Bead blasting alum transmission case?

I have a Boxster S transaxle which appears to be fairly oxidized. I would like to make it look nice and clean but not too shiny before installing, not looking for mirror like finish.

I have tried various methods for achieving the look I want and found the best outcome so far has been using a wire wheel on my drill, challenge is its very difficult if not impossible to get into the deeper recessed areas.

Now I'm considering glass bead blasting but would like some input from the brain trust, will this get me the look I want?

I realize the importance of protecting any openings from material entering where it shouldn't be, but assuming this is a viable method of getting the results I'm after is glass bead the best choice and if so any suggestions as to grit and psi to use?

Thanks,
Mike
 

Cliff Beer

Supporter
Mike, I think you'll find walnut shells or silica will get it clean in the all nooks and crannies, and leave the case looking a nice semi-dull shade.

Yes, absolutely, keep the media on the outside of the case!
 
Thanks Cliff, I will do more research regarding walnut shells and silica, hopefully others with experience doing this will chime in.
Mike
 

flatchat(Chris)

Supporter
Have you thought about the blasting media of sodium bicarbonate (soda blasting) or Co2 (dry ice blasting)
efficient cleaning and no risidual mess :thumbsup:
 
I was told by a blaster not to soda blast cast aluminium can't quite remember why but so somthing to do with the alkalinity iirc?

I have just glass bead blasted my RPM Manifold and it looks like new if that helps
 
Mike:
There is a mild acid I use to clean aluminum as a prep for welding. Spray it on with a spray bottle..let it foam up and rinse with water.
It is also also used to brighten aluminum at the truck washes, my local napa has it in gallons but you probably need a quart at most.
Cheers
Phil
 

Gordy

Lifetime Supporter
I am finishing the restoration of a Lotus 61 FF. I have tried walnut shells, plastic media and silica in past projects and found that glass beads do a superior job.

Like the others have mentioned, if the case is not completely apart and bare, it is imperative that you seal any possible openings. And a side benefit of glass is very little dust and a two second cleanup with a blast of air.
 

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Thanks very much for your input, from most of the research I've done it appears that glass beads have been the method with the most positive results but hearing first hand results is more assuring.

I am finishing the restoration of a Lotus 61 FF. I have tried walnut shells, plastic media and silica in past projects and found that glass beads do a superior job.

Like the others have mentioned, if the case is not completely apart and bare, it is imperative that you seal any possible openings. And a side benefit of glass is very little dust and a two second cleanup with a blast of air.
Gordy, this is a nice looking result you achieved, can you share with me what you used to protect openings (if you had to) as well as which grit and PSI used?

Thanks again for the help,
Regards,
Mike
 
80-120 grit glass beads and at least 65PSI will do the job if you go that way.
I have used a spray & wash-off product called Toonbrite, for cleaning aluminum pontoon boats. It works well and leaves a flat gray finish. Not expensive either
and sold by the quart. Simply follow the directions.
 

Gordy

Lifetime Supporter
What Jack Said !

I use 100 grit beads and 80 PSI, although you can go a little higher PSI without problem.
You can also vary the amount of shine by how long you blast an area and how close to the surface.

I clean around any possible opening with brake clean and fine steel wool, which in and of itself shines up the aluminum nicely. I then use Gorilla tape to seal any area I don't want to blast, sometimes using two layers. The stuff is tuff!

For the most part there are not many openings on a transaxle, and I don't direct any spray at the inside of the bellhousing or input shaft area, even though I tape them up carefully. Just check any vents or seals that may be exposed and cover or plug them.

Silica sand has a tendency to abrade the surface and leave microscopic pores to collect dirt and grease . Glass beading seems to work more like shotpeening and seals the surface.
 
I was told by a blaster not to soda blast cast aluminium can't quite remember why but so somthing to do with the alkalinity iirc?

I have just glass bead blasted my RPM Manifold and it looks like new if that helps
 
Thanks once again for all the input fellows. I'm looking forward to giving this a try. I will test blast the mounting bracket first to identify what will net the best look but it sounds like glass bead (80-120) grit starting with 60 and working up, if necessary, to 80 or so PSI.

I will vary the distance of the nozzle to the piece and be sure to protect any and all openings or exposed areas from contamination, including me. I will post my results with photos once completed.

Regards,
Mike
 
Mike I am from Newmarket I would love too see your build in the summer I can drive mine over. Joe is in orangeville we could get him to come too.
 
Thanks once again for all the input fellows. I'm looking forward to giving this a try. I will test blast the mounting bracket first to identify what will net the best look but it sounds like glass bead (80-120) grit starting with 60 and working up, if necessary, to 80 or so PSI.

I will vary the distance of the nozzle to the piece and be sure to protect any and all openings or exposed areas from contamination, including me. I will post my results with photos once completed.

Regards,
Mike
Suggest that you use a resperator as well. Those glass beads turn to dust. Keep that stuff out of your lungs! Make sure to blast outside. 65PSI minimum, 80 is better.
 
Mike I am from Newmarket I would love too see your build in the summer I can drive mine over. Joe is in orangeville we could get him to come too.
Would be nice to see your car, keep in touch and we can arrange a get together.
Regards,
Mike

Suggest that you use a resperator as well. Those glass beads turn to dust. Keep that stuff out of your lungs! Make sure to blast outside. 65PSI minimum, 80 is better.
Yes indeed, thank you for the suggestion.
Regards,
Mike
 
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