Group Buy CDV

I will look forward to seeing those. PVR has offered me and old one to play with. Would be handy if we could help our fellow Z4 friends and mod ourselves.

I will take pics as I attempt to mod PVR's and if any good will post a how to guide.

Don't think normally it would be worth the hassle, but with the hight shipping costs from the states, got to be worth a look.
 
Right I took my CDV out today, it makes a fantastic improvement, hell I could even feel the difference backing the car out the workshop.
I've got some pics of the CDV I took that I will post up later, but it does contain a small valve.
 
Here we go

CDV in place
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The valve is just a small piston with a 1.3mm hole (it says that on the body) that is free to float about in the main body.
It looks like the insert is threaded and screws down into the thread of the body, and could be removed with a stud extractor (carefully so as not to damage the beveled seat) to enable you to remove the piston and then replace the insert.
 
Top Pup

thanks for the post, one question though, why would yo need to replace the insert. I am guessing as you say, it's there to hold the piston in place.
But if there is no piston, then why put it back.

Did you notice if the one you put in had it or not?
 
srhutch said:
Top Pup

thanks for the post, one question though, why would yo need to replace the insert. I am guessing as you say, it's there to hold the piston in place.
But if there is no piston, then why put it back.

Did you notice if the one you put in had it or not?
Click to expand...

The insert has a taper on it that the male fitting for the clutch hose sits against, without it that side of the fitting will not seal.
You can see the male version of this fitting on the other end of the CDV to give you a better idea of the inside.

I'm pretty sure you could just run a 3.5mm drill through the CDV if you wanted, as long as you don't damage the female taper it wouldn't matter.

I left my CDV out for now so can't comment on the internals of a modified one, but the fittings match up perfectly without it, if anything the CDV looks like a bit of an afterthought.
 
Really need to see a pictuse of a modified one.

If you remove the piston, then the insert would probably sit further dow the bore, and then the location taper may not meet, but I owuld have thought the seal would be on the main bore anyway as metal to metal with hydraulic pressure surely can seal effectivley.
 
The pictures I posted are of a modified one, it just looks like it's been drilled out IMO.
 
So is the group buy on the Zeckhausen ones going ahead? If so, count me in.
 
I've just had my modified one fitted and all I can say is if you haven't done this already you MUST do it. Very pleased :wink: .

Looking at the unmodified valve it does appear to have some sort of moving piston inside it with a 1mm bore hole down the centre of the piston. If it was secured in a pedestal drill and drilled from the male end I'm sure the sealing end tapers couldn't be damaged. The main problem would be the piston would just spin on the drill bit.

Anyway should anyone want my old one to play with the first to PM me gets it for free. :thumbsup: That's how pleased I am with the swap! Please don't try this if you haven't got the tools :wink:
 
The restrictor inside the CDV is a thin washer that floats, as it sits in a widened area. You can simply remove the CDV from the car instead of having a modded one.

You can also mod the original CDV by simply inserting a small Phillips screw driver (as shown below) or punch. By doing this, the inside diameter of the very thin washer is widened and inside diameter edges are easily bent out, enlarging the hole.

The downside is if the washer splits and breaks up into pieces, shards of it could migrate to parts of the clutch hydraulic system and cause problems with seals etc.


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Clearly this part could be modified but for the cost I really don't think its worth taking the risk of shards getting near the clutch itself!
 
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