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PostPosted: Wed Apr 09, 2014 9:36 am 
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Location: adelaide hills
Front jacking point, changing front wheel.

Manual says to jack up the front on the chassis just in front of the front door. So to get the front wheel off the ground the jack's pretty much fully extended.

Seems to me it makes more sense to jack up the wishbone, get the wheel off the ground quicker. Dealer says not to, "it's an engineering thing."
Any thoughts?

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PostPosted: Wed Apr 09, 2014 10:29 am 
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It is safer to use the chassis as the angular change at the top of the jack won't alter as much.
It the jack doesn't sit on the wishbone so the pressure patch can rotate slightly, the jack can slip, then the result may not be good.

They are covering their backsides that is all.

Some areas of the wishbone won't be designed to take the vehicle weight if on a web area and not on a folded section where strength is greater.


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PostPosted: Sun Jun 02, 2019 10:24 am 
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Joined: Wed Feb 05, 2014 1:22 am
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Location: adelaide hills
Looking back through this forum, I found this post, by me. Thanks Ross, but obviously it's still niggling me. So here's today's effort.


There are questions at the end of this, but first, an explanation to make sense of them.
I just got back from a multi-car trip, lots of rocks, lots of flat tyres (not mine), but lots of fiddly work with OEM jacks that aren't really designed to be useful.
So when I got home, I got out both my jacks, my blocks of wood, etc etc, made some flat tyres, so as to find the best way to do stuff.

The instructions in the manual had never really made much sense.
Eg1, I have springs on top of the axle, but the manual shows springs on the bottom of the axle.
Eg2, the position shown for jacking up the front wheel (under the door) never actually gets the wheel off the ground, unless I use about 150mm of packing under the jack.

In the past I've queried stuff in the manual and Isuzu has said "Sorry, that was wrong, cross it out, we'll update it in the next version." So I've tended not to take it that seriously.

Anyway, given the manual is no guide, where are the safe jacking points that won't break things, and work. Can I get the jack in, and will it lift high enough?


Below are some photos of what I'm thinking is the best way to do it. Any comments welcome.

For the rear wheel, the jack won't fit if I use the axle. The jack fits in the upward concavity of U-bolt plate, just behind the axle, and between the U-bolts. Any probs there?
Attachment:
20190601_181601.jpg-20-rot.JPG
20190601_181601.jpg-20-rot.JPG [ 26.92 KiB | Viewed 454 times ]


For the front wheel, the jack fits into a little cut-out in the wishbone. Any probs there?
Attachment:
20190601_173913.jpg-20-rot.JPG
20190601_173913.jpg-20-rot.JPG [ 39.51 KiB | Viewed 454 times ]


Any thoughts about hi-lift jacks and wheel hooks, ie lift the rear wheel and put a block of wood under the axle.
Any thoughts about hi-lift jacks lifting bull-bars, which may or may not be attached to a solid bit of chassis?

And one last question. Not so long ago I used to see mechanics stick a trolley jack under a diff and lift a whole rear end, and likewise, stick a trolley jack somewhere in the middle of the front (the engine?) and lift the front end. I haven't seen that for a while. Is it safe (at least the rear end), or are diffs & axles weaker nowadays?

Thank you.

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PostPosted: Sun Jun 02, 2019 1:19 pm 
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G'day garrytre
You are obviously a thinking person and think of things into the future, many don't even think of potential problems. Where you showed the two jack positions I would use too. But you may have to double take on the jacking process to get the vehicle high enough.
I have considered, not perfected yet, A RHS metal bar of suitable wall thickness which has an extendable inner of smaller section size with locking pins. ie, collapses for compactness.
In the main section there is a U shaped piece, can be made detachable, so it fits upward onto the chassis to positively locate the bar and the extension goes under the vehicle to chain link around crossmember or other side chassis.
The outermost section allows a highlift jack to be used and so can lift either side quite easily.
Bit more fiddley to place for use but far more safe and almost no crawling under the vehicle.

