Home » Public Forums » GMCnet » Jack Stands
| Jack Stands [message #283877] |
Mon, 03 August 2015 21:04  |
jimtze
Messages: 92
Registered: June 2011
Location: Victoria, BC
Karma: 1
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A work colleague dropped a car on himself yesterday or the day before. First responders had to use air bags to get him out. Lucky to be alive. Several broken ribs, others cracked, punctured lung with fluid intrusion and broken collar bone. Should have known better as he works on cars regularly. When I asked him if he was using jack stands, he replied that he thought it would be ok because he was working on a Mercedes and was using the Mercedes jack. WTF!!!
Jim Bratvold
Victoria, BC
76 Eleganza ll
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| Re: Jack Stands [message #283904 is a reply to message #283877] |
Tue, 04 August 2015 07:50  |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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I crib everything with treated 4x4 lumber in about 20 inch lengths. I have had (supposedly) good jackstands fail.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Jack Stands [message #283907 is a reply to message #283904] |
Tue, 04 August 2015 08:44 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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If I remove a wheel, I also slide the wheel under the frame. Final protective procedure. I did have a GMC come down that I thought was well blocked. Gravity plus short distance equals a major problem.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: Jack Stands [message #283929 is a reply to message #283877] |
Tue, 04 August 2015 11:25 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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I miss Coke crates.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Jack Stands [message #283932 is a reply to message #283929] |
Tue, 04 August 2015 11:34 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Man, I hope you are kidding.On the front, I use two 6 ton jack stands
placed where the front clip bolts to the frame rails. On the rear, I use
two 3 ton jack stands per side. One placed at the intersection of the cross
member ahead of the front bogie, and another at the intersection behind the
rear bogie. NEVER, NEVER, EVER crawl under a GMC that is only supported by
a floor jack, even for a few seconds. One mistake, you die.
Jim Hupy.
On Aug 4, 2015 9:26 AM, "Johnny Bridges" wrote:
>
> I miss Coke crates.
>
> --johnny
>
> --
> '76 23' transmode Norris upfit
> Braselton, Ga.
>
> "Sometimes I wonder what tomorrow's gonna bring when I think about my
dirty life and times" --Warren Zevon
>
> _______________________________________________
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| Re: [GMCnet] Jack Stands [message #283946 is a reply to message #283877] |
Tue, 04 August 2015 14:59 |
Rob
Messages: 651
Registered: November 2013
Location: Victoria, BC
Karma: 3
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I always use stands and slide the wheel under the vehicle (if they're off) - but I still keep an eye on the things as I pull/push wrenches on the vehicle.
On another vehicle forum I'm on - a car came down on a member a few years ago and he was dead by the time someone found him.
Scary stuff. Especially considering the size of the GMC and the air bags involved.
Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath
On 2015-08-03, at 7:04 PM, Jim Bratvold wrote:
> A work colleague dropped a car on himself yesterday or the day before. First responders had to use air bags to get him out. Lucky to be alive. Several
> broken ribs, others cracked, punctured lung with fluid intrusion and broken collar bone. Should have known better as he works on cars regularly. When
> I asked him if he was using jack stands, he replied that he thought it would be ok because he was working on a Mercedes and was using the Mercedes
> jack. WTF!!!
> --
> Jim Bratvold
> Victoria, BC
> 76 Eleganza ll
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Rob -
Victoria, BC -
76 Royale - Rear Twins/Dry Bath
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| Re: [GMCnet] Jack Stands [message #283976 is a reply to message #283975] |
Tue, 04 August 2015 18:34 |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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Those Grade 8 bolts? If not, probably only buy you a second or two...
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: [GMCnet] Jack Stands [message #283991 is a reply to message #283976] |
Wed, 05 August 2015 00:25 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Chris,
Thanks for your comments; however, I'm going to disagree (kinda - sorta).
The bolt pictured in my album is a 1/4" 316SS Allen Head. As I understand it 316 SS has a shear strength similar to a grade 2 carbon
steel bolt.
Here's a link to a document that provides shear strength of bolts:
https://www.nucor-fastener.com/Files/PDFs/TechDataSheets/TDS_013_Shear_Strength.pdf
First - I direct your attention to the Shear Configurations diagram. I contend that the bolts in the jack stands are in Double
Shear.
