cleaning and painting diff housing

[cali-ti]

i would like to clean and paint the used E30 diff i got before i install it. can people suggest what the best way to do this would be?

would i be able to bead or sandblast it safely (flanges are still in place, old speed sensor is still there too) or would i need to use an abrasive manual sanding process to clean it?

i know diffs can get fairly hot (i did get the M finned aluminum diff cover already), so i was thinking possibly using caliper paint might be good. it would be nice to have it powdercoated, but i'm sure i'd have to disassemble it and just take the housing in (which would then mess up the bearing and stuff i believe).

any helpful info/suggestions are welcomed!

[DustenT]

I pressure washed my diff. with degreaser. It took all the grime off. Primed in with 2 coats of House of Kolor. Top coated it with DuPont Cromobase black and 3 coats of DuPont Cromaclear clear coat. It is overkill for something that nobody will ever see (unless I flip the car over).

Take a look, I think it turned out pretty good.

http://180customs.net/img/BMW/DSCF0284.JPG

[m44ic]

if possible sand plast it that would be the best way to clean it and if you are going to paint it yourself use duplicolor 500 degree engine enamal I just used it on my brakes and it looks awesome I did 2 coats of primer then 2 coats of paint and then 2 coats of clear all with about 15 minutes in between coats. well hope this helps good luck :)

[cali-ti]

finally got some work done on this :) duct taped all the areas which i didn't want sand to get into and then blasted the rest pretty well clean. next step will be to remove the tape and clean the remaining areas by hand. here's some pics.

[cali-ti]

removed the tape and hand cleaned (ok, used a wheel on my drill for a bit, until it got too late) around the half shaft and drive shaft flanges. i'll try to post more pics tomorrow. still need to get the drive shaft flange off so i can really clean under there and then paint before putting the new shaft seal and dust shield on. popped the half shaft flanges off (have new ones to be installed) so i'll be able to paint it easier. POR15 products arrived today too. i love it when a plan comes together!

EDIT: added pics

[m44ic]

nice, Im jealous

[cali-ti]

lol ... never had anyone be jealous of my diff before, that's a first! :p

[H3_2.1-ti]

If you can't sandblast it. use brake cleaner and a wire brush. I used Foliatec caliper paint. Beleive it or not the stuff is bullet proof. It comes with brake cleaner, paint and hardener and it's rust, oil and solvent resistent. I painted my diff. back in '98 and it still looks great.

Cheers,

[needle332rur]

Make sure you use ductape because it allows the sand/bead bounce off the unwanted areas without ripping the tape to shreds

[cali-ti]

i'm using POR15. similar resiliency against stones, rust, chemicals. using metal prep first, then POR15 rust preventative paint, POR15 self-etching primer and then the hardnose paint as a final coat. :)

[m44ic]

hey cali-ti where did you get your diff and how much did you pay for it?

[cali-ti]

vinesauto.com (via ebay). believe i won the bid with $200 (shipping was something like $40 from AL to WI).

[cali-ti]

stopped by farm and fleet to get a few items: galvanized eye bolts with nuts, flat washers and a 5/8" by 3' hardened steel rod. you may be asking, "what the hell do you need those for?" let's take a look :) need to break the input (driveshaft) flange nut free so i can replace the shaft seal and the dust shield. shortened the eye bolts with my friend the hacksaw and then put them through two of the holes in the input shaft flange (with a washer on either side and nut on the bottom). tightened them up and put the shaft through. we're almost ready to break the nut ... however, i discovered my 30mm impact socket won't fit over the nut, i believe because the outer diameter is a little too large. need to try to find another socket (back to farm and fleet tomorrow).

before installing any of those pieces, i followed the simple direction in the bentley manual, "pry off lock nut" for the input shaft. that was a pain in the butt! did finally get it off.

i also know some of you were looking at my previous pics thinking, "ummm ... i think you forgot to clean the diff cover ... that thing's still filthy!" well, you'd be right ... if i was going to use the original diff cover, but i'm not ;) i have a new finned m diff cover to be installed. see, i'm not (totally) insane :p

pics: old mangled lock nut, input flange nut ready to break, input shaft refresh parts (shaft seal, dust shield and lock nut), new finned diff cover