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nike001
10-09-2012, 02:24 PM
Terra was aiding me when my transmission drain plug split in two. Came out fine and was on its way back in so I could refill my transmission fluid and it snapped.

This happened Saturday and was stuck on jack stands until about 20 minutes ago. Somehow my BMW dealer didn't have it in stock so I had it rush ordered for today.

Pics of carnage
http://img.tapatalk.com/d/12/10/10/gana7a5e.jpg
http://img.tapatalk.com/d/12/10/10/atepu5yn.jpg
Meric
10-09-2012, 02:28 PM
Woah was it hard to get it off or what?
danewilson77
10-09-2012, 02:36 PM
Looks like it stress fractured at the head.
nike001
10-09-2012, 02:38 PM
Woah was it hard to get it off or what?

I was putting it in and I wasn't anywhere near spec torque and it snapped.

The top fell off and I just used my fingers and unscrewed the bottom part from the tranny
danewilson77
10-09-2012, 02:45 PM
Yeah...that's a failed "shit metal" part right there.
Meric
10-09-2012, 03:13 PM
I was putting it in and I wasn't anywhere near spec torque and it snapped.

The top fell off and I just used my fingers and unscrewed the bottom part from the tranny

Lucky it wasn't tightened or else pain in the butt -.-
JupiterBMW
10-09-2012, 04:46 PM
Looks to me like its been overtightened in the past, pulling the shank down into the bore, and subsequently placing all kinds of stress load on the head, eventually causing it to crack (most likely heat cycling had something to do with this also)...

What is the torque spec...? And I would assume there's a copper crush washer that goes in there too? Are you replacing it every time??
cakM3
10-09-2012, 06:59 PM
Damn! I've never seen that happen Dalton...I can see why it's good to have spares here (just in case)...
johnrando
10-10-2012, 06:27 AM
Damn! I've never seen that happen Dalton...I can see why it's good to have spares here (just in case)...

+1. And Charlie, like your new avatar.
Ryans323i
10-10-2012, 07:09 AM
Looks to me like its been overtightened in the past, pulling the shank down into the bore, and subsequently placing all kinds of stress load on the head, eventually causing it to crack (most likely heat cycling had something to do with this also)...

What is the torque spec...? And I would assume there's a copper crush washer that goes in there too? Are you replacing it every time??

Just looked it up: 37ft-lb (50Nm) for both the drain and fill, manual transmission.

For automatic transmissions it's a little more complicated. This is what it says:
-ATF drain plug to ATF sump
A5S 360R/ A5S 390R (M14): 14ft-lb(18Nm)
A5S 325Z: 26ft-lb (35Nm)

-ATF fill plug to ATF sump
A5S 360R/ A5S 390R (M14): 14ft-lb (18Nm)
A5S 325Z: 23ft-lb (30Nm)

-ATF sump to transmission
A5S 360R/ A5S 390R (M14): 7ft-lb (10Nm)
A5S 325Z: 4ft-lb (6Nm)
nike001
10-10-2012, 07:44 AM
Yeah 37ft-lb isn't much of anything.

I suppose it could be a bit much for the plug though since it's extremely light and obviously not metal
danewilson77
10-10-2012, 07:49 AM
Just looked it up: 37ft-lb (50Nm) for both the drain and fill, manual transmission.

For automatic transmissions it's a little more complicated. This is what it says:
-ATF drain plug to ATF sump
A5S 360R/ A5S 390R (M14): 14ft-lb(18Nm)
A5S 325Z: 26ft-lb (35Nm)

-ATF fill plug to ATF sump
A5S 360R/ A5S 390R (M14): 14ft-lb (18Nm)
A5S 325Z: 23ft-lb (30Nm)

-ATF sump to transmission
A5S 360R/ A5S 390R (M14): 7ft-lb (10Nm)
A5S 325Z: 4ft-lb (6Nm)

37 ft-lbs seems like an ass ton to me, for such a small plug.
nike001
10-10-2012, 08:05 AM
37 ft-lbs seems like an ass ton to me, for such a small plug.

Yeah, and try doing that spec while laying under the car... lol
MrMaico
10-10-2012, 08:56 AM
This shows 25.8 ft/lb for the 6 speed plugs. 37 ft/lb sounds a bit high for that light aluminum plug.

http://mrmaico.smugmug.com/Cars/BMW-ZHP-misc/i-Kgk5QGL/0/XL/01-08-2011-115718AM-XL.jpg
danewilson77
10-10-2012, 09:40 AM
I bet I torque mine to 15 ft-lbs.....
cakM3
10-10-2012, 12:12 PM
+1. And Charlie, like your new avatar.

Thanks John ;)
terraphantm
10-10-2012, 09:34 PM
Looks to me like its been overtightened in the past, pulling the shank down into the bore, and subsequently placing all kinds of stress load on the head, eventually causing it to crack (most likely heat cycling had something to do with this also)...

What is the torque spec...? And I would assume there's a copper crush washer that goes in there too? Are you replacing it every time??
No washer. The drain plugs have a little green gasket around the head that does the sealing. You're probably meant to replace the plugs each time in retrospect (the M3 has a similar style plug on the diff that's meant to be replaced).

I don't think 37 lb-ft will cause it to fracture. Requires a lot more torque to break it loose.

My guess is that the old bolt was impacted at some point in the past. Either that or the hex key wasn't completely in there (really tight clearance on the fill side), and it slipped a lot.

Dalton:

Pretty sure that plug was magnetic, wasn't it? If so it's got to be steel (or at least an alloy with a decent bit of steel). I think it's simply like an engine drain plug in that it's designed to fail in a manner that makes removal easy
Ryans323i
10-11-2012, 06:09 AM
This shows 25.8 ft/lb for the 6 speed plugs. 37 ft/lb sounds a bit high for that light aluminum plug.

http://mrmaico.smugmug.com/Cars/BMW-ZHP-misc/i-Kgk5QGL/0/XL/01-08-2011-115718AM-XL.jpg

FWIW, I got my info from my bentley manual. Didn't see a choice for 5spd vs 6spd. Good to know there's a difference though.