[MrMoe99]

So i have an 08 E92 335xi and i replaced the front passenger axle for the 3rd time (In the shop after it broke again today) Turns out my bushings are shot and i have to replace the lower tension struts. Could this be the reason for my axle breaking these many times? This is the 3rd time in a 2 month span and I had it covered under warranty but it wont be the next time it breaks.

[ajsalida]

What is the failure mode? In other words, what on the axle exactly is breaking and under what circumstances?

[MrMoe99]

Originally Posted by ajsalida

What is the failure mode? In other words, what on the axle exactly is breaking and under what circumstances?

I don't know the correct term to use but the spindle side of the axle remained intact but the other side is what broke off. The axle didn't snap in half or anything. I attached a picture. The past 2 times it broke on me was when i was on WOT. Thanks for the help.

[ajsalida]

Jeez that looks bad.

Some Q's:

1. How much power are you pushing? Any front axle wheel hop at WOT?

2. Are these used/rebuilt axles? It looks old in this pic.

3. Is this shop familiar with AWD BMW's?

I doubt bushings being shot would cause this unless you are pushing huge power and bushings are non-existent.

If the axle is not seated properly in the diff with the little snap ring washer thing it can pop out but this doesn't look like that happened. This looks like the inboard CV joint failed massively. If this is happening multiple times something very weird is going on. If somebody is rebuilding these maybe they are doing it wrong, or swapping in bad parts.

You can get perfectly good new non-OEM axles for about $100, like DSS etc.

[MrMoe99]

Originally Posted by ajsalida

Jeez that looks bad.

Some Q's:

1. How much power are you pushing? Any front axle wheel hop at WOT?

2. Are these used/rebuilt axles? It looks old in this pic.

3. Is this shop familiar with AWD BMW's?

I doubt bushings being shot would cause this unless you are pushing huge power and bushings are non-existent.

If the axle is not seated properly in the diff with the little snap ring washer thing it can pop out but this doesn't look like that happened. This looks like the inboard CV joint failed massively. If this is happening multiple times something very weird is going on. If somebody is rebuilding these maybe they are doing it wrong, or swapping in bad parts.

You can get perfectly good new non-OEM axles for about $100, like DSS etc.

Im basically stock except for an exhaust and DCI. When at WOT my steering wheel shakes a bit so i rarely push it cause i ordered new control arms (tension struts) in hopes to fix this problem. These are new axles and the pic i posted was the first time the axle broke, thats why it looks old. But the mechanic fixes 335i's a lot so I'm sure he's a reliable mechanic. Appreciate the help.

[ajsalida]

Originally Posted by MrMoe99

Im basically stock except for an exhaust and DCI. When at WOT my steering wheel shakes a bit so i rarely push it cause i ordered new control arms (tension struts) in hopes to fix this problem. These are new axles and the pic i posted was the first time the axle broke, thats why it looks old. But the mechanic fixes 335i's a lot so I'm sure he's a reliable mechanic. Appreciate the help.

Well that's not enough power to be snapping axles like toothpicks. Maybe it is the bushings, but that is an unusual run of broken axles. I would certainly take it easy on the gas pedal until you get the new tension struts put on, and then once you do, do not go WOT if you begin to feel the same vibrations through the steering.

However many people have bad tensions strut bushings and nobody is breaking axles because of it that I have read about. And people put serious HP through these AWD cars, and they do not break the way yours do.

I'd ask the mechanic if the inner shaft is seated properly in the diff (the ring thing), that is easy to mess up, and then what he thinks the reason is for such an unusual failure to happen multiple times so quickly.

[matteblue3er]

Is that picture with the wheel still on/control arms still mounted? The axle didn't break, it fell out of the inner CV housing.

It looks like the wrong axle was fitted and it is too short. It should not pop out like that.

Also was the support bearing/bracket replaced when the axle was replaced?

If you're using aftermarket axles, there your problem. They are notorious for failure. If you didn't pay $1000+ for this job, it's aftermarket crap.

[PhaseP]

Any chance gas being applied while brakes are on and standing?

[ajsalida]

Originally Posted by matteblue3er

Is that picture with the wheel still on/control arms still mounted? The axle didn't break, it fell out of the inner CV housing.

It looks like the wrong axle was fitted and it is too short. It should not pop out like that.

Also was the support bearing/bracket replaced when the axle was replaced?

If you're using aftermarket axles, there your problem. They are notorious for failure. If you didn't pay $1000+ for this job, it's aftermarket crap.

