Unstable Rear

[jabo731]

Guys help me out. about 2weeks ago this 06 Mustang and I went at it with about 4 passes{light to light}. I power braked twice, really came out of the hole. I nosed him but nothing to bragg about, but the problem is my car seems to be twiching in the rear when I accerlerate expecially when I turn. I have QA1 on all 4 corners with Metco upper and lower control arms. Addco bars front and rear 4:30 gears. Any suggestions of what to look for. thanks

[Bradley G]

loose/bad body mount(s), bad shock, play in axle bearings?

[HwyCruiser]

Mine started acting that way when the stock traction-loc limited slip started to go south, especially noticeable on accelerating in right-hand turns. It would point hard right as the left wheel was the only one wanting to gain traction.

[jabo731]

Cruser if this is the case do I need an axle or just a new differential.

[HwyCruiser]

Just the differential, but I'd diagnose this further.

I found out that my differential was going south was while watching a video of a burnout I did at the track when I noticed the right tire would just stop mid-burnout while I was in the waterbox. All along I was thought I was just blowing the launch at the staging lights.

Someone here should be able to tell you how to diagnose a bad limited-slip, other than observing a "one-wheel peel."

[Blackened300a]

Check for loose Lugs, I had this happen and it felt like the way you are describing. I found it a little too late and longated the holes.

[jabo731]

Thanks guys, I'll have to investigate more.

[SergntMac]

What HwyCruiser says is true. I had to replace my OEM Trac-Loc diff back in '03 due to a ring gear bolt failure. Cyclone03 has it now. I replaced it with an Auburn "High Performance" 28 spline diff and used the OEM axles. This diff lasted through two years of hard driving and racing abuse before it started to slip, but it was my left rear tire that came to a stop in the water box. I am pleased that I chose Auburn over the Eaton, 'cause for 125 bucks and my core, Auburn delivered a 31 spline "Pro" diff. I added the 31 spline Moser axles from Reinhart, and away I went.

Given your symptoms, your diff is worn out. One way to test for a bad/weak diIf, is to launch the car on dry pavement and measure your tire tracks.

Just my .02C, carry on gents.

[jabo731]

Thanks Mac I'll look into the Auburn.

[John F. Russo]

What HwyCruiser says is true. I had to replace my OEM Trac-Loc diff back in '03 due to a ring gear bolt failure. Cyclone03 has it now. I replaced it with an Auburn "High Performance" 28 spline diff and used the OEM axles. This diff lasted through two years of hard driving and racing abuse before it started to slip, but it was my left rear tire that came to a stop in the water box. I am pleased that I chose Auburn over the Eaton, 'cause for 125 bucks and my core, Auburn delivered a 31 spline "Pro" diff. I added the 31 spline Moser axles from Reinhart, and away I went.

Given your symptoms, your diff is worn out. One way to test for a bad/weak diIf, is to launch the car on dry pavement and measure your tire tracks.

Just my .02C, carry on gents.

What caused the "ring gear bolt failure"?

[SergntMac]

What caused the "ring gear bolt failure"?I don't really know, John. Fatigue? I owned the KB #1x less than 24 hours at that time, and it had gone through 16,500 miles of brutal testing prior to that. OEM bolts, maybe they just gave up? For the two rebuilds following that, I used the Ford Racing rear end kit with improved bearings and ring bolts, LocTite, as well as adding the Dana stud kit and Ford Racing girdle. Not a problem since, except for the expected wear out. Diffs of any brand do not last forever.