Getting the correct bell housing finish ???

[DAVEN1256]

Many, many years ago before I knew much about correct colors, I painted my bell housing orange. I know now that the correct finish should be natural aluminum. I'm getting nearer to getting it back in the car now and want it to look correct.

I degreased and cleaned it up the other day. Where the orange paint had worn off, some of the aluminum underneath was bright with a little shine to it. In most places though, it is a dark gray and blotchy.

So after I get the rest of the orange paint off, I was wondering the best way to go about this. I have no problem with painting it. There are a lot of aluminum replicating paints out there......but which one to use? I read some of the reviews on them and some will say one brand looks great while others will say the same brand sucks!

I have a small blasting cabinet with 80 grit glass beads. Is that an option using a clearcoat or some protective coating afterwards? If bead blasting is an option, is 80 grit way to coarse?

Any thoughts or ideas are appreciated.

Dave

[69Z28-RS]

If you have access to a 'steel shot' tumbler, that will restore the aluminum finish to 'like new' ...  If you have an auto electric rebuilder shop near you they might have one?   

[x66 714]

Your 1st paragraph you're 1/2 correct on the color. Since the bell housing was on the engine when it left the engine assm plant, it would've had some overspray from when the engine was painted...Joe

[rszmjt]

Steel shot cleaners make it way too dark almost a grayish tinge IMO. You could lightly glass bead it with Sil 8 or fIner glass beads using low air pressure and holding the gun at a distance ( about 8”) . I’ve used “Aluma Blast “ by Eastwood to lightly ghost aluminum parts after this, the trick is to just dust it, then Eastwood matte clear to seal it off from the elements.

A really awesome alternative method is “Vapour Blasting”, google to see if anyone in your area offers this service, it returns aluminum parts to a near factory finish.
The bellhousing was over sprayed approximately 2-3” originally as was posted and some examples have been found completely painted FWIW

Mike

[firstgenaddict]

I am with you on the vapor blasting. IMHO that would be the best way to get back to an original diecast appearance.

[bcmiller]

Yes - coverage of bellhousing paint varied from day to day and/or who was doing the painting.

[169INDY]

Que the drool; Vapor Blasting!
2nd the low pressure glass beading & post treatment, using ; DX501: Aluminum Conditioner DX501 is also chromic acid based but the conversion layer formed is clear in color, also intended to applied after the DX579 cleaning step. It is used when it is desirable to retain the aluminum substrate’s silver white finish, either unpainted or with a clear coating applied over the treated metal. Dilution of DX501 with hot water may change the color of the mixture

Jim

[Edgemontvillage]

Vapor blasted 403 bellhousings. If you can locate a vapor blasting service in your area its a good choice for refinishing cast aluminium.

[169INDY]

The Aquablast 915 is the smallest of our standard wetblasting models and is more suitable for degreasing and blasting smaller components with a maximum turntable of 600mm.

The water/media slurry is contained within the cabinet sump. Delivery of the slurry to the manual blast nozzle is via a glandless polyurethane pump and associated hoses located inside the machine.

Compressed air is added at the blast nozzle to accelerate the slurry and provide the cleaning effect. After contact with the component the slurry then drains back into the sump creating a re-circulating system. Fine broken down media and other contaminants are fed via an overflow to a sedimentation filter located at the rear of the cabinet.

The process cleans by flow not by impact, producing a 'soft' finish with the water acting as a lubricant which not only avoids media impregnation but also extends the life of the blast media.


Cut & Pasted from a site.

Lloyd what unit did you purchase again?

JIM

[Edgemontvillage]

Jim, mine is from Vapor Honing Technologies and made in the USA. The Vixen Aquablast is a very high quality line (and price point) however made in the UK with very limited parts and service availability in North America. There are a couple in use in my area and they've had some issues. 

[DAVEN1256]

Thanks for all the replies so far.

I had never heard of "vapor" blasting but doing a little research, it seems to be the same thing as dustless blasting. I found three companies in the Orlando, FL area who do the dustless blasting. They all told me they use the water and media slurry.

One company, the guy sounded short for time and somewhat unfriendly. Another's price was way too much. The last one had a good price and was easy to talk to (customer friendly)…...I'm going to stop by there tomorrow and check him out.

I know about the orange overspray on the bell housing done at the factory. I like to be factory correct when I can but I just don't like the looks of that. I'd rather have it all natural aluminum.

Edgemontvillage, those bell housings look great! Do you use anything on them afterwards to preserve the finish?

If by chance this doesn't work out, can anyone recommend one of the aluminum replicating paints?

Thanks.....Dave

[ZLP955]

Hate to hijack, but in Lloyd's picture, the upper bellhousing has a boss with a hole on the passenger side upper corner, while the lower one does not. Seems to mirror the boss on the driver's side in Dave's pictures at the beginning of this thread. Why the difference, and which one would be correct for the '69 model year?

[firstgenaddict]

I have seen that boss tapped with threads in the past... almost like for a clutch cross shaft which would be further back maybe in a big car?

[x66 714]

That's the passenger side. Maybe for a RH drive car?...Joe

[Edgemontvillage]

"Do you use anything on them afterwards to preserve the finish?"

Dave, for aluminium its not necessary to apply a protective finish or coating after vapor blasting as its not prone to short term oxidation. When vapor blasting steel and alloys I use RPM or Boeshield as they do tend to flash rust if not treated shortly after blasting. 

[uscrichter]

I have used my soda blaster for the bell housings and transmission with which look pretty good as well!

[Mike S]

I have used my soda blaster for the bell housings and transmission with which look pretty good as well!

  Which type? I was wonder if the Harbor Freight unit would work with small items like a bell housing or transmission body and what grade soda media did you use.

