Differential Catastrophic Failure

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration
Model T Ford Forum: Forum 2017: Differential Catastrophic Failure
Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Monday, May 08, 2017 - 07:49 am:



Several months ago, we were driving the '18 Touring and heard some unsettling noises. we stopped, but couldn't find anything wrong, so we continued on home without incident. A couple of weeks later, we went to back it out of the shop. It got outside, but then didn't want to move in reverse any further. No noises really. Just wouldn't move. I tried going forward and it moved about 2 feet and never moved on it's own power again. We pushed it back inside. Later, I did some quick checking and determined that the problem was definitely in the rear end, as the drive shaft would turn but the wheels wouldn't and the axles were not turning inside the hubs. Definitely an internal problem. I figured a split pinion.

Well, due to other hobbies and obligations, we haven't worked on it until yesterday. So we pull the rear end out and disassemble it. When pulling the housing apart, this is what I found. The carrier is in at least 15 pieces, and that was just the ones big enough to count. All the bolts were still safety wired except one ring gear bolt whose head had been sheared off flush with the carrier flange. The only other OBVIOUS thing I found wrong inside was both axles had worn badly where the bearings roll. I have not cleaned everything up and made any further checks, but that is all I KNOW is wrong with it.

Background:
I did a shadetree rebuild on the axle when we got the car 7-8 years ago. I say "Shadetree" because I did cut some corners. I reused the ring and pinion and also used a housing that had a slight warp to it. It's been so long now I don't recall the details, but I remember using heat on the housing to straighten it. I got some of the warp out of it, but not all. When installing one of the outboard bearings, it wouldn't just "fall" in, but went in without any real undue force. I mean I didn't have to use any tools to pry the axle off to one side or anything like that. I just had to kinda push it with my fingers and the bearing went on in. I figured it was good enough. New parts used in the rebuild included bronze thrust washers, bearing sleeves, both axles and drive shaft, modern pinion bearing and the bearing up on the front end of the drive shaft.

So.....what do you guys think caused the carrier to disintegrate? Was this caused by my ever so slightly warped housing? What about the wear on the axle shafts? Was that caused by the slightly warped housing or were they too soft? One other thing I did not mention, was that I shimmed the ring gear to the carrier. I have since read where that is not recommended, but didn't know it at the time I did it. Like I say, all the bolts were still tight and safety wired with the exception of the one with the sheared head. I don't know if that was the cause or just one the effects.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Monday, May 08, 2017 - 08:23 am:

Warped housing gets my vote. Every rotation it was flexing/moving the internal parts and the carrier eventually gave up the ghost.

Not sure why you're not supposed to shim the ring gear? On a Ruckstell you HAVE to shim the ring gear. That's the only way to get the ring and pinion clearance correct.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Wrenn-Monroeville OH on Monday, May 08, 2017 - 08:51 am:

I'm no expert by any means, but I agree with Seth..the second I read the word "warp" my eyebrows raised while the hairs on the back of my neck raised. I'm sure putting heat to it didn't do any good either. Wonder it lasted this long.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Monday, May 08, 2017 - 09:40 am:

Odd,
How much oil was in there?
If the bend in the housing was so slight that you could push in the outer bearings without really forcing the axle to the side, then there shouldn't be much strain on the carrier - only a little on the axles. Usually the carrier is worn a little so the axles can flex enough to not put any strain on the carrier. But maybe the carrier had been through another rear axle failure before you got it so it was full of small cracks that eventually grew until it broke apart.. But still odd, the ones I've seen seems sturdy and not very crack prone.. Maybe a faulty casting that day at the Ford factory that didn't show until now, almost 100 years later?

Another reminder that we need to practice to use the emergency brake anytime, no one knows when something in the driveline decides to fail..


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Monday, May 08, 2017 - 09:52 am:

I think I can answer at least one question. Were the axle shafts too soft? If they were original Ford parts I think the answer is NO. I think the leading suspect there is the warped housing. The axle book specifically warns about making sure they're straight. You certainly came up with an interesting catastrophe. It's not unusual to hear of other parts failing, but I think a disintegrated carrier is a rare achievement.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Monday, May 08, 2017 - 10:18 am:

Sorry about your carrier failure, hope your touring is back on the road soon.

I feel much better about Betsy's axle shaft break now. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe Helena, Montana on Monday, May 08, 2017 - 10:32 am:

Too bad to hear and see, glad you weren't hurt or didn't tear it up worse.

Seth, the Ruckstell is designed to go together with correct clearances and no shim anywhere. The reason clearances are off is usually due to the Bronze plate being bent in slightly, making the ring gear set closer to the housing the bearing goes in. If all parts are correct, they go together with no shims and the clearance is correct.

