I’m thinking about getting a car lift for my barn.
I can see advantages to both the 2-post and 4-post types.
On my XJ12 I am not too sure about the integrity of the lower body, so a 4-post might be safer there.
The Mark V and XK120 have a chassis with flat places on the bottom, so it should be easy to lift them with a 2-post lift.
My '38 SS chassis does not have flat places to lift it with a 2-post lift. There are welded edge seams on the bottom of both chassis rails, and there is a fuel pipe located on the bottom of the left chassis rail.
I was thinking of designing some steel straddle clips.
I came across this picture of a Mark IV up on one.
Safety of the person under the car has always been my foremost thought. Hence, when not using a lift I always use massive jackstands and never get under a car supported even partially by a jack (even for brake shoe work).
My safety comfort level does not do well under a 2-post lift. The redundancy in safety to avoid an error not consciously considered is absent in my mind for 2-posters. The 2-post can have user error in installation and while using. I just am much happier with the 4-post ability to take imbalanced forces in both usage and installation errors (like how well the grounding elements can take imbalance, either in installation method or earthquake).
Of course, there are various access benefits for 4-post versus 2-post which favor one versus the other. In my perspective, those access benefit variations cancel out over time and leave the basic safety question foremost for me.
Rob
I have a two post lift, I have had this now for over 10 years.
I am always aware of the safety aspects of a two poster and have 4 “Acrow props” to fit under each corner if any serious work is performed under the car.
I have also made hardwood blocks to fit on the chassis to allow for the ridge/seam on the chassis. Two poster. For: Good access with all 4 wheels of the ground: no additional jacking required. Against: More difficult to install, substantial concrete base for the posts: Safety - car is possible to rock: suspension “hangs”: setting up takes more time. Four poster. For: Easier to install: Safety - all wheels support car: easy to just drive on. Against: Working on wheels or brakes still need additional jacking up: poor access with support rails in the way.
Regards
David
I forgot there is also a wiring harness to the rear running along under there.
This is my own car at the dealer before I got it. They’ve got it up on a couple of side brackets on the chassis, which seems precarious to me. And these are pros who do this all the time. Well at least they didn’t crush the fuel pipe.
So you can see why I’d like to come up with something better, in case I or a subsequent owner should have to take it to a shop that has this sort of lift.
Having had a car fall off a two post lift I would no longer trust them for a classic car. I have a four post lift, which I feel is much more safe to work under - plus I can keep a car on it and put another one underneath when I’m not working on it.
Driving the car on and off the lift is much easier with a four post lift, and mine is not permanently fixed to the floor and comes with wheel sets - so (without a car on the lift) you can manouver the lift around the workshop if needed.
OK access to the wheels is limited when on the ramps, but I simply raise the car lift up, place tall axel stands under the correct positions, lower the lift down so the car sits on the axel stands, and then the wheels, etc are fully accessible.
When working hard on a car with all your strength on a two post lift they can wobble and never seem as safe to me as a good four poster.
This is my SS100 on my MaxJax two post lift. Works well. I have an ‘oil change’ pit underneath it since I’ve found that much of the work we all do is accessible that way.
Do you folks think that the BendPak scissors lift shown below would be a viable option for a Mark IV and also the XK120-140-150 range? This particular BendPak scissors lift is flush to the ground when not in use. This idea works for me because I really need the floor space when not in use. There are some inexpensive scissors lifts, such as the Harbor Freight model, that are mid-rise as opposed to full rise but I don’t do well at bending over when working. Also, they but do not allow access to the middle of the vehicle. The BendPak model below has two lifting platforms with a full center access. The price is very expensive to me but I do not see another option for a flush mount, full rise scissors lift with a full access center area. I have been researching this idea for a very long time so any pros and cons about this lift is appreciated.
wedcar: I am fine with a two post as long as the added support you mentioned is used when doing yanking and tugging. If I had the room I would get one.
goodoldgrandad: I would be plenty fine with a four post lift especially with the added bonus of storing two vehicles in one footprint. I have limited floor space though and a four post lift would take up precious room in my garage.
DavidXK: I like the MaxJax two post lift a lot and I have considered it, but I have a bad back and I am not so sure I could move the posts easily. My nephew has one though and loves it. Also, its reasonable in price for a lift with a 7000 lb capacity that is portable. It’s the only one on the market that I am aware of.
