CDV Delete/Replacement DIY

[MightyMouseTech]

HELP! Pulled out the CDV, removed the restrictor and put it back in. Did a quick vacuum bleed on the slave cylinder, now the pedal goes to the floor and just stays there. Can't seem to get anything out of the line anymore. Any ideas?

Edit: Just talked to a fellow tech over at BMW, and he says you have to "reverse pressure bleed" the system. Basically, push the fluid up from underneath into the reservoir. Will give it a whirl.

[MightyMouseTech]

After three hours, got the clutch pedal back. Had to dissasemble the entire clutch hydraulic system, then rig up some kind of pressure bleeding system. (old oil bottle filled with brake fluid and a line coming off).

Executive summary: DO NOT VACUUM BLEED THE CLUTCH LINE!!!!!!

Astie-Tabernak!

[Dackelone]

Originally Posted by FactorX81

Question for all those that have done this how smooth is your clutch pedal now? I did this about a week ago and I love the engagement however I feel as if my clutch pedal is not smooth it almost feels like it is rubbing or something I bled the clutch using a motive bleeder but did not have anyone to hold down the pedal. I also noticed the pedal now makes a faint squeaky noise not sure what the deal is.

You still have some air in your hydraulic clutch lines. rebleed your system again. I bet you also have a little bit of a soft clutch pedal too. Like free play in an old cable clutch system? Rebleed your lines.

Originally Posted by MightyMouseTech

HELP! Pulled out the CDV, removed the restrictor and put it back in. Did a quick vacuum bleed on the slave cylinder, now the pedal goes to the floor and just stays there. Can't seem to get anything out of the line anymore. Any ideas?

Edit: Just talked to a fellow tech over at BMW, and he says you have to "reverse pressure bleed" the system. Basically, push the fluid up from underneath into the reservoir. Will give it a whirl.

Yea... IF the pedal goes to the floor... you need to pull it back up(by hand) and then pump it up(pressing the pedal down and then pulling back up). It will take a while before the pedal gets firm again. Then rebleed your clutch.

Yea... using a reverse bleed is best. Pressure bleeder is 2nd best way. Vacuum bleeder is a no go.

This video might be of help...

[FactorX81]

I re-bled my clutch last night but it still feels funky I think whatever binding or rubbing I am feeling is actually not in the pedal part but in the transmission side. I had my wife cycle the clutch a couple of times while I was under the car and could hear the noise in that area. I'm thinking that maybe it has always been there and I couldn't feel it with the restriction in the original cdv. Other than that I love the way the clutch engages now I don't have that jerky motion during my shifts that I had with the original cdv in.

[Fume]

I just did this mod with the help of all the pictures, instructions, and clarifications in this thread. The difference was immediately noticeable on my first shift to 2nd gear! Wow. I should have done this earlier.

I was a little worried about bleeding the clutch with the problems people have been having but everything went well. Didn't have to re-bleed. Buying the motive pressure bleeder probably helped with that.

[CGMike]

I just removed mine and bled it this weekend. I dont like that the bleed screw takes so many turns to finally bleed. I ended up using offset racheting wrenches to bleed the clutch. These worked great and made everything a lot easier. 11mm. These are the ones I used from harbor freight.

[kobeballer96]

So. You don't physically have to buy another valve correct with the I sided deleted, I can just bypass it and connect point a to point b. my car is out of warranty so I don't care.

[wildacex187]

@kobeballer96


^^correct.

[Texan Engineer]

I just did the CDV delete on mine - shifter definitely runs smoother, particularly disengaging gears. More/faster pressure delivered to the clutch diaphragm (or whatever it's called) I think.

Also a top tip I found: an old beer bottle is perfect for catching any bled brake fluid from the clutch bleeder valve.

[prcsa77]

Did this mod and like @MightyMouseTech had the pedal go down to the floor. Did the reverse bleeding and it was fixed, with great results; or so I thought.

After enjoying close to 1K miles of crispier shifting, the pedal went to the floor (my GF was driving it while out of town). After pulling it up, it seemed to work/shift fine. She checked the reservoir and it seemed to be full still.

I'm guessing it's drawing air through the CVD itself (failed to replace "o" ring with a new one when I did the delete) or the bleeder valve. Still have to get the car back to take a look. Is there anything else I need to check or do?

thanks in advance...t

[berne]

aha, so if i get this right, i can take a thin, small screwdriver and push the small pieces thru the cdv and just reinstall it instead of buying a modified cdv?

[Dackelone]

Originally Posted by berne

aha, so if i get this right, i can take a thin, small screwdriver and push the small pieces thru the cdv and just reinstall it instead of buying a modified cdv?

You have two options...

1). remove the factory CDV and plug the two factory hydraulic lines together. Leaving the CDV out of the hydraulic circuit.

2). buy a new CDV and punch out the inner restricter jet. Then reinstall the mod'd CDV.

[berne]

Originally Posted by Dackelone

You have two options...

1). remove the factory CDV and plug the two factory hydraulic lines together. Leaving the CDV out of the hydraulic circuit.

2). buy a new CDV and punch out the inner restricter jet. Then reinstall the mod'd CDV.

Attachment 1068106

Attachment 1068107

and 3) i take the CDV thats on the car, and punch out the inner stuff?

ohh did u change the transmissions fulid after this, some one in the swe commenity, was saying it was a good ide

[Dackelone]

Originally Posted by berne

and 3) i take the CDV thats on the car, and punch out the inner stuff?

ohh did u change the transmissions fulid after this, some one in the swe commenity, was saying it was a good ide

+1 on #3.