That is pass side looking in towards the engine. I think the inner CV joint split in half, the other half with the big stub end and long shaft is still in there:



As for non-OEM his OEM did the same thing. Plenty of people use non-OEM without issues, esp at his power levels. What I meant about the ring clip thing is the end of the long shaft there is a groove in the splined area, it has a c-clip like thing that has to seat into the diff. If it doesn't that long shaft will move around in or out. I'm not sure what other thing you can screw up, or if screwing that up could cause this, but that is the main one. Also in order to seat it you have to compress the other end of the axle assembly inwards, before fitting the outer splined shaft into the hub. Then tap the outer splined shaft end gently with a soft mallet until that ring seats into the diff, and the seal/cup is flush up against the housing. Maybe if you hammer it too hard you could ruin the inner CV joint?

[matteblue3er]

Originally Posted by ajsalida

That is pass side looking in towards the engine. I think the inner CV joint split in half, the other half with the big stub end and long shaft is still in there:



As for non-OEM his OEM did the same thing. Plenty of people use non-OEM without issues, esp at his power levels. What I meant about the ring clip thing is the end of the long shaft there is a groove in the splined area, it has a c-clip like thing that has to seat into the diff. If it doesn't that long shaft will move around in or out. I'm not sure what other thing you can screw up, or if screwing that up could cause this, but that is the main one. Also in order to seat it you have to compress the other end of the axle assembly inwards, before fitting the outer splined shaft into the hub. Then tap the outer splined shaft end gently with a soft mallet until that ring seats into the diff, and the seal/cup is flush up against the housing. Maybe if you hammer it too hard you could ruin the inner CV joint?

I'm aware what the picture is OF, but my question is the knuckle still bolted to the control arms? The outer section looks way too high.

The retaining clip at the end of the shaft will not cause this. The inner shaft may slide side to side but that will not cause the failure above. In fact, the shaft sliding outward would cause the CV joint to slide further into the CV housing.

It very clear from the photo that the CV joint fell out of the housing, ripping the boot.

Also to the OP, have the passenger motor mount checked....it's a very common failure on this chassis and too much flex could have caused the CV to fall out under high load.

[ajsalida]

Originally Posted by matteblue3er

I'm aware what the picture is OF, but my question is the knuckle still bolted to the control arms? The outer section looks way too high.

The retaining clip at the end of the shaft will not cause this. The inner shaft may slide side to side but that will not cause the failure above. In fact, the shaft sliding outward would cause the CV joint to slide further into the CV housing.

It very clear from the photo that the CV joint fell out of the housing, ripping the boot.

Also to the OP, have the passenger motor mount checked....it's a very common failure on this chassis and too much flex could have caused the CV to fall out under high load.

Oh, I see what you're saying. I think it is still in there, in the hub side, what else would hold it up? Maybe we are arguing semantics. The inner CV joint looks like it sheared in half, right off the main big stubby end thing, and the inside half of the remaining axle assembly is still in the diff.

I agree that not seating the long splined end of the axle in the diff should not cause this, but I'm not sure what could. As I said many many of the tension strut bushings go bad or are bad for a long time and you don't see this kind of failure, let alone 3 times in a row. OEM or not. Which is why I was thinking installer error of some kind, at least on the last two. Just guessing though.

You do have to tap it gently in to seat the ring in the diff, and as I was doing this myself recently on my car I was thinking, man this would be a really good way to destroy a CV joint if you over do it with the hammer.

I guess the shaft end inside the boot that goes into the inner CV joint could have popped out if the motor mount was bad, but that would take a hell of a lot of engine movement. If the rest of the bearing in the boot is intact and only the shaft popped out, that would be pretty easy to check. Actually if that is happening that would explain why both the OEM original and the replacements were failing.

[matteblue3er]

It's hard to see from the photos but the it looks like the bearing may still be inside the CV housing....which means it binded up and torn itself off.

The long shaft that goes into the oil pan/diff is not connected to the outer section that bolts to the wheel hub. The only thing holding those 2 sections together is the rubber boot. When it's installed in a vehicle, it's basically sandwiched between the wheel hub and oil pan/diff. As the axle is loaded, it can freely move in and out of that CV housing.

[ajsalida]

Originally Posted by matteblue3er

It's hard to see from the photos but the it looks like the bearing may still be inside the CV housing....which means it binded up and torn itself off.

The long shaft that goes into the oil pan/diff is not connected to the outer section that bolts to the wheel hub. The only thing holding those 2 sections together is the rubber boot. When it's installed in a vehicle, it's basically sandwiched between the wheel hub and oil pan/diff. As the axle is loaded, it can freely move in and out of that CV housing.

