Homemade lift...Re-Tooling!!!
 

After all of the fantastic suggestions on this thread, I'm currently re-tooling the idea (before getting underneath) to make the height gain on the bottom end for better stability. The first thing was to take out the 3 ton jack stands and put in 6 ton stands with wider bases. Second, I'll be putting the additional height in a wide base that goes under the stands and not in beams above the stands. Third is looking into the lift pins fashioned for the top of the jack stands. There are several other ideas in the thread I'll be using (hopefully before this weekend so I can complete the clutch) and pictures will be posted for more comments/suggestions. Thanks rennlisters for the great ideas and dialogue! :thumbup:

For the cheap-at-heart or another guy who can't shell out 1-3K for a lift at this time, total cost was less than $40 in parts and 1 hour labor. Takes about 15-30 minutes to raise evenly it with two floor jacks I have, 1 small and 1 higher lift.

Basically, it's constructed of 3-8' pressure treated 4x4s cut to size and 6 3/8"-8" long bolts. All of the weight is supported directly under the 4 lift points and the cross beam with stands is strictly to keep from having a "roll" effect and still keep the undercarriage as open as possible. I use the two stands on the outside for added side-to-side stability. This gives you 7" more lift than only using stands, and much more stability (and for me, peace of mind). Since the bolt heads are inside the holes and the lift points sit completely on the 4x4s, it's rock solid. The 7" additional lift allows you to keep from putting the stands all the way up for even more stability.As shown below in the first picture (after I got it up to the height I wanted it) the jack stand is only 2/3 full height.

So what's 7" do? I have 22" clearance at the front spoiler and 26" clearance at the undercarriage i.e. a creeper beats the heck out of a blanket or mat. It's nice to have the room to breathe too. Finally, for those of you who are paranoid freaks like me, it will hold 34,000 pounds (a little more than the shark weighs) and I've grabbed every corner and tried to shake it...solid as a rock.

I also have a wall hanging system I'll post later which allows for easy storage.

So let me know what you think. Is it worth putting the CAD plans up on my site with instructions for lifting it evenly for others to use? Any engineers out there who want to chime w/ any suggestions?

Have a great day! :cheers:
http://www.theschillings.com/928/JohnsLift.jpg

http://www.theschillings.com/928/JohnsLift1.jpg

http://www.theschillings.com/928/JohnsLift2.jpg

http://www.theschillings.com/928/JohnsLift3.jpg

http://www.theschillings.com/928/JohnsLift4.jpg

Jphn:

Please proceed with posting the CAD. I'm very interested.

John,
I like the idea. :thumbup:
So, the through bolts on the extension blocks act as locating pins as they fit into the 4 jack points - correct? Is the mid point of the 4x4 (under the door) adequately strong to allow jacking? ( with knot-free timber). If so, what is the function of the cross member other than a convenience to hold it all together? It does appear that the cross member could be removed without comprimising stability - or if tilting sideways was a concern, use 2x4 pad blocks vs 4x4 ... just thinking out loud ...
What is the jacking sequence you like best with this (patentable) lift?

Hi John,
Looks like a nice way to gain some working room but I don't understand why this is more stable. I always thought the 'weakness' in having the car up on stands was:

1. how securely the top of the stand holds position in contact w the car
2. the possible tipping of the base of the jackstand w lateral pressure applied

It looks like the only difference in 1. is that the stand is contacting the 4x4 instead of the jackpoint and there isn't any difference in 2. except that the car is even higher.

Believe me, anything that makes the car more stable when it's up would be welcome and I believe you when you say it's very stable. Can you help me understand why that would be?

Jim
car going up in the next day or so for my first timing belt job

Great idea. Would you be preparred to provide drawings?

That looks scary to me.... no offense...

Very good idea, thanks for showing us, could be just what I need to help with the engine mounts.

What is the box on the right of the first picture in front of the cooling louvres?

interesting concept - thanks for posting.

Question; Once it's up it is resting on stands. If the car is raised from the cross member isn't the total weight of the car then balancing on a 4x4 while you go back & forth jacking up each side?
What is the height (from ground to say oil pan)?

Remote Radar/Laser detector/jammer?

John........your idea appears very comparable to a commercially available lift. I would have similar 'Garth' question as to utlising 2x4 for the direct contact with the car and/or using 2 or more bolts attaching the 'pads' to the lateral 4x4s. A commercial lift would raise both sides of the car in unison from the middle of the lateral 4x4s.........is this how you lift the car?

I had the same question about lifting it....Otherwise, it looks real interesting...

Damn.

Why did we spend all the money for those Rotary lifts? I hope that I can still cancel the order for the next three that just arrived. What do you really gain from doing it this way than buy having large jackstands that actually make contact with the car? Be careful regardless of how the car is lifted from the floor.

Thanks,

Garrity

I have a set of larger base/taller/larger weight capacity stands from Harbor Freight that do the same thing without the cross-bars in the way. The large bases mean the stands are less likely to tip over when a major horizontal force is applied.

The small footprint of the little 3-ton stands is fine until you start to add spacer blocks on top. Then the "roll center" of the stands starts to get a little too close to the surface it's sitting on. Having the 4x4's bolted together helps some I guess, keeping the spacers from rolling.

Meanwhile, the tall stands are designed for the service, are easier to store between wrenching sessions, no assembly/disassembly required, no temptation to cheat and not put the bolts in, etc.

If you want to SAFELY extend the height of a small stand, add the spacers UNDER the stand. Cut wood/plywwod spacer pads so that you have at least 2 thicknesses of spacer sticking out beyond the footpring of the layer above. You'll end up with a pyramid of spacers with a stand on top.


What you have is a good idea. I wouldn't get under there and do anything that required more wrenching than pulling an oil filter, though.

-----

I've seen cars that have fallen off of jacks onto people. Tough on the car, usually fatal to the person caught underneath. Not worth the risk IMHO.

I've been contemplating welding together a bar similar to this to lift the entire side of the car with one trolley jack.

It would be low profile with pads and locator posts at the jack points, with a steel beam connecting them. There would also be places to put jackstands when lifted into position.

The problem I still have is with the jackstands, IE. how to lift one side at a time without rolling the other? I don't want a connecting piece under the car, so I can drop the exhaust, or even the drivetrain.

Looks a bit like something I'd do:

https://rennlist.com/forums/928-forum/146241-jacking-cradle.html

I am concerned about the safety of John's set-up. While the stands might take 34,000 pounds, the 4x4's are resting on two patches of about 1/2 square inch at each stand. That could easily fail. Also, pressure treating doesn't make the wood stronger. I expect those are pine beams which is fairly soft. After time, the beams could start to twist as the bolts dig in to the wood.

Actually just got in from the garage for lunch and had put in my cradle. Planning to remove the shocks and steering rack..one shock out already. The rear of the car is still on the ground. This is what I think is safe:

Cradle is two 4x4s sandwiched between plywood.
One end has a stack of 4x4s running fore-aft.
Other end has a "rick" of 4x4s for front-to-back and side-to-side stability.

Might be overkill but I'm worth it. BTW - I've got a bachelors in Mechanical Engineering. Looking for failure modes instead of "success modes" becomes natural.