Hello fellow Subaru enthusiasts. I have a 1991 legacy awd with a auto trans. It idles great but when I put it into gear the rpms drop which is to be expected but there is a vibration. Is it normal for these cars to vibrate when in gear? Sort of feels like a possible worn engine mount, I just don't want to try to repair something that is inherent to the vehicle.

Check the pitch mount (dogbone) that goes from the bell housing to the firewall.

 

It could also be something like a heat shield on the exhaust.

there have been several threads on this in the past. some feel it has to do with the axles. but my personal feeling is if it isn't mounts it is something in the trans that is "grabbing" more than it should.

 

but that it just my opinion based on my own logic and observation, no actual evidence.

A bad, worn, broken inner CV joint will cause an annoying vibration in gear that will go away in neutral. I had a broken inner joint that did just that. FYI it was a new Advance Auto Axle Assy and the inner joint broke in the first month. I didn't realize that that was causing the vibration for months.

Assume you mean vibration in gear while car is not moving. I have seen this on my car after putting in a brand X replacement axle. The theory is the overall length is not quite right, and it transmits vibration that would normally be absorbed by the engine mounts. If you recently replaced a CV axle in front, it may be your problem.

I have 2 new Generic Chinese made front CV axles on the Brighton automatic, replaced the broken one under warranty from Advance and NO vibration at idle in gear when stopped. Was really bad though with the broken inner joint. I would slip it into neutral at long stops to stop it.

 

I didn't realize it was from the new axle because I replaced the engine at the same time and thought it was a problem with either the motor mounts or the aftermarket head pipe I used which was not exactly right where the cat bolts up. (I won't use an aftermarket head pipe again!)

 

I found the broken inner joint when doing maintenance to the car so I got another under their warranty. We'll see how they hold up.