928mac

Oh, I have a 12 foot ceiling. I thought that it would go high enough to walk under. No good for me, to bad, Great price.

Jon B.

Oh-ho-ho! It's funny because it's TRUE!

Herman K

A picture of that self made roller seat does it have a bcak rest incline?

dr bob

They use a gear-type flow divider that meters oil to both columns evenly. Think along the lines of two gear-type oil pumps, back to back and joined by common shafts. Oil to one column passes through one "pump", to the other column through the other "pump". Users in several forums suggest that you will bleed the two sides some to get them perfectly level initially, then all is well from then on. The pump unit is portable so it can be disconnected and moved out of the way when it isn't needed.

So far no serious problems reported where I've looked. Biggest issue seems to be technical arguments over the capabilities of the anchor bolts and how Dannmar did the stress and tension calcs. I guess I could buy better anchors, since I have a 6"+, 4000PSI floor.

underdog928

My biggest concern about installing a two post lift like this one is knowing whether or not my garage floor is strong enough to hold it up. How does one determine this? My house was built in 1972 so calling the builder is out of the question.

I'm sure I can drill a hole and measure the thickness of the floor but how do you know it has the right strength? (>+3000psi?)

dr bob

Bob, most if not all floors are at least 3000 PSI, and that's the 30-day strength. Yours has been curing for a while now so it's likely not an issue. If you are really nervous, get a baseplate of steel 2x the footprint of the lift base, and bolt through it to the anchors in the floor. If you are still insecure about it, weld the column base to the new plate, and add some anchors to the plate outboard of the column bases. If you use 3/4" steel, you'll never ever need to worry about it except when you go to move it. Add some casters like the Dannmar columns have now. Upsize the bolt lengths for the plate thickness too.

danglerb

That does not inspire me with confidence. I predict it will have issues as it gets more time and numbers in use, especially as its targeted to non professionals.

dr bob

I guess that the difference in column heights could increase with lots of uses and whatever leakage there is around one or the other gearset in the divider when there is a significantly unbalanced load on the cylinder as it is raised or lowered. There is no pressure on the cylinders once the carriage is raised and pinned with the safety stops. They rebalance in the full-retracted position, so the effects of any imbalance are not cumulative. I guess you could mess with the balancing by trying to lift with only one cylider connected and see how far it would go before the plugged opposite side stopped the balancer gears. Compare/contrast thi with the balancing cables and pulleys that are used to balance a 'standard' two-post lift. The self-balancing adjust-once never-stretch hydraulic 'cables' in the short lift seem to have a slight advantage.



I don't own a horse in this race. I've been looking longingly at a lift, but haven't pulled the trigger because I really don't want the lift columns in the way between uses. The Max Jax seems to work around that issue. Is a 48" lift enough? For virtually everything I plan to do to the car, yes. I on't be able to stand under the car with the pressure-washer wand at arm's-length, but for anything else I might consdier doing myself it will be fine. I looked long and hard at this when the Garage Journal crew arranged a group buy a couple summers ago, but didn't pull the trigger. Now that Costco offers it for teh same price, I'm looking again. I can just pop the utility trailer onto the 4Runner and go pick it up in Moorpark in less than 2 hrs round trip, and avoid shipping/delivery issues including damage. Lots of potential for this one. It's been a good year for my little consulting business; maybe I need a Christmas present.

87 Shark

I have been looking at a lift for my garage and have decided to go with the scisor style lift. I know my floor will not take the two post style. The scisor has the same capacity as the two post but is not fixed to the floor. It can also be moved outside if weather permits and you have a suitable work pad. You can workthe front or rear of the car and even service the torque tube.

underdog928

Well, if my floor meets their minimum spec, it should be fine. Not like I'm going to be lifting a 3/4 ton pickup. So maybe this is my Christmas present. My consulting work has been picking up lately also, so this purchase is now officially "On the list". Thanks Doc. (BTW, I thoroughly enjoyed meeting and talking with you at Frenzy!)

danglerb

Pressure side of the hydraulics is pretty much an irresistible force, motor might stall, but otherwise the pressure side in going to move. The low pressure side, if something blocked the input to one part of the pump I think would just cavitate and that side would stop going up. Likewise if the lift is going down and hangs up, gets stuck on one side, that side could stop while the other keeps on going.

dr bob

Bingo. Unless the piston with the irresistable force somehow encounters the immovable side of the car while the other side happens to be lifting the movable side, both will lift at the same speed thanks to the flow divider/balancr. Nothing to worry about.

dr bob

Bob, the pleasure was mine. The discussions about subjects far beyond the 928 world are always stimulating. Frenzy was a very welcome respite in the middle of a crazy project cycle. I'm getting ready to jump right back into the firestorm. What was theta definition of insanity again?

TheoJ

hi all,
so many questions. Yes, Dr Bob is very much spot on. I considered adding a steel floorplate but as it turned out the bolts hold very well. The distance is 2,53 mtr inner width between the floor plates. Good enough to manouver and open the doors while on the lift. The lift is removed from its bolts in 5 minutes. I have a ceiling that is so low that I can never stand under the car. Height is just 6.88 ft (2.1 mtr) I came to terms with that.
This two post lift is the best I've ever seen. If you put the car in between, lifting is very equal, but positioned a little out of center the lifting is a bit un-horizontal. Using the safety bars to rest the lift on equilizes the lifting and I rather have the car rest on the bars, not on the hydraulics. So it is not a big deal. The car is never at full lifting height the lift is designed for, the car is way below max specs considering weight, so I'm not even close to safety margins regaring anchors and concrete. I have a good concrete quality which was specified at the cunstruction drawings. It is a very nice and sturdy piece and I'm pretty pleased and proud with it. I should have bought this years ago

@Herman: dag Herman, alles goed? yes, I need every bit of room so the seat is just 4cm high with a nice inclined backrest. I must take a picture if you want to have a look. I also have another roller seat which is about 30cm high. Easy to sit on but way to heigh for under the car. Good for working on the wheels however

regards

linderpat

I will be watching this thread - especially if Dr Bob pulls the trigger - my main concern too is the floor depth. My house is about 3 years old. Not sure about the concrete strentgh, but i can ask the builder.