I bought 4 ton car jack from harbor freight and just got it.

And it is way to small... My jku is lifted 2.5'.. I lift my jack as much as i can.. But even i can touch any part of my bottom..

http://www.harborfreight.com/4-ton-h...ack-66450.html

Mine is this..





Did i buy wrong one?

Usually 3.5 of 4' lifted jeep owner what kind of jack use?

 

Put the jack under the axle rather than the frame.

 

I would take it back and just use your factory scissor jack with the AEV base or a piece of 4x4 to give it some extra height. Read this thread, started just a couple hours ago.

https://www.jk-forum.com/forums/modi...ptions-261083/

 

I've got 3" lift with 34's and the AEV base with the factory scissor jack works great on the axle. (not the frame) If you have after market bumpers you could use a hi-lift jack.

 

Under axel mean is under differential cover?

 

More towards the wheel on the axle tube.
Did you unscrew the top of the jack? It should have a threaded adjustment.

 

Take it back and buy a floor jack. 3 ton

 

Go with a good floor jack and an aev base for keeping in your jeep. My aev base works awesome. Bottle jacks are terrible.

 

Could u recommend me some good floor jack?

 

Sure, here is the one I use. Affordable around $80, works great. Up to 21". Or buy a larger floor jack, better for higher price though. This duralast suv jack works perfect for me. 1Duralast/2 1/2 Ton SUV jack (T83006FZ) | Jack | AutoZone.com