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Junior Charter Member
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Discussion Starter #1
My Roadster has a 8.8 diff from a 1998 Mustang. I recently installed the shorter axles, refilled with fluid and added the friction modifier. Now when I am backing up and turning there is a chatter/sticking/shudder in the rear differential. Any ideas on what is causing this and how to fix it?

Thanks.

Wade
 

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Junior Charter Member
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Discussion Starter #3
Along with the shorter axles you undoubtedly changed mounts and relocated the calipers inboard---when doing so did you reinstall the anti-moan brackets?

Jeff
Hi Jeff,

You are correct. I also installed 11.65 brake discs, FFR 3 link, and Gordon Levy adjustable lower control arms. I did not reinstall the anti-moan brackets as they will not fit due to a bracket that is welded to the axle tube. I am not sure what you mean by "mounts".
 

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Not a waxer
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11,764 Posts
By "mounts" mean the caliper mounts/brackets that relocate the calipers inward to match the narrower axle shafts. To reuse the anti-moan brackets you either need to cut off the quad shock mounts (the bracket welded to the tube that is interfering) or modify the anti-moan hardware. I always cut the quad shock mounts off.

Good luck,
Jeff
 

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Junior Charter Member
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Discussion Starter #5
Ok, yes new caliper mounts as well. Jeff, I am getting some noise from the lack of anti-moan brackets, but I am also getting what feels like a sticking or binding in the lsd when I am backing up with the wheels turned to the left or right.

Here is some info that I found on a TSB for this problem. I am not sure what is involved in changing a clutch pack :(

TSB 06-4-4

There is a TSB regarding LSD chatter that applies to 2002-2004 Mustangs. The text has been included for your reference.

Note, Ford has changed the recommended fluid to 75W140 (Synthetic highly recommended due to increase service intervals).


>>TSB 06-4-4

03/06/06

LIMITED SLIP AXLE CHATTER, SHUDDER, BINDING
SENSATION, OR VIBRATION DURING LOW SPEED
TURNING MANEUVERS

FORD:
2002-2004 Mustang, Explorer
2003-2004 Expedition
2004 F-150

LINCOLN:
2003 Navigator

MERCURY:
2002-2004 Mountaineer

This article supersedes TSB 06-02-16 to update the Service Procedure.

ISSUE
Some 2003-2004 Expedition, 2003 Navigator, 2004 F-150 vehicles equipped with a 9.75" or 8.8" limited slip rear axle, and 2002-2004 Explorer 4dr, Mountaineer, and Mustang vehicles equipped with 8.8" limited slip rear axle may exhibit a chatter shudder, a binding sensation, or a vibration during low speed turns. On 4X4 vehicles, the sensation may appear to be originating from the front axle or the steering gear.

ACTION
First verify the condition. On 4X4 trucks ensure that the vehicle is in 2WD, to isolate the rear axle. On all vehicles, turn the wheel fully right (or fully left) and then accelerate the vehicle. If the condition is verified to be in the rear axle, replace the limited slip clutch pack.

SERVICE PROCEDURE

CAUTION INSTRUCT THE CUSTOMER NOT TO TOW WITH THE VEHICLE FOR 500 MILES (805 KM) AFTER THIS REPAIR, TO ALLOW THE AXLE TO BREAK-IN PROPERLY.

Order and install the appropriate clutch pack, follow the instructions detailed in the Workshop Manual.

^ 6L1Z-4947-A (9.75" limited slip)

^ F5AZ-4947-BA (8.8" limited slip)
 

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FFCobra Craftsman
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22,705 Posts
I think I would drive for a month before worrying too much about it. I'd also try to get a few long drives in of maybe an hour to get the diff oil good and hot. I am pretty sure what you are experiencing is just a tight clutch pack that doesn't allow much slippage between the left and right wheel. I remember some rebuild instructions saying to coat the individual discs in the additive and then assemble the unit. I think that maybe the long drives will help the hot thin oil migrate to where it needs to go and also mix up the additive better throughout the 2+ quarts of gear oil.
 

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FFCobra Fanatic
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5,450 Posts
Hey Wade,
Not sure why the differential would be chattering if it didnt before the fluid change. I assume you didnt rebuild the trac loc unit which could lead to chattering until the fluid migrates. I always soak the clutches in Friction Modifier for a few days (outside in tupperware) before assembling a new trac loc. This assures the fluid is where it belongs and there is less of a chance of hearing the clicking/shuddering. I would give it a quick inspection in case the brakes are dragging. Did you make sure the brake bracket was centered on the rotor, it is sometimes necessary to shim them to get a proper fit. Good Luck and post your results.

Mike
 

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Junior Charter Member
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Discussion Starter #8
Hey Wade,
Not sure why the differential would be chattering if it didnt before the fluid change. I assume you didnt rebuild the trac loc unit which could lead to chattering until the fluid migrates. I always soak the clutches in Friction Modifier for a few days (outside in tupperware) before assembling a new trac loc. This assures the fluid is where it belongs and there is less of a chance of hearing the clicking/shuddering. I would give it a quick inspection in case the brakes are dragging. Did you make sure the brake bracket was centered on the rotor, it is sometimes necessary to shim them to get a proper fit. Good Luck and post your results.

Mike
Thanks for the input Mike. I really should have posted that my car is only recently on the road and it was just a little go kart driving before that. It is possible that the rear diff chattered before I owned it, but it did not do it during the go kart drives. I did spend quite a bit of time centering and shimming the brake bracket so I think I am ok in that area. The wheels are not hot after a long drive, so I am thinking that the brakes are not dragging.

Wade
 

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Junior Charter Member
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Discussion Starter #9
I think I would drive for a month before worrying too much about it. I'd also try to get a few long drives in of maybe an hour to get the diff oil good and hot. I am pretty sure what you are experiencing is just a tight clutch pack that doesn't allow much slippage between the left and right wheel. I remember some rebuild instructions saying to coat the individual discs in the additive and then assemble the unit. I think that maybe the long drives will help the hot thin oil migrate to where it needs to go and also mix up the additive better throughout the 2+ quarts of gear oil.
Thanks Craig. I have a longer drive coming up at the end of this week, so hopefully that will make some difference. My car was sitting during the build process for 10 years (yikes), and during some of that time, there was no fluid in the rear diff.
 

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Ford used to have a "service bulletin" addressing the issue. It advised, after adding the fric mod to make a series of left circles, then right handers in a parking lot. I have forgotten the number they used, but it must help expose the clutch pack to the lube.
I glass beaded the steels in the clutch pack in one of my car's rearend. It jumps and creaks like a detroit locker, but locks up good, until it wears out the fiber.

I edited my original post, as my memory worked on the past. The continuous circles works the clutches more continuous, resulting in full rotation of the fibers against the steels. Hope that makes some sense.
 

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Junior Charter Member
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Discussion Starter #12
Ford used to have a "service bulletin" addressing the issue. It advised, after adding the fric mod to make a series of left circles, then right handers in a parking lot. I have forgotten the number they used, but it must help expose the clutch pack to the lube.
I glass beaded the steels in the clutch pack in one of my car's rearend. It jumps and creaks like a detroit locker, but locks up good, until it wears out the fiber.

I edited my original post, as my memory worked on the past. The continuous circles works the clutches more continuous, resulting in full rotation of the fibers against the steels. Hope that makes some sense.
OK, thanks. I will try that too. I like the no cost, easy solutions. LOL
 
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