Axle slipped out - Why did this happen?

Transmission to Rear-end

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Cougar5.0
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Axle slipped out - Why did this happen?

Post by Cougar5.0 » Thu Jun 29, 2017 11:44 am

Ford 8" rear (fairly certain, I didn't build it) on my T-Bucket. Axle slipped out cleanly while driving, just before a hairpin turn. TG it was a left-hand turn as I was braking/turning while also slightly freaking out as I looked over my right shoulder and saw the tire way out there.

How does a bearing race just "un-press" itself from the axle after many many years of use on a minimal weight vehicle that's never beaten on?
Bye axle.jpg
Luckily I was able to jack it up and push the axle back in. It rolls just fine (smoothly) this way, though the axle slipped out 5x on the 0.5 mile drive back home :oops:
Back on.jpg
Gonna get a new axle and make sure the new bearing is pressed on with the proper force. I've lost axles by bashing bearings (wheel hop) before, but I didn't realize these could extricate themselves without any real effort on my part. I wonder if the wide tires played any role. #-o
Last edited by speedtalk on Sun Aug 13, 2017 10:17 am, edited 1 time in total.
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n2xlr8n
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Re: Why did this happen?

Post by n2xlr8n » Thu Jun 29, 2017 2:06 pm

I thought the 8" had the bearing retainers like the 9", no?

Did you build the car?
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Re: Why did this happen?

Post by Speedbump » Thu Jun 29, 2017 3:37 pm

I thought the 8" had the bearing retainers like the 9", no?

Yes it does. had to have ground through the retainer somehow or the bearing+ the lock ring had to really lose press. Deep offset wheels and wide tires will cause early bearing wear/failure but I can't believe it happened without some serious noise and vibration before the event. This seems to be a question like "does this dress make me look fat?". No good answer.
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Re: Why did this happen?

Post by pdq67 » Fri Jun 30, 2017 1:16 am

May I suggest rear disc brakes because the calipers should hold a loose axle in place.

Can you install big bearing 9" axles in her?? I flat don't know, but do know the press on big bearing 9" lock ring is pretty hefty!

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Re: Why did this happen?

Post by Cougar5.0 » Fri Jun 30, 2017 2:11 am

It seems 28 spline axles are interchangeable between 8 & 9", seems the real issue has to be an improper amount of interference between the axle and bearing/lock ring? The retainer plate seems to indicate "large bearing" based on it's rectangular shape and the size of the studs. This all should be irrelevant for a 1500 lb car that is only driven for pleasure, though. I haven't even removed the old axle yet to check it's length and see what the bearing looks like (need to remove retainer plate to remove bearing and seal which are still in the axle housing.) I need to stop being angry at it for trying to kill me. Even after shoving the axle back in to drive it home, the car rolled smoothly without any sound. Weird! I did not build this one so I have to assume someone screwed up when pressing the bearing/retainer on.

I do have disk brakes on the Cougar as a backup if the c-clip breaks (8.8") - that car I do drag race.

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Re: Why did this happen?

Post by Geoff2 » Fri Jun 30, 2017 6:08 am

Does this rear axle use sealed wheel brgs [ either ball or roller ] , held on with a pressed on sleeve. If so, here is what happens: the grease in the brg dries out out from from brake heat. Brg, [ which is also a tight fit on the axle ] then spins on the axle & hammers away at the retaining ring....which comes loose...& the axle walks itself out. Not one of Detroits better ideas.....

Buick, Olds, Pontiac A body cars of the 1960s used this arrangement. A simple fix. There will be an oil seal inboard of the brg, inside the axle tube. On the BOP diff, the gap between the seal & brg is about 3/4". I drill a hole through the axle tube into this space & fit a grease fitting. I remove the inner side seal from the brg. I pump grease into the cavity & give it a couple of pumps with every engine oil change. Brgs now have fresh grease.

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Re: Why did this happen?

Post by Dutchman » Sun Jul 02, 2017 10:50 am

You mentioned you did not build this,so for the most part I have straighten out several rears over time. The biggest offenders are the street rod guys,most of them state " I welded a small amount at a time and let it cool between welds. I have never seen a rear not bent when a 6 inch pass is done on one side of a tube. Plain and simple if you put brackets on a housing or tube you need to check it for straightness.
If you have a bent housing you will never keep a wheel bearing in it for long,open car large tires with road noise wind in face it's hard to hear a axle bearing beginning to fail.
Gets hot,rig looses interference,there you have it.
You got really lucky you were not hurt or worse. Please check your housing before you put your car back in service.
There seams to be some oil on the back of the backing plate,possibly rear oil seapege from a failing axle bearing.

