It's very slight and it's something that my old pickup would do and do much harder, however that was an automatic transmission, and I'm wondering if it's normal for them to kinda thunk around just a hair against the driveline lash? It doesn't do it when stopping and then restarting at all so I'm thinking it's in the transmission and am just wondering how much would be normal, it does have almost 107k miles.

 

There is no reverse gear in any of the FEHs. The Traction motor spins backwards to backup. It sounds like a lose joint after the transmission, but not in the transmission. Have your FEH put on a lift in neutral and spin the drive wheel forward and backward to find the bad joint.

GaryG

 

No, I don't own a lift and it's the middle of winter here yet, so doing it on jack stands is not a good idea. I'm hoping I can get someone who has the four wheel drive to let me know if that's normal for that one since two wheel drive you have has less parts that could cause problems.

 

It's not severe at all, in fact it's close to being almost imperceptible compared to most vehicles I've driven, just worried because it has planetary gears and I thought that meant it shouldn't do this at all.

 

I suspect, that much like normal automatics, it might help if you paused briefly with the brake applied between using reverse and then drive.

Just a guess but what you might be feeling is the ICE starting back up when you shift back into drive.

 

No, this is cold start with ICE running all the time, each shift forward neutral reverse has a slight feeling in the vehicle that you can tell it shifted.

 

I also have my foot on the brake the whole time and since it's not moving it should be friction brakes. It's not much, less than most automatic pick ups would do, but I thought it shouldn't with planetary gears.

 

It seems to me that having the ICE remain running in reverse would be counter-productive but my only test would be with our '03 Prius.

So, anyone with an FEH F/awd wish to weigh in...?

With the ICE running and the car stationary the electric motor(s) must be running opposite and equal and then when you shift into neutral still opposite but beyond equal in order to "drive" backwards. The butt "feel" of that might not be much different from going from neutral to reverse in a standard automatic.

By-the-by, IMMHO the planetary gearset does not really enter into this equation, it's the electric motor direction of rotation and rate of rotation that changes in order to go from reverse to neutral to drive. Automatics also have planetary gearsets, as many as three these days.

 

"..foot on the brake the whole time..."

In that case the HSD system would NOT have actually tried to move the car backward (or forward). So the only source of "shudder" would be the ICE stopping as you shift into reverse and/or restarting as you shift back into drive.

Brake application ALWAYS disables ANY drive torque to the wheels forward or backwards.

 

I thought I already said it happens even if the engine is always running, it happens even in the morning when it's in open loop and the engine is never warm enough to shut off, it is not an engine start stop sensation, it is an automatic transmission shifting directions sensation.