Differential clean-up method

[Steve L.]

My diff is on an engine stand. I want to replace the yoke and pinion seal and proper rear cover since the ears are broken. The yoke play is around .020"

It worked fine before the restoration so I don't intend on doing anything else other than go through the checks that Gerry has suggested once the cover is off.

What's a good way of cleaning up the exterior. I'm afraid of sandblasting because of contamination. So far I've just wire wheeled it to get the first layer of crude off.

Once cleaned,I was thinking of a light spray of clear.

What about soaking it with phosphoric acid for a short time- I know about hydrogen embritlement, but for a short time maybe this is acceptable.

Just looking for ideas.

[Chuck S.]

Re: Differential clean-up method

My diff is on an engine stand. I want to replace the yoke and pinion seal and proper rear cover since the ears are broken. The yoke play is around .020"

It worked fine before the restoration so I don't intend on doing anything else other than go through the checks that Gerry has suggested once the cover is off.

What's a good way of cleaning up the exterior. I'm afraid of sandblasting because of contamination. So far I've just wire wheeled it to get the first layer of crude off.

Once cleaned,I was thinking of a light spray of clear.

What about soaking it with phosphoric acid for a short time- I know about hydrogen embritlement, but for a short time maybe this is acceptable.

Just looking for ideas.

Define "crude"...Is this caked on grease and dirt (what I would expect on a differential), or rust? Sandblasting is a bad idea. Acid will not remove grease...it will not even touch grease. Acid will remove rust, but I can't imagine rust is the problem with a differential.

If you're cleaning off caked grease and dirt, seal up the pinion and yoke areas well. I would cover the seal area with a short length of absorbent cloth, and wrap the cloth well with duct tape. Soak the caked grease and dirt with mineral spirits by brushing it on liberally several time. Let it soak for awhile, then try cutting off the accumlation with a steel scraper...don't worry about using a steel scaper; you won't hurt the cast iron. I would avoid hacking or stabbing action. You may have to repeat the soaking/scraping steps several times to get to the original cast iron.

[Pete B.]

Re: Differential clean-up method

Mine was grimed up and coated with heavy rust in spots (corners) but it was mostly just surface.

I did sand blast it but not before wrapping the side yokes and the pinion with several layers of duct tape. This prevented the sand and grit from getting close to the seals. Seal up the vent good too.

When i got it back, disassembled it, cleaned up the yokes and pinion, flushed it, resealed it, replated the cover bolts and lightly wire wheeled the outside to make it look more "as cast"

So far so good.

[Gary R.]

Re: Differential clean-up method

I blast, etch,POR15, and paint mine. I only do it as a bare housing and tap a drain as well. Not correct but sure easier to maintain and won't rust.

[Steve L.]

Re: Differential clean-up method

Thanks for everyone replies.

I had bought a used rear cover, had it sand blasted and magnefluxed. It looked good. Then stored it for 2 yrs inside my garage. Today, just sitting there, there is a lot of surface rust inside and out. The garage is built into the house so it is fairly warm all year.

A knotted wire wheel easily cleaned it up in less the 10 minutes.

As Garry says, I wish I could just POR it. But it just wouldn't look right.

BTW Garry, thanks for your excellent write-ups on diff's and TA's. I followed your instruction on the TA's and will do so on the diff.