deliriousga

First things first, I love the fact everyone's noodling this stuff out. Fantastic ideas I'll be using. I'm not getting under any setup until I've checked everything out throroughly while the car is up and also have a mech. engineer come over and check everything out too. I may "feel" like it's solid, but I don't trust myself because I'm not an engineer, just looking at ideas. Cheap is cheap, but life is worth the extra bucks. If it ends up not being safe, it's coming down and I'm trying again. I want my shark back on the street again, but I'd like to be the one driving it.
Erik, that's what I worry about most with plain stands (slipping off the tiny top). The first set of stands I ever bought long ago had a long, wide, flat top and a 3 point base much like the ones in the link you quoted. Personally, I like the 3 point base. If used properly, (as they are in the photo at the bottom of that site you quoted) there is a point inside or outside that has to be pushed against if the force is side-to-side. This is due to the angles (120 & 240 degrees) being different from the car's rolling angles (0 & 90 degrees). That leaves you with only 1 vulnerability at 360 degrees. With 4 point bases, the angles match and make it easier to roll, plus with points contacting the floor, it's more difficult to keep all points contacting the ground (concrete is never completely level).

New Question:
My personal preference would be to have it lifted by the tires (i.e. high ramp or cradle) with the base being 2' wide for stability. Basically, I'd like the base to wider and harder to move, but higher than the ramp on jorg's site (maybe a variation of that). I think this could be done with the steel 2x4s discussed before, but does anyone know how much weight an average 2x4 piece of hollow steel would hold at the center point if it were ~2' in length? If so, what's the strength at both placements (i.e. if it's placed horizontally on the 2" side and also on the 4" side).

What about pins that go through the steel and have a coter on the other side to keep them from sliding out. Anyone know how they affect the strength since a hole is drilled through the beam? What about the pin's strength itself, what size pin would be strong enough? By using 4 pins I think something could be constructed at a low cost and still be disassembled for easy storage.

PorKen

Chaadster,

That adapter is exactly what I was considering making, sweet.



But I would want locator posts and fixed height pads (no screw), have the balance point for the jack made specifically for the 928, and add two good spots for jack stands.

deliriousga

I must say, I like Bill's idea the best so far. Please post pics & ~cost for the fabrication. If you have measurements of the top part you had fabricated that would be great too.

wds928

I'll post some pics later tonight when I get home from work, should be around 9pm or 10pm EST, give or take.

Tony

Interesting. but my car would NEVER go that high as shown with something physically under each wheel.

When i did my TT many years a go i used solid wood that they use for the main beam above garage doors. I found mine in the scrap piles at local constructions sites. I cut them to 12" lengths then stacked and placed them under the wheels/ or the jack points.

In that design illustrated i would also put locater bolts in the wood so the bolts would drop into the holes on the jack points. It would help prevent the car from sliding of the blocks at that point.

wds928

Here are the jackstand adapters to fit the cradle and the jackpad on the 928's. The cost for 4 of them was $136, made by a local welding shop. I sketched it up, showed them what I needed and let them use one of the jackstands and a Porsche floorjack adapter I had purchased from Pelican Parts. It took them about 2 weeks to finally get around to it, but they did a great job. They used 1/8" steel plate to form the upside down "U", then welded a circular plate on top of that, then used bar stock (shaped exactly like the jackstand adapter) cut to size to weld onto the top of the circular plate. Topped it off by painting them black and everything. I should have had them powdercoated.









Anyway, with the car up on stands, I've got 15 to 21 inches of clearance (probably more if I need it) and I worry a lot less about the car slipping. I do use a floor jack as an safety, just in case.

The floorjacks themselves are "GoodYear Racing" 6-ton units, with a safety pin to lock the upright into place, along with the ratchet action. The base is about 10" square or so. Got them from Sam's Club, really inexpensive, like about $25 for a pair.

James-man

You could probably build a batch of those adapters cost effectively and sell them. A really neat idea.

James-man

Homemade lift idea...

I like the concept. It seems like a PIA to jack and to place jackstands to get the car fully up using usual means. Ideally we would all have 5-car garages - one bay having a hydraulic lift.

