2 vs. 4 post Lift

[apxfndr]

OK. I am trying to sort out which type of lift to get. I want to be able to work on the car easily with basic stuff-remove wheels, bleed brakes, fluid changes. I would also like the ability to store a car up on the lift(so I can stack should the need arise-hope it will). From what I can tell a 2 post lift is best for working on cars and the 4 is best for storing cars. Is it horrible to store a car on the jack points? Is there a way to put a deck or something on a 2 post lift so a car can be storing resting on the wheels?(so there is compression of the suspension) Thanks.

[dstevens]

I have an asymetrical two post, and and buying another in the next month.

A two post lift is much better for working on the car than a four post. I don't see the problem with lack of suspension compresssion (actually, this would be good), but I would be concerned with a car on a two post lift during an earthquake (can you tell I'm in California?)

Putting the Lotus on a two post lift is a pain - I've hardly bothered since the undertray has to come off and you really need extensions on the rear of the chassis to lift from. For all other cars, a lift is great - you'll do a lot more work on the car that you otherwise would put off.

Sounds like if storage and basic maintenance is your goal then a four post might be better.

[ZAMMY1]

my answer to the two post lift for my lotus:

i back into the thing. the back suspension is not available to work on but it's ok for storage and maintenance work
2" square tubing, etc.
sam

[RoadDad]

Originally Posted by dstevens

I don't see the problem with lack of suspension compresssion

This is bad advice. Just because you don't see the problem, or know what the problem is does not mean that there is not one there.

Originally Posted by dstevens

(actually, this would be good)

I'd love to know why you believe this would be "good" when in actuality it is quite the opposite.

Storing your car from the jacking points will not be good for your suspension... but what do I know?

[dstevens]

My understanding is that springs stored in a compressed state over a long period of time change their characteristics.
It would be constructive if you were to give reasons why you think the opposite is true.

[apxfndr]

Zammy-do you have one of those for the front so you can lift the whole car?

[TimMullen]

Originally Posted by dstevens

My understanding is that springs stored in a compressed state over a long period of time change their characteristics.
It would be constructive if you were to give reasons why you think the opposite is true.

The springs are only a small part - and the easiest to fix.

The concern with storing a car with drooped suspension is that the rubber in the bushings are twisted from their normal "relaxed" position. That twisting for an extended period of can/will cause deterioration of the rubber. The bushings are much more of a pain in the neck to change than any spring.

Additionally, the spring being compressed is a very minor point. All cars sit on the ground with their springs "compressed" at normal ride height. You do not see cars with sagging springs on the road. At least I haven't seen one for about 40 years or so...

[NMRJock]

I went through this same thing. Wanting to store cars stacked makes the 4-post the way to go, IMO.

I wouldn't want my suspension sagging when I store the car. Besides, the 'rolling jacks,' jack trays, etc. that fit on 4-post lifts make wheel-off work fairly easy when you want to do that.

The other nice thing about the 4-post lift for daily use is that the posts are at the corners. They don't interfere at all with any of the vehicles doors. Oh, and a 4-post lift doesn't have to be anchored to concrete and can go on the 'standard' 4" of concrete that is code for a garage floor in most places. A 2-post lift takes 6" of high tensile concrete and has to be bolted down.

If I had room for a dedicated work bay where I didn't have to park and only worked on cars I'd get a 2-post asymetric lift.

[dstevens]

The relaxed state of the suspension bushings on my Lotus is close to full droop. Anyhow, I do not wish to get off topic.

[JLSELISE]

Originally Posted by dstevens

The relaxed state of the suspension bushings on my Lotus is close to full droop. Anyhow, I do not wish to get off topic.

Then someone made a big mistake when the car/suspension was assembled.
Manual clearly says suspension bushing fasteners should only be torqued with the suspension set at ride height. So ride height is the "neutral" position for the bushings.

[JLSELISE]

FWIW, a 4-post lift is the only way to go in earthquake country .

[tesprit]

For a residential garage, go with the 4 post lift. It allows for stacking your cars for storage and keeps the suspension on the car on top from drooping. They aren't as good for major mechanical work, but most guys don't do that much in their home garage and if you need to, you can purchase jacks for your 4 post lift to raise the wheels. Not having to bolt down the 4 post lift is a nice advantage too. The two post lifts are better suited for a repair shop and offer better access to the underside of the car, but for home use, the 4 post lifts are the way to go. I have a 2 post lift right now and my next one will be a 4 post with wheels and jacks.

[TimMullen]

Originally Posted by dstevens

The relaxed state of the suspension bushings on my Lotus is close to full droop. Anyhow, I do not wish to get off topic.

Most people don't really understand the bushings unless they have replaced them.

The bushings consist of two metal tubes with rubber bonded between them. Typically, the outer tube is a press fit into the suspension arm - the tube (bushing) is not free to rotate relative to the suspension arm. The arm, with bushing installed, is then inserted into the brackets on the chassis and bolted in place. The inner tube is slightly longer in length, so that when you tighten the mounting bolt, the inner tube of the bushing is clamped in the bracket - it is not free to rotate relative to the brackets. The only movement that the bushing allows is the rotational movement permitted by the twisting of the rubber between the two tubes that comprise the bushing.

When you tighten the suspension's bushing bolts, the has to be at the normal ride height - don't do it with the suspension drooped. If you tighten the bolts with the suspension drooped, when the weight of the car is placed on the suspension, the rubber in the bushings will be twisted. This has two problems; first, the bushings will deteriorate faster; second, the twisting of the rubber will act as a spring, attempting to "lift" the car on it's suspension. The suspension is designed and tuned for the springs, not the added springiness of the twisted rubber bushings.

Bottom line is, it is better to store a car with the suspension fully loaded, and ALWAYS tighten the suspension bushing bolts with the car at it's normal ride height.

[dstevens]

I can see the logic behind keeping the suspension at ride height. For my race cars I have made delrin replacement bushings - which don't have the same potential problem.