CDV DIY

[simonlpearce]

Big thanks to dicky for providing me with his CDV Delete which he didnt need as his was already done i believe, here a DIY on what i did with a little explanation as to what it does and the benefits. I have only driven a couple of miles and it is probably the most noticeable Mod i have done, really makes a massive difference when going through the gears. I reckon this coupled with short shift and a clutch stopper could take at least a second from each shift!

Its fairly easy providing you are nimble or have a lift/ramps, anyone could do it really providing you have a little knowledge of

Theory of Operation - What is a CDV?

The Clutch Delay Valve (CDV) is a one-way restrictor installed by the factory between the clutch slave cylinder and clutch master cylinder, as shown in Figure 1. It "delays" the engagement of the clutch, much like old record players used a damped tone-arm to gently lower the needle onto the surface of a record.

Because of this valve, no matter how quickly you lift your foot off the clutch pedal, the clutch engages the flywheel at a constant (slow) rate. In theory, it can save the driveline from shock, were an inexperienced (or immature) driver to dump the clutch at high RPM. But in practice, all it does is prematurely wear out the clutch and turn experienced drivers into people who, despite 20 years of practice, cannot shift gears smoothly. During parallel parking maneuvers, the delay can be infuriating, causing constant clutch slippage. And during hard acceleration, the large amount of clutch slippage can greatly shorten the life of your clutch. During normal, sedate driving, the shift from first into second gear is often jerky, leading passengers to question your skill.

Ok so what do you need?

1) Set of decent spanners particularly 11mm x 1 and 17mm x 2

2) CDV Delete (Although not essential can be done without)

3) Mole Grip (Or G-Clamp if you cant find moleys)

4) Jack and stands

5) 2.5 hrs spare time

6) A light if your working in the dark like i was

7) Something to rest on as you will be under that car for a while

8) A catch pan and rag

Ok so you need to start by jacking up the car - i used a jacking point just behind the rear front wheel and a piece of 2 x 4 to spread the load. An issue i had was that i needed to raise the car first before the jack would go under, I used the standard car jack to achieve this. I also did the rear on the same side using the rear subframe as a jacking point.

Next locate the CDV, which should be on the passenger side of the transmission just under half way from the front. Follow the flexible pipe back and clamp to stop the flow of fluid, this is where you need either mole grips or a g clamp.

Next you will need your 11mm and 17mm spanners. Place the 11mm spanner on the side with the solid pipe and the 17mm on the side where this attaches to the flexible pipe, then simply undo.

NB - Be careful not to round off the 11mm union as it is a fairly soft material (Flared Spanners may be a better option). You may also need you catch pan and rag as a little fluid may still come out as you will se in the second picture. This also shows how very little flow the CDV allows through.

[simonlpearce]

The next picture shows the CDV removed, and the second image where it was removed from.

These next pictures show comparisons of the old CDV and new CDV Delete, you should be able to see how much light comes through the new one compared to the old. Imagine this restricting the fluid flowing through and you should see why this mod will make a massive difference.

Refitting is the reversal of how you removed it.

Use x 2 17mm spanners to attach to flexible pipe.

[simonlpearce]

New CDV Delete attached to flexible pipe, notice the pipe is still clamped this is the last thing to remove but keep checking it is secure so not to lose any fluid.

Install CDV Delete to fixed pipe on car using 11mm and 17mm spanners, as you did when first removed.

Final picture shows the CDV Delete in place, as you will see it looks exactly the same as the CDV but gives a much better flow of fluid.

Once you are happy with everything and have checked all connections for leaks you can remove the clamp/mole grips.

Providing you didnt lose much fluid (i lost only a few drops) you will not need to bleed the clutch. However if you do need to bleed the clutch simply locate the bleed nipple a little further back and attach a piece of clear pipe flowing into a catch tank, get someone to press the clutch 3 times then hold, open nipple until no bubbles are visible then close. Repeat this until no bubbles flow through, make sure you have plenty of brake fluid as it runs off the same system reservoir. It will not affect your brakes in any way as they are on a different system.

Lastly once you are happy you can lower the car and remove the jack. Remember you may need to take the weight with the cars own jack stand to finish off lowering if like me your jack doesnt fit under the car.

HTH.

[MattBMW]

Nice right up SI...well done...dicky would be and Idea to post that link here where you got the CDV delete too m8.

another thing I need to do.............

[simonlpearce]

Happy i could help, if anyone needs a hand and are local let me know.

[///Marty]

Good DIY Si,

Definetely give this and the clutch stop a go before the next santa pod weekend.

[Wayne'o]

well done si

proper job

[Dicky]

Simon, excellent write up and really glad it made a difference

For those interested I got it from here http://www.zeckhausen.com/CDV.htm

Think it was $35 for the CDV and $35 for postage arrived in a couple of days of ordering to

That is a serious difference with the light coming through them together

[simonlpearce]

Yeah i thought so, it really shows how much you are restricted. I reckon it saves me point something of a second if not more each time i shift, which when going round a track can make the world of difference. Just need to get me a UUC short shift like you dicky, so if you see one reasonably priced on your trwals of ebay let me know.