Given space concerns (and reality in general), isn't this design heading in the right direction?

wds928

James:

I thought of that actually, but I have noticed that not all jackstands have the same saddle size, which becomes a problem. Let's see, I could make custom jackstands, with jackpad adapters......

Let me check with the legal department on the product liability aspects of that one...

hacker-pschorr

Now that is what I call a perfect PC way of saing you decided not to
With your photo I don't see an issue having them made up locally.

deliriousga

Bill...Thanks for the pics. That's a fantastic idea! I've seen some adapters in one of the catalogs I get for the Boxster that fits on the round top of some floor jacks, but not jack stands.

James...now that would be a garage! 5 bays and an in-ground lift would be my personal choice. But with one in college and one 5 years away from it, not in my near future.

I think I'm going to try Bill Sanders' jack stand pads with dr. bob's suggested larger, wider based stands and pads under the stands at 1'x1x and 1'-6"x1'-6" for the additional height.

I think the setup I have is pretty stable, but would be more stable as dr. bob suggested with the additional lifting on bottom. I'll post pics of that once it's done for everyone's comments on stability before I get under it.

Thanks for all the good stuff!!!

hacker-pschorr

I'm thinking of an idea - get ready to shoot me down.
How about a square steel 2x4 the length between the jacking points
At each end, one of the jack points that fit into our chassis welded to the 2x4
Is that about 5 feet? So at 1/4 thickness that would be about 45lbs per side
Would that be strong enought to jack the car up in the middle of the steel 2x4 or would it flex too much, hitting the undercarriage?
If a wood 2x4 is strong enought between the car and the jack stand, I'm sure a steel 2x4 would be safer, correct?

Weight of Square Steel
Tubing Size Wall Thickness Weight per Foot
2X3 3/16 5.59
2X3 1/4 7.11
2X4 3/16 6.87
2X4 1/4 8.81
2X4 5/16 10.58

deliriousga

At either thickness I would think it would be strong enough. The distance, center to center-front to back, of the jacking points is 4'-6".

With the tubing sizes you have listed at the end, I'd think the 2x3 would be stronger vertically (assuming you're talking about the beams laying on the 3" or 4" side) since there is less distance from the sides. As you said, it should be much stronger than a 2x4 piece of wood.

If you use the 2x3 or 2x4 as you suggest in order to have a single jacking point, what would the final setup rest on? If it's jack stands, what about "taking apart" Bill Sanders' jack stand cap. You talked about welding a jacking point to the top (the top half of Bill's piece) so what about having the bottom piece that wraps around the top of the jack stand welded to the bottom of that beam underneath the jacking point? That should make it very stable side-to-side.

Anybody know the strength of the different thicknesses HP has listed above at different lengths?

hacker-pschorr

Here is some costs, not bad considering it's something I'll use for a long time.
1/4 thick steel 2x4 is $12 per foot = $144 in steel.

Maybe even rig up something where the U bracket on the bottom and the nipple going into the car is a solid piece that slides over the 2x4. That way I could also use this for my 944.

I was thinking about the 4" part resting in the jack stand, seams sturdier that way. Welding the U shaped bracket on the bottom is a great idea.
I plan on having a jack stand under each factory jacking point. The only purpose of having the 2x4 stretch the length of the car is to raise the car up once per side to place the jack stands.
For strength, you wouldn’t have to jack the car up in the middle, maybe 6" away from the jack point, leaving enough room for the jack stand to slide under. Go high enough and you could squeeze both stand under the car that way.

This still doesn’t fix the possible issue of tipping the jack stand over. My whole purpose for this idea is to jack the car up once per side and have a solid base between the car and jack stand.

deliriousga

I think Bill's U-shaped holder would make it much more difficult to tip the stands. If you look at the top of that U, the edge fits inside the top of the jack stand. I think the very beginning of a tipping problem comes from a shift in the weight of the car on the top of the stand.

One other thing I believe would help even more with tipping would be to weld the U-shaped holder at a 30 degree angle. If the stand is angled a little, it would give a wider area going against the 90 degree angle the car would most likely push at. Just thinking outloud on this part so please chime in if you know anything about that theory.