Does the E89 have a CDV?

[Vel]

I was poking around some Z forums and came across a thread where users with older Z's had removed their CDV to make for smoother shifting - is this still a big deal in the E89?

[Merefield]

Originally Posted by Vel

I was poking around some Z forums and came across a thread where users with older Z's had removed their CDV to make for smoother shifting - is this still a big deal in the E89?

Smoother for who? Not the power-train ... CDV's are there to protect the car and prevent rather expensive damage ...

[Vel]

Yeah, I had heard that it's only there to prevent an unskilled shifter from damaging the power train, but for someone who's been driving stick for years, it's not needed and it's only an annoyance that screws up shifting in 1-2

[parnassus]

...well, if it hasn't bothered you so far then I suppose the point is moot.

[Vel]

I've test-driven a few Z4's, but the dealers around me only have automatics - I'm told that manuals are on the way out and hard to come by, so I haven't been able to experience this myself

At this point, I'm more or less set on a 35i with manual, but I'm just wondering if anyone else can comment on this

[HerrK]

Originally Posted by Vel

I've test-driven a few Z4's, but the dealers around me only have automatics - I'm told that manuals are on the way out and hard to come by, so I haven't been able to experience this myself

At this point, I'm more or less set on a 35i with manual, but I'm just wondering if anyone else can comment on this

The dealers avoid ordering/stocking manual trans for their own inventory as they tend sit on the lot longer. So it is costly inventory for them. The steptronics and DCT's have a larger appeal and are easier to sell to both sexes. I find them boring. I admit that the DCT's can shift faster than me. No big deal I'm not racing or tracking the car.

All new BMW manual trans come with CDV's including the Z4. If you are rapidly dumping the clutch often - the CDV will accelerate clutch wear as it delays the lockup of the clutch by restricting the fluid flow from the slave cylinder back to the master cylinder (brake & clutch are common master cylinder). So this results in more clutch slippage - as others have stated - protecting your transmission, driveshaft, differential, axels, tires from shock loading. Personally I only do this rarely.

It is relatively easy to do a CDV'ectomy. I purchased a spare CDV (about $8) and removed the orifice mechanism, which is merely a screen, ball valve and plastic plug.

1. Pinched off the rubber line leading to the CDV to limit the fluid loss.
2. R&R the CDV with the unorificed CDV.
3. Release the pinch point.
4. Bleed the slave unit.
5 Top off the master cylinder.

It is about a 90 min DIY if you are competent and feel comfortable messing with the hydraulics.

Normal driving no real difference as you are gradually easing out the clutch anyways. Much quicker clutch lockup during spirited upshifts.

If you are not so mechanically inclined or prefer to have someone else (your local independent shop) do the work, you can buy a modified (orifice less) CDV from Zeckhausen Racing (link below) for about $50 with shipping and replacement CDV included. Probably another $120 shop time for your local independent shop to R&R and bleed the system. FYI - Our E89 Z4's use the same CDV's as the E90 3'ers (PN 21526764872)

http://www.zeckhausen.com/CDV.htm