Second - I direct your attention to Single Shear Calculations, Min. Lbs
Nominal Bolt Diameter - 1/4"
Body Shear Area Sq In - 0.04908
Gr 2 = 2,179.2
A307A & B = 1,766.9
Gr 5 / A325 = 3,533.8
Gr 8 / A490 = 4,417.2
My theory: I believe that the SS bolt is in double shear therefore the amount of force required to shear it in two places and allow
the center of the jack stand to collapse is 4,358.4 pounds.
The GVWR for a 1978 GMC is: 12,500 lbs
The GAWR is:
Front: 4,500 lbs (2,250 lbs per side)
Rear: 8,000 lbs (4,000 lbs per side)
4,358.4 is greater than 4,000 therefore the bolt should not shear.
HOWEVER, 358.4 pounds is too close for comfort as far as I'm concerned so I am going to take your suggestion and get some Grade 8
bolts as it will take twice the force to shear them. I will get them long enough so that the unthreaded portion extends completely
through the jack stand.
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: Chris Choffat
Those Grade 8 bolts? If not, probably only buy you a second or two...
--
-Chr$
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Jack Stands [message #284004 is a reply to message #283877] |
Wed, 05 August 2015 08:15 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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James Hupy - were you worrying about Coke crates? They were hell for strong. I watched a bud crib an International TranStar II completely off the ground with a stack of them, centered under the front axle and under the side of the rear axles while he rotated tires. They were the standard crib when I was growing up... I've never seen one bust. Coke dropped them because they were too costly, and returnable bottles were becoming a thing of the past. I haven't seen one in decades.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Jack Stands [message #284016 is a reply to message #284004] |
Wed, 05 August 2015 09:48 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Johnny, you must mean the 1940's coke that sold for 5 cents. Those crates
were steel framed. I still wouldn't use them personally. I had a mental
picture of the plastic ones in current use. Makes me shudder to think about
using those. When we were preparing to leave on our route 66 rally last
year, Dwayne Jacobson's coach arrived making bad grinding noises in the
final drive/inboard CV area. At the campground, several well intentioned
but poorly equipped gmcers jacked up Dwayne's coach on small bottle jacks
and the tripod stands that employ a jackscrew that are intended for
stability, not support. They proceeded to run the coach in gear while
attempting to isolate the noise. Judy and I were hosting the rally, so I
did not have an involvement with this stuff. I happened upon the coach
while they were running it. I had them shut the engine off, and crawled
under the front of the coach to feel the final drive and CV Joints. (Did I
mention that I had consumed several adult beverages previously?) Long
story short, the tripod stand failed and the bottle jacks slipped their
poorly chosen locations and the coach fell while I was under it. I sensed
the movement and rolled out from under it in the nick of time. I dodged a
very large bullet that time. I stand by my previous statement. High quality
lifting and support stands ONLY. NO EXCEPTIONS.
JIM Hupy
On Aug 5, 2015 6:16 AM, "Johnny Bridges" wrote:
> James Hupy - were you worrying about Coke crates? They were hell for
> strong. I watched a bud crib an International TranStar II completely off
> the
> ground with a stack of them, centered under the front axle and under the
> side of the rear axles while he rotated tires. They were the standard crib
> when I was growing up... I've never seen one bust. Coke dropped them
> because they were too costly, and returnable bottles were becoming a thing
> of
> the past. I haven't seen one in decades.
>
> --johnny
> --
> '76 23' transmode Norris upfit
> Braselton, Ga.
>
> "Sometimes I wonder what tomorrow's gonna bring when I think about my
> dirty life and times" --Warren Zevon
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: Jack Stands [message #284022 is a reply to message #283877] |
Wed, 05 August 2015 10:31 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Oh yeah, wood with steel strapping. They were for 6 ounce Cokes, the trucks were designed for them and the bottling machines were too. They would support dam' near anything. I wouldn't even use plastic drive - on ramps for the GMC.
I had a supposed three ton stand fail and pull a leg from the reinforcing. I wasn't under the car at the time (Mopar minivan) but it put me off using jackstands. Someone gave me a pickup bed full of 4x4x8 treated beams a while back. I built a screen porch and some other stuff, and sawed about four of them into cribbing lengths. I crawl under the GMC when I've got them in several places holding it, not before.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Jack Stands [message #284032 is a reply to message #284028] |
Wed, 05 August 2015 12:16 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Hal, I always jack a GMC front end completely off the floor. I do not raise
one side at a time. That has been known to crack windshields. I use
identical stands in pairs. When I have a coach completely off the floor, I
use 6 stands. 2 ea. 6 ton stands on the front, and 4 ea. 3 ton stands in
the rear. All are placed at frame intersections where there are doublers or
crossmembers. Just what I do. Safety before work, during work, after work
we drink. (Grin).
