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Inspection pit - how deep?


L835
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After many years I'm about to dig myself a pit, no more crawling underneath to grease or change oils! Width and length are obvious, but how deep to make it? Will have to work on 'ordinary' cars too, am 6'2" tall so any ideas? Also any tips on construction?

Thanks in advance!

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After many years I'm about to dig myself a pit, no more crawling underneath to grease or change oils! Width and length are obvious, but how deep to make it? Will have to work on 'ordinary' cars too, am 6'2" tall so any ideas? Also any tips on construction?

Thanks in advance!

Height is a personal thing, when I built mine I sloped/stepped the floor so one end was 10 inches taller that the other this means I can use it on a car or the Landy and not bang my head or struggle to reach, I tiled the sides of mine brought some very cheap white tiles from B&Q but really reflects the light and makes it easy to clean

Other things to consider are:

· Lighting/electrics/compressed air

· Sealing the thing against it filling with water (I tanked it)

· Adding a sump/sloping the floor to allow for spillages and cleaning

· Making sure it's long enough to get down with the 110 parked on it

A friend of mine sunk a RSJ into each end below the floor (you have to duck when walking down the steps) then he welded a 5 ton bottle jack on it then put another RSJ on top the width of the pit so he has a beam jack on the pit which is very useful when doing axel things taking wheels off etc.

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If you haven't got the spade out yet I'd really recommend a flat floor and lifts or a powered ramp. If you must have a pit, make sure you can vent any falling vapour, that you can get out of it quickly in an emergency, and that you can cover it up so you don't fall in it! You could form a slight lip in steel around the edges so you can "feel" the chasm as you drive on, though it will obstruct access slightly.

If you've got the option I'd take wheel lifts instead every day of the week...

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Glad everyone is saying about using a ramp instead of a pit.The local Mazda garage had a pit fire and the poor bloke died from it,our Snap on rep told me the story - really put me off.A ramp is the way to go,and unless you want to do cars or just Freelanders a 4 poster is the best.Several places I know have one outside as well - excellent for waxoiling etc. My preference is for a jacking beam rather than the wheels free option with them - but both have their place.

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Thanks for that, have noted safety issues with pits. Seems lifts aren't as pricey as I thought. One reason for a pit was having changed the transfer box in the snow, I'd quite like to work inside and garage doesn't have the height...

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Make the pit deeper than you need it, then floor it with wood. This allows you to adjust the height, and gives a warm surface to stand on. Make a very stout elephant box to stand on when you need to reach higher than normal, like up alongside the gearbox, or an upper shock absorber mount. This box has to be strong enough not only for your weight, but also to allow you to push upwards. 1/2" wood thickness as a minimum, cut a hand hold in the top, but mainly you will kick it into position. Two, one stored at each end, might be good, for convenience.

Insulate the sides of the pit, and / or place a heater in there. As well as a sink for heavier than air gases, the pit will also act as a sump for cold air. While you are young and fit, working in a cold damp sump 'won't matter', but working in such conditions, even while young, will make you susceptible to muscle strains, lumbago, and arthritis, as you get older. Experience working in 5' deep pavement cable jointing chambers proves this.

If you haven't got the length to leave an escape route at the end, an alternative is to make a walkway extending sideways halfway along. With a standard narrow pit this has to have a (removable) roof section so the wheels can pass over it.

An option I've seen, used commercially in a tyre and exhaust fitting place, was to dig a half height pit, wide enough to take a four post lift. The user had removable stops fitted so the lift normally stopped at floor level. Note the Safety rep insisted these stops placed the ramps about 2" above floor level, so there was no risk of an operator having his toes trapped between the edge of the pit and the ramp as it descended.

The hidden cost with a lift is the need to provide either a 3 phase supply, or buy a very powerful single phase motor. For the same power, single phase motors are more expensive that 3 phase motors. If you buy an ex-commercial lift you will have to do one or the other, or buy a single phase to three phase converter. All of these carry a noticeable expense, as even a converter needs a high current single phase supply to it, perhaps more than you can route through a domestic Fuse box (Distribution Box). Nowadays you need a professional electrician for this sort of work. More money.

As you can see, I've some direct experience to share, and have thought about doing 'something' along these lines for myself, but at the moment the armchair is warmer :-)

Good Luck, and don't begrudge spending the money on infrastructure, because the benefit will stay with you.

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My four post ramp is a refurbed Laycock,made in 1983.Because my workshop is in the middle of nowhere it would cost a fortune to have 3 phase mains.(We do have a 27Kva genny for 3 phase.)My ramp has a single phase motor fitted - it works a treat,far better than others I've seen with phase converters.The ramp is rated at 3 tons and it happily lifts L322 range Rovers.Today it has had an early E Type on it,so useful to be able to lift or lower the car by 1/2" if necessary to get exactly the right working height to make the job easy - esp when welding where the right height can make it possible to do a much better job.Plus access to the sides of the car to do brakes,sills etc.

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  • 10 years later...
5 hours ago, landroversforever said:

Bit of a thread revival here! A pit isn’t that deep, the ground source heat pumps are normally much deeper from memory. 

Much deeper, also soil type, water flow through the soil, the size of the heat pump vs the area one is planning on putting it into all factor in to ground heat pumps. 

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Also bear in mind which type of 'ground source' is envisaged.....  essentially two types, a 'drilled' well which maybe 100's of feet deep but a very small footprint, or a pipework matrix which would be maybe just a few feet deep but cover a large area.....  totally different concepts, .... it will depend on a survey, your property size and  location, water table depth, geology etc. etc.  There may be some advantage to having the termination of the groundsource in your garage space, but it could take some creative juggling to bring it together. For all it takes to dig a pit is it worth the potential compromises?? 

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