Anyone experience this issue with a Detroit Truetrac?

[tn_kayaker]

1987 Jeep Cherokee 4.0 4x4 with Dana 44 rear axle. I bought the axle from a junkyard and completely rebuilt it. The only thing I used out of the original axle was the ring and pinion (3.54). All new bearings (carrier, pinion, and axle) (Timken). Used Detroit Truetrac LSD. Also put a set of disc brakes off a 1994 Crown Victoria on it. Drove for ~250 miles with no issues except an occasional 'pop' from the right side. Pulled the passenger side wheel and disc off, placed a dial indicator on the outside face of the axle flange and found it was slightly warped (.015 variance when rotated). I put a new axle shaft in that side, but still found I had some play in that wheel as shown in the video. Just trying to verify what I have here before dumping any more money into it. My first inclination is that it appears there is play where the axle shaft splines engage with the Truetrac unit. But I have never used one of the Truetrac units before, and I wanted to see if anyone else has experience with these in case there might be some normal amount of play in these units. I doubt it, but worth checking before I tear it back open again. Any opinions?

 

[Evan03]

Man id run it as is. Probably never ever have any issue with it

 

[tn_kayaker]

Man id run it as is. Probably never ever have any issue with it

Tempting, but I've got so much time and $$ in this thing already, I hate to take the chance of something coming apart in there and turning the whole thing into scrap metal. Right now I'm leaning towards driving it for a while and then checking to see if the amount of play has increased, or if there is any unusual wear pattern on the axle splines. Got an email in to Eaton technical support on this too, but don't know if I'll get a response.

 

[sdspearo]

That looks like it's pointing to the axle shaft bearing. Since the end of the shaft is splined and slides in/out of the carrier in the same direction of the slop you're measuring, I don't see how any play within the carrier should affect that measurement. The measurement is reduced after the gears are engaged (when you slightly rotate the wheel in the video) because of friction against the splines. I bet if you take your measurement at the center of the axle/wheel, and not at the outer wheel, and use more force when taking your readings you'll get closer results before and after.

 

[Ol Blue]

Pretty normal isn't it? Not sure how this would be the differential's fault. The axle is free to move in the carrier since the Dana 44 shaft isn't retained by a c clip. It's the axle retainer plate that would stop that movement in and out. So are the axle retainer bolts torqued correctly? Maybe you need a shim under the retainer to push harder on the shaft keeping it tight.

 

[Ol Blue]

Oh and people love to over tighten the shaft retainer bolts which ends up bending the retainer plate. Make sure that plate is perfectly flat. This could also give you a leak at the axle seal.

 

[tn_kayaker]

I had someone else ask me to compare this to the lateral movement of the axle by pulling in and out on the entire tire, and I confirmed that this movement is negligible (<0.001) It is a brand new bearing with 0 miles on it at this point, so it hasn't worn in at all yet. To clarify, the play does not appear to be a horizontal movement of the axle shaft in and out of the axle tube, but rather a rotational movement of the axle shaft with the pivot point being the axle bearing. So it seems that either A) the mating surface between the splines and the carrier is not tight, or B) the part of the differential that engages with the axle moves within the carrier.

As far as the backing plate goes, the disc brake conversion required the use of a 2003 Wrangler retainer plate. This is a thicker plate with a lip. Torque specs on the original drum brakes were for 32 ft/lbs, the Wrangler calls for 45 ft/lbs and the Crown Vic called for over 150 ft/lbs. After much debate I compromised and went with 40 ft/lbs. I did verify when I pulled the first axle back out that the bearing race had seated firmly against the lip in the axle tube, so I do think the bearing is held in properly.

 

[sdspearo]

I just re-watched your video...yeah, disregard my last comment pointing to the bearing...I thought you were measuring lateral play.
To rule out a loose spline fit, I would look for something to temporarily make a tight fit, just for a quick measurement with your dial indicator like before.

 

[ChillyB]

Bearings don't wear in. They're as perfect as they'll ever be when new. Any change to a bearing is progress toward wearing out. If a bearing is noisy then quiets down that indicates it was damaged or misaligned when installed, then wore out enough to be sloppy and quieter. Not always catastrophic, but it should not be expected as normal.

 

[tn_kayaker]

Bearings don't wear in. They're as perfect as they'll ever be when new. Any change to a bearing is progress toward wearing out. If a bearing is noisy then quiets down that indicates it was damaged or misaligned when installed, then wore out enough to be sloppy and quieter. Not always catastrophic, but it should not be expected as normal.

Sorry, maybe a poor choice of words on my part. I was just trying to convey that the bearings were new and had no play due to wear.

Unfortunately, it looks like I am going to be pulling it all apart again. I removed the cover and there was a LOT of metal in the oil even though I'd only driven it ~250 miles.

 

[Evan03]

My first set of gears turned into a molten ball of metal. So i guess yes good to check things