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Re: Why did this happen?

Post by Cougar5.0 » Sun Jul 02, 2017 6:01 pm

Thanks for the good info - got a few things to look into when I have a chance to look at the 'Bucket.

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Re: Why did this happen?

Post by peejay » Mon Jul 03, 2017 9:35 pm

I have found that bent rearend housings put enough of a cyclic force on the bearing's inner race that it actually thins the axle out. Press a new bearing on and once it presses past the old lockring area it "falls on" with no press fit.

Is why I went overkill on my little 270hp car and went with a Ford 9" with a backbrace. And found a shop about 90min away (only open during hours I'm at work... natch!) that has the proper jigging to straighten a 9". You gotta have a solid platform if you want the bearings and axles and differential to live.

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Re: Why did this happen?

Post by Cougar5.0 » Tue Jul 04, 2017 6:15 pm

I'm pretty sure this Bucket was built by a reputable rod shop in AZ, for what it's worth.

Axle out.
2017-07-04 15.39.55.jpg
I don't like the look of these 2-stage retainer rings, does this seem like enough/normal contact area?
2017-07-04 17.55.43.jpg
Otherwise the axle appears to be straight (using straight edge every 90 deg); bearing is not new feeling, but it's not blown either; the diameters check out and the seal was working well. I'll bring it to a shop to see what they think.

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Re: Why did this happen?

Post by machinedave » Tue Jul 04, 2017 9:57 pm

I have pressed thousands of axle bearings over the last 20 years. The bearings have a small amount of press fit but the locking collars have much higher press fit. The locking collars are so tight on the axle that they cannot be pressed off without bending the axle. The have to be cut off. I have seen many people attempt to reuse the collars by welding them. This never seems to work. Take a look at the axle and inspect/measure the bearing and collar surfaces and if the are good the a new bearing and collar should take care of the problem.

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Re: Why did this happen?

Post by jred » Wed Jul 05, 2017 12:00 am

I also pressed about a zillion axle bearings , being behind and auto parts store for twenty some years,, only had trouble with 1 set of axle bearings and that was on a friends pro stock car back in the 70's.
The bearing is not pressed on very tight, but the retaining ring is and with a axle that the bearing has 0 or no press fit the axle will move out of the bearing..

If you were to say that you pressed an old bearing off you will notice that the axle will flex and bend and you get a large bang when the bearing and retainer moves this what we call heat set, because if you pressed off said bearing and installed a new bearing and retainer and then had to repress the new bearing off it will come off quite easily, but if you install that axle in the car and drive it around and then have to remove it, it again will pop with bang,,

Axle bearings are quite hard and the retainer is quite soft and grips the axle more after heat set..

The axle bearing will also come off easy if the bearing is loose on the axle and we used to see a lot of those.. the customer can not believe that and would want you to weld the retainer on the axle we would do that sometimes but would have the customer sign the receipt that there was NO WARRANTY.

As for welding the retainer we had to pay for a axle repair on a welded axle when the axle broke and left the customer stranded and when the broken parts came back to us guess were it broke???

yea right next to the weld..

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Re: Why did this happen?

Post by 582r10 » Sat Jul 08, 2017 7:43 pm

Personally I wouldn't re-use that axle if for no other reason than it has had the wheel studs welded into it. That dangerous. Moser will sell you an axle with studs, bearing retainer and wheel bearing very reasonably.

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Re: Why did this happen?

Post by Cougar5.0 » Sat Jul 08, 2017 11:41 pm

582r10 wrote:Personally I wouldn't re-use that axle if for no other reason than it has had the wheel studs welded into it. That dangerous. Moser will sell you an axle with studs, bearing retainer and wheel bearing very reasonably.
Funny, I was just shopping for axles tonight. I have never seen studs welded in, perhaps they bought the wrong ones. Also, the diameter where the bearing sits is about 1 mil under, even thought the diameter where the retainer will be is about right, I don't wanna risk it.

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Re: Why did this happen?

Post by rfoll » Wed Aug 02, 2017 10:42 am

This happened to a friend of mine on a twisty road, but it actually came out when he got to a straight section. The rear axle was a BOP. Being familiar with the road they were on, it's too scary to even think about. Unlike the OP car, this one was a poorly built throw together, and used the same tires in the pictures. The axle was stone stock with a fresh coat of paint.
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