Hi

My upper limb was broken and I have replaced the limbs with a new set.
So what shall I do with the old limb, can I keep it and use it as a spare part?
If not, why?

Thx

usually busted limbs are just thrown out, but if you are a pack rat then by all means keep it.

use it for an add a leaf suspension in a 4X4

so it´s not possible to mix limbs from different set "and save the day" if one of my new limb breaks. Or?

I mean, what is really happening if I mix limbs?

I'd save the limb that didn't crack, toss the bad one. If one of your new set ever did go bad you just might be able to save the day with your standby. But tuning it to match the deflection of the newer limb may be in order.

It will make a good fishin pole holder, that's about it.

I would not trust it as it was a match for a busted one. Bad gene's. You could make a catapult for water balloons out of it.

The limbs on all modern compounds are matched for weight. I doubt the extra limb will be a match for either of the other two. If they aren't matched, one could eventually make the cam(s) 'roll over' at a different time than the other, causing the bow to need to be 'tuned', or corrected. You'd find your shots would eventually hit either lower and lower, or higher and higher, depending on which limb is stronger.

The catapult idea's a good one.

I vote paper weight.

If you don't have a backup bow, I'd recommend keeping it. According to Bob Ragsdale (a very knowledgable archery engineer), you can get any bow to shoot perfectly by adjusting tiller and nocking point. I remember reading where he once said that you could put a 60 lb and 70 lb limb on the same bow and get it to shoot perfectly. I believe him.