CDV Delete/Replacement DIY

[Dackelone]

Originally Posted by Scuderia000

How much brake fluid do I need to properly bleed the clutch?

I just got the motive euro pressure bleeder in the mail and the tank is pretty big. I only have about 1/2 a bottle of Motul RBF 600 (a full bottle is still only 500mL). Will that be enough? This brake fluid is $15 a bottle!

If I need to buy more can someone recommend a good fluid that isn't so expensive or is that normal?

Thanks!

I would order another bottle. I like to have one liter one hand when I flush teh brakes or when I did the CDV. The LAST thing you want to happen is to run out of brake fluid and get some air in the system/lines. Then this job becomes a real PIA job. Get another 1/2 liter just to be safe. You probably won't need it, but...


Dackel

[BlueforMonaco]

Will any DOT4 brake/clutch fluid do, such as Prestone, or is it recommended to get from the dealer?

[BlueforMonaco]

I think I would prefer to use OEM, although I'm a little concerned the dealer will wonder why I need it.

[Dackelone]

Originally Posted by BlueforMonaco

Will any DOT4 brake/clutch fluid do, such as Prestone, or is it recommended to get from the dealer?

Any DOT-4 or Super DOT-4 brake fluid will do. Just do NOT use silicone DOT-5. Also make sure you use the clear/brown fluid and not some BLUE brake fluid. That would be a red flag to some dealers that someone messed with your brakes/clutch. Use a clear brake fluid, preferbly German brake fluid.

You can just tell the parts guy your gonna bleed your brake fluid yourself. No need to tell them about the CDV delete. Or order it thru United or Tischer.


Dackel

[Focusedintntions]

Monaco...i just did the cdv this past weekend. Bleeding your brakes or clutch won't do anything to your warranty. If you want some help or anything let me know as I'm local and could help you if you get stuck.

[e82n54]

I just switched mine tonight. Wow does it feel better. Thanks to the original poster, larryn, and all who have contributed to this thread. I have almost no experience working on cars and got this done without any issues thanks to you guys.

This is very late in the thread, but I thought I would summarize most of the great tips and instructions previously posted. I purchased the CDV/lock valve from United BMW (~$16 including shipping) and modified it myself. I just stuck an allen wrench in the small end and smacked it once with a hammer. The 2 internal constrictive parts popped right out. I purchased a floor jack and 2 jack stands. I made wooden ramps (using free scrap wood from the Home Depot) to allow the floor jack to slide under the front bumper. I cut up a hockey puck and inserted the pieces inside the jack points to prevent damage to the plastic jack points. I switched the CDV, which was very easy, and had a bunch of towels and a drip tray ready. I was able to keep fluid loss to a minimum by plugging the rubber hose with my thumb. I bought a motive brake bleeder (for European cars) from amazon.com and used some spare DOT 4 - Motul RBF 600 brake fluid. I poured about 3/4 of the 500 mL bottle into the motive bleeder tank. As stated previously I pumped it to about 10 psi (I think that's the recommended pressure). I then pumped the clutch about 20 times, but it already felt firm after the first pump. (I don't know if the clutch pedal should be pumped before attaching the motive bleeder or not, but I pumped it after pressurizing the motive bleeder and didn't burst anything.) I bought a 11 mm half moon wrench from amazon.com, which worked very well considering the position of the valve. That was the only wrench I used. There's a picture of this wrench in post #84. I turned ~1/16 of a turn at a time, repositioned the wrench, and turned again... over and over. I counted ~14 partial turns to get fluid out of the bleeder nipple. I banged on the hoses and metal tubing while bleeding, but I didn't see any big bubbles only tiny ones. I hope I didn't leave any air in there. After bleeding and detaching the motive bleeder tank I noticed that the brake fluid reservoir was overfilled (above the max arrow) so I sucked out the excess with a syringe. I closed everything up and took it for a short spin. Total time was about 2 hours because I was so slow and didn't want to make any mistakes. Releasing the clutch in 2nd gear (after 1st) is much smoother now. It was definitely worth the effort.

Thanks again guys!!!

[BlueforMonaco]

No more pausing at the engagement point! 1st to 2nd shiift is greatest improvement, but 2nd to 3rd is very fast now. All shifts are able to be performed smoother, faster, and I'm sure with less clutch wear.

Just a note - brake fluid will dissolve the white numbers on the CDV immediatly.

Thanks to all that posted and provided assistance.

[HALOTHANE]

Anyone know of any reputable shops that can do the CDV mod in Miami?

[ulrichd]

Just had my mechanic do it while he had my car for an oil change. I was skeptical but pleasantly surprised by the change. It's subtle but there is slightly more resistance when depressing the clutch and it allows for a more nuanced engagement. Together with the modified clutch stop it's a real pleasure to shift this car, and it wasn't bad before.

