1993 Accord Auto Transmission 200k miles

Hard to describe the issue but here we go... Whenever I'm driving,
especially around 45-50MPH and going steady or on cruise, the car
seems to shake/wobble/shimmy but not to side to side but front to
back. It almost feels like the transmission cannot figure out what
gear it wants to be in.. Speeding up or down doesn't make a
difference. I can only notice it while going at a steady speed,
slowing down or speeding up, it's not noticeable. It "wobbles" the car
and it's just super annoying. Any help would be greatly appreciated.

Just a couple notes:

1) Just did a transmission change with Honda fluid and no change.
2) Not a tire issue. Been balanced, rotated etc.
3) Checked all motor mounts. Replaced front engine. All others look
fine but I'm not 100% sure on the rear one (big honking one with valve
thing) it looks good, but I may be wrong.


Thanks!

 

I'm suspicious of the rear engine mount, the big one with the valve
(actually a vacuum motor). It is meant to soften when idling in gear and
firm up under all other conditions. A quick test: you will see the vacuum
hose to that mount goes to a control valve mounted nearly dead center on the
firewall near the top of the engine. With somebody holding the brake and
idling in gear with the A/C on, remove the hose at the control valve where
it goes to the engine mount and cover the fitting on the valve where you
removed the hose. The car should shake a lot, demonstrating the engine mount
is firming up when vacuum is removed. If it passes that test, leave the hose
off and the port plugged, then see if the symptoms are still present. If the
symptoms are gone the problem is in the control valve or in the electrical
signal (DC) that controls the valve.

The vacuum control part of that valve gets stiff too easily. You can try
spraying it with silicone lubricant and exercising it with your fingertip,
but it isn't easy to reach and the chance of success is not great.
Considering the price of the valve (about $150 US IIRC) and the
inaccessibility grasping at straws seems reasonable to me

Mike

 

Mike,

Thanks for the reply. I will try that and post back.

 

Well, I tried what you mentioned Mike and the engine made no shaking
difference with or without the valve connected. So I'm assuming its
control valve or electrical signal? Any suggestions would be greatly
appreciated.

Thanks for all your help so far.