Crank hub really cracks?

[Shadow]

Does this really happen for real?

This was made a big deal a while ago I remember but
has anyone experienced this or know anyone that has?

The "fix" is a $350.00 billet replacement.

[winfred]

i looked into it while building my m88 and the problem comes with really high rpm, not sure when the harmonic occurs but i think you gotta get above 7k, saw one thing where the m1 race cars with 9k rev limits would have the balancer glowing on dyno testing

i got a titanium hub for mine, not sure if its better or not but the alloy is in the same rockwell range as the replacement hubs, id love a fluid damper to kill that harmonic but they don't make one that i know of

[Shadow]

I'll see if I can dug up that thread, but there was
a guy who had ati, I believe, make him an m30 damper
through ppm.

The cost was over 1,000bux though!

-update-


http://forums.bimmerforums.com/forum/sh ... ?t=1455591

[marc79euro645]

I had one crack just like that. I've also had the key shear several times.
marc

[turbodan]

Theres not much reason to rev that high with the M30. Without tremendous modification its not efficient and is not making power above 6k anyway.

[Jelmer538i]

Where do you guys get the billet ones from?

Frank Fahey or PPM:

http://www.pureperformancemotorsport.co ... cts_id=483

I'm glad the B38 uses a different setup but my brothers B36 hub is already loosened once.

[FirstFives Dictator]

Theres not much reason to rev that high with the M30. Without tremendous modification its not efficient and is not making power above 6k anyway.

^this

I think mostly they are distorted from over torquing them.

[Shadow]

How about with a cam?

[turbodan]

The stock intake manifold has an even greater effect than the cam on the engines torqur curve. Adding a cam will only slightly increase top end power.

Getting rid of the stock intake trades off a great deal of area under the curve for a little bit of top end. Its not really worthwhile in most cases. I have a feeling that even if you do get an M30 to make power at super high RPM its not going to live very long doing so. Leave that business to the guys with tiny motors who have no other way to make power. The M30 does fine with a sub 6k RPM powerband.