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Boy, did I screw up!

3K views 21 replies 10 participants last post by  Pete S 
#1 ·
While repairing my brakes the other day, I was bleeding my calipers and I only have only really good floor jack so I was having to move it around and it was getting tiring removing and installing tires each time as I was moving from caliper to caliper.

So I thought I would just place a jack stand on the undercarriage as I do on my other vehicles.

Hard lesson learned here but Mercedes doesn't reinforce the unibody channel beams as they are on my Honda and Acura vehicles.

I did have my floor jack in the proper location but I assumed (incorrectly) that the undercarriage would support the car on the jack stand.

Wrong :eek

Well here's what it looks like now:





Unfortunately I didn't notice my mistake until I had done both sides.

I'm sure that I can fix it once I remove the seats and pull back the carpet and lay down a short 2x4 and hammer the channel back down into it's original position but as I found out today, removing the seats is a job in itself.

I'll have to plan that project when I get some more time off from work.
 
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#4 · (Edited)
there are Jack stand points on all four corners, big rubber donuts. The spot meant for jack stand placement. And it looks like you put the jack stands under the floorpan, not the outer edge channel where the jack stand points are
 
#5 ·
I hate this arrangement. Once I've jacked the car no where to put my axle stds (jack stds) so I end up using the OEM pillar jack from the tool kit to raise the car and jack stds under the donuts.
At least the whole thing is secure once up but I can't raise the car far enough.

The whole thing is exacerbated by a 15% slope on my drive. :eek
 
#7 · (Edited)
I got tired of the dance I have to do to put the front end on jack stands (run car up on ramp, undo floor panel, use the floor jack to lift car up - remove ramps, lower onto jackstands (on rubber lift pads)

So....when I changed my front brake pads I just jacked the thing up on one side - removed wheel - made sure I kept my feet out from below the car - and changed the pads. Anytime I am using a floor jack I am assuming the thing can give way.

Repeat on the other side.

For me it worked out well but by all means keep body parts away from the bottom of the car.

For heavier stuff of course you need the jack stands on the lifting pads.
 
#8 ·
I was a little surprised at the engineering logic behind this. I understand about the rubber boots being designed to jack the car up or put a jack stand underneath but that's hard to do when you are using a floor jack.

You cannot jack up the car and have room to place a jack stand at the same time.

The rest is on me, I should have tested that area to see if could hold the weight which obviously it cannot.

I'll have to rethink how to arrange lifting solutions in the future.

Also I agree about jacks failing, I've seen it happened and the guy had some serious head injuries. If it's not a shop lift or a jack stand I won't get underneath it.
 
#15 ·
'

On my E420 and SL there are lifting points for the floor jack besides the four jack stand points.

There is a lifting point at the rear of the engine mounts, jack the front up there, At the back put the jack under the differential carrier and lift. you do need a low clearance hydraulic jack, but it works fine and easy enough to get the car jacked up enough to put the stands underneath.
 
#10 ·
When I got this car I was surprised at how difficult it was to simply use jack stands. On my W124, I just jacked it up at the crossmember - or differential - and put the jackstands on the pads.

This car is so much lower, and the crossmember has the 2 re-enforcement "bars) for structural rigidity - Here's just one thread listers have had on the subject - I borrowed one fellows picture to show what I meant -

I didn't want to put the weight of the jack on this part that surrounds the bolts so I had a "collar" of 1/2" steel made - can provide the pic if you want - but it goes around the black piece and rests on each end of the cross member.

But I found that even this isn't a perfect solution - once, when I was jacking it up it started to slip on the crossmember and I was going to just let the car fall where it would. I should show you the part I had made - but I think it needs a little "improvement".

Or, just put the floor jack on this black piece but I suspect it would bend it.
 

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#16 ·
I put the floor jack pad under the black piece and lift, no issues.
 
#11 ·
Using the standard wind-up jack can be scary unless the car is on perfectly level ground. It can move to an alarming angle from front to back and from side to side. I always make sure that the remaining three wheels are securely choked, and from habit, I always slide the removed wheel under the car so if the jack fails the car falls onto the wheel and not me
 
#12 ·
I'm reluctant to crawl right under the car. With wheel, suspension, brake work I don't feel too vunerable.

Ramps for rear (with the slope on the driveway the car sits almost level) or jack stands, chocks, wheel under sill. My car is too low for the ramps under the front, I even have to lift the car a little to get my trolley jack under the jack pads.

I need to do front and rear together to get enough clearance for some jobs, so these jobs go to a mechanic.
My garage has a level floor but is too small, once my SL is in no space to even open a door!

Super careful now, I had my Sunbeam fall off a trolley jack (no injuries except the front valance)

Years ago my dad had a pit in his garage, if only I had such luxury.
 
#13 ·
Speaking of inclines I have a mildly funny story. I was jacking up the rear of my Toyota MR2 on my driveway - on what we call a floor jack and you across the pond call trolley jack. I had my e-brake on but guess what - when the rear wheels left the ground the car starts rolling back.

Duh.

The car starts rolling towards me and I just get out of the way, watching it roll, with its rear high in the air and jack still holding it - rolls into the street.

Seemed almost like a Benny Hill skit.

And my driveway has hardly any incline - a few degrees?

But it was enough.
 
#18 ·
Don't feel too bad - my fancy chinese hydraulic racing jack decided to play games and slipped off the steel pad behind the engine and cracked my aluminium sump:crying

Well got to see the inside of the engine which is spotless at 100 000 miles and all back to normal with lesson learnt on jacking.

While at it also replaced all the oil seals at the oil cooler and oil test port - now a leak free engine:grin
 
#21 ·
What Redliner was talking about the standard factory jack - I can attest.

Some years ago I go out to my garage and notice the left rear tire is flat on my 300E. This was before I bought a floor jack, which would have made the job easy.

So I fish out the factory screw-type jack, put it on the concrete, and start turning the crank. (I start to feel like an organ-grinder monkey but that is a different subject).

Anyway the tire lifts off the ground, I bend over to loosen the bolts and the damned jack slips out from the smooth concrete. The tire almost came crashing down on my foot.

I have a lot of respect for jacks and what they can do to you.
 
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