DIY Jack crossbeam adapter- design help

I would use steel. But that is just me. I get freaked out under heavy objects even with jack stands. All that weight at each end on aluminum with a bolt hole in the maximum stress point? Sounds a little scary.

S**t happens:

[ame]http://www.youtube.com/watch?v=OKfqjA6mhGo[/ame]

 

How big is the pad on the jack under the cross beam that you propose? If it's large I suppose a 4X4 is cool but if it's small I donno. I have seen 4X4s used in shops to lift and also on tow rigs.

Sorry if I creeped you out with the video but like I said being under heavy stuff weakens me.

 

overkill is cool! Can't be too careful in my book.\

Also with wood you may not need the puck

 

Dunno about in the States, but you can buy these things over here:

http://www.diytools.co.uk/draper-56756-2-tonne-cross-beam-jack-adaptor.html

Not terribly expensive by the looks of it & not sure if it will go wide enough (though I would have thought it would work on the front chassis rails around the front wishbone pickups.)

You'd have to get the car up onto something just to get a jack under it first though?

 

It's pretty ridiculous that the lift didn't have a mechanical lock/latch engaged? Nice commercial for Kobalt cabinets. That wasn't staged? If that was genuine, I guess the drive line went bye-bye.

 

For what it's worth, my 3.5 ton Arcan low-profile floor jack rolls right under the second crossmember with a 2x4 on top. I chock the front wheels front and back and take the car up and place it on Hein-Werner stands (3 ton pair) with tension on the jack also.. It's very stable and doesn't move at all. I have a pair of Race Ramps to elevate the front (1500lb each) and will be buying a second pair of Hein-Werners for undercarriage work (6 tons of stand capacity). When the wheels are off, they are always under the frame as well.

Personally, any kind of add-on beam would freak me out more than my 2x4. With the board, the load is still where it's supposed to be, right on the saddle. I wouldn't want to have that car cantilevered up there somehow.

 

This reminds me of a time that I had a clutch replaced in my MKIII Golf. I took the car back after they did the work to get the clutch cable adjusted. As I watched, they wheeled my car into the shop with a single post lift with no lift arms. It was basically a big steel pole that came out of the ground. One of the guys slid a single 4x4 under the midpoint of the car and lifted it 6 feet off the ground. Here these guys were working underneath my car which was precariously perched and I'm just watching it move up and down like a teeter totter...

Anyhow, I would (and have) lift(ed) the end of a car with a 3' span of a wood 4x4. I agree with the above and would use steel instead of aluminum. One question is, would you have enough room under the car for your jack and 2"-4" crossbeam on top?

 

I just use 2 jacks when jacking the front, then stands.

 

Now that's cool and it's adjustable and it's steel.

 

I get it. Good luck, sorry to have made an issue of it just don't want to hear about a fellow fchatter getting hurt is all.

 

A couple of comments. An I beam is meant to have the web vertical with the flanges horizontal to prevent flexing that could lead to failure. They are rated with this expectation. It does not mean they are not strong enough to meet your needs but I am not sure if they list data on using them on their side.

I am not sure how the shoe of your jack attaches to the jack but perhaps you could weld it to the beam. This would eliminate cutting in the middle of the beam which in this application would be the maximum point of stress and likely failure.

In your sketch, the shoe is not flat. If you choose to use a 4 x 4, I recommend placing 1/2" plywood between the shoe and 4 x 4 which will prevent the high points of the shoe from possibly splitting the 4 x 4.

You also may want to consider using a glue lam beam. Basically a wood beam that is made by laminating wood. It is like a thick piece of plywood that is structural. This is strong stuff and not too heavy. I a not sure of the design rating in this type of application but it may be worth looking into.

Aluminum would probably be a very good solution as it is both light and strong. I am not sure on the size but again, the wider dimension typically bears the weight. There should be some tables that present the performance data for various applications. I will take a look but it is not my area of expertise and expertise is needed given the potential risk of failure.

I will be interested in your final solution.

 

Cute commercial, very clever. But real lifts don't behave like that....

 

I think 2 x 2 aluminum is probably the best bet. If the span is an issue, you could always have some gussets welded on to provide additional strength. If I have a chance, I will take a look to see if I can find some specs on the typical 2 x 2 aluminum.

The next trick is securing it to the jack. It is probably best to reinforce the area where it connects to the jack.

 

I have no degree in materials science but I did stay at a Holiday Inn last night.

In the application suggested by the OP, aluminum and wood will have a different failure mode than steel. Aluminum (and wood) tends to snap when overstressed, where most steels will bend.

Which would you rather have happen?

I'm just scratching my head here as to why someone wants to do engineering experiments by lifting his F-car in the air with various materials...

 

2 x 2 steel will probably work and I totally agree on how it fails. The difference may be that the aluminum is sufficiently stronger. If the steel can support 2-3x times the required load then it will be cheaper and probably the best choice.

 

I kinda agree. The car just fell and the first thing that happens is someone goes over and starts shaking the car...

 

I just came across a jack cross bar from Summit Racing. $43.