Hello,

I'd like to share some pictures on why it's important to change gear oil more often than once every 5 decades.

This donor vehicle is partially a parts car, which is a long story, but I wanted to save some money by scavenging parts from this car's 3rd member to build my custom 9 inch axle.

Well here's what I was greeted to when taking it apart. Mind you, this car was unearthed from an Indian reservation of which it had sat since 1972. Someone had already removed its FE 352 engine when we bought it.

There was so much crud on everything I couldn't get to the bearing through the backing plate and ended up removing them with the axles. What's really surprising is that after 50 years in the desert, the brake line unscrewed, by hand no less, from the wheel cylinder once nudged loose with a line wrench.

That's the oil coagulated on the axle shaft.

The smell was unbelievably rancid!

It's "The Blobs" new home it seems. I had to scoop it out; it was hardening.

If that's not reason to change your axle oil more often, I do not know what is. I know it's a pain in the arse to take the third member down and more painfully to put it back up into place. I did this on my back and almost had a coronary lifting 85 pounds back in. One more thing, the wheel bearings on this 9 inch do not share axle oil and are packed independently with lube. And after 50 years, those bearings need replacing — they were not happy or healthy. I would never try to actually use this rear end without replacing all the bearings and seals.

As a side note, I couldn't use this third members housing as it's the light duty 9 inch (28 spline and small wheel bearing.) The 28 spline third member has smaller differential bearings than the diff for 31 spline axles, plus this is not a nodular iron case, so I bought one from Summit. I did however use this pinion support and galaxie yoke which saved me 250 to 400 dollars from having to buy those new.

I did clean everything I took out and had a Lincoln pinion support and companion flange I put back on to keep water, dust and dirt from getting back in even though it's a parts car.

I found it interesting that even in the 1966 galaxie line up, that Ford both used light duty, heavy duty 28 spline axle shaft housing and diff, and then a 31 spline axle shaft with larger bearings on the diff and third member.

At first I thought the lightest duty 9" was only for the models with the 6 cylinder and small Windsor, but it turns out that our two 1966 Galaxies with the 352 and FX transmission also came with the light duty 9". Only our Galaxie with the 390 and C6 had the heavy duty 28 spline 9 inch. And of course none of them were 31 spline or with the "N" or nodular iron (strong) third member.

But the most important lesson is to change the oil. What a mess that was to clean up!

The end.

Further Thoughts :

The Ford full size line with the Q code would have come with a 31 spline axle shafts and most likely the matching "N" nodular iron third member case along with the large bearing axle housing.

Most of the 9" series rear axles are sealed ball bearings with the seals inboard of the bearings. There are a few instances of the 9" that use tapered bearings and seals outboard.

Just measure the bearings before you order them as there are different size axle bearings. Although chances are with a small block it is the small axle shaft bearing, but it's a good idea to check none-the-less.

Even though I wasn't able to use the third member case above for my new 9" axle housing for my Caprice Classic I was able to use the pinion support and the yoke from the spare parts car galaxie which saved me about 300-400 dollars depending on what type I bought new.

Still a new nodular iron third member case was only 210 dollars. That wasn't too bad I suppose. Until I needed a new axle in the Caprice, I never thought it would be this much to buy a brand new one. Just a case of one thing leads to another. It'll be about $3,000 now just to replace the axle with new disc brakes as I couldn't even use the old drum brakes from the existing axle. Rats.

About replacing the bearings on your 9", you really can't press off the old bearing and retainer. You can carefully crack off the outer race of the old bearings, remove the balls and cage, then use a die grinder to slice through most of the inner race, obviously be careful not to nick the shaft, then use a chisel to crack the inner race and the bearing retainer and then they just slide off.

You'll need a press to put on the new bearings and retainers. It's very much like a 12 bolt GM axle if you have ever replaced those bearings.

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