Topic: Differential Housing & Backing Plates, Semi-Gloss Black Paint questions

[67gtasanjose]

This topic may need moved to DRIVETRAIN (may be same answers over multiple years)

I am about ready to spray my axle housing and backing plates. I understand these are all Semi-Gloss Black.
My questions are:

1.) What is a common type paint used (I have a lacquer SGB available). Otherwise, is Rustoleum SGB a good choice or not?
2.) Since backing plates were pre-assembled elsewhere (one is "Bendix", other is "K/H, Kelsey Hayes", should I consider choosing 3-different Semi-Gloss paint sources?

[ruppstang]

I used Semi gloss black powder coat on housing and plates. It looks great and is much more durable.

[CharlesTurner]

The backing plates were usually dipped in semi-gloss black paint, the appearance will vary, but generally will not match exactly to the rear end housing.  I would not use the same black for both.

On the rear housing, a semi-gloss black is fine.

Powder coating will be more durable, but could fill in stretch marks and other manufacturing details on the housing and backing plates.

The best, most correct appearance, will be using epoxy primer as a base, followed by a catalyzed single stage urethane.  The trick is to not get a high build-up of paint.  If there's any pitting in the metal, care will need to be taken to not fill in things like FoMoCo stampings in the backing plates.  If I have to fill in pits, what I normally do is apply epoxy primer to bare metal, then tape over the stampings before spraying build primer.  Pull the tape off and then sand to smooth out any pits.

[67gtasanjose]

Thanks Charles & Marty. Powder coat DOES look nice but I think I'll go the direction Charles is suggesting for that more-or-less "authentic-looking" job

Question on fixing scrapes and such on the housing. Some obvious floor-jacking scrapes in the middle section, what would be a good filler? (assuming I will not be jacking at that point ever again). Conventional Body filler?

Also, it looks like some clamping points (like vise teeth marks of a sort) on the axle tubes, any special detail to those areas?

[jwc66k]

You don't have to powder coat everything. Select undercarriage items that take the most abuse when driving for a start. The cross member under the engine, the front bumper mounting brackets, brake backing plates, etc. The rear axle could be on the list too. If you have a daily driver, this is the way to go. Note key words - "select", "abuse", "daily driver". Charles did point out a key drawback to a powder coat finish, the loss of detail. That's a two edge sword. It also covers 50 years of wear and tear.
Jim

[CharlesTurner]

For marks that build prime won't fill in, there are lots of products.  My body guy uses one called 'Rage Gold' by Evercoat, which I generally keep a gallon of to use now and then.

[J_Speegle]

Allot of time powder coating just looks like it was dipped in plastic, makes the edges looked rounded and covers the details so on restored cars I've chosen paint like originally done. Not like the cars get exposed to much of any wear and tear.

Any good quality paint with a hardener will do the job. If you have an imperfection work out the higher points and fill/address them individually rather than skim coating the whole backing plate.  If they are bad get some better ones

Just what has worked best for me

[A12pilot]

And to answer your question on filler,  if you want a rock hard filler,  I'd go with USC's All Metal.  It's what I use to replace factory lead joints and can be drilled and filled if necessary it's so tough.   It's an aluminum powder filled body filler.   Just another suggestion for you!

Cheers
Dave

[carlite65]

+1 on the all-metal filler. good stuff.

[Bossbill]

I've looked at half a dozen posts and this one looks like the best fit.

I had my housing media blasted at a commercial outfit as its size meant I had no choice.
I plugged the differential and axle holes with a piece of plywood, a gasket and goop.
The vent also got plugged. See pic (a dupl. from another post).

When it came back I mounted it to the rear rotisserie stand using the holes that mount the crossbar to the car and some large "L" sections I had laying around (NHRA front driveshaft hoop pieces). Using the hydraulics you can go up and down to get into tough places.

A bit of 120 on the deep gouges and 80 grit on a DA with tape applied to area with welds and other character I wanted to keep.

Here is a pic of the square marks make by the Sterling plant holding fixture.

I also found a weird number on one of the axle tubes -- see pic of me pointing.

I will use black SpeedoKote to fill the many, many pits on this housing, covering the main character feature with tape before spraying. I was going to just finish it up with generic semi-gloss but will ponder using a 2 part. What 2k are you guys using here?

[had to edit 5 times to add each pic. Weirdness strikes again.]