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rough shifting between gas and electric mode? on 2004 Toyota Prius

When I bought my wife a new Prius, I decided to keep her old one (2004) as a small run-around and parts getter for my Jeep (my obsession and money-pit). I have noticed that the Prius seems to shudder and clunk in and out of electric / gasoline mode. My wife says it has always been that way. I do not recall noticing it before and I am not sure that she pays as close attention to things automotive as I do. So...is this normal in the older hybrids? Should the shift between gas / electric modes be smoother or is the shudder and clunk normal? The power-train (including the hybrid system) is covered under Fairfax Toyota's "Auto For Life" program, but I do not want to waste the trip and the diagnosis fee if this is normal.

Asked by for the 2004 Toyota Prius
Sounds like a power train mount is wearing out. found no bulletins, but this is where I would focus my inspection.
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Mine does this from time to time. If it is a true "cluck" yes, you may have a mount wearing out. What type of fuel are you using? I always used Top Tier fuel in mine. Go to the web and Google Top Tier Gasoline. When your Prius goes from gasoline to electric there can always be shift shock. But, if you use good gas this can be eliminated because of less knock or pre-detonation of left over fuel in the engine. Don't worry, a Prius will never leave you stranded.
Get your ~$130 transmission maintenence done, and report back. My Prius had been doing this recently. I thought the engine was misfiring and needed a spark plug or ignition coil change, until I got my transmission drained+filled at Toyota. Make sure to get the service done at Toyota, because the Prius is a CVT engine.
Thanks for this discussion forum. Recently I purchased 2008 Toyota Prius base model. It has the same symptom described here. That is knocking or shudder when transitioning from gas to electric when the car comes to a stop. This happens only the initial stages of driving the car. As you drive further this symptom disappear. It was worse before the spark plugs were changed.
I think the plausible explanation is bad transmission fluid. I am going to change and let you all know what happens.