Cheap jacking solution
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cardo0 (08-12-2016)
08-12-2016, 10:57 AM
#2
I actually like this idea with a few modifications. Would be much easier to get the front of the car high enough using this method than just a floor jack on the frame rail and would cost a lot less than the expensive ramps that are available.
Wood cribbing is actually one of the most fail-proof methods of supporting a car. You see it used everywhere something needs to be temporarily supported. Go look at boats in a boat yard or houses that are being jacked up: wood cribbing for support.
It doesn't make a ton of sense for an SUV like this guy is using it for, but for a low car like our Vettes I could really see it working well.
Wood cribbing is actually one of the most fail-proof methods of supporting a car. You see it used everywhere something needs to be temporarily supported. Go look at boats in a boat yard or houses that are being jacked up: wood cribbing for support.
It doesn't make a ton of sense for an SUV like this guy is using it for, but for a low car like our Vettes I could really see it working well.
Last edited by daverulz; 08-12-2016 at 10:58 AM.
08-12-2016, 11:04 AM
#3
Le Mans Master
This is enough to give a structural engineer a heart attack. A 2x10 on the flat is nowhere near adequate support for that much mass. When it fractures, the vehicle will drop abruptly, and those 4x4 supports will likely get tossed sideways with a lot of velocity.
Buy a sturdy set of ramps instead. This isn't anything to play around with.
Live well,
SJW
Buy a sturdy set of ramps instead. This isn't anything to play around with.
Live well,
SJW
08-12-2016, 11:04 AM
#4
Melting Slicks
Thread Starter
yet another
I actually like this idea with a few modifications. Would be much easier to get the front of the car high enough using this method than just a floor jack on the frame rail and would cost a lot less than the expensive ramps that are available.
Wood cribbing is actually one of the most fail-proof methods of supporting a car. You see it used everywhere something needs to be temporarily supported. Go look at boats in a boat yard or houses that are being jacked up: wood cribbing for support.
It doesn't make a ton of sense for an SUV like this guy is using it for, but for a low car like our Vettes I could really see it working well.
Wood cribbing is actually one of the most fail-proof methods of supporting a car. You see it used everywhere something needs to be temporarily supported. Go look at boats in a boat yard or houses that are being jacked up: wood cribbing for support.
It doesn't make a ton of sense for an SUV like this guy is using it for, but for a low car like our Vettes I could really see it working well.
08-12-2016, 11:57 AM
#5
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St. Jude Donor '05
Walmart has race ramps cheap will support the car easy
08-12-2016, 12:14 PM
#6
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St. Jude '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17-'18-‘19-'20-'21-'22-'23-'24
I've got a set of those that don't clear the front spoiler.
So I just jack and slide the ramp under the wheels.
They do work great for the other cars though
So I just jack and slide the ramp under the wheels.
They do work great for the other cars though
08-12-2016, 01:17 PM
#7
Melting Slicks
Thread Starter
2x10
This is enough to give a structural engineer a heart attack. A 2x10 on the flat is nowhere near adequate support for that much mass. When it fractures, the vehicle will drop abruptly, and those 4x4 supports will likely get tossed sideways with a lot of velocity.
Buy a sturdy set of ramps instead. This isn't anything to play around with.
Live well,
SJW
Buy a sturdy set of ramps instead. This isn't anything to play around with.
Live well,
SJW
Always a naysayer.....
08-12-2016, 01:20 PM
#8
Melting Slicks
Thread Starter
08-12-2016, 01:46 PM
#9
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St. Jude Donor '05
Those dont look the same as what I bought
Appears to be a heavy truck that pulled up too far on them?
Have 2 trucks, one 5800 and the other 8500 lbs need to try them out
Appears to be a heavy truck that pulled up too far on them?
Have 2 trucks, one 5800 and the other 8500 lbs need to try them out
08-12-2016, 02:24 PM
#11
Team Owner
Pro Mechanic
What a WASTE OF TIME! And questionable safety too, as has been mentioned.
The guy in the vid has a hydraulic floor jack. Why doesn't he just jack the darn thing from it's jacking points, jack stand it under the frame, and then he can remove wheel, tire, suspension parts too. I don't "get it". He could have had that thing in the air in 1/4 the time.
I guess that I'm a "naysayer" too. I like to do it fast and safely.
