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      03-25-2010, 01:31 AM   #42
bobbydole
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Drives: 2007 BMW M Coupe
Join Date: Dec 2008
Location: Torrance, CA

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2007 Z4M Grinding - My First Experience

I've been reading on the forums about the 1st to 2nd grind. I bought my 2007 Z4M last year at 23K miles and now it has 33K miles. I never experienced a 1st to 2nd grind until tonight and I would like to share my experience.

First I want to admit I've been driving manual for only one year and I have accidently grind the gear before on this car; for example when I accidently down shift from 6th to 5th on the freeway and not push down the clutch all the way. I know in those situations that it was user error.

But tonight as I was pulling out of a parking lot onto a main road, I am 100% certain I had the clutch all the way down to the floor. I shift from 1st to 2nd and the tranny made a grinding noise and the gear wouldn't engage.

I notice there is a difference in the sound when I accidently grind when shifting 6th to 5th and 1st to 2nd. In the 6th to 5th case, it was more like a thud thud thud sound. Whereas, the grind from 1st to 2nd was had a higher pitch grinding sound.

After the grinding happened tonight, I gave it some more thought as I drove home and I am certain I had the clutch all the way down. It's a funny feeling to have when you're certain you didn't do anything wrong; the clutch just won't go any further past the floor. However, I was driving the car harder than I usually do. Let me quantify my statement some more.

Normally, I shift from 1st to 2nd at around 3-4K rpm. Tonight when the grind happened I was shifting between 4-5 , but most definitely under 6K rpm.

So my first experience with the 1st to 2nd grind, so far, is consistent with what people have described in the forums. That the 1st to 2nd grind usually happens when the car is driven harder and while shifting at higher RPMs. I have not experienced this type of grinding (with the clutch down all the way) in any other gear combos (yet).

I have to say, after the grind occurred, it was quite a strange feeling. I was thinking to myself, "Wow, is this the 1st to 2nd grinding that people are talking about? I think it is!"

Now I'm a little worried about the tranny in my Z4M. What kind of damage does this kind of grinding do to the tranny and if I should have a mechanic check it out?

One additional info out my car; the CDV is deleted and replaced with a valve without the restrictor.

Last edited by bobbydole; 03-25-2010 at 01:36 AM..
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