Thanks for the Forditude boost

[Milton]

I knew I had to to do it. I had never done it before. But now I have and I owe many thanks to a couple of esteemed members on here. I had to work up my courage and gain some insight into what lay ahead and that is when Tom Endy came to my rescue with help from Marco Tahtaras. I found and read Tom's "Differential (Rear End) Restoration (Revised 2008)". This was just the forditude booster I needed. I also found on Marco's website a warning against chasing theads, which I would have done. This is the first time I had ever opened a rear end. I built a spreader and proceeded to open it up. Would you believe?

Well at least I didn't have to undo the carrier bolts.

[Chris in WNC]

interesting that the loose pieces never bounced up into the right position to lock everything up tight, or at least lock up one wheel.......

[Farrell In Vancouver]

I am amazed the entire housing didn't blow up?! Took a lot of force to break five of the carrier bolts off!
Well Milton, now that you know what happened, the real learning curve starts. I too read Tom's informative articles and found them invaluable. Take your time and soldier on, you'll be on the road again in no time!
Good Luck!

[Tom Wesenberg]

How long have you owned the car?

Any idea what led up to this?

I've never heard of carrier bolts breaking.

[Milton]

Originally Posted by Tom Wesenberg

How long have you owned the car?

Any idea what led up to this?

I've never heard of carrier bolts breaking.

I aquired the car three years ago last month and had it on the road two months later. Until the ring gear broke there was no discernable clue that it was failing. I had turned the wheels by hand when adjusting the rear brakes and spun the wheels under power to check the speedo and never heard nor felt anything out of the ordinary. Even after the gears failed I had it jacked up with the wheels spinning and using a screw driver for a hearing aid I could not really hear any noise.

I drove a bolt remnant out of the ring gear and the shoulder was deformed. This tells me that it had been broken for some time. According to Tom Endy's article early and late carrier bolts are not interchangable and the bolt orientation is opposite between the two carrier styles. Anyway, I think that is what caused the failure. It just took awhile to manifest itself since the axle housings wouldn't allow it to seperate and fall apart.

[Milton]

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"interesting that the loose pieces never bounced up into the right position to lock everything up tight, or at least lock up one wheel......."

Very true Chris, especially since I had to limp it home for 10 miles. Fortunately the carrier rotation is prone to push the 600W and the larger fragments back away from the pinion/ring gear mesh area.

"I am amazed the entire housing didn't blow up?!"

I certainly agree Farrell, as I removed the left axle housing the ring gear, axle, carrier half and the spiders all fell out onto the driveway. It appears that a small reinforcement web at the top of the carrier bearing race seat was a main point of impact for the carrier bolts. The bolts were the late style, rectangular head, and the carrier is an early version. I believe the bolts snapped early on after a previous rebuild and the axle housings held it together until it finished itself off.

[Tom Endy]

In the photo showing the flat side of the ring gear at the very bottom you can see where a number was inscribed free hand by some kind of vibraring tool. I have seen this on numerous original Ring gears. Usually you cannot see the number until the gear has been cleaned. This number should match a number that is stamped onto the end of the pinion gear.

My theory is that when the R&P was installed at the factory the worker took a pinion gear from stock that had a number stamped on it. He then inscribed the same number on the flat side of the ring gear he pulled from stock, thus they became a matched set and indeed were matched after a few hundred miles of operation.

I have seen these matching numbers, as such, so many times I am sure it was not a random thing, but a called out procedure. Is there anyone who has more knowledge of this?

In the failed unit above, as mentioned, the carrier is the early style and the bolts are the later style. The bolts were installed backwards. The early bolts have a domed head that notches into the carrier. It is not a good idea to mix early and late carrier hardware, it may have contributed to the failure.

Tom Endy

[d.j. moordigian]

Originally Posted by Tom Endy

In the photo showing the flat side of the ring gear at the very bottom you can see where a number was inscribed free hand by some kind of vibraring tool. I have seen this on numerous original Ring gears. Usually you cannot see the number until the gear has been cleaned. This number should match a number that is stamped onto the end of the pinion gear.

My theory is that when the R&P was installed at the factory the worker took a pinion gear from stock that had a number stamped on it. He then inscribed the same number on the flat side of the ring gear he pulled from stock, thus they became a matched set and indeed were matched after a few hundred miles of operation.

I have seen these matching numbers, as such, so many times I am sure it was not a random thing, but a called out procedure. Is there anyone who has more knowledge of this?

In the failed unit above, as mentioned, the carrier is the early style and the bolts are the later style. The bolts were installed backwards. The early bolts have a domed head that notches into the carrier. It is not a good idea to mix early and late carrier hardware, it may have contributed to the failure.

Tom Endy

Tom,
This is an NOS set, the pinion is a little ruff, but the ring gear is great.
I believe the numbers were done with an "electric pencil", that etches.
I also believe the numbers were written on the gears before lapping,
as opposed to the "T's"...any gear will work with another...no sets.
Just my opinion.
Dudley

[Milton]

Tom,
On reading your reply I went out and checked the pinion. It was stamped with a "50" on adjacent teeth. The number etched on the ring gear is "593" which doesn't surprise me. You can see in the carrier photo that the two carrier halves are different at the spider yoke area. That leads me to believe that in the past someone built/rebuilt the differential from random parts (maybe a junk yard vendor between OK and CA). Is this carrier arrangement something that you have come across before?

Again, thank you for your informative article. The "Part number cross-reference" alone allowed me to get the pinion cone and bearings through Autozone and save $50.

[GordonJ]

To Dudley's comment - having purchased axles for Ford for nearly 5 years, the standard process for North American axle manufacturers today (and probably for many, many years prior) is to machine the ring and pinion independently, bring them together and run them through a lapping operation. This an abrasive slurry that flows over the gearset, removing inperfections and "mating" the two components together - highs to lows and lows to highs. From that point forward, the set needs to remain together. This would explain scribed or stamped numbers on the individual components if they were a replacement set. In normal assembly plant operations, the sets are packaged together such that they are picked and assembled together.

For those who care, the other method of making axle gearsets is to machine and grind. This process is most often found in European axles. In this process, the gears are machined first and then put into a grinding machine to finish the gear lands. The action is so precise that the individual components do not need to be mated and can be picked independently for assembly into the axle. Why aren't all axles made this way? Many, many reasons. Primary reasons are Grinding is a little more expensive and grinding leaves what some have described as a "harder" gearset. This really has nothing to do with material hardness, but more of a feel or sound of the gearset. The ground gears are described as harder and potentially louder because of the precise fit of the gears as they lock together and the lapped gears are described as softer and quieter because the gears tend to flow into each other since they are less perfect but mated together. Design Engineers tend to feel strongly about one approach or the other but the only real difference I ever saw was that ground gears were used in performance applications while lapped gears were used in everyday vehicles. Another interesting sidenote told to me by a gear design consultant was that ground gears can sometimes be so precise that if not properly designed, they can act like a bell in operation - like striking tuned metal with a metal hammer.

Enough axle trivia...

[Milton]

Update! The rearend went fine (I think). The rear brakes were a mess so I did some temp work on them. A cam was frozen so I got that freed up. The adgusting shafts were two different lengths with the wedge ends destroyed so they got welded and ground down to be equal. The e-brake arm wear was filled in with JB weld and the brake arm got shimmed with some Pepsi can material. All of this was on one side, the side that I couldn't tighten to adjust the brakes. A clothes hanger centering tool and they work and that buys me time to figure the best way to do a permanent fix. Farmer fixes got nothing on country boy fixes.