The guy in the vid has a hydraulic floor jack. Why doesn't he just jack the darn thing from it's jacking points, jack stand it under the frame, and then he can remove wheel, tire, suspension parts too. I don't "get it". He could have had that thing in the air in 1/4 the time.
I guess that I'm a "naysayer" too. I like to do it fast and safely.
08-12-2016, 02:31 PM
#12
I agree with not taking it lightly, but I would also disagree with dismissing something without the facts.
I would also argue that a structural engineer would not have a heart attack, they would pull out their calculator or cad program and calculate the loads and make a recommendation based on that. This is what engineers do.
I am no expert, but I can plug numbers into a math equation and get an answer.
I pulled this from here: http://forums.yesterdaystractors.com...7e5a515abca896
The guy in the last post seems to know what he’s talking about. I’ve quoted it below. In this reference, people are talking about using 2x10’s or 2x12s to load tractors onto trailers, so he is calculating using a 6 foot length.
So here he is talking about a 6 foot (72inch) plank
I substituted 24 inches into his equations and got the following:
Span Deflection: 24/128 = 0.1875
Plain Pine 2x10 Load for .1875" deflection over 2 feet
W= .1875 * (48 * 1200000 * 2.6) / (24* 24* 24)
W= .1875 * 149,760,000 / 13824)
W= 28,080,000/ 13824)
W= 2,031.25lbs
Southern Yellow Pine or Doug Fir with E 2x10 Load for .1875" deflection over 2 feet
= .1875 * (48 * 1600000 * 2.6) / (24* 24* 24)
W= .1875 * 199,680,000 / 13824)
W= 37,440,000/ 13824)
W= 2,708.33lbs
Plain Pine 2x12 Load for .1875" deflection over 2 feet
W= .1875 * (48 * 1200000 * 3.16) / (24* 24* 24)
W= .1875 * 182,016,000 / 13824)
W= 34,128,000/ 13824)
W= 2,468.75lbs
Southern Yellow Pine or Doug Fir with E 2x12 Load for .1875" deflection over 2 feet
W= .1875 * (48 * 1600000 * 3.16) / (24* 24* 24)
W= .1875 * 242,688,000 / 13824)
W= 45,504,000/ 13824)
W= 3,297.66lbs
So the answer is a 24 inch long regular old pine 2x10 over a span of 24 inches is more than sufficient to hold up a corner of the car, if you want additional security get Southern Yellow Pine, Doug Fir, a 2x12 or for the ultimate, both.
That being said, I did add the qualifier that I would use this design with modifications, that modification would be to fill the void below the tire with blocking.
I think I've said enough at this point, I'd have no qualms with using this method to support my car.
I would also argue that a structural engineer would not have a heart attack, they would pull out their calculator or cad program and calculate the loads and make a recommendation based on that. This is what engineers do.
I am no expert, but I can plug numbers into a math equation and get an answer.
I pulled this from here: http://forums.yesterdaystractors.com...7e5a515abca896
The guy in the last post seems to know what he’s talking about. I’ve quoted it below. In this reference, people are talking about using 2x10’s or 2x12s to load tractors onto trailers, so he is calculating using a 6 foot length.
This problem is harder than it sounds.
As an engineering material, wood is highly variable from one piece to the next. The laboratory breaking strength of a "perfect" small piece of wood is 5 to 6 times the allowed usable design strength of even a very good grade of lumber. There is a fairly involved series of adjustments applied to come up with a "safe" load for any particular size, species, lumber grade, and even duration of load.
As the others mentioned, the load needed to break a ramp depends on the length of the ramp. In fact, it depends on the CUBE of the length of the ramp, so the difference between a 6 foot ramp and a 12 foot ramp is a factor of 8; the 12 foot ramp will carry just 1/8 the load. So a rather critical detail is missing.
A 2x12 is nominally 11.25 inches wide, a 2x10 nominally 9.25 inches wide, so the difference in strength is naively 21 percent. It isn't that simple, though, because the probability of a defect (knot, check, or split) gets higher as the plank gets wider.
To get a first cut guess on something like this, I usually calculate the amount of bending, rather than trying to figure out the theoretical breaking strength. If you use something like Span/128 as a safe amount of bending, the stresses are at least in the ballpark for being OK. The amount of bending depends on the stiffness of the wood (that dreaded modulus of elasticity), and not so much on lumber grade, etc.
Beam bending for a point load is given by the formula:
Displacement = W * L * L * L / (48 * E * I)
Where E is the modulus of elasticity and
I is the moment of inertia.
