Does this sound mean immenent death of my gearbox? Did I make a mistake putting a single mass flywheel in a forester?

I recently blew out the clutch on my 2002 Subaru Forester (SG9 2.5L manual dual range version)

In order to save some coin and under the advice of my local mechanic, I put in a single mass clutch instead of a dual mass clutch.

The gearbox would make some crazy race-car sounding transmission whine when I was in low range, and rattle like crazy below 2k RPM, but I didn't think too much of it, until this week.

I pushed it pretty hard off road last weekend, getting bogged in a bit of saltwater and deep sand and now it makes this noise:


My mechanic thinks I've broken a bearing in the gearbox and need a new one. I'm a little suspicious that we cut a corner with the single mass flywheel and that's why it's now broken.

Has anyone had much experience with switching to a single mass or these dual range gear systems?

The sound goes as follows:

Engine on, Stopped, clutch pedal all the way in: no sound

Engine on, Stopped, clutch pedal released: Popcorn like rattling from gearbox

Engine on, low range gears selected, stopped, clutch pedal released: Popcorn monster in gearbox

Engine on, 1st gear accelerating: Popcorn like rattling from gearbox

Engine on, low range selected, 1st gear accelerating: Loud popcorn and grinding transmission whine

Engine on, cruising in 3rd gear high range down hill: minimal popcorn noise but still noticeable if listeting closely

  • 4
    Have a car which has a dual mass flywheel as standard and followed the forum where several people put in a single flywheel then wished they had not: vibrations early failure and other issues. The manufacturer usually knows why they specify a dual mass flywheel...
    – Solar Mike
    Commented Sep 30, 2020 at 21:17
  • Yeah... kind of regretting it already. If a mechanic recommends a single mass and I confirm, do you think I'm liable from that point on? Commented Sep 30, 2020 at 21:22
  • 1
    Legal questions are generally off-topic here, laws vary over the world and we aren't lawyers, I will say that in general you have little recourse as you agreed to the work, you'd have to prove your mechanic gave bad advice. In practice, taking your car back to a mechanic who messed your car up is a bad idea. Go elsewhere, and see if you can get some money back.
    – GdD
    Commented Oct 1, 2020 at 7:24

1 Answer 1


Update on this, I'm pretty confident it was the throw out bearing (clutch bearing)

The noise steadied out after about 10,000 kms. I'm maybe 30,000kms into the the new clutch and haven't had any issues other than the low range making an insane amount of rattling noise

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