Most, if not all, shift kits make this mod as SOP because it is such an annoyance. At least, the Transgo and Superior kits I am familiar with do it by default. There are a couple ways to do this and the dead easiest is just replace the OEM manual valve with a Sonnax part that will allow fluid to circulate in park and changes nothing else. You have to remove the VB to change out the valve but it is relatively easy to do.


Highly unlikely damage would occur with that scenario. Nothing is really dry, and, the fluid will flow from the sump to the pump then to TC. You will have line pressure to apply the clutches before the TC fills becuase the pump is the source of the fluid fill and pressure for the clutches. The reason it is slow moving is due to the lack of fluid in the TC for the fluid coupling to function, not a lack of clutch apply pressure.

To reiterate really well hashed over issues, the main reason to mod the VB for fluid flow in park is due to the fact that in park the pump HAS NO LUBE. The manual valve blocks fluid coming from the sump and there is less than a pint of fluid in the pump gears on start up. Idling the engine for any length of time is hard on both engine and trans unless mods are made. Shifting immediately to neutral on startup is is about the only to mitigate possible damage.

 

Oh well, par for the course. Until the converter is full the line pressure is not able to come up to normal. This being the case the apply pressure builds slowly with low pressure. The forward clutches are not slip clutches but are designed to engage and stay engaged. Slipping them will burn them from low pressure. And actually it is a leak that causes the problem in the first place, that and a poor design that for some reason Chrysler did not choose to fix for 40 years. Generally the leak down comes from leakage at the slip rings on the front hub. Sloppy pump gears can also do it. Generally when we built a leaker we would pull it, replace the front pump assembly and valve body and most of the time it would cure it. Sometimes it is easier to part out the trans and put another unit in it.

Fixing the park pump problem actually is a band aid to the leak down that occurs, but is not noticed with the lube in park fix. Trying to find and repair the leak down on any given transmission can be hair pulling and I might add, pulling the trans a few times. If you want to get technical about it, the problem comes from an excess gravity leak down of the converter through the transmission and has nothing to do with the "no pump park" problem although the leak down is covered up by the park fix.

Any time you try to pull away from a stop and there is not enough fill in the converter or pressure to engage it, you are damaging the trans front clutches or the clutches that are engaged in reverse.

 

Nope, doesn't work that way according to the schematics on a 48RE. Converter fill is secondary to line pressure at low pump pressures and that is controlled by the PR valve. Once line pressure is up the PR valve allows the TC to fill faster but it will build line pressure for clutch apply first.

This makes sense as damage would occur if the clutches are slipped like you imply. That just doesn't happen on a good trans.

If you are burning up the forward clutch pack there are other internal issues causing it.