jims95z28

I installed a new Detroit TrueTrac in my Moser 33 spline 12 bolt rear. Since day one, this rear has made a clunking sound whenever the driveline is loaded or unloaded. Since I have a six speed, it's usually every time I shift. Have about 1000 miles on it now. With both wheels on the ground, I can rotate the driveshaft about an inch. This movement is occurring either in the TrueTrac unit, at the axle splines, or a combination of both. I'm pulling the axles and carrier out tomorrow. Any advice on how to check the axle spline clearance in the carrier side gears? When I test fit the axles into the carrier at initial assembly, the splines seemed kind of loose compared to the fit in the old posi unit. Visually, the axle splines showed no wear. I called Eaton and they said this amount of backlash in the helical diff gears is normal. They said the noise was related to my particular combination of drivetrain variables. I'm fairly pissed off since this is supposed to be a quiet unit. Anyone else having TrueTrac problems?

stevenc1703

To your last question, yes. Mine is doing the same thing, I can even feel the play with the carrier off the car. I was having bad vibrations on the highway that I wasn't liking. I pulled the rear and I'm resetting everything this weekend. Good luck to you and keep me posted on your results.

jims95z28

So I pulled the axles and diff out this morning and set them up on my bench to see where the backlash is coming from. Most of it was between the axle splines and side gears. There was a little bit of play in the TrueTrac helical gears, but less than I expected to see. I measured the axle shafts and called Moser to see if they were within tolerance. They said yes and the amount of backlash I'm seeing in the splines is normal. They also said that the amount of backlash I'm seeing in the TrueTrac is normal, too. Other than the noise, it's working like it should. Probably wouldn't be as noticeable with an automatic. Guess I'll have to live with it. If/when it breaks, I'll be getting something else. In the meantime, I'm going to look for a good deal on a clutch type posi unit.

guppymech

iTrader: (7)

Maybe give Strange a call and see if they can make you some better axles. Not bashing your setup but over the years on the forum I've seen more issues with Moser stuff. Make some marks on your DS and measure the play, if you haven't measured it always looks worse by eyeball. FWIW my 3" DS has .250 free play, S60 w/Strange S-trac helical diff. I always get a clunk when going into 1st from idling in neutral and clunk in power on/off transition cruising.

01ssreda4

iTrader: (96)

Behind my auto my trutrac was dead silent and performed very well. I liked it....I ended up going to a spool for weight reasons though.

jims95z28

Initially, I thought the Moser axle diameter was off. Mark Williams lists 1. 4167" as the diameter of their 33 spline axles. Moser says theirs is 1.4050". I measured 1.4100" on one axle and 1.4040" on the other. The smaller axle diameter is probably driving some of the looseness in the splines, which Moser says won't hurt anything. I'm not inclined to throw any more $$$ at this rear for now. Just gonna put it back together and use as is.

stevenc1703

Ill get to mine this weekend, how much torque should the pinion free spin at?

jims95z28

If I recall, it's 15 inch pounds, but you'll want to verify that. For what it's worth, I didn't use a crush collar on this set up. I used a Ratech solid pinion spacer and shims to get the correct pinion bearing preload. They are a heck of a lot easier to use than a crush collar. They're also reusable. Pinion preload with the Ratech spacer is measured with the pinion nut torqued to 125 foot pounds. I used Ratech shims between the housing and pinion race too, which takes away the need for honed set-up bearings. I got my rear back together and in the car today. Still clunks when the driveline loads or unloads, but it is what it is.

Good luck with yours.

stevenc1703

I used a new crush sleeve and accidentally over torqued it to 20in lbs instead of the correct 6-9in lbs on used bearings. I backed it off to 7in lbs and it feels smooth. I've heard about over tightening it but I didn't go over by much at all. Do you think I'll be ok or is it defiantly messed up?

jims95z28

I'm not an expert, but I don't think you're supposed to back off on the pinion nut once you compress the crush sleeve. Randy's Ring & Pinion has a pretty good tech line. I've called them before when I've had questions about gear set-ups and they were very helpful.

stevenc1703

Install done, feels much better. I think the brakes are dragging a little but over all the ride is much smoother and less noise at 80mph. The 4.10 gears barely wine at all and the drive shaft is pretty quiet. I checked the play in the drive shaft and it's minimal as well as both wheels feel solid with no play in the axle splines. The differential feels great through the turns. I would recommend this setup to anyone looking for something to replace the posi.