Changing your transmision fluid is not a bad idea. I would change it before your car reaches 50Kms. Also change the diff fluid too. You will need a pump that can suck out the old diff fluid.

But I would NOT do this at the same time. Sometimes its best to do ONE mod at a time(!)... so you can feel what has changed on the car.

You will need 2.1 liters of manual trans fluid: BMW MTF-LT5 (I use Red Line's ATF-D4 in my manual trans)
For the diff you need 1,2 liters of Castrol SAF-XJ 75w140, GL5 API.

[vwbrady]

oh geez that made a huge difference! Thank you!

[AtlRyan]

Thanks for all of the info guys! Successfully deleted the CDV and bled the clutch line without issue.

I'm much more accurate with the clutch now

[7smurfs]

Does doing this basically count as doing a brake fluid replacement service?

[Dackelone]

Originally Posted by 7smurfs

Does doing this basically count as doing a brake fluid replacement service?

Well... not really, bc you would still need to bleed out any air bubbles(trapped) at each brake caliper. But yea... most of the brake fluid would be changed when you bleed the CDV.

[7smurfs]

okay thanks! I was just wondering because my brake fluid service indicator came on however having done the CDV a short while ago.. .wondering whether a full change is needed!

[BigRussia]

Ok finally did this yesterday with a BMS modified CDV after wanting to do it since I found out the cause of my cars jerkiness and bucking was from the damn factory CDV! Honestly I was getting worn and tired from it, especially the 1-2 shifts.

All I can say is even if you can drive the car smoothly with the factory CDV do this mod!!! Its not worth the extra effort to drive the car smoothly with the factory CDV. The modified/unrestricted/bypassed CDV reduces the jerkiness by at least half and feels like it dampens and smoothens the clutch operation. While it could be a placebo effect but even the shifter action feels smoother, specifically the usually notchy 1-2 shift. It's definitely made my car more enjoyable and easier to drive and no longer feels like a chore.

The install itself really is straightforward and easy, honestly what took the most time for me was getting to the damn bleeder nipple with a straight 11mm wrench (thank you BMW for putting it at the most awkward angle possible). Bleeding involved 5 pumps and there was hardly any air in the system (my helper had kept his finger capping the hose when I swapped out the factory cdv for the bms one, maybe that helped). Did not need to add any DOT4 fluid afterwards either.

Here's some observations from my install that I hope will help anyone on the fence about doing this install!

- If you cant get to the retainer clip on the connector because its pointing up, no problem if you have a thin/tiny enough head on your flathead screwdroiver you can push out the two bottom parts of the clip to get it to pop out rather than having to pull it up.
- The bleeder nipple is in a very tight space between the tranny and car frame and at an awkward angle, definitely buy a 11mm crescent or S wrench like others have posted pics of or will be hating life trying to loosen the nipple.
- Definitely have a helper during the bleeding! To get the fluid from shooting onto the car frame I attached a vacuum hose going into a empty water bottle.

Hope this helps and thanks to everyone who contributed to this thread, it was a great help!

[naeshy]

Ok, just got this done this week. I did this at the same time I was bleeding the brakes (they were due) since I was going to open the system anyway. I went with the "punching the restrictors out" method and that seems to have gone fine. I ended up losing a lot of fluid as my hose clamp wasn't tight enough and the plug I made didn't work too well... oops.

The hard part was definitely bleeding the clutch line. You have to really crank that bleeder nipple open before you get a path (thanks CGMike for the helpful PMs). Also be careful when tightening and loosening the bleeder nipple... it's plastic and won't hold up to much torque (I started to strip mine before I switched over to a socket to safely break it open). I ended up doing a reverse bleed with a Motiv style DIY bleeder (https://www.youtube.com/watch?v=Mdcn1USVQ-w) that worked pretty well once the nipple was open. Word of caution on that, I started to fill the reservoir a lot faster than I intended and overflowed fluid into my engine bay. Go low with the pressure and be ready to siphon off fluid as well as release some pressure on your bleeder to slow it down. No bubbles though after initial bleeding, so hopefully it's clear.

Now on to my question... I didn't get the nipple all the way closed before I took my bleeder off so I got a couple of drips of fluid back out before I closed it. I assume this is ok though since the reservoir was full and I essentially just gravity bled it for a couple seconds? I had to pump up the pedal quite a bit after the bleed but it's fairly firm now and drives fine. The clutch is a lot softer now (like my old Integra) but still seems to catch in the same position. Is this what I should expect from the larger opening in the CDV or is this a mushy, poorly bled line? Just not sure how the modified line should feel vs. a line with air in it.

Thanks for any comments and this thread has been super helpful!

[tjswarbrick]

My BMS modded valve is in. Going to try it this weekend.
I haven't noticed any trouble with my 1-2 shift, but I note occasionally when I shift quickly at high RPM that is takes 1/2 second after clutch release for forward motion (hard acceleration, anyway) to resume. Feels like turbo lag, but even happens above 4k rpm. Hoping this will clear that up.

Unrelated, but this morning was 10+ degrees colder than it's been since I got the car. Needed to wear a coat and turn on the heater to put the top down (registered 56 deg F.) Transmission was notchier feeling until I got to the freeway and fully warmed up. May need some synthetic fluid in there.

Found the offset ratcheting box-end wrench set at Harbor last night! CDV-delete here I come. Wish me luck...