I just put in a Moser 12 bolt with a TrueTrac differential in it. It seems to work fine but it makes a very loud knock inside the pumpkin when its engaged. I can rotate the driveshaft almost 45 degrees either way before it engages and turns the wheels. Why would it have so much play in it? Can anyone shed some light on this? I'd really appreciate it.

 

I also have a Moser 12 bolt with a TrueTrack. I have never had a clunking sound out of mine at any time.

 

Mine is dead silent.

 

Do any of you guys know what could be causing this? I'm thinking maybe it wasn't set up properly, and there might be too much backlash. It howls and whines pretty bad also.

 

My gears whine a bit but I think that the gear set installed in these units do whine to some degree.

Regardless you should not be getting a cluncking sound out this diff. I would take your car to a local rear end shop and have them open it up and inspect. They can verify the differential type and whether it was installed crrectly. They can also check the gear backlash and tooth pattern. I would try to do this relativly soon so if there is a problem it can be addressed before something is irreperably damaged.

 

I have a Moser 12 in a 97ss (3.73:1). Tru-trac diff with 33 spline axles. No excessive gear lash when I rotate the drive shaft RH-LH. All gears in there, so, there should not be any angular dwell before torque transfer engagement starts. Both wheels will rotate, or, a single wheel. I have notice this phenom in other "clutch" type chevy diffs (my chevy truck). B.

 

I've got the Moser 12-bolt w/tru-track and I've never gotten the clunking sound but I do have a lot of gear whine with the motive 3.73:1 gears. Be sure the pinion nut is tightened down all the way. No need to "crush" it though if you have that type of install kit. Just be sure it's tight.

 

As it turns out I got a new Truetrac mid last year and used it but ever since it was new it had lots of play inside between the axles. Without moving the carrier inside the housing, 1 wheel on the ground, the other wheel has 6 degrees of play. That feels pretty much to my hand. But that's not the worst part. The worst part is the pinion (with perfect backlash on the ring) has 20+ degrees of movement before it engages the axles. I'm guessing that's the 3.73 ratio in play, converting 6 degrees at the wheel to 22 degrees at the pinion. Imagine I'm at 6000rpm+ and shifting 2nd and the 20 degrees start getting inertia and when they hit it's like BAM! Feels nasty

Seems like we have the same problem here my friend. But the difference is you're in the US and I'm over in Romania...

I'm trusting you'll send it to the manufacturer (eaton), as per their instructions over the phone, to look at it and find out what's the problem. If we know what's wrong with yours maybe I'll know what to do with mine too.

 

Just an FYI most all GM trucks have the GovLoc posi which will normally clunck or clank on engagement.

 

up! come on someone give us a solution

 

As of yesterday, after a 400 mile drive, the Truetrac is wasted. It is giving lots of new "dead carrier" symptoms -when turning-, including grinding, squealing, body vibrations (strongly felt on the rims) and the good old rattling. It works on straight lines and still locks but it's gone far beyond the safety limits.

R.I.P.

 

Well that diff went to Eaton, they accepted the warranty claim, I got a new one. Guess what? Tons of engagement play also. Meanwhile they assured me all Detroit differentials have plenty of engagement play, that's their nature and it's normal.

You guys aware of this "well known fact" that detroit differentials have engagement play out of the factory?

It's not pleasant but I can live with it, given the awesome locking performance it has compared to my old Torsen.