Mike

[ZLP955]

That's the passenger side. Maybe for a RH drive car?...Joe

Not with the clutch fork hole on the left, it would have to be a different casting.

[uscrichter]

Yes, The soda blaster I have is the blue one from harbor freight and I also use it to strip paint on panels that will warp with other media and it works great as long as you keep the air dry! 

[rszmjt]

Hate to hijack, but in Lloyd's picture, the upper bellhousing has a boss with a hole on the passenger side upper corner, while the lower one does not. Seems to mirror the boss on the driver's side in Dave's pictures at the beginning of this thread. Why the difference, and which one would be correct for the '69 model year?

There is another post on the Yenko site about 403 bellhousing differences I have been involved in under-
“Technical & Restoration”

FWIW I have found 403 bellhousings with the mold numbers 1-9, and some have the extra boss and some don’t. It seems like late 69, early 70 the rh boss is more frequent.

Lloyd , which bellhousing is out of your car and can you post pictures of both bellhousing cast part number areas including the status markers and mold number 1-9. I’ll add them onto my bellhousing list. Thanks.

Mike.

[x66 714]

That's the passenger side. Maybe for a RH drive car?...Joe

Not with the clutch fork hole on the left, it would have to be a different casting.

Right. I wasn't thinking the whole thing through...Joe

[Edgemontvillage]

Hate to hijack, but in Lloyd's picture, the upper bellhousing has a boss with a hole on the passenger side upper corner, while the lower one does not. Seems to mirror the boss on the driver's side in Dave's pictures at the beginning of this thread. Why the difference, and which one would be correct for the '69 model year?

There is another post on the Yenko site about 403 bellhousing differences I have been involved in under-
“Technical & Restoration”

FWIW I have found 403 bellhousings with the mold numbers 1-9, and some have the extra boss and some don’t. It seems like on known original cars that late 69, early 70 the rh boss is more frequent.

Lloyd , which bellhousing is out of your car and can you please post pictures of both bellhousing cast part number areas including the status markers and mold number 1-9. I’ll add them onto my bellhousing list. Thanks.

Mike.

Happy to post photos Mike, my original 403 is at my shop (that photo is about 2 years old) and the other bellhousing on the stack is from a 68Z, don't recall which is which. I'll post photos in the next couple of days.

[Edgemontvillage]

Additional photos of bellhousings (as requested by Mike rszmjt )

1. My original (with additional boss)


 

2. Buddy's 403 bellhousing 4C LOS 68 Z (not original to the car) NO boss

[rszmjt]

Thanks very much Lloyd.

If the first picture posted is your bellhousing it appears “ not” to have the additional RH passenger side boss. The second picture looks like the drivers side boss? FWIW All 403 bellhousings have the drivers side boss but the passenger side is hit & miss. Yours is mold 8 and appears to be dated 10 month /4th week ? Think your car is 02B?
Your buddy’s bellhousing is mold 3, it has the additional gm logo by 403 number, again hit & miss. It also has the raised rib around the casting number. I have yet to see a bellhousing with the additional GM casting logo without this raised lip .

[Edgemontvillage]

Yes, you're correct Mike, I've mixed up the descriptions and yes my Z is a 2B Norwood car. Here is the GM casting from my buddy's 403. You'll note the letter font is different from the one on my bellhousing

[rszmjt]

Thanks very much Lloyd.  It’s weird they changed the GM font, I’m wondering if GM had 2 casting plants, I’ve been keeping a small record of 403 bellhousing differences for quite awhile .

Cheers and Stay Safe.
Mike.

[firstgenaddict]

Were there any right hand drive chevrolets built?  Would explain the boss on the right.

[x66 714]

Were there any right hand drive chevrolets built?  Would explain the boss on the right.

I thought of that also but there is no fork hole...Joe

[DAVEN1256]

In reply #10, I said that had I found three companies in the Orlando, FL area that did dustless blasting and that I was going to check out the one that seemed the most promising.

Well, that didn't work out so well. I thought I had communicated with the  guy over the phone the finish I was after. Maybe his idea of what a "satin" finish was and mine were two different things. When I got there, the guy I spoke to on the phone was not there and but a couple of his workers were. When I started talking to them about what the final finish would look like, what they told me didn't sound right. I asked them to hit a small area on the inside of the bell housing so I could see what it would look like. It was nothing like what Lloyd's vapor blasted bell housings look like! It just looked like basic blasting. Rough and dull. So I politely thanked them but told them I didn't want to do it. They were nice guys and said no problem. It didn't cost me anything, just some time!

So the one thing I learned from this is that dustless blasting and vapor blasting are not necessary one and the same. I'll have to check if there are any others who do vapor blasting in the area. This time though, I would send them the picture of Lloyd's bell housings and be sure that's what the finished product would look like before even leaving the house.

This was never something I was looking to put a lot of effort or money into. I wanted to check out the vapor blasting since it was mentioned and the results looked great. If the blasting doesn't work out, I'm still willing to go with paint and still looking for a suggestion on a good aluminum replication paint.

Thanks.....Dave

[68camaroz28]

Dave, what Lloyd showed is one of the best ways and of course there is Jerry M who has what he call re-skinning (might be a vibratory deburr type that uses plastic stones), and there is a NCRS person who offers the same type of treatment. Or what can be done is glass beading but at 30-40PSI max. At that low pressure it does not etch the aluminum but the drawback is its size as it takes time. Small pieces I have used this method and it works well. For example look at my build thread for "radiator clutch fan" and that aluminum piece was done at 20PSI. JohnZ years ago mentioned that and it works but again a slow operation for a large piece like a bellhousing.

[69Z28-RS]

PRESSURE matters...  no matter what the medium is...