Differential housing paint or just clean it off?

[Lord Warlock]

In the never ending project, I removed the gas tank, cut the trunk floor rust out, and trying to get the trunk area ready for a floor replacement soon,  however, as i look down into the hole I see the differential, and it is coated in mud/dirt from 40 years of driving and some of it had fallen off leaving thin areas of mud/dirt and thick areas.  So I pulled out the power tools, scrapers, trim tools etc climbed under the trunk and sat down with my head sticking thru the new hole back there, and proceeded to get 90% of the dirt off the entire housing, rear plug, exhaust pipes etc, I can actually see the factory paint marks on the differential cover now, never knew they  were even there.  The 8 3/4 axle doesn't have a fancy cover like the dana does, so would like to clean it off as much as possible then repaint parts of it, I'm leaning toward leaving the round diff. cover alone since the paint marks are now showing, but i will probably repaint the rest of the rear axle black just to make it look better than dirt color.  The small 3 inch round air sander wore down to the hub and don't have another to replace it with, will have to find a new pad/disc for it. 

I know some people actually totally remove theirs and make it look as fresh as it was from the factory, with shiny black paint and clear coat, I'm not planning to going to that extreme, i do however want to make it look better so if anyone actually looked under the car it would appear to be clean and the right colors.  I will likely never have the opportunity to do it again once i put the new trunk floor in,  as i don't have a lift available to me. 

Would pressure washing suffice, or just hose and scrub?  Was thinking of using some Chassis black paint on the axle housing but leaving the center alone, and just washing that off as best i could.  It'd look better if i sanded and painted it and just re-did the factory markings, but I really don't think i need to go that far on it.  The car won't likely ever be shown in any event that anywone would climb under the car to look at anything, the engine and trans aren't original matching number pieces.  maybye i'll get some pictures of the differential Just so others can see what factory markings look like. 

[will]

Try some of that sanding screen stuff plumbers use to prep copper. The stuff falls out of the screen and the prep is done. I sprayed roll bar black from vht on mine. It's been sitting outside in the elements and hasn't rusted.

[Dino]

Get some engine degreaser and soak the axle.  Use a stiff bristle brush to clean the axle and repeat with the degreaser when needed.  Then just hose it off and paint.  To catch the mess I have thick mill plastic under my car that has the corners tied to the car and I have a single pan under the axle.  When I'm done the plastic holds all the water so you can just poke a hole in it over the pan and drain everything in there without making a mess.

Chassis black would work just fine.

[Lord Warlock]

Cleaned the axle off, it was black underneath all the dirt.  While i was in the trunk painting the trunk areas showing surface rust with Por15 prep and Por15 paint, I went ahead and painted the differential housing with Por15 as well, its fresh black now.  As careful as i tried to be, I still managed to have some run down the brush and get on my hands and I didn't get it all off quick enough, looks like I'll be wearing por15 for a few days or weeks.  Only thing i didn't paint over was the factory chalk marks on the diff cover.  Also painted one leaf spring.  Didn't paint any of the trunk floor area since i'll be needing to grind some of that to prep the surface for welding the new floor in.

pics after the fact: before, 40 years of dirt


after cleaning most of it off


After a coat of Por15 black only one slip thru the chalk marks, beginning of upward tail.

[Lord Warlock]

Was happy that the rear frame rails are both in very good shape, only the floor over the tops was affected, the rails are solid.  Added a few pics to the previous post.  Cross brace is also very solid, should be fine using it again.  Only the spot welds need grinding flat. 

[Lord Warlock]

No more hole in the trunk.  New trunk floor went in last week. 

[cdr]