M5 Diff Mount Broke

[Eon]

Last Tuesday night/early wednesday morning 2am I was pulling away at a traffic light, the road was wet and I had the DSC off (to avoid the inevitable power cuts in 1st and 2nd). I did not launch the car hard, but with 400HP on a wet road, some controlled wheelspin in 1st and 2nd is to be expected. As I was about to shift to 2nd, I heard a large knock from under the car followed by a very worrying grinding noise as I let off the throttle. When I get back on the throttle, I hear the knock again and the grinding goes away.

I did some reading up on the symptoms and I suspected the differential mountor bush had failed. I then took the car to a family friend of ours to check out on his lift. My fears were confirmed, but I was quite shocked to discover this piece of work:

Now some of you guys identified the car as Biofreak's ex car. I did some digging into Biofreak's threads on here and on M5Board.com and it seems that he had drag raced and hooned the car to within an inch of its life, eventually broke the diff mount and attempted to weld it back onto the aluminium subframe again. http://www.m5board.com/vbulletin/showthread.php?t=152053

YOU CAN'T WELD ALUMINIUM!
I would need a whole new rear subframe or diff carrier in order to repair the car.
After Biofreak, the car belonged to a friend of my father's (older chap in his 60's) who upon asking him was unaware of this abomination of a welding job. He, however is willing to assist me in fitting the replacement subframe that I am willing to pay for.

So within the first month of owning my dream car, I have only driven it for two weekends, and now I'm missing out on all these lekker dyno days and breakfast runs that I was looking forward to.

So this is what I need:

I can get a used E39 subframe, but I'm not too sure if it will fit all models. The M5's subframe looks almost identical to the 523i, 525i, 530d, 540i etc. but the part numbers are different.

Can any of you please confirm that it fits the M5?

 

[rodga]

eish man, hope you get sorted

 

[KarshS]

That Sucks man :thumbdo:

Hope you get it back on the road ASAP

 

[Nikhil]

This has happened to another forum members M5 aswell, the dude has a E36 Coup as a daily and also lives in CT. I believe that he managed to repair an re enforce the mounting point

i cant seem to find the thread :hammerhead:

 

[Fordkoppie]

YOU CAN'T WELD ALUMINIUM!

Yes a qualified welder can:chef:

---

This has happened to another forum members M5 aswell, the dude has a E36 Coup as a daily and also lives in CT. I believe that he managed to repair an re enforce the mounting point

i cant seem to find the thread :hammerhead:

http://www.bmwfanatics.co.za/showthread.php?tid=55877&pid=1007807#pid1007807

 

[Xack]

Like Ford Koppie said, you can definitely weld aluminium, it's jus a specialist job.

In your research on biofreak, you also get an idea of how many hot hatches got ran by your car,lol

Hope you get it sorted dude, new subframe, probably the best way to go.:cartel:

 

[Enzio]

As per the above Aluminium can definitely be welded. It would be smart to have some additional support welded on as well which should prevent it happening in the future.

 

[JadielM]

Sorry bud

 

[Gizmo]

The subframe needs to be TIG welded which is an art in itself, get a specialist with a good reputation to do it for you and have him add extra aluminium plate welded onto it to make sure it doesn't happen again. Its a rather common failure point due to aluminium fatigue and your axle tramp by turning off DSC was the final straw. Bad things happen when DSC is turned off, keep it on.

 

[Eon]

YOU CAN'T WELD ALUMINIUM!

Yes a qualified welder can:chef:

---

This has happened to another forum members M5 aswell, the dude has a E36 Coup as a daily and also lives in CT. I believe that he managed to repair an re enforce the mounting point

i cant seem to find the thread :hammerhead:

http://www.bmwfanatics.co.za/showthread.php?tid=55877&pid=1007807#pid1007807

---

Thanks, you're right, but It is quite obvious that mine wasn't done by a qualified welder. It looks like he didn't even remove the subframe in order to weld the mount back on. I just wish Biofreak had approached the job the same way as exhibited in that thread.

Now it's my job to fix his mess. :smashScreen:

---

The subframe needs to be TIG welded which is an art in itself, get a specialist with a good reputation to do it for you and have him add extra aluminium plate welded onto it to make sure it doesn't happen again. Its a rather common failure point due to aluminium fatigue and your axle tramp by turning off DSC was the final straw. Bad things happen when DSC is turned off, keep it on.

Would you recommend that I remove the subframe and broken diff pinion and take it to a specialist TIG welder, instead of just replacing the subframe altogether?
It's coming out either way, so I'd like to replace the thing but only if I know for certain that a standard E39 subframe will fit on the M5.

