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Remove CDV

Machine monkey said:
Ok i dont have a full grasp so this might not be 100% correct.

But my understanding the CDV is to prevent harsh and sudden shocks causing damage to the DMF. From surges of power from say the clutch being drooped or poor gear changes. Its sole purpose is to protect the DMF from shock.


Exactly right :thumbsup:

This is another "can o' worms" topic. Ultimately your car your choice. The effect on an M is apparently less than the non M, but it doesn't take too long to adjust to driving style.
 
Can anybody quantify how long the stock CDV "lengthens" catch time? Is it more on the verge of milliseconds or is it more substantial?
 
Can anybody quantify how long the stock CDV "lengthens" catch time? Is it more on the verge of milliseconds or is it more substantial?
 
There is also the argument that due to the delay in the clutch being released that there is an increase in clutch wear.

One of the best mods I did on my old car, but as above not so noticeable on the ///M.
 
Deleting it totally transformed my M, I am still on cloud nine with this mod, 8 days after removing it and it feels like a different car. I can't stop grinning and love the smooth gearchanges as after six months of ownership I was still unable to completely drive around the CDV.
I don't want to be too evangelical about this but DO IT!

Silver grey Z4MC
Mods: Strongstrut 3 piece / CDV delete / Stormworks ST1 gearknob / clutch stop / stubby / ipod integration / LED interior / Magnaflow custom exhaust
 
The beauty of the E89 setup is, if you don't like the feel after removal, its easy to put the valve back in place, its just a push fit with clips.
Unlike earlier version requiring the drilling out of the valve or similiar.

I,ve misplaced the valve, otherwise would have a closer look.
Basically i think its gives full flow on depressing the clutch, but delays the release by restricting the flow through a smaller orifice, so the clutch plates close more slowly giving a constant closure rate.

Unfortunately in the winter i think the hydraulic fluid is a bit more dense so doesn't flow as easily giving me the judder on take up.
Perhaps the reason for the wiggly metal pipe to warm the fluid up a bit in winter?
Perhaps they had a load of wiggly pipe work to get rid of!
 
flybobbie said:
The beauty of the E89 setup is, if you don't like the feel after removal, its easy to put the valve back in place, its just a push fit with clips.
Unlike earlier version requiring the drilling out of the valve or similiar.

No drilling out required on the earlier version... on the e85 the CDV just unscrews and you put the hose back without it then bleed.
 
That's one of the great things about a forum like this for new members and owners of the car. I've been thinking about the awful gearchange particularly when going from first to second and have been trying to drive round it since I collected my car. A quick search through the 'new posts' after a couple of days away and this pops up. Really helpful. :)
 
I've had CDV removed and changed gearbox oil to Redline MTL and Redlline ATF4 in a 50/50 mix as recommended by Opie Oils.

Vast improvement, do it, you won't regret it. Smoother, easier and nicer gear change, my mechanic who is into motorsport (Fords) was sceptical but agreed afterwards.
 
I'm glad I ran across this topic. Interested in doing anything to improve driving performance. New to the group and I'm really enjoying having this form to learn from. My 03 Z4 2.5 has become the new love of my life. You know you got it bad when you find excuses just to get in the car and drive anywhere. :thumbsup:
 
Simon Blythe said:
Does anyone have a picture of the e85 CDV please.
I'm sure someone will have one knocking around they can post up for you... if not I'm planning to take mine out on the weekend of the 8th/9th April so can post one up for you. :thumbsup:
 
Removed last night and at first wasn't too impressed as the car jumped forward when I raised the clutch. After a few minutes though I realised why people do it - you can essentially "feel" the clutch more now so you can launch it better.
I literally clamp the flexi hose, removed the CDV, reconnected it and drove away :D
 
Machine monkey said:
Ok i dont have a full grasp so this might not be 100% correct.

But my understanding the CDV is to prevent harsh and sudden shocks causing damage to the DMF. From surges of power from say the clutch being drooped or poor gear changes. Its sole purpose is to protect the DMF from shock.

Trouble is Mat, is slows down engagement of the clutch, masking the bite point and causing slippage that wears the clutch prematurely. Also when you are going for it, it hinders smooth changes.

Mike
 
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