47RH Electronic Conversion

I have always seen a 15psi pressure drop when the shift to OD is initiated. Under a second later it finally shifts, but the pressure never recovers. Anyone have an idea what causes this?

Redrider2911 said:

I have always seen a 15psi pressure drop when the shift to OD is initiated. Under a second later it finally shifts, but the pressure never recovers. Anyone have an idea what causes this?

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Pump Volume. Are you using a 47 pump? The 47 pumps are either 14 or 11 lobes and do not have enough volume for the demands up upgraded TC's and the likes. Try a 48 pump on there. They are 11 lobes but the lobes are much larger. It is a 10-15 percent increase in volume and it is very noticeable on the pressure gauges.

When 3 disk and super singles converters came out and I would install them in 47 equipped trucks I would see main line pressure drop almost 30 psi and the converter would lock almost 2 seconds after the command was issued via pcm using a scanner. With a 48 pump I would get lock up in less than 1 second from the command being issued and main line pressure drop was less than 10 psi.

I never did try on a 47RH measuring the pumps; always 47RE's. But on the builds I have done I always use 48 pumps.

So i popped a direct drum piston. Happened while reversing. I never checked line pressure in reverse but i know in drive WOT i was about 170. I know that reverse is usually a lot higher line pressure... so is there a way to limit that? Or just go with a billet piston and call it good?