Removing CDV Valve

[motco]

Unfortunately, removing the CDV doesn't delete the God-awful fly-by-wire throttle. My late 2.2 Z3 and my son's Z4MC both have these products of the Devil and manoeuvring smoothly is impossible because of the slight delay in response of the engine to the pedal. The Z4MC has a 'sport' button which substantially removes this delay, but my Z3 has no such feature unfortunately. Taking out the CDV helps, but not a lot.

I have a Westfield with a Pinto engine which has carburettors, a type 9 gearbox and clutch, and a real cable throttle, and I swear it's so much easier to drive that car smoothly than either Z

[CousinDupree]

helix402 said:

Touring442 said:

Removing the CDV is 50/50 waste of time. It makes the clutch pretty sharp, some like it, some don't. It masks a worn clutch quite well so a heavy pedal will be the clutch coming to the end of its life. Make sure you use a pressure bleeder to bleed the clutch - pedal pumping can easily flip the master cylinder seals and ruin it. Replacing a master cylinder on one of these (same as E46) is not funny at all. It's a fking horrible job.

I agree with this. I’ve never removed a cdv from any of my BMWs. It seems to be an Internet “thing” to do as according to the net all manual BMW gearchanges are terrible.

Yes exactly. You can still dump the clutch as fast as you ever would need to, with the CDV present. There is just no point.

I love the gear change on just about all BMWs I have driven. The mechanical feel having the gearbox under your wrist can't be beat. Just as it was in the first E30 I drove moons ago. Those used to the easy sloppy VAG group gearchanges always seem to have an issue. The oil does need to be changed when scheduled and is usually skipped..

[Touring442]

I drove a manual E46 325i quite recently - it reminded me how bad E46's are to drive. As you say, that awful throttle, the dreadful clutch control and the inevitable 'thunk' from the drivetrain as you try and drive smoothly - all the slop in the diff, prop and driveshafts all winding up as one and clunking. They were such a bitter disappointment after the E36.

[BFleming]

I did my CDV delete with my Dad; I was in the pit, did the delete, we did the bleeding, then I asked him to start it up & try the clutch. He almost shot to the far end of the garage, such was the early engagement of the clutch. In my opinion the clutch feel afterwards completely justified the modification.

[Sardonicus]

Touring442 said:

I drove a manual E46 325i quite recently - it reminded me how bad E46's are to drive. As you say, that awful throttle, the dreadful clutch control and the inevitable 'thunk' from the drivetrain as you try and drive smoothly - all the slop in the diff, prop and driveshafts all winding up as one and clunking. They were such a bitter disappointment after the E36.

Granted but not sure I agree with the drive-line lash all things being as they should they have FA slack in that area clutch with no CDV I have no issue with but yes the throttle response is wooly to say the least

[gizlaroc]

CousinDupree said:

Yes exactly. You can still dump the clutch as fast as you ever would need to, with the CDV present. There is just no point.

Sorry, that is not correct.

The difference is not subtle with the grommet removed.

It comes up very quickly still with it still in place, the difference between having it in and out is fine, but it makes all the difference.

It is hard to describe the difference between cars with the CDV and without, but once you have tried it without I doubt you would ever go back.


The biggest differences are on car built between mid 2005 and mid 2011, the restricted release of the clutch exaggerates the crappy judder from the crap dual mass flywheel.
It took them over 5 years to work out how to sort the issue, they added a balance plate to the flywheel and its solved the issue, but the CDV really does make it worse.

[gizlaroc]

Touring442 said:

I drove a manual E46 325i quite recently - it reminded me how bad E46's are to drive. As you say, that awful throttle, the dreadful clutch control and the inevitable 'thunk' from the drivetrain as you try and drive smoothly - all the slop in the diff, prop and driveshafts all winding up as one and clunking. They were such a bitter disappointment after the E36.

I disagree with that too, I had a 330i from new and it was great.

You sure it was not the fact the car is now between 15-18 years old?

[motco]

BFleming said:

I did my CDV delete with my Dad; I was in the pit, did the delete, we did the bleeding, then I asked him to start it up & try the clutch. He almost shot to the far end of the garage, such was the early engagement of the clutch. In my opinion the clutch feel afterwards completely justified the modification.

You didn't bleed it properly then. CDVs make no difference to where the bite point is only how fast you can get there.

[motco]

The best gearchange is in a Honda S2000. If you can, try one.

[Touring442]

gizlaroc said:

I disagree with that too, I had a 330i from new and it was great.

You sure it was not the fact the car is now between 15-18 years old?

They're all 15-18 years old. But so are a lot of other cars - E36's for example are older yet drive much better. Cable throttle, single mass flywheel and much better quality driveshafts and diff planet gears. The E36 ones were machined from steel, the E46 ones are sintered monkey metal and its the wear on these that caused so much of the driveline backlash. This one's done 125'000 and it's impossible to drive smoothly without the awful E46 clunk.

I had a 320d Touring new in 2001. They were a different car to drive to the petrols though.

[BFleming]

motco said:

BFleming said:

I did my CDV delete with my Dad; I was in the pit, did the delete, we did the bleeding, then I asked him to start it up & try the clutch. He almost shot to the far end of the garage, such was the early engagement of the clutch. In my opinion the clutch feel afterwards completely justified the modification.

You didn't bleed it properly then. CDVs make no difference to where the bite point is only how fast you can get there.

It was his first time in the car, so he had no idea where to expect the bite point. Much earlier than he thought anyhow. It was bled properly, don't worry about that!

[motco]

BFleming said:

motco said:

BFleming said:

I did my CDV delete with my Dad; I was in the pit, did the delete, we did the bleeding, then I asked him to start it up & try the clutch. He almost shot to the far end of the garage, such was the early engagement of the clutch. In my opinion the clutch feel afterwards completely justified the modification.

You didn't bleed it properly then. CDVs make no difference to where the bite point is only how fast you can get there.

It was his first time in the car, so he had no idea where to expect the bite point. Much earlier than he thought anyhow. It was bled properly, don't worry about that!

Fair enough, but I drew the inference from your comments that the bite point had changed and that it was that which caught him out. If he'd never beeen in it before then all bets are off CDV or no CDV.