[amowolves]

excellent write up simon. will defo look into doing this at some point. totally agree with you with regards to the jerkyness....no matter how smoothly i change the gears from 1st to 2nd it always seems amatuerish. i might have to pop down to urs though as im useless at mechanics ;-)

[simonlpearce]

excellent write up simon. will defo look into doing this at some point. totally agree with you with regards to the jerkyness....no matter how smoothly i change the gears from 1st to 2nd it always seems amatuerish. i might have to pop down to urs though as im useless at mechanics ;-)

By all means make your way down, would be happy to help a fellow member. PM me if you decide to do it at any stage i have everything needed except the CDV Delete which is not essential.

[Dicky]

Yeah i thought so, it really shows how much you are restricted. I reckon it saves me point something of a second if not more each time i shift, which when going round a track can make the world of difference. Just need to get me a UUC short shift like you dicky, so if you see one reasonably priced on your trwals of ebay let me know.

Will do mate, if i see anything I will give you a shout

[MattBMW]

dicky your meant to be looking for me first m8...lol anyway just looking at the diffrence with the valves can't you just bore the old one out??

[simonlpearce]

dicky your meant to be looking for me first m8...lol anyway just looking at the diffrence with the valves can't you just bore the old one out??

I dont see why it would be a problem, you would have to get it spot on though and would have to be careful not to over do it. Zackausen even do you a discount when you send them your old ones so i assume they just clean them up and bore them out, although it does say they havent been drilled.

[chris]

You dont need one on the E46, just on the 5 series Mines perfect without As said its such a difference in engaging gears, and changing speeds too. Die CDV

[Dicky]

You dont need one on the E46, just on the 5 series Mines perfect without As said its such a difference in engaging gears, and changing speeds too. Die CDV

True, but some people have complained of a rattle under the car if they haven't used one on the E46

[MattBMW]

Hmm..might bore it our then it out then.....do you know diameter of Zackausen one is?

[simonlpearce]

Not 100% sure what diam it is and to find out would be a right PITA. I would estimate at around 4-5mm but i couldnt say for definate.

I have just found the following on the Zackausen website though so if you do decide to bore the CDV perhaps start off with a smaller drill bit and work your way up to a size which you feel to be suitable.

We do not drill these CDVs, as some have suggested. Drilling enlarges the openings on the tapered seats at each end, causing leaks. Drilling may also result in loose bits of metal destroying the seals in your clutch slave cylinder. We have developed a technique for removing the guts of the valve without damaging the tapered seats that allow these valves to seal properly. To avoid the risk of a hydraulic leak and subsequent clutch failure caused by modifying your own CDV, you can have one modified by Zeckhausen Racing.

I think any change you make will be noticable compared to what you currently have, and if all else fails either a new CDV will cost a few ££ or to run without will not be an issue.

[chris]

True, but some people have complained of a rattle under the car if they haven't used one on the E46

Does yours rattle Na fair point, but a BMW guy said he just removes them on the E46.

[Dicky]

Does yours rattle Na fair point, but a BMW guy said he just removes them on the E46.

It doesn't and that was the first thing I thought when I found it wasn't there

Just a word of warning if people pick up a rattle if they don't use one

[Dubya]

I got my CDV delete this morning, from the said website above. I ordered it Sunday evening, and the postman stood knocking on the door before i left for work this morning. £43 all inc for parts, import tax and postage.

[MattBMW]

Still gonna have a bash at drilling mine out... as long as you clean it properly to ensure there are no shards of metal should be fine....I'll let ytou know how it all goes......the developed a method excuse sounds a bit vague to me.....what kind of tool do you think they use.....a spatula.....

[simonlpearce]

Still gonna have a bash at drilling mine out... as long as you clean it properly to ensure there are no shards of metal should be fine....I'll let ytou know how it all goes......the developed a method excuse sounds a bit vague to me.....what kind of tool do you think they use.....a spatula.....

You know Matt - I did wonder what this special "Method" of theirs was, i can only imagine they have drilled it or laser cut it or something similar.

[MattBMW]

Just they sound very vague...I know it's a secret but....please how hard can it be.....ok this is what I'm gonna do with it.....once removed gonna clean it....then drill it then sand it down (if need for any sharpish edges) and then another clean before reattach it.

Sorry SI not trying to take way anything from your purchases...just seems a bit of gimmick to me......

[simonlpearce]

Haha, i didnt pay for it - got it from dicky for free as his already had one, otherwise i would of just gone without one.

I reckon it may be advisable to screw the CDV into a bolt or something when drilling it to stop the drill bit from forcing any of the flares out at the end, it will also allow you to clamp it without the fear of fouling the CDV in any way.

Let us know how you get on.