I`m trying to find a thread to modify 280zx struts to coil overs for my 510.

[510NewProject]

I`m sure this is been gone over a thousand times. But I can`t find the specific info on how much to remove from the tubes prior to welding and where to weld the new collars on.

Thanks

[datzenmike]

Cut them to match the new shorter inserts you plan to use. I can't remember the ones people usually instal so ask what inserts are used. Then cut the strut tube to match. If tube is a little long, stack washers in the tube bottom as shims so it can't bang up and down.

 

If only wanting a couple of inches trim the lower spring perch off the zx and the stock strut and grind the weld down smooth. Assemble the 510 perch onto the zx strut and support it at the height you want with 2" split collars. If you want stiffer spring rate cut your 510 springs. A few careful measurements on your coil and using the formula 11,250 X wire thickness⁴ / 8 X number of coils X coil diameter³ will give you your spring rate. The 510 is around 89 pounds per inch. By varying the number of coils you can arrive at the spring rate you want. Total cost of adjustable ride height is the 2" split collars, about $20. Once you are happy with the ride height they probably will never used again anyway. Or alternatively buy ready made springs in the rate you want.  

 

2-2 1/2" maybe 3" but you would want stiff spring rate to prevent bottoming on a stock length strut.

[yenpit]

As Mike says, you need to decide & purchase the shock/inserts BEFORE you cut, because you cut the strut tube to match the shock/inserts you will use!  I just bought stock ZX inserts, KYB GR2's, cuz although I am lowering my 510, I am NOT "slamming it in the weeds"!  If you are slamming it, you will want SHORTER inserts & then cut the tubes to suit whatever inserts you get.  iirc the common SHORTER insert is the Toyota MR2, I think second generation MR2 rear inserts.............??

 

Once you buy inserts & cut the tubes to match, if tube is still a little too long, you can stack washers/spacers in the bottom of the tubes, as shims so it can't bang up and down.  DO NOT CUT THE TUBES TOO SHORT...............unlike hair, they will NOT grow back!!

[datzenmike]

The same applies to cutting a coil spring. If it's too stiff the only cure is to replace it, you can't put it back.

 

BTW you never cut a coil spring to lower it.

You never heat them with a torch to sag them lower.