Well that is not entirely true. The middle part of the axle shaft between the two CV joints is connected to the innermost long shaft by another splined slider type shaft segment that slips into the inboard side of the inner CV bearing. I know you know this but for others, it slides in and out and gives the ability for the axle to change length as the suspension moves up and down or the wheel is steered. The inner boot will accordian in or out as the main axle shaft moves in this fashion.

If that is pulled out beyond where it is seating into the inner axle assembly, it will come apart as you say. But I would think that would take a lot more movement than even a busted motor mount would allow. Who knows but it is definitely worth checking motor mounts as you suggested.

It looks to me like the entire inner CV joint just sheared off at the face of the big meaty section but as you said it is hard to see in that pic.

[matteblue3er]

Originally Posted by ajsalida

Well that is not entirely true. It is held in there by another splined slider type shaft that slips into the inboard side of the inner bearing. I know you know this but for others, it slides in and out and gives the ability for the axle to change length as the suspension moves up and down or the wheel is steered. The inner boot will accordian in or out as the main axle shaft moves in this fashion.

If that is pulled out beyond where it is seating into the inner axle assembly, it will come apart as you say. But I would think that would take a lot more movement than even a busted motor mount would allow. Who knows but it is worth checking mounts as you suggested?

I just re did my entire front end (oil pan gasket, front diff seals/fluid, support bearing, axle boots, and motor mounts) and did not notice anything holding the inner and outter sections of the CV joints together. The inner side just slipped out once I took the boot off. Then I slipped it back in and rebooted it, putting new grease pack in.

Unless you're talking about the bearing, then yes, it's held in by a circlip to the splines axle section.

But those 3 bearings just slip into the CV housing.

[ajsalida]

Originally Posted by matteblue3er

I just re did my entire front end (oil pan gasket, front diff seals/fluid, support bearing, axle boots, and motor mounts) and did not notice anything holding the inner and outter sections of the CV joints together. The inner side just slipped out once I took the boot off. Then I slipped it back in and rebooted it, putting new grease pack in.

Semantics again. Yeah it slips in and out of the inner portion, and nothing prevents it from pulling all the way out, but it is in a rigid slider type configuration (otherwise it could not transmit rotational force). Once installed it would have to slide way the hell out to come apart like you suggest with a broken mount. But maybe you are right. That would be a hell of a lot of engine movement, maybe the OP can chime in as to whether he felt any of that.

Should be pretty easy to inspect the busted axle(s) and see if the inner CV joint itself is intact or if the segment just after it slid apart as you suggest.

[matteblue3er]

These bearings are secured to the outer shaft via a circlip as can be seen in the photo. But that bearing assembly just slips into the CV housing and the only thing holding the inner and outter sections of the axles together is the boot.

[matteblue3er]

Originally Posted by ajsalida

Semantics again. Yeah it slips in and out of the inner portion, and nothing prevents it from pulling all the way out, but it is in a rigid slider type configuration (otherwise it could not transmit rotational force) and would have to slide way the hell out to come apart like you suggest with a broken mount. But maybe you are right.

I get what you're saying now.

I agree it's odd it would come all the way out but that's why I think the replacement axle is too short.

[ajsalida]

Originally Posted by matteblue3er

I get what you're saying now.

I agree it's odd it would come all the way out but that's why I think the replacement axle is too short.

OK good now I see what you mean by too short. Your idea is the only one that makes sense (either bad motor mount or too short or both). I just replaced the driver side axle on my car, and it seemed like there was a lot of travel that inner portion could slide in or out, more than any mount moving would use up. But if it is short then yeah that would pop right out. Except his OEM did it too, an the pic is the OEM axle. Anyway I am stumped but your idea should definitely be checked out.

Another thought. Maybe a bad motor mount PLUS bad tension struts bushings would get things cockeyed enough under hard accel (and/or maybe some wheel hop) to pull it out?

[PhaseP]

Another thing to look at if there is anything loose around the area that may come into contact with the boot as it is spinning and eventually tearing it. I see heat shield above the steering tie rod in the picture, could it have been bent or gotten loose?

[bryansoccer7]

Did you end up finding the problem? I'm having the same issue with my 335xi.

[Blakhorse]

I'm now on my 4th axle in a year. Trying to figure out if it's the front diff causing failure. I've had a bad bearing on passenger side, replaced entire housing and it worked for about 7 months.

[xthejuicex]

Are you using OEM axles or 3rd party like Napa, Autozone, etc?