[frogsthatmoo]

So, I've had my Outback for almost a year now. 5-speed manual and love it but there's one thing I am getting really sick of and that's the shuddering and jerking. I consider myself "good" at driving stick but for ***** sake this thing acts like I'm dropping the clutch all the time with all the jerking and it honestly feels like the motor is going to fall out of the car.


I purchased the Group-N transmission mount to hopefully help (and it did, mildly) but now there's this shudder when accelerating in 2nd and 3rd gear (rarely 4th) pretty much always around 2300-2700 RPM. I initially thought the driveshaft bearing/bushing may have gone bad but I really have no idea. Based on what I've read, the rubber "donut" is inherently soft so I didn't think it was bad.

The shudder is a real low frequency (almost like bass) and seems to emanate from the rear but I'm not exactly sure if that's accurate. My best description is that it sounds like I'm lugging the motor but at that RPM I know I'm not. I've tried searching but really with no luck.

 

[lockmedic]

If it feels like it's coming from the rear, check your rear diff mounting bushings in the subframe. Mine were totally shot in a 2001 5 speed I had a while back and it clunked around/vibrated.

If that's the issue, eat your Wheaties before you attempt to change them. Those things are cheap enough (about $12 ea from the dealer which is pretty much the only place you'll get them), but the whole subframe has to come out to replace them, and they have to be pressed in/out. Next time I have one with those out I'm just gonna swap in a rear subframe from an auto (as they never seem to break).

 

[frogsthatmoo]

Are you talking about these bushings? This isn't my picture, just for reference. Indeed mine are cracked but definitely not as bad as these ones. Could that really be the problem though? I looked at them for a little while thinking about whether or not they were the issue, but I didn't see how they would induce such a deep shudder sound. Do you think these would also help with the bucking problem?

 

[nipper]

Also check your driveshaft, especially if it is rythmic.

 

[frogsthatmoo]

What should I be looking for when I check the driveshaft? I've looked over it before and based on what I've read it seems normal. People on here reported that the "donut" bushing/bearing inherently has a lot of play and movement in it so I don't really know what else I should actually look at.

 

[cardoc]

If its loud enough to record, it may be helpful. There are a lot of things that can cause what you describe and different variables involved. And you don't want to spend time and money on parts that won't repair the issue.

You may want to look into the exhaust system. The "deep bass" at specific rpm's is interesting.

How old is the car/mileage? Is the rpm you posted also your shift rpm? If yes, its torque related, if not, pressure or rotation related.

To check the driveshaft, you are looking for movement in the u-joints where the end yokes connect to the main shaft. When/if the u-joints fail, you will have movement. This is most likely not the issue since your noise is rpm specific and not vehicle speed specific unless the rpm you shift in is also when the noise occurs. Most times, joint noise is related to rotation of the drivetrain and motion of the car and would be a progressive noise/vibration with the speed of the car due to stress on the joint and imbalance. Again, unless your shift rpm is also the rpm the noise/shudder occurs.

Warm up the car good and let it idle. Put your hand down to the tailpipe and see how much air flow you feel. If it is very little, you may have restriction in the cat or muffler. If this is the case, it will cause a shudder as the engine load increases trying to push past the restriction at certain rpm's and could cause the "bass" sound. The engine can't breath with restrictions, like you trying to run a marathon with chest congestion.

Also, while it is warmed up, steadily increase the engine speed with the clutch in and listen for the noise to occur, then again with the clutch out. You may or may not be able to hear it without a load on the engine/transmission, but its worth a shot. This would help narrow it down between the engine/exhaust or something within the transmission, and whether its torque related or otherwise. You could also try setting the park brake and blocking the front wheels and ease the clutch in out to put a load on the drivetrain and listen for any noises. Try not to do this too much and without slipping the clutch. You just want to put torque on the system, not move the car.

Anther possibility is the input shaft bearing. The input shaft speed changes with the engine speed. If the bearing is scored/worn it could cause a shudder and the bass noise.

A flywheel/flexplate out of balance could also cause this.

I can make a long list of possibilities here. If you can record it and post it, then if I hear it I may be able to narrow it down.

 

[frogsthatmoo]

Thank you cardoc for all your help. I've been trying very hard to get video but nothing I own is able to pick up and record such a deep tone that it makes so it's impossible to replicate for you guys.

I'm going to make your post into a check list tomorrow and I'll let you know my findings and report back again.

 

[frogsthatmoo]

Thank you cardoc, lockmedic, and nipper for all your help. I've been trying very hard to get video but nothing I own is able to pick up and record such a deep tone that it makes so it's impossible to replicate for you guys.

I'm going to make your post into a check list tomorrow and I'll let you know my findings and report back again.