For many years, our Forester has had this annoying shuddering when we accelerate from a stop. We’ve mentioned this several times to our mechanics, some who have even taken the car for a test drive, and no one has been able to identify the cause or make it stop. Does anyone else with a Forester have this same problem? And more importantly, has any one been able to fix it?
Automatic transmission? CVT? I don’t know if these things are all automatic, CVT, or if they’re available with manual.
How many cylinders? Engine size (displacement)?
Knowing the transmission is critical to even making a guess.
And the mystery tranny is… ???
in 2006 Subaru did not yet use CVT, so it is very likely to be a classic automatic, judging by the year 4-speed one, as they started using 5-speed somewhere around 2008 only
If it’s an automatic, I’d be inclined to wonder about the torque converter.
If it’s a manual, I’d be inclined to wonder about the clutch and its respective components (pressure plate, release bearing, and maybe even the flywheel surface) as well as the age/mileage of the clutch and how long it’s been shuddering. I’d also wonder how many different drivers the car has.
In either case, I’d wonder about the engine mounts.
But the questions I’d have about these depend on whether it’s an automatic or a manual.
Knowing the miles on the vehicle might also help. It could be a faulty CV joint problem.
In most cases the front joints fail before the rears.
It’s also possible this could be caused by an engine performance issue due to a misfire that is covered up at speed.
It’s even possible that the shuddering could be from a damaged Center Viscous Coupler.
Have the tires been rotated on schedule, consistently over the past 10 years?
Has the car ever been run with mismatched tires?
Has a donut spare ever been used for an extended period of time?
If the answer to any of those questions is “yes”, then I would add a bad Center Viscous Coupler to the list of suspects, along with a bad CV joint and a failing torque converter.
With the emergency brake on and your foot firmly on the brake pedal “load” the engine with the gas pedal (without moving). Still get a shudder? If yes it’s an engine problem; if no, it’s a drive-train problem.