Rear Axle End Play For C-Clip 10-Bolt

[GoreMaker]

I'm rebuilding my 10-bolt rear end. I'm switching to an Eaton TrueTrac in place of some unknown clutch-type LSD that was in there before (didn't look original, used a Z-spring for pre-load rather than coil sprung plates). I'm also switching to rear disc brakes with fixed calipers. To minimize pad knock-back, I'm trying to keep axle end play to a minimum. Because of the way the TrueTrac secures the axles, any end play basically applies to both sides equally as each side takes up ALL the clearance between the axles because there's no fixed cross-shaft between the axles, just a floating spacer.

In my initial setup using regular components (0.795" spacer and 0.150" thick C-clips), I was getting 0.070" of end play on each axle (!!!) which is way too much and could knock the brake pads back even if I'm running a 10 pound RPV. Heck, that's practically half the thickness of a C-clip, which I find alarming. By using a combination of different spacer (0.840") and thicker C-clips (0.155"), I was able to get that down to 0.013", which I think is perfect!

However this means that there's only at most an average of about 0.006" of clearance on either side of the spacer. Is that enough for 80W90 gear oil to get in there and maintain a film? If not, I could open it up by changing one or both of the C clips to the thinner ones, thereby adding 0.005" or 0.010" as needed. I'd rather not wear down the spacer or the axle end buttons if I can avoid it. There's also the issue of expansion to consider, will that take up all the available clearance when the rear end heats up?

[GoreMaker]

Had a talk with a tech at Dutchman Axles (who made my new axles). He felt that the 0.013" of end play would be just fine and is in fact ideal. The only heat expansion that matters is in the buttons on the ends of the axles and the spacer between them, and that shouldn't be an issue at all in this case. The only clearance needed to accommodate lubrication is less than 0.001".

[Hotwire]

If your calipers are on slide pins you shouldn't have to worry about pad knock back.. The slides will work w/ the axle play before the brake fluid starts getting pushed out of the caliper bores.

[GoreMaker]

They're not, they're fixed 4-piston calipers