I have a Fox DHX 4.0 rear coil shock. 200 x 51.
It came with 550x 2.35 spring.

I need a 650ib spring and bought a 650 x 2.25 spring as shop advised me it would fit although a little longer. But the internal diameter of the spring does not fit being not wide enough.

Mojo site shows that they do a 650 x 2.30, would this fit or does anywhere do 650 x 2.35?

.05″ won’t be an issue.

Worth checking TFtuned + go for a Cane Creek spring (which will fit DHX shocks – internal diameter etc.) they are only £20 plus P+P. They have 650 x 2.25″ which will be ok for 51mm stroke.

The internal diameter of the 2.25 springs I have is less than the 2.35 spring, does the Cane Creek internal diameter bigger? Thanks

not all after market springs fit all shock bodies.

The 2.25 on your spring refers to the stroke length of the shock. If you buy a fox spring it will be the correct internal diameter. Make sure though that you buy “2.35” as this refers to how much the spring can be compressed before it becomes coil bound, rather than the shock stroke. Just a Fox anomaly.

Im sure you will get a 600X2.35 from TFTuned.

The Cane Creek springs from TF Tuned will fit a DHX shock fine.
Also Fox mark there springs differently from other manufacturers – so a CC 650 x 2.25″ will be the correct size for a 51mm stroke shock.
Look here for a better explanation of how Fox mark their springs.

There are two internal diameters on Fox springs, the ‘old’ shorter spring have a smaller internal dia, which won’t fit the more modern shocks, this is probably the issue.