Jim Hupy
Salem, Or.
78 GMC ROYALE 403
On Aug 5, 2015 10:03 AM, "Hal Kading" wrote:
> Jack stands - logic (at least to engineer me) says that a jack stand with
> 6 tons embossed on it would hold up 12,000 lbs, right? Wrong! As near as I
> can find out they are rated in pairs. Two 6 ton jack stands will hold up
> 12,000 lbs or 6 tons. I have confirmed this with Harbor Freight. Not sure at
> this point if true with all.
>
> Hal Kading 78 Buskirk Las Cruces NM
>
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| Re: [GMCnet] Jack Stands [message #284035 is a reply to message #284028] |
Wed, 05 August 2015 13:18 |
GMC.LES
Messages: 505
Registered: April 2014
Karma: -2
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I have always wondered about jack stand ratings. I've seen several examples of failed stands. My personal preference is to use the vehicle GVWR as a guideline, and use 4 stands rated for that weight. For the TZE (and my crew cab pick-up) I use four of HF's 12 ton stands. They are quite stout (and heavy), but provide good stability even when raised to their height limit.
Regarding 4x4s as cribbing. I recently had some 4x4 cribbing break on me. The subject piece appeared solid from the exterior, but was several years old. Don't always trust a piece of wood, especially when it has been stored outside, or is of unknown age.
Les Burt
Montreal
'75 Eleganza 26'
The EWIP (Eternal Work In Progress)
> On Aug 5, 2015, at 1:03 PM, Hal Kading wrote:
>
> Jack stands - logic (at least to engineer me) says that a jack stand with 6 tons embossed on it would hold up 12,000 lbs, right? Wrong! As near as I
> can find out they are rated in pairs. Two 6 ton jack stands will hold up 12,000 lbs or 6 tons. I have confirmed this with Harbor Freight. Not sure at
> this point if true with all.
>
> Hal Kading 78 Buskirk Las Cruces NM
>
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| Re: [GMCnet] Jack Stands [message #284076 is a reply to message #284028] |
Wed, 05 August 2015 20:18 |
Rob
Messages: 651
Registered: November 2013
Location: Victoria, BC
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That depends on the jack stand in question - I've seen them rated both ways.
For example: http://www.usjack.com/products/Jack%20Stands.pdf
So - ALWAYS understand the rating!
Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath
On 2015-08-05, at 10:03 AM, Hal Kading wrote:
> Jack stands - logic (at least to engineer me) says that a jack stand with 6 tons embossed on it would hold up 12,000 lbs, right? Wrong! As near as I
> can find out they are rated in pairs. Two 6 ton jack stands will hold up 12,000 lbs or 6 tons. I have confirmed this with Harbor Freight. Not sure at
> this point if true with all.
>
> Hal Kading 78 Buskirk Las Cruces NM
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Rob -
Victoria, BC -
76 Royale - Rear Twins/Dry Bath
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| Re: [GMCnet] Jack Stands [message #284106 is a reply to message #284076] |
Thu, 06 August 2015 07:50 |
Jim at the Co-op
Messages: 291
Registered: May 2014
Location: Orlando Florida
Karma: 2
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You are always more vulnerable when you think you have something handled
Jim Bounds
On Wed, Aug 5, 2015 at 9:18 PM, Rob wrote:
> That depends on the jack stand in question - I've seen them rated both
> ways.
>
> For example: http://www.usjack.com/products/Jack%20Stands.pdf
>
> So - ALWAYS understand the rating!
>
> Rob
> Victoria, BC
> 76 Royale - Rear Twins/Dry Bath
>
> On 2015-08-05, at 10:03 AM, Hal Kading wrote:
>
>> Jack stands - logic (at least to engineer me) says that a jack stand
> with 6 tons embossed on it would hold up 12,000 lbs, right? Wrong! As near
> as I
>> can find out they are rated in pairs. Two 6 ton jack stands will hold up
> 12,000 lbs or 6 tons. I have confirmed this with Harbor Freight. Not sure at
>> this point if true with all.
>>
>> Hal Kading 78 Buskirk Las Cruces NM
> _______________________________________________
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