nice looking jack stands just like mine!

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

A car can come off jack stands if too much force is applied so don't instantly consider ramps bad / stands good.

Jack stands would be more unstable than ramps ( thought still acceptable ) since the upper contact point is smaller relative to a ramp and can be raised higher than a ramp. For a jack stand, the stability comes from the base alone, for a ramp there is a base and a large contact patch for the tire.

A ramp is a square block, when it is rotated the top and bottom edges rise relative to the center point. A jackstand is a triangle where the bottom edge rises relative to the center point, but the top point falls relative to the center point, this makes it less stable as it takes less rotation to go over center. In other words, the balance point of a square block is 45* rotation where a triangle is much less than that.

For the 2 cars that came off ramps, we don't know all the details. We don't know if the ramps were home made/ altered to be too high, car rolled down ramp due to the wheels not being chocked, tires were flat.

In any event, when working under a car be aware of pulling sideways too hard, pull a bit and check stability, the car isn't going to go from 100% stable to on the ground instantly. Try to pull down, if you need to pull sideways, brace your feet against the car so a counteracting force is transmitted from you to the car. I've also gone so far as to block the socket / extension against the body then used a jack to operate the breaker bar.

Harbor Freight specials. They are the 6 ton versions. I believe in overkill when it comes to supporting a car over my head which is why there is another pair of stands plus the ramps there to catch the car in case one fails.

I have the HF stands too - they work fine though I check that the ratchet is firmly seated in the rack before I drop the car (it's possible for them not to be).

About the 2 sets of ramps that crushed the guys - one guy was a fella I went to HS with and his dad was an engineer for GM - he designed and made the ramps. The ramps were made out of husky angle iron and were used on a solid, stable concrete floor. This was in the late 1960s so commercial ramps were not common. I don't know that they were any taller than any other ramp but nonetheless, they went over sideways as described.

The other set was commercially made and I don't have as much info on them or on the situation but I think the car rolled backwards and pressed the oil pan into the man's chest - he was changing headers.

As far as jack stand stability - NEVER use 3 legged stands. Those suckers will topple in a second and will fold up without warning. The HF stands as shown are fine as long as:
a) they're on a solid footing. If concrete is not available I've cut squares of 3/4" plywood (NOT particle board!) about 18" square and used them under the stands. The feet of the stands will dimple the plywood a bit so they stay put really well.
b) as noted, you assure that the ratchets are properly set.
c) they are NOT used on asphalt as they'll sink in and can subsequently topple

Whenever I put a vehicle up, INCLUDING ON MY HOIST, I shake the snot out of it before I climb under there. After seeing cars fall off hoists (generally probably the safest method available), having had 3 legged jackstands fail (that was scary!), trying to raise a car with a bumper jack (stupid but I didn't know no better as a kid - that's my excuse), I'm REALLY cautious about holding that much weight up off the floor and keeping it that way until I decide it time for that to change. Gravity is demanding and unrelenting.

Dan

I've replaced MB transmissions single handedly - well, thankfully I have two - but I've had to have help working with a hoist. Could be just me. The question I have is how to hold the engine while separating and attaching the transmission? The engine bay holds the engine well enough.

I replace transmissions using a floor jack and a pair of stands, so it can be done. I work on a sloped driveway so I want two chockable wheels on the ground. The rear only has to go up when working on the diff end of the drive shaft.

I don't think my floor jack will raise the car enough to take full advantage of a transmission jack so I don't bother. It's easy enough to shift the transmission around the floor jack pad so it aligns with the engine. Could be I'm repeatedly lucky, and I cheat by tilting the engine with a jack under the oil pan.

What might nudge things in my favor is I've worked on 116, 126 and 140 models. 123, 124 and 201 models might not be as accommodating of my methods.

I live in earthquake country so it's not a matter of ramps or stands - ramps AND stands when you can

Sixto
83 300SD
98 E320 wagon

I have the same ramps as GatorBlue92, these are the Rhino Ramps, available at Walmart. These are made of molded fiber reinforced composite plastic. These will not collapse or fold up like metal ramps.

Definitely a concrete garage floor or flat driveway is the safest work surface. Dirt and asphalt can and do compress and can allow the ramps or jack stands to sink.

A hand dug trench scares me. I've been through too many trench safety briefings from being on construction sites for my job and that just screams 'bad idea'.

Depending on your soil conditions, it could easily collapse due to the weight of your tires on the surrounding soil. Also any flammable vapors will collect down there and either explode or asphyxiate you.

The pits at the quick lube places are made of concrete and steel, and have forced ventilation.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

A friend owns and operates a repair shop close to our house. He just moved out of the old shop (which was immediately torn down for a shopping center) and into the new one next door that is in a brand new building purpose built for him. They lost their grease pit - and were glad for that! The old shop building was grandfathered in but any significant change to the building would have required all sorts of changes to the pit along with other upgrades so he was very pleased to move to the new location and it's a palace!

That said, I don't think the guy suggesting the trench was thinking about a grease pit, just a slight depression in the ground so the trans would clear. I think that would be OK as long as it doesn't exceed maybe 12" deep or so. I tend to overdo everything so I'd see myself digging a trench then lining it with 2x12 sidewalls with 4x4 posts set to retain the 2x12s but I'm an idiot. A shallow scoop would probably work and be OK.

Dan

Thanks for all the inputs so far. So when separating the transmission from the engine, will the engine stay balanced while in the engine bay or will it need to be supported?

I like this kind of ramp, a similar type was used for alignment racks.

Car lift/ramps - the simple unique patented MR1s for DIY mechanics

Also 3 of 4 leg jack stand still presents a triangular profile.

All this said, I haven't used ramps in a long time, jack stands are much more adjustable.

Have a look at this pic, looks pretty stable to me.

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In a 126 a 617 is balanced on just the engine mounts. Or it's held by the radiator hoses I set a jack under the tail end of the engine so it doesn't get any ideas and to keep it where it was when the transmission separated.

Sixto
83 300SD
98 E320 wagon

I've had my trans and clutch out several times w/o supporting the engine - no issue. Though it's in the S-10 I'm using the Mercedes-style motor mounts though aftermarket replacements so I expect it would be pretty much the same. In fact, I have to pull the rear of the engine down a bit to get the scattershield out and the engine pops right back up and sits on the mounts when I let go.

Dan

Its similar with a OM 616 in the W123 but i need the jack under the oil pan to keep the engine from tilting forward.

Yard uses 2 wheels/corner. One is vertical under the frame and centered on another lying flat on the ground. I frequently put a spare wheel under one or both ends to have an extra 6" or so in the event of a screw up.

Transmission shops R&R trans multiple times per day. It is like eating lunch to them. A local guy will do it on the cheap. The only downside is the vehicle is at his place and I can't do other stuff.

Perhaps I'm getting lazy but I now prefer not dragging stuff around in the gravel.

Interesting thread. Having escaped crushing from a house jacking incident by one second, and crushing by a car when removing a starter from an Intl Scout ( it was not even on jacks at the time) Ive also learnd to be very very careful when undera vehicle or raising it off its tires.

I use ramps and jackstands, and also keep the jack extended close to my body. i also stack the wheels under the side im working on, as i am thinner than a pair of tires��

Those salvage yard "jackstands" (wheel on a wheel style) are pretty stout. When I first saw them I was at a PnP and I shook the heck out of a car because I was curious and there was no wiggle. I'm comfortable climbing under a car there - well, as comfortable as one can be on gravel. Still, I shake the car before going under there.

Dan