Rear differential issues?

[MEANMCHN]

I have no idea what's normal in terms of rear differential "play" but I've noticed lately that in 1st and 2nd gear when I roll on and off the throttle there's a clunk coming from the back end. I just jacked up the car and with the rear end in the air if I turn the wheels clockwise and counter clockwise there's a few degrees of play before it feels like anything in the rear end connects. It's an annoying noise and at first I thought it was the transmission, but after turning the wheels it's definitely the differential, ring, pinion, etc.

What's the most likely culprit? BTW, I beat the utter shit out of my car so nothing surprises me, would just rather know what I'm looking for.

Scott

[Nghtrdr]

Open the rear and see what's wrong. Sound like your rear gears are toast but you won't know till you open it up

Dan

[tulowd]

Some play is acceptable and required - make sure its not just a worn u joint on the drive shaft. Since you track your car I assume you have a Ford Racing alum driveshaft. Those come with new HD u joints.

Also ensure the dog bone weight attached to the rear housing is not knocking around if you changed gear ratios, get rid of it, only good to dampen harmonics based on factory set up.

FWIW, my 400 000 km 7.5 rear end with 4.10 gears did that just before I lost the pinion bearing...ended up breaking a couple of teeth off the ring and she was toast.

[ZR]

Unless you having a bearing or gear failing, lil tic of extra backlash won't kill it.

[MEANMCHN]

Ok, we'll see if it gets any worse on my next track day Monday. Just seems a bit worse than usual.

[horseplayer]

I had play like this in my rear end a few years ago - more than a few degrees of drive shaft rotation for play.

Aside from being annoying, it never caused any real issue. You just learn to drive accordingly and try to keep the car from bucking back and forth at times by keeping constant forward pressure on the rear.

[MEANMCHN]

Ya, I've always had this "lash," any way to get rid of it? From a mechanical stand point isn't this pretty shitty on components?

[tulowd]

backlash in part will depend on the differential you have. My TruTrac has a lot of play in it since brand new - Torsens with the springs less so, as well as the typical LSD's and Auburns

[RedSN]

You just learn to drive accordingly and try to keep the car from bucking back and forth at times by keeping constant forward pressure on the rear.
This drives me bonkers in slow traffic, or driving slow in a parking lot. It will get into a feedback loop and just get worse and worse, and I have to jump on the clutch to stop it. I do think the torque arm lessened this effect somewhat by eliminating the the axle wind up.

[ZR]

On some gear sets, requires more or less lash vs optimum to get a decent gear pattern. In my view, gear sets don't cost enough to expect high quality outta the box. Market demanded less expensive, they responded with cheap gears at a lower price.

[MEANMCHN]

Well this at least puts my mind at ease a bit knowing that other people have the same issues. It's really annoying going down the paddock land into the pits and you're the only car clunking along...

[horseplayer]

Well this at least puts my mind at ease a bit knowing that other people have the same issues. It's really annoying going down the paddock land into the pits and you're the only car clunking along...

Clutch foot, neutral, coast. Done.

[MEANMCHN]

Clutch foot, neutral, coast. Done.

Thanks, I'll tape that note to my steering wheel.

[horseplayer]

Thanks, I'll tape that note to my steering wheel.

just make sure your wheels aren't turned when you refer to the cue card.

[Tailites]

check both ends of the rear lower control arms..

[MEANMCHN]

check both ends of the rear lower control arms..

Thanks, I'm installing the new Steeda HD rear sway bar and quad shocks, all of the bushings look good, will let you guys know how it works out. Track day on Monday.

[cf105arrow]

My 09 GT has the same issue. I brought it into Ford last year and showed them how much play there was. They said it was normal and was needed for expansion of the gears when they heat up. Driving technique was the only way around the annoying clunking.