[Dackelone]

Originally Posted by ianf2002

I don't understand the need for this mod. The clutch is precise as is. Perhaps later models don't have the issue

You are just too smooth a driver. You are not using the clutch pedal fast enough to "feel" the delay of the CDV.

Ever sit att a traffic light in neutral, then when the light turns green try to put the car in gear quickly? Ever try to fast (medium speed) 1st to 2nd gear gear change? Then you will notice the delay of the CDV.

[romak47]

Originally Posted by Dackelone

You are just too smooth a driver. You are not using the clutch pedal fast enough to "feel" the delay of the CDV.

Ever sit att a traffic light in neutral, then when the light turns green try to put the car in gear quickly? Ever try to fast (medium speed) 1st to 2nd gear gear change? Then you will notice the delay of the CDV.

+1 on that, faster the shifts and clutch movment the more you notice the CDV..

[135i, MD]

Best mod ever. I think this is arguably as satisfying an upgrade as my $800 Cobb AccessPort!

Just reiterating what others have said--the 1-2 shift is so smoooooth now!

[Dackelone]

Originally Posted by ianf2002

yeah, now after reading this thread I have started to notice the shifts more...just ordered one from BM...

Congrats Brother! Soon you will be singing the praises of the CDV-delete mod.

[jaf89f]

Holy Cow! What a difference. The best $16 spent ever. I always knew there was something odd about the clutch, brought it in a couple times, they said it was normal, normal my arse.

The car drives like a dream now, silky smooth, not to mention the clutch is now predictable unlike before.

Whoever hasn't done it, it's a must. If you're worried about warranty, just do what Dackelone, me, and I'm sure others have done where you just punch out the restricting piece inside the stock CDV.

Gotta love modding...revitalizes your love for the car again and again.

[ansch]

+1 just done mine. No more feeling like I'm "smashing the synchro" into 2nd and 3rd

[wolfe]

Did mine today, haven't tested it yet but wanted to share something that tripped me up. I also flushed the brake fluid which might have been part of my problem.

The dividing wall in the fluid reservoir goes REALLY high up, basically to the top of the reservoir. I had to fill the reservoir to within 3mm of overflowing to get the fluid over that divider and into the clutch cylinders. Wasted half a liter of brake fluid before I figured it out.

I found that to flush the clutch fluid I had to do just a little at a time, keeping a very close eye on that back 1/2" of the reservoir.

[gkmunch]

Edit: Nvm. I'm going to punch out a stock CDV instead of buying a "modified" one.

Is the part # for a 2012 135i still 21 52 6 764 872 ?

[JimD]

When I bleed brakes or flush out old brake fluid, I do not put the new fluid in the container of the brake bleeder. It wastes fluid, give the air more surface area of the fluid to try and work moisture in, and it creates more work by creating a need to clean the container. Instead, I refill the brake reservoir every wheel or two. It is really bad to let it go dry (you will then inject air in the lines) but this doesn't happen unless you don't check it. It is a bit of a pain to take the cap off the reservoir to put in new fluid but it is a bigger pain to clean the big bleeder reservoir. If you leave old fluid in the reservoir, you will start your next job at least potentially putting in worse fluid than you are replacing - moisture pickup is a big part of why you need to replace the fluid in the first place.

Jim

[Dackelone]

^^Welcome to the "CDV delete" club brother!


I think that click is from the driveshaft (R&R). Many people have complained about that noise right after having their LSD installed. Not sure what causing it though. ???

[larryn]

Nice to see the good ole thread still getting some mileage.

[gkmunch]

Just performed this, thanks for the great thread! I thought I'd add some content via some iPhone pics:

I used the rag/vice grips clamp method and this is the amount of fluid I lost:



Something like this works great to catch the fluid while you bleed. Just some $0.29/ft tubing and a plastic bottle:



A photo of the bleed nipple's location:



The bleed nipple and CDV relative location after I installed the new CDV with the restrictor punched out. If I were to do it again I would NOT buy a second CDV to swap in. No fluid came out when the vice grips were clamping the line, giving you plenty of time to punch out the restrictor pill from the CDV on your car:



As stated, this kind of obstruction wrench worked well on the bleed nipple:



And I found that a cheap pick tool like this worked much better than a small flathead screwdriver for releasing the lock clips on the CDV:




:tup:

[Riley1524]

Finally got around to doing this mod and it's a necessity that everyone do this. I was initially going to install the modified CDV, but just decided to take the CDV out completely and boy am I glad I did. The car is a pleasure to drive and isn't inconsistent as before in the lower gears, but most of all it seems to help with rev matching during down shifts in 2nd to 1st. Awesome MOD!!!