G’day Rob, I had the same decision to make a few years ago about what type of hoist/lift to buy. I finally opted for a “Tufflift” four post hoist from down here in Oz. The 4 posters are inherently safer and mine is movable around my garage. My garage is a domestic one so a 4 poster did not require extra concrete footings, and the is no problem with “balancing” a car in the right position. I also have a jack that is built for the hoist and slides along the full length of the hoist, so I can lift the front or rear axles, or both, whilst elevated on the hoist. I can’t recommend these highly enough, they are great. Hope this helps. Merry Christmas. Nik C.
Unfortunately this thread seems to have drifted rather quickly to the pros and cons of 2-post lifts.
I was really more interested in discussing how to lift the '36-'48 chassis.
So I changed the title.
I had an idea to make lifting pads that would be either temporary or permanent.
Here is a quick sketch of an idea I was kicking around.
I suppose Rob it depends on how confident you are of the car chassis. In the UK, where salt is spread on the roads during winter and icy weather, then more corrosion on classic cars is typically in places you cannot see, as most people will waxoil or underseal their cars covering up surface rust. So as the MK IV, etc are not lightweight cars then I am always nervous of lifting with a two post lift. My humble view is that cars of this era were designed to spread their weight over four wheels and across two axis, and they have jacking points that assume you are lifting one wheel and the rest of the weight is spread onto the other three wheels in contact with the ground. Lifting at 4 points inside the wheel base could cause the chassis (if weak) to buckle as the cantilever weight front to back is different to the axle distrubution. By bitter experience of one of my Jags falling off a two post lift, fortunately only a couple of feet off the ground and no person in the way, I now have a drive-on 4 post lift.
If you are confident of your car’s structure and strength, then your bracket idea seems very logical - perhaps making them as robust and as wide as possible to spread the point contact weight. No doubt you will already be aware that spreading and positioning the lifting pads as wide and as near to each wheel as possible will also spread the load better. Providing a central locating hole in each bracket and making “pegs” to attach or fit each of the lifting pads would enable the lift and car to mate together without fear of any slippage. Welding the brackets in place would make them secure, or at least your 4 screw-in bolts to grip the chassis sides would prevent slippage.
Certainly your good idea is more secure and trustworthy than a piece of wood !!!
Hi Rob, sorry to have contributed to more broadened thread topic than you had intended. My direction in answer to your specific question at the end instead was to aim at a larger-scale solution more in line with the start of your entry than the specific ending question.
For your specific ending question about brackets to use on a 2-post lift, temporary or permanent seems a good question. If permanent, how will they handle and balance variable load from vehicle if major weight items are present/absent, e.g. rear axle, engine, bodywork? If temporary, should they be made to fit in multiple locations?
For load-bearing portion of bracket, what width and length would assure sufficient load spread on the bracket to avoid altering frame shape (such as indentation of frame inside the bends)? With vertical sides of your drawing, the chance of slippage laterally is significantly reduced, perhaps to point of elimination depending on design.
For location of brackets, maybe there are old photos which show factory usage locations. That would help give frame torsion guidance at least for when frames were at full strength. Twisting frames is undesired to some degree.
I would probably go for temporary rather than permanent brackets. Temporary allows versatility, ability to change design and placement location, keeps the car closer to original, and removes potential future liability questions if the car is sold on.
G’day Rob,
My apologies for going off topic. The first part of your post suggested you were deciding between the two types of hoist. Being a lazy person, I am a great believer in not having to re-invent the wheel if a solution already exists. Once again, my apologies.
Of course I appreciate all your concern for safety.
I have stood under 20 ton magnets at Fermilab, but I knew they were safe because I built the stands and installed them.
I even installed the hoisting beam that installed them.
So any lift I install would be safe with twice the weight of an XJ12.
The chassis on the '38 SS is in very good condition. The underside has a fair covering of tar. It spent the first few years in Chiswick, then was in Peterborough, then Sioux City, before coming to the Chicago area. I don’t imagine it has seen any winter weather since 1966. The difficulty is no flat places to lift, with that welded lap seam running all along the bottom on both sides.
The Mark V chassis has not seen snow since 1971, and is restored.
The XK120 chassis is also in very good condition, and has not seen salted roads since about 1970 or possibly before.
The XJ12 already has jacking points, but I need to inspect them before I make my decision.
I have used a scissors lift many times at Fermilab for lifting 10 ton magnets. All our scissors lifts had steel caster wheels and tow hitches for pulling them around in tunnels with a magnet on them.