 

[Gizmo]

It will eventually happen to the new one also, get yours fixed and strengthened so it never happens again.

 

[E63AMG]

So this is apparently my ex car? Let me then comment on some of the accusations slung my way.

Now some of you guys identified the car as Biofreak's ex car. I did some digging into Biofreak's threads on here and on M5Board.com and it seems that he had drag raced and hooned the car to within an inch of its life,

Uhm, no. Not quite. My car was raced yes. It went to ODI once and to Tarlton once.
Never saw a race track other than that while in my care.

I'm obviously not a single lady driver and the car has a clearly documented history.

eventually broke the diff mount and attempted to weld it back onto the aluminium subframe again. http://www.m5board.com/vbulletin/showthread.php?t=152053

I experienced a knocking noise on the car. I sent it in to a mechanic on Ontdekkers road. House of BM. He fixed the mounting issue without any input from myself. I asked him to fix it, he fixed it. If this was indeed the repair that I paid for, I was not aware that it was welded and I certainly did not do it myself.

The invoice for the fix was included in my selling documents.

After Biofreak, the car belonged to a friend of my father's (older chap in his 60's) who upon asking him was unaware of this abomination of a welding job. He, however is willing to assist me in fitting the replacement subframe that I am willing to pay for.

Actually, I sold the car to a gent by the name of Farley who went on to modify a few more things. He was not in his 60's. So the car actually then had a few more owners in the last 3+ years.

 

[Eon]

So this is apparently my ex car? Let me then comment on some of the accusations slung my way.

Now some of you guys identified the car as Biofreak's ex car. I did some digging into Biofreak's threads on here and on M5Board.com and it seems that he had drag raced and hooned the car to within an inch of its life,

Uhm, no. Not quite. My car was raced yes. It went to ODI once and to Tarlton once.
Never saw a race track other than that while in my care.

I'm obviously not a single lady driver and the car has a clearly documented history.

eventually broke the diff mount and attempted to weld it back onto the aluminium subframe again. http://www.m5board.com/vbulletin/showthread.php?t=152053

I experienced a knocking noise on the car. I sent it in to a mechanic on Ontdekkers road. House of BM. He fixed the mounting issue without any input from myself. I asked him to fix it, he fixed it. If this was indeed the repair that I paid for, I was not aware that it was welded and I certainly did not do it myself.

The invoice for the fix was included in my selling documents.

After Biofreak, the car belonged to a friend of my father's (older chap in his 60's) who upon asking him was unaware of this abomination of a welding job. He, however is willing to assist me in fitting the replacement subframe that I am willing to pay for.

Actually, I sold the car to a gent by the name of Farley who went on to modify a few more things. He was not in his 60's. So the car actually then had a few more owners in the last 3+ years.

Thanks for your input. I am sorry if my accusations hurt your reputation/feelings in any way.

I am just quite angry that I had to fall victim of this kind of workmanship. Especially within the first month of owning the car. I have not been conveyed any documented history on the car.

I add that I am also not going to treat the car like a single lady owner, and If I knew about the weld, maybe I might've been a bit more sympathetic. Or maybe I wouldn't have bought the car in the first place!

 

[E63AMG]

Thanks for your input. I am sorry if my accusations hurt your reputation/feelings in any way.

I am just quite angry that I had to fall victim of this kind of workmanship. Especially within the first month of owning the car. I have not been conveyed any documented history on the car.

I add that I am also not going to treat the car like a single lady owner, and If I knew about the weld, maybe I might've been a bit more sympathetic. Or maybe I wouldn't have bought the car in the first place!

Bud, this is a 180k Km, 15 year old M car with probably 6 owners now by the sounds of it. The E39 M5 had common problems from day 1 and my car was not immune to them.

The owner (Jacques from the Renault Sport forum btw - In case you want to accuse him as well.) before me had the motor replaced because of the oil usage.
I experienced the diff carrier failure and I had the alternator stop working.

By buying a second hand M car of this age and mileage, you have to expect some upkeep issues? Surely you budgeted for the inevitable replacement of parts?

As an aside, how much did you pay for the car btw?

 

[Eon]

Thanks for your input. I am sorry if my accusations hurt your reputation/feelings in any way.

I am just quite angry that I had to fall victim of this kind of workmanship. Especially within the first month of owning the car. I have not been conveyed any documented history on the car.

I add that I am also not going to treat the car like a single lady owner, and If I knew about the weld, maybe I might've been a bit more sympathetic. Or maybe I wouldn't have bought the car in the first place!

Bud, this is a 180k Km, 15 year old M car with probably 6 owners now by the sounds of it. The E39 M5 had common problems from day 1 and my car was not immune to them.

