I have never heard of this happening before--and neither have any of my friends, and neither have any of the guys at the dealership, who offered to order me a new one for $60--but on Saturday I demonstrated that it can occur. So be careful!
The stock scissors jack in my '92 Sentra failed. Didn't topple over, didn't slip, didn't budge--it failed. I mean it collapsed. Gave it up & went straight down under load. As in having the car jacked up for a repair on a level concrete surface, ready to put a jackstand under the frame (since you never want to get under a car unless it is supported on jackstands or ramps, and even then you don't want to trust it too much unless you enjoy joking with your life), and the threaded rod goes ZIP! all the way out the hardened steel fitting on the end of the jack it had screwed through.
The jack had gotten sort of stiff, so before this incident I'd spent a while spinning it after putting fresh grease on the threaded rod, making sure it was free & wiping off the excess grease. It was still binding slightly on the way up, too--but I hardly expected this.
So anyway, folks--even if you take every precaution, be aware that this can happen. If the jack had decided to let go 15-20 seconds later, one of several things might've happened:
1. Since I always make sure the jackstand is the first thing that goes under the car (before any part of my torso) when I have the car jacked up, the car would've been supported on the jackstand someplace other than where I intended it to be supported. The weight of the car might have broken and/or bent something--plus getting the jackstand out from under there would have been a real hassle.
2. Before I had the jackstand set, the weight of the car coming down might've forced the jackstand to move violently in one direction or another. Odds are pretty good it would have come after my face.
3. Despite my mania for safety, I might've gotten my shoulder(s)/ribcage/head crushed.
At the time I was really hacked off because I couldn't complete the job. Now I figure it can wait until Saturday.
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well-maintained winter blue B13 w/4-speed auto OD still itching for some upgrades (90+K on the clock)
Yeah. . .but even a floor jack (hydraulic or otherwise) can fail. I never like to get under a car unless I've got it secure (!) on stands and/or ramps. Even then you have to respect all that mass.
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well-maintained winter blue B13 w/4-speed auto OD still itching for some upgrades (90+K on the clock)
yup... and I agree... hydraulic jacks are better... the kit I got with my sentra was all POS... my wrenches bent out of shape THE FIRST TIME I used them... I've dumped all my stock tools for real stuff.
__________________ Bigbigcar.com
My new hobby... driving.
Ford Lynx RS / Mazda Protege MP3: Slow but Furious out of the box. :D
I've used the stock lug wrench once (way out on the road in an emergency), but around my place I like a good old American quad wrench. Makes a man feel like a genuine grease monkey spinning that thing.
As far as a scissors jack to keep in the trunk. . .do they make a hydraulic one that'll fit in the stock space? Not that I know of. I'll skip the dealership model at $60 & see about one from a salvage yard for $5-10.
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well-maintained winter blue B13 w/4-speed auto OD still itching for some upgrades (90+K on the clock)
With that tiny clamp put in for the stock scissors, I don't see any hydraulic going in there, except the stump ones... and i'd rather have an alligator than a stump.
__________________ Bigbigcar.com
My new hobby... driving.
Ford Lynx RS / Mazda Protege MP3: Slow but Furious out of the box. :D
Location: Car is Richmond, VA but I'm in Orlando, FL
Posts: 450
If you get a hydraulic jack and lift the car, then put the jackstand right next to the jack...then slowly let down the jack until the car contacts the jackstand...that way, you have about 50/50 weight distribution between the two supports, and if one fails, the car wont "fall" onto the other (thereby decreasing the force of impact)
__________________ Why did I pick such a slow car?
That's fucking scarey. My gandpa had to help a neighbor lift a car off his dead son once. Also, don't put your car up on four jackstands if possible. I did that a couple times and damn near had my car fall off into my garage pole once. Always try to keep two on the ground, or use blocks of wood on one end that the wheels are set on. I don't trust ramps they're too flimsy. As for jacks, I say toss your factory one and get one of the small floor jack types that come in a plastic case for $20 and velcro it to your trunk carpet. It'd be nice if someone made folding jack stands that were light and inexpensive, you could keep a pair in the trunk. Now by folding I mean, the legs wouldn't bear the weight, just keep a pedastal upright, so there really wouldn't be any risk of it folding up on you and tipping over or collapsing.
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Rob '93 SE-R
PM or e-mail me for Progress swaybars $190 shipped, B13 Progress coilovers $1300 shipped and B13 Progress LCA brace $160 shipped.
I usually do what BeEleven said above. I don't really trust being under the car with only one sole means of support. Even when I'm taking a tire off the first thing I do is place it somewhere underneath so if the jack were to fail at least the car would be stopped by the wheel instead of hitting the ground or hurting me.
Just a lesson from last week when fixing my crank seal; when you jack the car up make sure the hand brake is on and the rear wheels are blocked to prevent the car from rolling forward. I had my scissor jack on top a piece of 4x4" while turning away with my hand held 1/4" driver and long extension placed through the jack hole instead of using the absurd hook rod. Well, before the car was raised high enough to place the jack stand underneath it rolled forward and the first thing that went through my mind is "oh great, I'm going to get hurt some how". The jack stopped at a 45° angle which didn't make a lot of sense until the sound of the front tire contacting the ground registered in my head.
My dad once used some cheap ass bricks to hold a boat hauler (I don't know if that's the name... It's the thing you put a boat on and pull it with your car ) we used to have, and with the boat on it. I was really confused, since my dad never does anything stupid! I told him; "Those bricks look a lot less denser than normal ones" and all he said was "Naw, they're fine". Once he go out of the underbelly of the boat, BOOOOOOM!!! The bricks fuggin' exploded!!!! They didn't break in two, or three, they just blew up into dust!!! The trailer/hauler/boat puliing thingamajig would have landed right on my dad's stomach.
All he did was look at me. He didn't say nothing.
All I could see in his eyes was "That was f'in stupid.. Sorry for not listening to you"
Jacks stands go around 10 bucks each here. I don't have them... So I use two 2-ton hydraulic jacks, just like Beleven.
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My nickname has nothing to do with the italian accesory company of the same name.
Safety Warning: Scissors Jack Failure
) we used to have, and with the boat on it. I was really confused, since my dad never does anything stupid! I told him; "Those bricks look a lot less denser than normal ones" and all he said was "Naw, they're fine". Once he go out of the underbelly of the boat, BOOOOOOM!!! The bricks fuggin' exploded!!!! They didn't break in two, or three, they just blew up into dust!!! The trailer/hauler/boat puliing thingamajig would have landed right on my dad's stomach.
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