By the way, the Ford dealer flat rate for installing a Ruckstell was ONE hour. A lot of places they could do it in less than that.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Monday, May 08, 2017 - 10:37 am:

It was full of 75/140 gear oil. This one had the filler on the centerline. Oil level was up to where you could touch it with a bent finger through the hole.

Axles were not Ford. I don't recall which vendor I bought them from. Almost certainly either Langs or Sniders.

The straightening technique involving heat was gotten from either the MTCFA/MTFCI Axle Book or else from this forum. I don't recall, now, as it's been several years. Actually, I don't remember exactly what the technique was, but I remember heating the tube 2-3 times trying to get it straight and finally deeming it "Good Enough". But that may have been faulty reasoning. As it would appear I will need to visit THAT again here soon, I am certainly open to other/better techniques on straightening a warped housing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Smith, Lomita, California on Monday, May 08, 2017 - 10:40 am:

Sorry to hear of your incident. Axle housings are commonly bent, and should be straightened. Shimming the ring gear is not what Ford did, and should not be done. Read the Ford Service book, it pretty well covers it all. The only place I know of that straightens housings is the Tin Shed in Santa Fe Springs, California. You might check with Dan Hatch in Alabama. He may be of help.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Kossor - Kenilworth, NJ on Monday, May 08, 2017 - 12:59 pm:

Sorry to learn of your rear end woes Hal. Glad you were near home when it finally failed and no one was injured. Good luck with the repair and appreciate learning from your posting with the details.


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Menzies on Monday, May 08, 2017 - 02:49 pm:

Are all the spider gears in tact? I was reviewing some spider gears I have and one is relatively thin I was wondering if a spider gear split?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Monday, May 08, 2017 - 04:09 pm:

It could be that it was nearly 100 years old.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem - SE Michigan on Monday, May 08, 2017 - 04:09 pm:

Hal,

We'll all know more once you get everything cleaned up and inspected. The rear end in my Roadster looked like that. Just after dad bought it, he drove it home, maybe 50 miles. He didn't think it sounded quite right. Opened up the rear and everything fell out in pieces. It was all held together by being squeezed between the thrust bearings. Probably like that for a long time. You may never find the root cause and it really doesn't matter as long as you put it back together right. I really don't believe your slightly warped housing was to blame, nor soft axles or used gears. Sometimes things just break after 100 years of use. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Monday, May 08, 2017 - 04:44 pm:

Hal

Might the tip off be of that only one sheared off ring bolt head?

As you posted all the others intact and wired. Was the wiring in pairs like Service Book?

Just perhaps that bolt head aged with torque applied decided to leave.

Worked its way into the diff. case like a depth charge and got caught among the gears whirling inside and torpedoed that rear end.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Monday, May 08, 2017 - 08:52 pm:

All,
Thanks for the condolences and well wishes.

David,
Yes, all three spider gears were intact.

Dan,
That certainly sounds plausible. Yes, they were wired in pairs, and the wire was still attached to its mate.

I'm not sure when I'll get back on it. Probably not before the weekend.

I wonder what caused the wear on those axles? What little force there was due to misalignment in the housing would have paled in comparison to the weight of the car pushing down on that axle. I really wonder if they weren't too soft. Does anyone know the hardness spec? I think I can get them checked at work. If not, I think I know a machine shop that would check them for me.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie Spokane, WA on Monday, May 08, 2017 - 09:23 pm:

I believe the root of all of the trouble is the shimmed ring gear. I've seen what happened to you happen many times. The ring gear drives the carrier through friction, not from the shear strength of the attaching bolts. A shim adds two surfaces. These extra surfaces divide the friction.

This allows the ring gear to slip. When the ring gear slips, even microscopically on the carrier, that puts stress on the bolts. They tip sideways, ever so slightly which puts stress onto the bolt heads. Eventually, a bolt will shear, or the head will pop off. In your case the head popped off and then must have gotten between the ring and pinion. Usually the safety wire doesn't allow this happen, so how it happened is somewhat of a mystery to me. There are two types of carriers. The "stud" kind and the "bolt through" kind. The "stud" kind is much weaker. I can't tell from your picture, but I presume that you have the "stud" kind and it just gave up when the nut head went through the gears.

Sometimes several bolts will shear and the driver doesn't realize it. Finally the last few bolts that are driving the case suddenly and give up - usually during a hard stop. Very dangerous. I have been preaching against ring gear shims for years. Some folks think I'm nuts, but I know I'm right about this.

A Ruckstell with a worn housing can be shimmed behind the ball bearing, by the way.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe Helena, Montana on Monday, May 08, 2017 - 11:15 pm:

You are right. Another way to shim a Ruckstell is with a shim behind the ball bearing between the bearing and the bronze plate. The problem with that -- as I see it -- is the every time you try a thinner or thicker shim you are pressing the bearing off the boss, which will eventually loosen the bearing ever so slightly. I do not do that but I've seen a lot of them shimmed there. .


