2 post lift, frame support jig

PostPost by: h20hamelan » Wed Jan 30, 2019 8:13 pm

I know the glass fiber body is fairly strong for lifting.
My hoist grabs the body only, rather than the frame.

My plan is, to have arms. Which attach/slide-into the existing lift arms of my two post hoist.

I obviously flunked out of Drafting in school, though I hope you get the idea.
The Bow is wider, and stern more narrow. So as to not touch cars A (control) arms.
A soft rubber or wood stability block will be added to the hoists arm to support wobble. I would mill the soft wood to be a tight fit.

Any and all thoughts appreciated.
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PostPost by: bitsobrits » Wed Jan 30, 2019 11:33 pm

Your design, while valid, is an unnecessary complication. I have a Max Jax two post that lifts both my S1 roadster and S3 FHC from the body "corners" without issue (comes with rubber pads on the lift arms). If you are worried about glass fiber cracking (which I've never experienced) then use a board under the sill area. To make yourself feel better you can also place supports under the chassis after you have lifted the car by the body. But unless the body has some sort of major structural damage, lifting by the sills alone works. Witness the fact you can lift one side of the car clear of the ground with a suitably placed single scissors jack with its small lifting pad.
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PostPost by: h20hamelan » Thu Jan 31, 2019 12:09 am

Yes, I can lift the body. I have lifted with the body. I dont want to lift with the body.
The main reason, although I am sure the floor can and will be open for debate. Is, that glass fibre deteriorates. Structurally, seven years about the life span of glass fibre with poly resin. Epoxy is somewhat longer, vinyl somewhere in between. That is, understood, in direct sunlight. I do not suppose the underside gets any or much sun. I know there is reinforcement surrounding the bobbins. I have read many posts of bobbin failure, and more of stress of glass fibre in aviation and marine.
So I am probably over the top here. I would prefer that the frame hold the vehicle. I do have a drive on ?pit?. Which allows me access to the transmission, and if I park rear in. I can easily access the rear. So this is the choice. Though when the cars are in the air, I would like some more confidence that I am not stressing the already weak (because it is chop strand, not even mat, let alone weave or stronger woven roving).
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PostPost by: Slowtus » Thu Jan 31, 2019 1:58 am

h20hamelan wrote:Yes, I can lift the body. I have lifted with the body. I dont want to lift with the body.
The main reason, although I am sure the floor can and will be open for debate. Is, that glass fibre deteriorates. Structurally, seven years about the life span of glass fibre with poly resin. Epoxy is somewhat longer, vinyl somewhere in between. That is, understood, in direct sunlight. I do not suppose the underside gets any or much sun. I know there is reinforcement surrounding the bobbins. I have read many posts of bobbin failure, and more of stress of glass fibre in aviation and marine.
So I am probably over the top here. I would prefer that the frame hold the vehicle. I do have a drive on ?pit?. Which allows me access to the transmission, and if I park rear in. I can easily access the rear. So this is the choice. Though when the cars are in the air, I would like some more confidence that I am not stressing the already weak (because it is chop strand, not even mat, let alone weave or stronger woven roving).



With the greatest of respect - truly - because I lack the desire to find out about such sciency things and the knowledge to to improve whatever that knowledge may uncover...I have separated three Plus 2s from their chassis and after much twiddling, fiddling and diddling, have put them back together again.

I have done it, every time, on my own, albeit aided and abetted by crude and rude sawhorses, often assembled on the spot as needed - or similar devices - and all three have eventually gone down the road happy.

No question there is potentially flawed science attached to these bodies, the materials, the methodology used to construct them etc but once you easily (and I am a typical Scot, short, not sweet and not blessed with muscles) hold one corner of a separated Plus 2 body in your hands as you kick that sawhorse over to take that light weight of the other side you simply oblivate such concerns.

