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Drivetrain 'clunking'. Doh!

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Old Feb 22, 2014, 10:40 PM
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Drivetrain 'clunking'. Doh!

I'm suspecting the rear diff as the culprit of this, but i wanted to make sure before I fork over the cash for a used diff.
When turning hard at medium to low speed a clunking and popping is heard(and felt). I can also hear the rear tires skidding(as if I had a welded rear diff).

Another possible culprit i read about is the RSB?
Old Feb 23, 2014, 08:56 AM
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First try turning off the single-wheel braking help for the AYC by holding the ASC button down for three seconds (if you haven't tried this already). Also, note that the AYC is programmed to do something very strange when you steer sharply at low speeds: it actually send more power to the inside rear wheel. This causes a noticeable clunk if the surface is uneven. I used to get a nasty clunk when turning into an uphill driveway from an uneven road. That went away when my ACD/AYC pump died.
Old Feb 23, 2014, 10:45 AM
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Originally Posted by Iowa999
First try turning off the single-wheel braking help for the AYC by holding the ASC button down for three seconds (if you haven't tried this already). Also, note that the AYC is programmed to do something very strange when you steer sharply at low speeds: it actually send more power to the inside rear wheel. This causes a noticeable clunk if the surface is uneven. I used to get a nasty clunk when turning into an uphill driveway from an uneven road. That went away when my ACD/AYC pump died.
Just tried. There was no change.
Old Feb 23, 2014, 11:17 AM
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If it were me, I'd next cut the power to the ACD/AYC pump and try again. I would not want to go through the hassle of replacing the rear diff only to learn that it was the AYC, instead.
Old Feb 23, 2014, 11:38 AM
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Originally Posted by Iowa999
If it were me, I'd next cut the power to the ACD/AYC pump and try again. I would not want to go through the hassle of replacing the rear diff only to learn that it was the AYC, instead.
Just went out and yanked the AYC PTC relay in the fusebox. It actually seemed to make it worse.

Last edited by FoxFister; Feb 23, 2014 at 11:48 AM.
Old Feb 23, 2014, 11:57 AM
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Can you have a friend watch the car as you drive around him or her in circles? Clunking, etc, could be a variety of things, including the sway-bar, but if tires are skidding then it's more likely the driveline. Again, I'm trying to rule out simpler things than replacing a diff.
Old Feb 23, 2014, 12:15 PM
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Originally Posted by Iowa999
Can you have a friend watch the car as you drive around him or her in circles? Clunking, etc, could be a variety of things, including the sway-bar, but if tires are skidding then it's more likely the driveline. Again, I'm trying to rule out simpler things than replacing a diff.
Going to drop it off at a shop tomorrow. Not having a place to work on it sucks . After searching around, I found a couple of offroad forums with people having the same symptoms. Turned out to be the gears in the rear diff binding up.
The driveline of the car has been a nightmare so far.
Old Feb 23, 2014, 01:09 PM
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Depending on what you do with the car, you might consider anything from dumping the AYC and getting a hard-locking mechanical rear; swapping in a Cusco RS, instead of a new planetary, and keeping the AYC; or getting a new (or repairing the current) planetary.
Old Feb 23, 2014, 03:53 PM
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I wonder if this is a symptom of those diff pins failing? What year evo you got?
Old Feb 23, 2014, 04:03 PM
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Originally Posted by Thomar
I wonder if this is a symptom of those diff pins failing? What year evo you got?
2010.
The diff pin issue is a problem with the center diff if im not mistaken. Those were replaced with the revised shep pins about three months ago
Old Feb 23, 2014, 05:55 PM
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Originally Posted by FoxFister
2010.
The diff pin issue is a problem with the center diff if im not mistaken. Those were replaced with the revised shep pins about three months ago
wow dude your just having all the bad luck
Old Feb 23, 2014, 06:12 PM
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Yep. Diff pins is a center-diff issue. But folks that launch hard have been known to chew up rear diffs, too. The ACD locks; lots of the torque ends up in the rear; the rear diff doesn't like it. Remember: the rear diff is a planetary, in order to double the ability of the AYC to reroute torque, and planetaries are often less strong than a four-spider conventional.
Old Feb 24, 2014, 10:37 AM
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Well, I believe I can now confirm a rear diff failure. I had someone lay underneath the rear while I pulled forward and the whole rear axle seemed to be shifting every time the loud banging is heard. I seem to indeed have all the luck at this point.
Old Feb 24, 2014, 12:05 PM
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Originally Posted by FoxFister
Well, I believe I can now confirm a rear diff failure. I had someone lay underneath the rear while I pulled forward and the whole rear axle seemed to be shifting every time the loud banging is heard. I seem to indeed have all the luck at this point.


Now that is one trusting "friend" you've got there!
Old Feb 24, 2014, 12:23 PM
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Originally Posted by Swolin
Now that is one trusting "friend" you've got there!
Lol! He was underneath the rear bumper.

I went ahead and drained the rear diff gear oil, and low and behold pieces of gear was stuck to the drain plug. I knew the car was beat on by the previous owner but I didn't think it would be quite this bad.


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