I have a squier jazz shortscale bass and i want to convert it to longscale (i dont care if its worth it right now). Will this happen just by changing the neck to a longscale one or do i have to do more things to it?
The longer scale neck will have wider fret placement. That means that the distance from the nut to the 12th fret will be longer than a short scale. The bridge must be located at a distance from the 12th fret that is equal to the distance from the nut to the twelfth. Since that nut-to-12th distance is longer, so the 12th-to-bridge distance must also be lengthened. Thus the need to move the bridge back. Otherwise everything but open strings will be out of tune, getting worse as you go up the neck.why do i have to move the brigde back?
Jim_Dragons, Turnaround has given you an excellent visual representation of the issue: everything on your short-scale instrument is designed to scale. The distance from bridge to nut is built so that the overall length is 32". You can't just slap a long scale neck on without changing the scale of the entire instrument.
Even if the long scale neck fits, your overall length from bridge to nut WILL NOT be 34"...probably closer to 33.2", which would mean all the fret spacing was off, and no fretted note would be correct. You have to move the bridge to make the overall scale length correct.
Edit: If the body is for 32" scale, actually, a 22 fret neck with a 1/2" spacer should do it, 24 frets will be too long, unless you route the pocket a little.
Actually, my necks convert a standard 34" to 32" with no modification.You can make a short scale a long scale by changing the neck IF that neck is designed to do so, it would almost certainly be a custom job and the realitive pickup locations will change to be closer to the bridge so it won't sound the same as a regular jaguar. I think @BeeTL and @Bruce Johnson have experience doing such a conversion, but it will cost you quite a bit.
You can do the same thing that you do but in reverse, the same math that makes it easy to convert the longscales to medium and short scales makes it simple to convert a short scale to a long scale, you just have to deal with the extra neck dive and having the pickups in the wrong spots.Actually, my necks convert a standard 34" to 32" with no modification.
It's actually quite simple, and I'm surprised it had never been done before.
By contrast and as detailed above, converting a 30" to 34" is fraught with difficulties.