Good photos detailing the problem would help but at a best guess, you will probably lose the broken branch. Unless they are repaired very soon after damage, splits or partially broken limbs do not heal properly and even if they do, will be a continued point of weakness.

But post photos anyway....it may not be as bad as it sounds.

Obviously I haven't seen the damage to your Japanese maple, but I can tell you my experience. After several severe ice storms and the Easter freeze of 07, I found out Japanese maples are a lot tougher than you realize. Even though I did lose several trees (32) and I had many broken limbs and severely damaged trees, many came out OK. Here is Beni shichihenge encased in 1 inch of ice last year. I would go the pruning route (if even that is necesary) instead of trying the repair route myself. You will have some damage probably, but you should still have a tree, let's hope. Your tree may be able to heal a 3 inch break on it's own.

I have the same problem after the massive snow we got a couple weeks ago. I don't know when the split occurred - sometime between Feb 6 and yesterday when i uncovered the tree. There was a large split right at the crown (?) of the tree and one of the three primary branches was splitting off too.

See pictures before and after my 'repair'. I used cotton rope (might be sash cord), and wound it VERY tightly. The split at the top is pulled nearly completely together, but as you can see from the pics, there's still a little 'crack' showing. I don't think I can pull it together any tighter. Do you think what i've done is good or do I need to adjust, use different materials, or try a different method?

Thanks for any advice you can give.
-Chris

Here is a link that might be useful: split maple and repair

Chris - I responded to your post on the Trees forum. The photos were helpful. Thanks. Unfortunately, I don't hold out a lot of hope for your little tree.

Here is a link that might be useful: Chris's other post

I had a Bloodgood that broke that bad. I sawed it off below the split and the tree regrew. That was 5 years ago. The tree is still growing.

Good rescue job! However, that rope will not last for long. I would put 2 stainless steel lag bolts (not huge ones, mind you) right through the split to give it some strength. The bark will heal over and conceal them in time. I would also remove that third, smaller limb, as its just adding stress to the split.