Hi, I have installed a new Delta mixer system that feeds the shower and tub and when the tub is on the water trickles out the shower head. When the shower is on there is no issue with the tub leaking.

I am using 1/2" pex tubing for the pluming from the mixer to the shower/tub.

When I take the tub spout off the issue is not as severe but only takes a slight pressure change (like me placing my finger over the end) before it starts to drip.

Could it have something to do with the distances they are from the mixer? I believe I am in the guidelines set out on the Delta website.

Any thoughts would be greatly appreciated.
Also forgot to mention the diverter pin is located on the mixer assembly not the tub spout.
Thanks!

You may have too much pressure in your system. It think water pressure should around 55 psi. Your "problem" should have nothing to do with "distance".

Could it have something to do with the distances they are from the mixer?
The distance between the mixer valve and the shower head has everything to do with it. Read on. There are three reasons that shower heads leak. 1) a faulty diverter, 2) Excessive house pressure and 3) Too short a shower raiser.
The average house pressure's 45 PSI, (that's why water towers are 100 feet tall). You should have about 27" of raiser from the mixing valve to the shower head. Good luck, Tom