Okay many do not but I easily do. :D
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PostPost by: prezoom » Thu Jan 31, 2019 2:03 am

I have been lifting my S2 and Plus2 at the corners of the body with my 2 post lift for several years with no problems. But, I wouldn't leave it up on the lift for long periods.
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PostPost by: h20hamelan » Thu Jan 31, 2019 2:13 am

Truly, they are light. And once apart, I am sure no problem...
I am more concerned with holding them together. I dont trust the 50 year old (if 7 years in sunlight) maybe a composite engineer could chime in. With gasoline in the vicinity also weakens these fairly fragile bodies. Strength of metal is a different story, as are the welds that hold it. Glass fibre weakens over time. I simply believe I am putting too much faith, in some failing fibre glass. To hold 800+ lbs above the ground with me under it. That is, as long as I am not heaving on a spring, A arm. Adding to the wight with pulling/pushing flexing however.

One could however argue, the un engineered cross brace I purpose has a fail rate too.

Thanks
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PostPost by: jono » Thu Jan 31, 2019 8:03 am

I use 2 long lengths of 100mm x 50mm with 10mm neoprene foam glued to them to lift my plus 2

These are placed length ways under each cill and the lift pads go under each end - it spreads some of the point load along the length of the cill and the foam takes up the irregularities (the timber deflects to the curverdform of the cill). I've had the car stored up on the lift this way over a full winter and never had any issues.
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PostPost by: miked » Thu Jan 31, 2019 8:49 am

I don't have that kind of lift but the principal is the same on my EZcar lift. Being a non believer I have four small planks that I set up across the car. Two rear from inboard of chassis to outer cill. Just inboard of A frame mounts. Then two at the front. From Y of chassis to outer cill edge. The lift pads then positioned mid way on the timber so that 50% of the weight is shared between chassis and body. This gives full acces to rear and engine area.

About 25mm x 125mm section cut to length.
I have two sets, one for lifting an Elan and one for when I had the Plus 2.
Whilst I figure the glass will support the lot I would personally not want to tempt fate for the reasons you give. Also if helping a friend on my lift would not want to hear a dreaded crack. I am always cautious and aire on that side. I would not want to be the one in fifty or one in one hundred that gets a fracture. IMO it depends on what kind of life your body has had and quality of any repairs carried out. That's my view and I am sticking to it. Each to their own with there personal attitude to risk. Bit like investments. :D
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PostPost by: Emma-Knight » Thu Jan 31, 2019 10:43 am

In the tool shop catalog I once saw an exchange device, a bar with two rubber wedges, in place of the lifting pods. The wedges were pushed under the tires, so lifting the vehicle on its wheels. The idea lifting a Lotus chassis, castiron block, gearbox etc. on sixteen monkey metal bobbins, wrapped in a bit of fibre glass doesn't appeal too good to me.
Even if it does , somehow, work in practice.
I always remember these tickling, cracking sounds when people lifted their Lotus in a practical way :?
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PostPost by: JonB » Thu Jan 31, 2019 11:05 am

When working under my Plus 2, I use the "two stout bits of timber under the sills" method. To get the car to this state I had to use a jack on the sill insert jacking points to raise it a bit, then a trolley jack. I noticed the ticking, cracking sounds from the fibre glass. Scary. And the passenger door gap closed up so much that the window rail fouled the paintwork. I ended up leaving doors ajar.

When Wheeler Dealers featured a DHC Elan, Edd China had it on a two post lift. He'd extended the arms enough to lift the car by the metal chassis rather than the body. This meant a bit of wobble at the back (as the chassis is narrow there) but I think it was the safest thing to do, despite the wobble which could have been addressed by using a pair of wedges under the sills, resting on the lift arms.

I've asked Spyder about this and they've assured me it is safe to lift an Elan by the sills. "We do it all the time". Well, rather them than me... despite the fact that I do it, but only for short periods and with a ramp under the front wheels (where most of the weight is) to catch the chassis if it releases itself from the body.

Reading miked's reply, I'm inclined to agree with his approach.
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