Bead Blast Assembled Differential

[Bill L.]

I was planning on using POR 15 over the rust and cast blast paint on the differential since there is nothing wrong with it and the seals have been replaced.

Can a fully assembled differential be safely bead blasted? If so I may rethink and use Pre lube 6 to protect the bare casting. I will tape off the plated parts and use temporary bolts for the blasting.


Thanks,


Bill

[Gary R.]

Re: Bead Blast Assembled Differential

Bill,
I blast diff's but only when apart. I suppose it can be done if you seal up the vent and seals but I don't recommend it. I can't say I like the Pre Lube 6 much either, it is an aircraft cable lube and is meant to stay wet. On a bare iron diff that will be built as a natural finish I use Fluid-Film, soak it into the bare iron for 30 minutes, then buff it out with a towel. Leaves a wax like film on the iron with out any appearance of a sealant.

[Bill L.]

Re: Bead Blast Assembled Differential

Hi Gary,

I was thinking of using rope caulk and press it in to the seal areas to keep media out and then tape off the metal part of the new seals. I was even thinking of using one of the 3M scothbrite pads that fits in a drill to remove most of the rust first to minimize blasting. I experimented with the drill and the cast iron cleans up really well but it ends up too shiny. I have been trying to figure out if there is a way to take the shine off to avoid blasting before using Fluid-Film. RPM on the bare casting sounds like it might be worth a try too. Camaro and Mustang guys seem to love it.

Any thoughts?

Thanks,


Bill

[Gary R.]

Re: Bead Blast Assembled Differential

Hi Bill
I still would not attempt it on an assembled diff but it's your choice. I'm sure others have done this but if any bead gets by it will wreck the seals and bearings inside. Just not worth the risk to me. Have you ever disassembled a diff before? I have also wire wheeled them to clean them up, that is what I on the inside in fact. I don't know how that PRM works but it does sound interesting enough- I may get some and try it. For NCRS T/A's the supports where natural so it may be an option there, although for a street driven car the POR15 prep and top coating works pretty good and is easy to touch up if needed.

[Ron G.]

Re: Bead Blast Assembled Differential

Bill,

Gary is right. The only way to it is have it all disassembled. Media flys every where. Even when you think you have it all taped and protected. Been down that road.

[Bill L.]

Re: Bead Blast Assembled Differential

Bill,

Gary is right. The only way to it is have it all disassembled. Media flys every where. Even when you think you have it all taped and protected. Been down that road.

I do know I can get it back down to the raw casting with a 3M pad in a drill. However, it ends up with some shine. Any ideas on dulling it down before I try the RPM?

Thanks, Bill

[Tracy C.]

Re: Bead Blast Assembled Differential

Naval jelly might help with the rust. Overnight soak followed by Hot soapy water and a stiff brush.

[Bill L.]

Re: Bead Blast Assembled Differential

Thanks Tracy.

I can get the rust off ok. I am just trying to dull it down before I try some treatment to keep it from rusting.

Bill

[Donald H.]

Re: Bead Blast Assembled Differential

I have used muritic acid to tone down something that was to shiny or bright. I bought a jug of it at Home Depot. It's not something you want to breathe, so if you try it, do it outside. You might try a small test spot that you have already cleaned with the 3M pad. The acid will etch the cast iron some. Don't let it set long. Try a minute or so, if that doesn't work let it set a little longer. Rinse with water and dry it good. I might even use a heat gun to make sure you don't have any residual water to start the rust process again.

I'm not chemist, so I don't know if there is any reason otherwise to not do it.

Don.

[Terry M.]

Re: Bead Blast Assembled Differential

I do know I can get it back down to the raw casting with a 3M pad in a drill. However, it ends up with some shine. Any ideas on dulling it down before I try the RPM?

Thanks, Bill

If the 3M pad you are talking about is the abrasive "cookies" I am familiar with -- be very careful. Abrasive flies off of those too, and if it gets inside the assembly it will be no less harmful that the blasting media. I don't think there is a low to no risk way to do what you want without disassembly -- however Clint Eastwood (in his youth) said it best: "Do you feel lucky ..."

[Mike E.]

Re: Bead Blast Assembled Differential

I hate to be a kill joy but if I wanted the differential to really look good IMO it should be taken apart and all rusty surfaces media blasted. Cleaning yokes and all the nooks and crannies to make it look like new without taking it apart could be difficult if not impossible. I know a guy that I trust to take the guts out of the case and put it back in for not that much cost, as most folks probably do too. While he’s at it he can and should look at the posi clutches, bearing, side yoke and seals. A side yoke failure could be catastrophic, I saw this image of one on Corvette Forum.





Any Corvette that has a cast iron differential is at least 34 years old. The seals should at least be checked or replaced unless it’s a Bowtie/Survivor then it shouldn’t be cleaned anyway from what I understand of the rules.


Mike

[Bill L.]

Re: Bead Blast Assembled Differential

Good Advice Mike,

Already had it opened up and checked out. At the time I was planning to just use POR 15 and top coat with cast blast. However I really like what I hear about RPM so now I thought I might try to clean it up. The side yoke seals were replaced when apart. I left the front yoke seal intact as it had no signs of leaking. I replaced the driver's side yoke assembly as it had too much play and was close to hitting the case. Glad I caught it before it destroyed the case.

I hate to open it up again so I think I have to decide whether to stick with my original plan or use the red scotchbrite pad in a drill to remove the rust before trying RPM. I experimented on a very small area and it cleans up nicely but has some shine to it that is too much. I use the black pad to remove the tougher rust and a variety of small wire wheels to get in some of the tougher areas to get in to.

What do you consider not that much cost? If I could get it done for under $100 I would do it in a heartbeat. Just don't see spending $250-$300 to have it cleaned up.

Bill

[John H.]

Re: Bead Blast Assembled Differential

I hate to open it up again so I think I have to decide whether to stick with my original plan or use the red scotchbrite pad in a drill to remove the rust before trying RPM.

Bill -

Scotchbrite residue is the kiss of death for bearings, seals, and machined surfaces - it's like diamond dust; I wouldn't use it at all.

[Bill L.]

Re: Bead Blast Assembled Differential

Bill -

Scotchbrite residue is the kiss of death for bearings, seals, and machined surfaces - it's like diamond dust; I wouldn't use it at all.

Geeze. Sometimes the truth hurts/costs At least I got my answer!

Bill

[Terry M.]

Re: Bead Blast Assembled Differential

If the 3M pad you are talking about is the abrasive "cookies" I am familiar with -- be very careful. Abrasive flies off of those too, and if it gets inside the assembly it will be no less harmful that the blasting media. I don't think there is a low to no risk way to do what you want without disassembly -- however Clint Eastwood (in his youth) said it best: "Do you feel lucky ..."

Bill -

Scotchbrite residue is the kiss of death for bearings, seals, and machined surfaces - it's like diamond dust; I wouldn't use it at all.

Geeze. Sometimes the truth hurts/costs At least I got my answer!

Bill

You are believing us now? Or do you need me to tell you how I know?