For a plank, I is given as:
I = b * h * h * h / 12
A 2x10 has I = 9.25 * 1.5 * 1.5 * 1.5 / 12 = 2.6
A 2x12 has I = 11.25 * 1.5 * 1.5 * 1.5 / 12 = 3.16
E is around 1200000 for ordinary "pine"
or around 1600000 for Southern Yellow Pine
Putting the formula to work, assume a 6 foot long ramp. Allow span/128 deflection, or 72/128 = 0.5625 inches.
0.5625 = W * 72 * 72 * 72 / (48 * 1200000 * 2.6)
Solving for W gives
W= .5625 * (48 * 1200000 * 2.6) / (72 * 72 * 72)
W = 225 pounds. A 2x12 would be good for 273 pounds.
Stepping up to Southern Yellow pine or Douglas fir with E = 1600000 gives 300 and 364 pounds
As an engineering material, wood is highly variable from one piece to the next. The laboratory breaking strength of a "perfect" small piece of wood is 5 to 6 times the allowed usable design strength of even a very good grade of lumber. There is a fairly involved series of adjustments applied to come up with a "safe" load for any particular size, species, lumber grade, and even duration of load.
As the others mentioned, the load needed to break a ramp depends on the length of the ramp. In fact, it depends on the CUBE of the length of the ramp, so the difference between a 6 foot ramp and a 12 foot ramp is a factor of 8; the 12 foot ramp will carry just 1/8 the load. So a rather critical detail is missing.
A 2x12 is nominally 11.25 inches wide, a 2x10 nominally 9.25 inches wide, so the difference in strength is naively 21 percent. It isn't that simple, though, because the probability of a defect (knot, check, or split) gets higher as the plank gets wider.
To get a first cut guess on something like this, I usually calculate the amount of bending, rather than trying to figure out the theoretical breaking strength. If you use something like Span/128 as a safe amount of bending, the stresses are at least in the ballpark for being OK. The amount of bending depends on the stiffness of the wood (that dreaded modulus of elasticity), and not so much on lumber grade, etc.
Beam bending for a point load is given by the formula:
Displacement = W * L * L * L / (48 * E * I)
Where E is the modulus of elasticity and
I is the moment of inertia.
For a plank, I is given as:
I = b * h * h * h / 12
A 2x10 has I = 9.25 * 1.5 * 1.5 * 1.5 / 12 = 2.6
A 2x12 has I = 11.25 * 1.5 * 1.5 * 1.5 / 12 = 3.16
E is around 1200000 for ordinary "pine"
or around 1600000 for Southern Yellow Pine
Putting the formula to work, assume a 6 foot long ramp. Allow span/128 deflection, or 72/128 = 0.5625 inches.
0.5625 = W * 72 * 72 * 72 / (48 * 1200000 * 2.6)
Solving for W gives
W= .5625 * (48 * 1200000 * 2.6) / (72 * 72 * 72)
W = 225 pounds. A 2x12 would be good for 273 pounds.
Stepping up to Southern Yellow pine or Douglas fir with E = 1600000 gives 300 and 364 pounds
I substituted 24 inches into his equations and got the following:
Span Deflection: 24/128 = 0.1875
Plain Pine 2x10 Load for .1875" deflection over 2 feet
W= .1875 * (48 * 1200000 * 2.6) / (24* 24* 24)
W= .1875 * 149,760,000 / 13824)
W= 28,080,000/ 13824)
W= 2,031.25lbs
Southern Yellow Pine or Doug Fir with E 2x10 Load for .1875" deflection over 2 feet
= .1875 * (48 * 1600000 * 2.6) / (24* 24* 24)
W= .1875 * 199,680,000 / 13824)
W= 37,440,000/ 13824)
W= 2,708.33lbs
Plain Pine 2x12 Load for .1875" deflection over 2 feet
W= .1875 * (48 * 1200000 * 3.16) / (24* 24* 24)
W= .1875 * 182,016,000 / 13824)
W= 34,128,000/ 13824)
W= 2,468.75lbs
Southern Yellow Pine or Doug Fir with E 2x12 Load for .1875" deflection over 2 feet
W= .1875 * (48 * 1600000 * 3.16) / (24* 24* 24)
W= .1875 * 242,688,000 / 13824)
W= 45,504,000/ 13824)
W= 3,297.66lbs
So the answer is a 24 inch long regular old pine 2x10 over a span of 24 inches is more than sufficient to hold up a corner of the car, if you want additional security get Southern Yellow Pine, Doug Fir, a 2x12 or for the ultimate, both.
