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Transmission shifts hard Tim Miller 7-23-17  
1986 winnebago with chevy 454 v8. Forward and reverse work perfect however shifts hard as you drive. The engine revs up high before shifting. I was told to replace the fluid and filter which I did but no change in the shifting. Any other advice would be appreciated. Thank you
Re: transmission shifts hard ROBERT LEE 7-24-17  
1st You Motor home is severe duty and someone may have put in a shift kit that will protect the trans by making the shifts shorter and more positive, thus Harsh

This would also explain a small increase in RPM at each shift

2nd If there is an issue look to the "Vacuum Modulator" to be at fault.

In effect it measures the load on the engine and causes the trans to shift later and harder at high throttle settings.

If there is a vacuum leak in that system you will get harsh delayed shifts.

If it is a case of a little late and annoying harsh but not violent there are adjustable versions of this valve and if one of these is installed it may just need "softening up".

The modulator is mounted to the transmission case near the rear of the oil pan. It is connected by a vacuum line to manifold vacuum.

Before changing or adjusting check vacuum supply with a proper gauge. These things are a pain to adjust correctly, not cheap and if the issue is a cracked line you will be angry.

Good Luck
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