As far a jacking in the centre of the diff housing, there are many mechanics who are dumb and know not what they do. As for jacking under thin cross member thicknesses, they obviously haven't done a riggers course to realize the forces they apply. It is easy on some vehicles to use a hydraulic jack and deform the cross member 30mm bent before Dumbo realizes the vehicle isn't rising. Worse if it an air operated hyd jack. Just because a mechanic does things, doesn't mean it is a sensible way to do it. Be afraid, very afraid with some of them. Only 9% of mechanics ever get a decent level of qualification in the trade. Just because they get repetitive experience with the same item doesn't mean an overall understanding of the trade. I have some experience in this field, trying to instruct some apprentice mechanics is nigh on impossible, they simply do not have the capacity to learn. Not suitable for purpose but can't be legislated against..


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PostPosted: Sun Jun 02, 2019 5:15 pm 
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Joined: Wed Feb 05, 2014 1:22 am
Posts: 612
Location: adelaide hills
>Where you showed the two jack positions I would use too.
Thanks
>But you may have to double take on the jacking process to get the vehicle high enough.
Yes, actually getting the jack(s) under is kind of OK on a flat concrete floor, but with rocks & holes last week it was a bugger. I've thought of a two stage jacking process on the rear axle. A small jack to start as in the photo, then when it's high enough, my 150mm block of wood and another jack on the axle, a bit inboard so it'll fit. But, like my Q about lifting the diff, I didn't know how far inboard would be safe. A bent axle housing mightn't be very funny. Any notion of how far inboard, ie closer to the diff, is safe? (like, how long's a piece of string)

Your invention sound like a kind of safer, non-collapsing, car to Hi-lift jack interface. Maybe patent it. Lots of blogs & 'reviews' carry warnings about hi-lift jacks going sideways.

Nevertheless, I'd wondered about getting a hi-lift jack, and one of those hook-on-strap things, to lift the wheel up enough to get a block of wood under. Big & heavy, but I suspect far more convenient & probably safer in the long run.

>You are obviously a thinking person and think of things into the future, many don't even think of potential problems.
Yep, born pessimist, good for OH&S and emergency management, but never endeared myself to my bosses. Not positive enough.

thanks again
Garry

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PostPosted: Sun Jun 02, 2019 8:17 pm 
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Garry
I have a high lift jack and used it mostly when I owned a HJ61 cruiser. With the Dmax I considered a wheel lift strap unit but felt the steel hook bits would mark the spokes of the wheel on the inside and maybe cause a future failure point. Possibly ok if only a poly strap went through there though. A High lift jack would be too close to the bodywork and as you said, if it moved then damage body.

Properly chocked and securely set the HL jack should be quite stable. perhaps some folk don't check or secure it well. I always used to pad the top with a sleeping bag so IF it moved the body panel was cushioned. No good having a steel thing burrowing into the side door.

If using the HL jack to lift the front of a Dmax bulbar, I would initially place a length of poly pipe or similar taped to the bonnet and resting on the bulbar top. As you jack and lift you can then see if the bar moves relative to the bonnet, ie, chassis bending or the force is simply lifting the vehicle with no distortion beginning to happen.
I used to lift the whole of the HJ61 front via the bulbar, but would certainly check with a Dmax or similar vehicle.


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PostPosted: Mon Jun 03, 2019 8:49 am 
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Joined: Sat Apr 29, 2017 7:58 pm
Posts: 247
Location: Brisbane
How good are the new lightweight ARB high lift jacks, can pick them up Sale for 3/4 of a million dollars !
If the bar work has the high lift points then is OK just not sure why people use them like a hoist on the uneven dangerous ground. Great for fencing & getting trees of the track or using your in a garage with flat concrete floor. I suppose like everything can be used safely. Jacks are o e of this things you don’t think about until it’s to late. Good reminder post for me to check it all.


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