When in gear, coasting or going downhill, the car seems to have a slight jerking motion, back and forth, as if there were something loose in the drive train. If I put in the clutch, it stops. Need help. Lawrence

 

How fast are you going when this is happening?

 

Could be bad U-joints in the drive shaft, or a bad tranny mount.

 

It happens at moderate to slower speeds, under 40 mph. I have thought about engine, transmission mounts, and u-joints--I have to get it somewhere to have these checked out. Sometimes I wonder if I am just shifting up to quickly--perhaps this rotary engine (new to me) needs to go to higher rpms before shifting? Lawrence

 

Additional info: today I discovered that if I pulled on the choke--making the mixture leaner I suppose--I pretty much stopped the back and forth jiggling. Idles faster, of course. So, I presume the carb needs some adjustment? Lawrence

 

If you are in a higher gear at around 1500 rpm's then its normal. The shutter valve is starting to operate. You need to downshift if you are going to put around at low speeds.

 

Ive noticed this in every rotary Ive driven. From 12a to Renesis. If your in too high of gear at too low an RPM then it will get jerky. As said above, simple fix is to down shift.

 

If you pull on the choke, you're making the mixture hitting the intake manifold RICHER in fuel than air...it is the lean condition that is making the engine jerk the drivetrain when coasting. When I'm in a long line of cars going through an all-way stop sign intersection where every car has to stop for the stop signs, I just barely keep the butterflies open and basically creep along at 300 rpm so I don't have to touch the brakes or clutch pedal, leaving a half car length in front of me. If the carb butterflies are completely closed to stop the creeping cuz numbnutz in front of me hits his brakes too soon, the hacked off RX-7 starts the stupid bucking until I push the clutch pedal.

Check your fuel filter, then go an eighth of a turn clockwise on the mixture screw and see what that does.

Mario III