The owner (Jacques from the Renault Sport forum btw - In case you want to accuse him as well.) before me had the motor replaced because of the oil usage.
I experienced the diff carrier failure and I had the alternator stop working.

By buying a second hand M car of this age and mileage, you have to expect some upkeep issues? Surely you budgeted for the inevitable replacement of parts?

As an aside, how much did you pay for the car btw?

Tis true bro. The car was bought by my dad from the aforementioned uncle for R170k. It's a gift for my 25th bday.

To be honest, no I don't earn enough to be able to constantly fix things that break. Only using it as a weekend car so I was hoping to save up some cash in the first few months to do some preventative maintainence.

How's your E63 holding up?

 

[E63AMG]

Thanks for your input. I am sorry if my accusations hurt your reputation/feelings in any way.

I am just quite angry that I had to fall victim of this kind of workmanship. Especially within the first month of owning the car. I have not been conveyed any documented history on the car.

I add that I am also not going to treat the car like a single lady owner, and If I knew about the weld, maybe I might've been a bit more sympathetic. Or maybe I wouldn't have bought the car in the first place!

Bud, this is a 180k Km, 15 year old M car with probably 6 owners now by the sounds of it. The E39 M5 had common problems from day 1 and my car was not immune to them.

The owner (Jacques from the Renault Sport forum btw - In case you want to accuse him as well.) before me had the motor replaced because of the oil usage.
I experienced the diff carrier failure and I had the alternator stop working.

By buying a second hand M car of this age and mileage, you have to expect some upkeep issues? Surely you budgeted for the inevitable replacement of parts?

As an aside, how much did you pay for the car btw?

Tis true bro. The car was bought by my dad from the aforementioned uncle for R170k. It's a gift for my 25th bday.

To be honest, no I don't earn enough to be able to constantly fix things that break. Only using it as a weekend car so I was hoping to save up some cash in the first few months to do some preventative maintainence.

How's your E63 holding up?

Wow... I sold it 3 years ago for R135k... Goes to show, a car is worth what someone is willing to pay for it.

 

[Xack]

Of course it is, jus look at the crazy prices e46 m3,s are fetching

 

[ANiMOSiTY]

Oh dear.
Unfortunately, that was a weak point on the E39 M5.

Exactly the same thing happened to mine.
I was driving down to Sodwana, during the time of the major roadworks going on down there and klapped a pothole.
A few KM later, the diff mount broke.

Yes, I'm sure driving style contributed to the failures happening a little quicker than not, but it's inevitable for anybody who drives an E39 M5 the way they should be driven. In fact, "drifting" isn't any more taxing on that part of the subframe than pulling off in or driving in rush-hour traffic. It's a twisting effect from torque transfer down the drive shaft.

Bad things happen when DSC is turned off, keep it on.

That's a silly thing to say, dude.
The issue, both the weakness of the part and the cause (which is axle hop), has nothing to do with switching off DSC.
A lot of M cars will axle hop in unfavourable traction conditions in the wet. It's the suspension geometry.

Eon, I wouldn't question the maintenance and care given to any E39 M5 that was owned by guys who frequent these sorts of forums. It's a helluva solid car.
The weaknesses were mostly all suspension related.
It's 15 years old, and will need maintenance and TLC.

The sub-frame is not the same as the rest of the 5 series.
Like you said, the part numbers are different.
Check on M5Board.. I think the difference was simply regarding torque handling or overall strength. (Although I recall the diff mounting being slightly different or something)

 

[Philip Foglar]

I remember something that happened in even my humble E90 that could have under the right circumstances caused damage - was pulling out of a side street onto a busy 80km/h stretch and had to give it beans, which I did, and there was a nasty bump in the road just as you get going a few metres on (I would think because of other cars and trucks having to do the same thing), and there was quite a noticeable thud through the drivetrain as I went over this. If I was accelerating quite a bit harder, or had M5 brute power, I am sure something could have ended up broken then. And as normal, this was with traction on and just driving normally.

 

[ANiMOSiTY]

I remember something that happened in even my humble E90 that could have under the right circumstances caused damage - was pulling out of a side street onto a busy 80km/h stretch and had to give it beans, which I did, and there was a nasty bump in the road just as you get going a few metres on (I would think because of other cars and trucks having to do the same thing), and there was quite a noticeable thud through the drivetrain as I went over this. If I was accelerating quite a bit harder, or had M5 brute power, I am sure something could have ended up broken then. And as normal, this was with traction on and just driving normally.

Multiply that by 15 years and add the ever worsening conditions of our roads.. and yes, exactly.