iv been catching a lot of small bass on a square bill 2.5 crank bait.20 to 30 in 2 hrs. my problem is i loose all the big ones? in the last 2 weeks iv hooked and lost over 8 bass over 4 lbs.today i lost 3 and one was over 5 lbs...iv been bass fishing for over 50 years and the only crank bait iv had this problem with is a Rattle Trap.i changed out all the hooks for bigger better premium hooks,switched rods and changed line from 17 lb to 12 lb.same thing! ??? could it be they are short striking?

Could be a couple of things. An inbalanced population like Joe Pool has, automatically means a large number of small ones for each decent fsh you catch. In that case,just enjoy the little ones!
If other folks are consistently catching bigger fish on the same lake, I would move out deeper on the same structures you are catching the small ones.

I don't think they sare short striking--and you've already changed the hooks----

Sorry I misread your post. You have the bass located, they are coming unbuttoned. Premium gammy hooks have always solved that problem for me.

I'm guessing that the hooks are ripping free from the bass' mouth
What line type are you using?

Best tip that helped me with crankbaits. Thanks again Mr. Thad Rains--loosen your drag so that a 3lber could pull some drag. This gives you a bigger advantage at the beginning of the fight (not ripping the hooks away on the hook set). Keep steady pressure (you can always tighten up the drag some if needed to turn the head of a big one). Keep the rod tip low and if she jumps, lower even more retrieving to put more pressure on the fish.

Old school glass rods are sometimes still the way to go.

What is the rod you're using? After upgrading the hooks and the fact you're not breaking off the only thing that I would think it could be is that your just applying to much pressure for the rod that your using.

That's my favorite lure in sexy shad color. It's a killer at every lake I've ever fished. I've used it a lot and initially experienced the same problems as you. The enemy you're fighting with this lure is a slack line...and it only takes a split second of slack for the fish to throw it.

My fixes:

1) Hooks. I started by changing to Gamakatsu hooks. I soon realized I could fix the original hooks and save some money. Bend the hooks so the tips are
pointed inward towards the shank. They're usually pointed away from the shank out of the package. It doesn't take much. This will help more than
anything. Compare the bend in the original hooks to Gamakatsu hooks and you'll see what I'm talking about.

2) Rod. Use a flexible rod. This will help keep your line tight. The fish will throw the hook when the line is slack (usually when jumping out of the water).
Also, keep your rod tip down, either close to the water or even in the water. This will discourage the fish from jumping out of the water.

3) Line. Don't use braid. You need the line to stretch so it will help avoid slack during the fight. I usually use 8-10 lb. fluorocarbon unless I'm at Fork and then
I use 14 lb.

These easy changes will greatly help you get fish to the boat.

Tight lines!

What hooks are you using?

Add an extra split ring.

im using Mustad Ultra Point hooks,17 lb test Bass Pro Mono and 12 lb test Berkley Big Game.. a bait caster and 6 1/2' MH Berkley Lightning rod.and i know how to fight a fish after fishing Bass tournaments for 40 years...this time im stumped.iv never lost 8 bass in a week over 4 lb! it must be the bait as i hate crank baits anyway...im a Jig fisherman by hart! thanks all

All these pointers folks are giving are good tips. That said, you could just be going through a bad streak of cards. I made a post almost identical to this last year about this time. I had like 3 or 4 outings where I was losing like 50% of my fish on cranks. I haven't really changed much, other then trying to keep fish from jumping and I've probably batted 90%+ this year. The trick is knowing when you are just in a slump or when your technique really is costing you fish.

Just the wrong rod for the job bud!! Or if you want to stay with that one just back your drag off some.

I would go to a #2 short shank vmc 1x or gami magic eye ewg on 2.5 size and the same hooks but #4 on 1.5 size cranks. I'm not a big fan of Mustad trebles, could be how the fish are eating the bait aswell. Sometimes just changing from a round bend to a kvd style hook or from the kvd to the round bend will make a huge difference. I keep both ready to go at all times if the fish are really eating the bait I'll run the ewg or kvd hook. If they are slapping at the bait I like round bends to increase the chances of getting more hooks into the fish.

My guess would be you're either giving some sort of slack during the fight or not giving line at all on the surge and the trebles tear out.
Once you have a decent fish on, and you know it's big, push the button when the fish surges and give some line, NOT slack, but some line so that those last attempts to escape don't pull the treble hooks out.

The rod you are using is not really a great choice for cranks. The smaller fish are no problem but as they get bigger they are able to shake a crankbait more easily on a short, stiff rod. A 7'or longer med action rod would probably give you better results. Keep you rod lower and avoid slack in your line. Good hooks help a lot, but the proper action and length rod along with keeping steady pressure, not too much and not too little, are critical for consistent success with cranks.