011, 01:47   #1
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Merc S-Class slips from jack.

This occured about 2 days back at the Mhasoba gate petrol pump, Pune. A Mercedes S-Class was jacked up to repair the punctured front left tyre. The driver of the car and the puncture guy had their collective efforts in jacking up the car. They used the jack provided by Merc. The wheel was removed after which the jack slipped and the car came down with a thud. The underbody and the disk were resting on the ground.
After a few moments of silence there was a lot of commotion. Now the mechanic couldn't find a place to apply the jack again but he managed eventually. The fibre skirts of the car were damaged and there were a few scratches on the bumper. I cant say what was the effect on the suspension and disk allignment. Looked unharmed. No one was injured in the accident.
The wheel was replaced and an arguement between the driver and petrol pump authorities followed with both blaming each other. Both of them were visibly frightened.
It seems that there is a need of a thread demonstrating proper techniques for using the jack so that we can avoid such incidences.
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Old 23rd September 2011, 02:53   #2
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Re: Merc S-Class slips from jack.

Ouch, looks like an expense that might run into a Lakh or more.
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Old 23rd September 2011, 08:48   #3
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Re: Merc S-Class slips from jack.

1: Did they use the correct jacking point?
2: Was the transmission in Park mode and handbrake activated?
3: Was the ground uneven?

I wold consider these issues before making an inference
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Old 23rd September 2011, 09:21   #4
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Re: Merc S-Class slips from jack.

It almost appears the Jack was mounted on the sides of the car than the actual mount point which has a slightly different texture(solidity) with a groove for that jack to sit.

Also crashing down and breaking the side skirts does look like the job of the Jacks positioning and not from the crash itself.

But i may be wrong. . I just drove down to coimbatore. Just before the drive i tested the jack at home, removed the wheels and re-mounted to make sure i am aware of doing things. I feel a little practice could have atleast warned a bit.

THats one costly affair to get it fixed hoping the disk brakes are fine as per MERC mechanics
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Old 23rd September 2011, 10:23   #5
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Re: Merc S-Class slips from jack.

The only way this could have happened is the handbrake not deployed, right?

I don't know about the jack Merc provides but the ones I've used with Maruti and Opel, they are built in such a way that they wouldn't topple easily. Something like an arch on both sides.

So, it would take a good push to topple it off the jack.

Without doubt, placement of the jack is important; not just to avoid this but also to ensure the load of the car is balanced on the right point.

OT : is the side-skirting made of fibre? Shouldn't it be metal?
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Old 23rd September 2011, 12:16   #6
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Re: Merc S-Class slips from jack.

aw shucks, Thats a tata nano RIGHT there!!


PS:that jack came with the merc?
its base is already rounded.
made of mercury or what?
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Old 23rd September 2011, 12:22   #7
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Re: Merc S-Class slips from jack.

It had happened with me once, couple of years back. My honda city had a front left wheel puncture at the office, I was trying to change the tyre and the jack slipped. The reason - hand brade was deployed and not to full extent (my mistake) and and there was heaving pneumatic stone crusher working close whose vibrations could be felt.
I was able to get another jack from my friend to raise the car. Changed the wheel and immediately went in to check the alignment. Luckily no issues with the disk or wheel alignment.
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Old 23rd September 2011, 12:28   #8
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Re: Merc S-Class slips from jack.

That is one costly error. It seems the jack wasn't placed at the right place and it could have damaged the side skirt itself.

O.T- The side skirts are usually of fibre only,never metal.
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Old 23rd September 2011, 12:34   #9
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Re: Merc S-Class slips from jack.

There is a slot under the car where you slip the top of the jack in so that it doesn't slip.
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Old 23rd September 2011, 12:49   #10
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Re: Merc S-Class slips from jack.

I fail to understand why they used the jack provided by Mercedes when they had a 'crocodile' jack available.

Out of curiosity, how would you jack up a car that is resting on its underbody and discs?

The proper manner of using a jack is to ensure that the vehicle is on level ground, the gear is set to park (for AT) or neutral (for MT), the handbrake is set, and if the vehicle is parked on loose soil, place some rocks on either side of the tyres (except the one to be changed) to prevent any movement. The jacking point for vehicles can differ (esp. very old vehicles) therefore refer to the owner's manual to find the jacking point. Always loosen the nuts before raising the vehicle with the jack.
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Old 23rd September 2011, 13:01   #11
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Re: Merc S-Class slips from jack.

Quote:
Originally Posted by k_nitin_r View Post
The proper manner of using a jack is to ensure that the vehicle is on level ground, the gear is set to park (for AT) or neutral (for MT),
Why park for AT and Nuetral for MT? 'Park' would lock the front wheels for AT, and 'Nuetral' would free up the front wheels for MT? (Assuming front wheel drive)
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Old 23rd September 2011, 13:08   #12
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Re: Merc S-Class slips from jack.

Also a spare wheel was not put under the car when it was jacked up .It would have prevented this .
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Old 23rd September 2011, 13:13   #13
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Re: Merc S-Class slips from jack.

Quote:
Originally Posted by jinojohnt View Post
Why park for AT and Nuetral for MT? 'Park' would lock the front wheels for AT, and 'Nuetral' would free up the front wheels for MT? (Assuming front wheel drive)
For an AT, the park would engage the parking pawl (pin to lock the transmission) and prevent the front wheels (for FWD), rear wheels (for RWD), or all wheels (for AWD) from moving. At least some AT vehicles prevent you from shutting off the engine if the gear is not in park or neutral.

On an MT, there is no parking pawl mechanism and the next best option is to set it on neutral.

Avoid keeping a vehicle in gear unless you are parking on an inclined road where the handbrake alone cannot keep your vehicle stationary (assuming MT) because if the vehicle is started without shifting to neutral or holding the clutch, the vehicle would jerk forward/backward (depending on the gear) and can risk causing injury.
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Old 23rd September 2011, 13:37   #14
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Re: Merc S-Class slips from jack.

Looks like a case of jack mounted at wrong spot. The jack mounting points are clearly mentioned in owner's manual of most cars. The guys at at these tire repair shops do not know/care about proper mounting points, they just look at the underbody to find a safe spot and mount the jack.
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Old 23rd September 2011, 13:58   #15
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Re: Merc S-Class slips from jack.

Has happened to me once earlier with an NHC. A friend of mine released the handbrake by mistake while the tire was getting fixed. Minor damage on the front bumper and side runner boards. Brake Discs, Suspension, Alignment all were fine.

This Merc seems to have taken quite a hit. That side skirt needs to be replaced. Also, thats a silly looking jack for a 2 ton Merc costing 1C!!
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