cdv gone forever

M

mad4slalom

Senior member
meant to do the delete on my z3m, still got the new braided clutch hose but never fitted it as the z3 wasnt too bad; as you will have red since i got the z4mc a month ago i have been struggling with the damn clutch, finally had enough and today changed the dif oil, swaopped out the gearbox oil for amsoil mtf, and then got my nerve up and removed cdv, reconnected lines to check it all went back together, which it did, asyou guys said it would, so proceeded to knock out the restrictor in the cdv, took 30 mins of careful tapping with the right size drift, but got it all out in tiny pieces, so put it back, a quick bleed and out for a test.... well all i can say is anyone who has been thinking about this mod, i can now drive the car normally, now you see just how bad it was, even posters on here who say they dont see the need to remove as they dont have a problem with the clutch , ifeel should make the effort to at least drive one with this mod and then hand on heart say its no better, pm me if you need convincing more, cant emphasise enough the improvement .zero cost if you diy too and really really satisfying couple of hours work. its like a different car. :D :driving: :thumbsup:
 
Of more interest, has the Amsoil MTF gearbox oil made any difference to the gear shifting? This is the cure that I'm looking for.
 
I drove my newly acquired z4mc over 300 miles today with the CDV in place and the car drives like any other - you just need to double clutch if you are throwing it through gears or heal/toe depending in styles
 
mine certainly didnt drive like any other car, but it does now, when i first got the car it was'nt as bad as i was expecting after reading all the posts, so ithought i would get used to it , but in real world driving situations i was finding way to many annoying missed changes, jerky take offs, clutch riding incidents and just not smooth changes, it just felt like no other car i had driven, a clutch stop helped by about 30% but now the cdv has helped the other 60%, the missing 10% ? i guess thats just the notchy box,... or Moi ?, ... nay !! seriously tho changing to amsoil feels a bit better, i dont think it will cure the first to second grind or crash,keeping lever toward the left and changing slower, ie almost two stage shifting from first to neutral and then neutral to second over just over a second instead of half a second seems to enable quiet gearchanges 80% of the time now, and still working on that, in my z3m the amsoil did take a while to get better but cured the sticky fifth gear gate that many experieced. in the z4mc my worst shifts were 1 to 2, upshift ing the 4th to 5th going across to the right was stiff and downshifting sometimes the last bit of 5th to fourth was tight as was fourth to third, these are better already, but is early days as has only driven 35 - 40 miles. so really glad as i feel it will still improve further. which takes us back to the cdv , with or without debate, 300 miles, isnt many miles yet, have you really been 100% happy with every single gearchange, more important, have your passengers ? have you thought of any other possible explanations,? heres three, ...1, bmw may have forgotten to fit a valve in your car, 2, you may be a driving god, or 3, a previous owner my have done the cdv delete , and not documented it for warranty reasons, you would never know without stripping it out. all of which are totally irrelevant as long as the car drives normally and you are enjoying it as it should be enjoyed. :thumbsup:
 
I have recently had my CDV valve removed.

Why didn't I do this sooner! :oops:

I can now feel a bit point, gear shifting is less baulky and 1st to 2nd is also improved.
 
I find that I can smooth out the 1st to 2nd lumpiness, but it means riding the clutch a bit more than I'm comfortable with. The other way to get a clean shift is just to smash it into 2nd at 6k RPM, but obviously this isn't ideal for driving around town. :?
 
I decided not to take the CDV out whilst the car was under warranty. However, I didn't expect to have the warranty in place for this long (80k miles / 4.5 years).

It's still in there, and despite me doing 80k miles of motorways, hoons, track days and 'Ring trips, there's no sign of slippage - so it's not like it's ruining clutches.

Although it could be because I'm a driving god and frequently do clutchless changes (just to keep up the skill).
 
I've been meaning to do this for ages, but never seem to get round to it. Probably because I've put 40,000 miles on the car with the thing in place and have been annoyed with the gearbox a total of about 10 times. Maybe i've just got used to it? I dont often do 1st gear flying starts into 2nd anyway, and the box is decent enough in all other situations
 
I get really frustrated with 1st to 2nd but its 100x better in sport mode so I can live with it!
 
Guess I was lucky, took 15 mins to whip it off and rebleed whilst car was on the ramp to change a broken rear coil spring :).

Helps having a relative with a garage :)


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