Mar 22, 2013 update to the Subaru Impreza WRX project car

Unchattering a Clutch

Our Subie's engine is out and at the machine shop. What better time to check out the clutch?
No doubt there's some wear on that aluminum shaft.
Sumo Parts' stainless steel sleeve and new release bearing should take care of our chatter problem.

We cooked our Subie’s clutch during a round of overzealous testing, but we had installed a replacement—with a lightened flywheel—from ACT. We figured this would also solve our issue with chatter, but alas, it was still jiggly on engagement with the new clutch.

Now that the engine is out, we had another look. The clutch release bearing rides on a part of the transmission case, and that part is made of aluminum. According to the guys at Sumo Parts, this soft metal is prone to wear under this kind of use, and that usually manifests in a chattering clutch.

Sure enough, our transmission housing showed significant wear on that spot—no big surprise after 200,000 miles. Thankfully, Sumo Parts offers a solution that doesn’t require replacing the trans case. They sell a stainless steel sleeve to slip over that shaft, and it comes with a new release bearing. That bearing has a larger inside diameter to accomodate the sleeved shaft.

The sleeve installs in minutes, but, of course, you need access to the clutch first. Once it’s all back together, our clutch should shake no more. But we still have a long way to go. Our engine is still in pieces.

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Comments
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Alan Cesar
Alan Cesar Dork
3/22/13 10:40 a.m.

It's a snug fit, but not a press fit. You can tap it into place using a piece of wood to prevent damage.

Alan Cesar
Alan Cesar Dork
3/22/13 10:47 a.m.

We cooked our Subie's clutch during a round of overzealous testing, but we had installed a replacement—with a lightened flywheel—from ACT. We figured this would also solve our issue with chatter, but alas, it was still jiggly on engagement with the new clutch.

Now that the engine is out, we had another look. The clutch release bearing rides on a part of the transmission case, and that part is made of aluminum. According to the guys at Sumo Parts, this soft metal is prone to wear under this kind of use, and that usually manifests in a chattering clutch.

Sure enough, our transmission housing showed significant wear on that spot—no big surprise after 200,000 miles. Thankfully, Sumo Parts offers a solution that doesn't require replacing the trans case. They sell a stainless steel sleeve to slip over that shaft, and it comes with a new release bearing. That bearing has a larger inside diameter to accomodate the sleeved shaft.

The sleeve installs in minutes, but, of course, you need access to the clutch first. Once it's all back together, our clutch should shake no more. But we still have a long way to go. Our engine is still in pieces.

Wicked awesome Scooby Rexes in your treeware mailbox. Subscribe to Grassroots Motorsports now.
NGTD
NGTD SuperDork
3/22/13 11:53 a.m.

What were the symptoms? Did it chatter all the time?

Mine 02 WRX does it but only when it is cold.

Alan Cesar
Alan Cesar Dork
5/2/13 9:00 a.m.

Ours chattered all the time.

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