That being said, I did add the qualifier that I would use this design with modifications, that modification would be to fill the void below the tire with blocking.
I think I've said enough at this point, I'd have no qualms with using this method to support my car.
Last edited by daverulz; 08-12-2016 at 02:31 PM.
08-12-2016, 02:34 PM
#13
What a WASTE OF TIME! And questionable safety too, as has been mentioned.
The guy in the vid has a hydraulic floor jack. Why doesn't he just jack the darn thing from it's jacking points, jack stand it under the frame, and then he can remove wheel, tire, suspension parts too. I don't "get it". He could have had that thing in the air in 1/4 the time.
I guess that I'm a "naysayer" too. I like to do it fast and safely.
The guy in the vid has a hydraulic floor jack. Why doesn't he just jack the darn thing from it's jacking points, jack stand it under the frame, and then he can remove wheel, tire, suspension parts too. I don't "get it". He could have had that thing in the air in 1/4 the time.
I guess that I'm a "naysayer" too. I like to do it fast and safely.
With my jack, which is admitadly small, I have trouble getting the car high enough to do much under it from the stock jacking points.
I agree, in this guys case with an xterra it's dumb. But I see real uses for this on our cars.
08-12-2016, 04:32 PM
#14
Team Owner
Pro Mechanic
How do you figure that? Jack stands were engineered specifically for that purpose. Note that I said "purpose"...not capacity. Both can have way more than enough capacity (it would seem from your calcs) but the car can still roll on wood, the wood can topple...it all depends on how someone built their cribbing...which is a variable. Stands are engineered for both capacity and purpose. You put them under the car in the proper location, on level ground....it's pretty hard to mess it up.
What I don't get is why people feel the need to re-invent the wheel here. They publish things like this all the time, like they've had some monumental cranial break through. All this stufff has already been thought about, engineered and there are cheap, easy solutions for. That guy spent several minutes just getting all his crap out and into position. In that same time frame, I'd already be under my car and working on it...in 12 ton (per axle) safety. AND, I can do wheel and suspension work.
I'm not saying you "can't" or shouldn't...If you've got nothing else, the methods in teh videos will work, for sure. I just don't get how this could possibly be better than the, what...century old (?) method that was designed to replace cribbing?
.
Last edited by Tom400CFI; 08-12-2016 at 04:44 PM.
08-12-2016, 04:43 PM
#15
The most simply, to use in this way are lift stand IMO
http://myliftstand.com
I Think is great item... Just I think it would be a little expensive
http://myliftstand.com
I Think is great item... Just I think it would be a little expensive
Last edited by Christi@n; 08-12-2016 at 04:45 PM.
08-12-2016, 05:10 PM
#16
Melting Slicks
Thread Starter
What's with all the anger?
What a WASTE OF TIME! And questionable safety too, as has been mentioned.
The guy in the vid has a hydraulic floor jack. Why doesn't he just jack the darn thing from it's jacking points, jack stand it under the frame, and then he can remove wheel, tire, suspension parts too. I don't "get it". He could have had that thing in the air in 1/4 the time.
I guess that I'm a "naysayer" too. I like to do it fast and safely.
The guy in the vid has a hydraulic floor jack. Why doesn't he just jack the darn thing from it's jacking points, jack stand it under the frame, and then he can remove wheel, tire, suspension parts too. I don't "get it". He could have had that thing in the air in 1/4 the time.
I guess that I'm a "naysayer" too. I like to do it fast and safely.
Chill out!
08-12-2016, 05:58 PM
#17
Team Owner
Pro Mechanic
Yep... You're right about that. I thought about this after my last post and realized that I had overlooked a key word in your title; CHEAP.
For someone who doesn't have the tools, this is a cheap way to get it done, so I should have acknowledged that.
For someone who doesn't have the tools, this is a cheap way to get it done, so I should have acknowledged that.
08-12-2016, 06:21 PM
#18
Team Owner
Pro Mechanic
Say what?
So was I. I acknowledged your original position; a cheap solution. What'd I do wrong now??
So was I. I acknowledged your original position; a cheap solution. What'd I do wrong now??
08-12-2016, 06:24 PM
#19
Melting Slicks
Thread Starter
