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Courtesy of Aaron Sterry (with contributions from Peter
Florance, Mike W, Frank
Fahey Motorsports)
After going to get a roadworthy test done on the E12, the
Mechanic doing it discovered after taking it for a test drive
that there was funny noise coming from the front harmonic
balancer and pulleys, after putting it on the hoist he discovered
that the whole unit was loose and spinning freely on the crank
shaft...not a good thing, not only that the crank-nut was missing
too; that’s even worse.
So loaded with the Knowledge of what had to be done to get a
roadworthy we towed it home.
After removing the radiator, fan, and belts, the harmonic
balancer just slid off.
The reason why is because the woodruff key or key-way was
completely missing from the slot that it sits in on the
Crankshaft, when it finally went it took a bit off the side of
the slot the key fits into too, as well as splitting the Harmonic
balancer hub that slides on to the Key.
| Peter's note: Frank
Fahey Motorsports offers a hub, primarily
offered for M5 S38 motors, It is made from much harder
steel which is supposed to prevent this problem. Renee
from Fahey states: "The crank hubs are the same and you should definitely be running our improved crank hub if you do any sort or racing or track events.The M30 motors have a tendency to vibrate the crank hub nut loose when run in higher RPM for extended periods. This is actually caused by the soft stock crank hub. I'm sure you read all about it before, so I won't go into detail. Just make sure your crank nose is in good condition and that the keyway is still tight (your woodruff key should be tapped with no slop what so ever). Our replacement hubs will fix the problem, but they won't make up for an already hurt crank." The complete article can be found at http://www.frankfaheymotorsports.com - Peter |
The operation isn’t all that hard, but figuring out how
to fix a new woodruff key in to position was the problem. I asked
the guys at the first fives site and had several suggestions.
1/Just bolt it all together with the new key and Hub, and should
be fine.
2/use Red Loctite, pour it in too the Slot and sit key back in
let dry.
3/Make a new Woodruff key to fit it out of key steel.
4/ Use JB-Weld to hold the key in place.
5/Swap out engine to a 3.5 litre form a 7 series...Yikes
I hadn’t heard of JB weld before so i went down to the shops
to find some, and low and behold they did, I read the pamphlet
that comes with it and it is meant for Crankshaft pulleys and
Keyways; so I was convinced.
JB weld is like Araldite, it has 2 parts, Steel and Hardener and
you mix the 2 together in equal parts.
I put the Woodruff key in position and dab the JB weld around the
edge were it had torn away from the crank.
Let dry over night.
Here’s a Photo of the crank after i put the new Woodruff
key in and Oil seal (should do this while down there)
The photo is not the best, a little fuzzy, but you can see that
gray looking stuff on the left next to the key, that’s the
JB weld, after it had dried I used a razor blade to cut off the
excess JB and then a bit of wet and dry to clean up the excess JB
around the key, you can also use a file. (Peter's note: note the
smart-looking new seal. This is a great time to fit a new
crankshaft seal. See specs below)
After doing all this, it was now time to put the harmonic
balancer back on. I got the new Harmonic balancer hub from my
Spare e28 M30 I have hanging around that saved me $350, as well
as the crankshaft nut too.
I placed the hub on, and it slid on for the first bit then just
wouldn’t go any further, I figured excess JB weld in the way
as it is difficult to get rid of all the excess after it dried,
so as it was lined up with the key way i pulled it on by doing up
the Crankshaft nut to push on the Hub and balancer, this worked a
treat.
There is a special tool you can buy from BMW to lock the flywheel
while doing up the Crank bolt, I didn’t have it, but got my
father to hold the Flywheel from timing whole with a larger
screwdriver.
Specifications:
Crank nut: 36mm socket
Crank nut torque: 440 newton-meters (My torque wrench doesn’t
go that far only 220NM, so I jut did it up as tight as I could
....well until the screw driver slipped of the flywheel)
Harmonic balancer to Harmonic balancer Hub 8x13mm bolts tightened
to 22NM each.
Oil seal dimensions outside 62mm inside 42mm width 12mm (don’t
have part number)
Woodruff key, there are 2 one for the Harmonic balancer and the
other for the timing chain both are identical, only one is needed.
Part Number: 07 11 9 951 485
And that is it, Crankshaft nut is difficult to remove, you will
need 3/4 drive with a 36mm socket and a extra piece of pipe for
leverage, some mechanics even put the socket on with the bar and
quickly crank the engine, the bar hits the ground and loosens the
nut.
I just had my father hold the flywheel with a couple of
screwdrivers took a couple of attempts, but we got it.
I have since driven the car about 200klms, checked the balancer,
nut, etc, and they seem to be fine; no oil leaks either.
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