Top of pagePrevious messageNext messageBottom of page Link to this message  By Nevada Bob Middleton on Monday, May 08, 2017 - 11:56 pm:

If the tube is bent that bad the outer bearing be tight to roll and it would bind is you spun the ujoint
I say more thrust washer failure or a cracked part was used that failed


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Tuesday, May 09, 2017 - 07:41 am:

Tom,

The studs you are referring to..... do you mean what holds the ring gear to the carrier or what holds the two carrier halves together? The ring gear was definitely held on by bolts, not studs and nuts, and it was one of those that the head popped off of. As for the ones that hold the carrier halves together.......I'm pretty sure those were bolts, too, but I will have to verify that.

What you say makes sense. I think I may have used the word "Shear" above, but the bolt was not "sheared" at the joint between the ring gear and the carrier. It was broken off flush with the carrier flange. In other words, all that broke off was the head. No shank at all. It just popped the head off like you described. After I got the ring gear off the carrier, I removed what was left of the bolt with my fingers, as there was 1/4" or so sticking out to grip.

Assuming this is what happened (And it all makes sense, so I don't believe it's a bad assumption), a possible explanation for why the bolt head got loose from the safety wire is that the head popped off the bolt as you described above. It was then whipping around inside on the end of the safety wire and either wore through the wire or else impacted something hard enough for the wire to break and the head came off the wire.

Nevada Bob,

There certainly could have been a crack in the carrier, but definitely no thrust washer failure. They were modern bronze bearings and are still intact.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie Spokane, WA on Tuesday, May 09, 2017 - 11:09 am:

Yes, to clarify, the carrier is either held together with three bolts (good) or three studs (not as good).


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dick Fischer - Arroyo Grande, CA on Tuesday, May 09, 2017 - 11:15 am:

Hal,

Did you find the head from the ring gear bolt ? The condition of that piece may tell you a lot about whether it went through the gears and caused the carnage. If the head is in good shape, then it probably wasn't the culprit.

Dick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Tuesday, May 09, 2017 - 12:43 pm:

Dick,

Yes, I found the head. I'll try to remember to look tonight and maybe take a couple of pictures of it. I'll also look to see if the carrier had bolts or studs. I'm thinking bolts, but I'll have to look to be sure.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Duey_C on Tuesday, May 09, 2017 - 08:18 pm:

Dare I post this?
I'm thankful to Tom for explaining the WHY about NO shims under the ring gear. He's correct and NOW the warnings make sense since I've heard his case. I have a shim to remove.
Well, there was a fellow here a few weeks ago smarting off about secrets between the veterans of this forum yet I KNOW the posts were NOT pointed at T C...
Sorry.
Hal, I'm anxious to see a pic of that bolt head. The bite marks may be very small IF I have my own head on square.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Tuesday, May 09, 2017 - 08:43 pm:

Having not yet seen the bolt head, this is still pure speculation. But from the way that differential carrier exploded, I would almost bet that the bolt head worked its way inside the carrier and forced its way between the gears while the car was not going straight and narrow forward.
It could still be old damage that finally let go. Check the breaks in the pieces for different shades of gray and silver, or rust. The sooner you check it, the more you can tell from it. Especially after cleaning the grease off, the silver turns to gray fairly quickly.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Wednesday, May 10, 2017 - 07:14 am:





Here's a couple of pictures of the bolt head. I don't see any major damage like it tried to go through the gears, nor did I see any major damage to the gears themselves. I haven't put them in the parts washer yet, but I did wipe them off with a rag and gave them a cursory look. I'll probably use the axle gears and spider gears again unless I see something after cleaning them good that I didn't see already.

Note the bolt head is worn, rounded, kinda polished.....It's pretty obvious that it moved around a good bit inside there after it popped off.

Upon looking at the carrier, or rather the pile of chunks that used to be the carrier, it was indeed the "Stud" type.

I had another axle/carrier assembly laying around that was pretty rusty. As a matter of fact, while the bolts came out of it easy enough, the axles are rusted in the carrier halves. I have it soaked with PB Blaster, hoping it will come apart and I can use the carrier from it. The gears and axle shafts are shot, but the carrier MAY be good. We'll see. I also have another, fairly complete, rear end that I can probably rob a carrier from, but I'd like to keep it together (Read that "Don't want to have to pull it apart"), if possible.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Wednesday, May 10, 2017 - 07:20 am:

BTW, the rusty carrier I'm hoping to salvage is the "bolt together" type. Hopefully, I will be able to use it.


Add a Message


This is a private posting area. Only registered users and moderators may post messages here.
Username:  
Password:

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration