My fear of Modifing the CDV

Ive been driving standard for a long time and like to think I am very good at it. I havent stalled a car in over 4 years. I ordered a UCC clutch stop for the car, and I also wanted to get a modified CDV however I have a fear. I work for a car dealership selling Nissan's. Over the course of any given week I drive about 30 or so cars that are not mine.. I would say 5 or 6 are standard. My problem is if I drive a car for a few hours I start to get used to that clutch, then I hop back in my own car and it takes a few minutes to adjust to my car again. Im not stalling the car by any means but sometimes I have to adjust how much gas to give as I release the clutch. My problem is I dont want to damage my clutch if I modify my CDV when I have to readjust to the car. Im left in a position as I dont know what to do. What would you do? Modify it? Keep OEM? Thanks for the help!






Matt

The CDV actually IS damaging to the clutch. It saves on the drivetrain - supposedly. That's it's purpose (that is limit torque delivery to wheels, through all the 'stuff'). By removing the CDV, you're going to INCREASE clutch life, but possibly increase the likelihood of damage to, say, the diff.

Hope this helps you - and btw, do it and don't look back!

I don't think the CDV's purpose is to save the driveline from the occasional stall. That's not nearly the kind of stress and wear and tear that would come from dumping the clutch at high speed or doing power shifts which is what I think it is made to help protect against. I had a 330i for 4 years, put in a modified CDV after one year and never looked back. Made a huge difference. About a month after I got my M Coupe I didn't even bother with the modified one, I just took it out. My vote is do it. If something is going to break just because you let the clutch out a little too fast and stall the engine once in a while, then it's going to break anyway.

peeti is absolutely right. The CDV shifts wear and tear from the drivetrain to the clutch. I experienced this first hand in my 330i. While doing full acceleration shifts I could tell the clutch was slipping. These weren't power shifts, but close...full throttle until close to redline, clutch in and lift throttle and shift up, all at the same time, as fast as possible, then clutch out and full throttle, also as fast as possible. Under that full throttle, immediately after shifting, the clutch took 1/2 a second to fully engage. With modified CDV, that 1/2 a second of slippage went away. I didn't drive like that very often of course, but when I did, it was a good indication of what was going on and helped explain why, as everyone else has indicated, it was also hard to drive smoothly when you are driving normally. It just adds another unpredictable variable to the shifting process. I took it out of my M before it was broke in so I never got to do a before and after comparison regarding hard acceleration, but it did make a difference as far as smooth shifting during normal driving.

My replacement CDV is going in later this morning. I can't wait to get that OE POS outta there. Also, Hawk Ceramic brake pads.

Why bother putting in the fake CDV? If something breaks and you try to claim warranty on it, I think you'd have a much better chance with BMW by just not having the part versus having an obviously bogus (fraudulent?) part in the car.

And if you're not going to claim warranty, then why put a fake part in at all? It's not like it's an aesthetic consideration.

From the exterior, the replacement CDV looks exactly the same. And I would bet that no service tech is going to notice or care that the hole is larger. If he does notice that its larger, he'll probably just assume it was manufacturing change. Therefore, he will never report the modification that could potentially void the warranty.

Originally Posted by IraXI

............Im left in a position as I dont know what to do. What would you do? Modify it? Keep OEM? Thanks for the help!


Matt

Like the Nike slogan "just do it"

Have you read this?

As I'm not at all mechanical, I'd want someone to do it for me so I don't screw something up. Where are folks going to have the CDV removed?

Originally Posted by SacM3

As I'm not at all mechanical, I'd want someone to do it for me so I don't screw something up. Where are folks going to have the CDV removed?

I was going to be asking the same question. Im obviously not taking it to the bmw dealer to do this. I dont trust the nissan service techs in my dealer to do it either.

In most metro areas there is usually one or two highly recommended independent BMW shops that have probably done this before. A bit of local investigation will probably turn someone up. If you don't have the tools and knowledge to do it yourself, this is the way to go.

After 2-3 hours laying in brake fluid trying to get my UUC stainless line on my car, I gave up and went back to stock. At least I can drive the car again.

Somehow, the hardline had damaged threads, and the stainless line simply would not go on. The "factory" one went right back on no problem. However, I am beginning to wonder if it was already "fixed" be a previous owner, because the ID of the stock line looked bigger than the ID of the stainless line, and I've never had any of the clutch problems CDV users complain of. *shrug* Will have to drive another S52 car with a CDV delete to compare.

I'll help anyone in Dallas / Ft. Worth area with theirs. Just bring it by.

My honest opinion is that the CDV is only there for one thing. To make sure the M cars clutches last the 36000 mile 3year maintenance period. I bet it does nothing but put more stress on the drivetrain to save the clutch a little.

I would change it immediately. If I don't want to dump the clutch, my foot can feather it just fine.

Originally Posted by reidconti

Will have to drive another S52 car with a CDV delete to compare.

I'm close by if you're interested, but I also have a LTW fly, so that'll be different as well.

Originally Posted by IraXI

I was going to be asking the same question. Im obviously not taking it to the bmw dealer to do this.

My BMW dealer did the CDV removal for me.

I have Turner Motorsports about 20 minutes away from me, Im sure they wont have any issues doing it for me.

I'm no "super-wrench". but this was an easy install for the weekend warrior. Two wrenches and a vice-grip. MUCH better clutch engagement!

Originally Posted by DaveZ

My BMW dealer did the CDV removal for me.

Same here. My dealer also did my clutch pressure line swap out. Dealer charged 1/2 hour labor ($62.50) to do work. I had work done while car was in for programing recall. HUGE difference thru all gears, but especially 1st to 2nd.

BMW is aware of CDV, center over and extension spring along with after market clutch pedal bushings.

Hey now... what's this about the clutch pressure line swap? Did I miss something while I was building my home theather room and not watching the forums? I've done the CDV but I'm all for anything that makes this thing drive more like it should... can someone point me to a URL?

Thanks!

I just got my UCC Clutch Line and will have her installed next week.

Originally Posted by Adam12Hicks

Hey now... what's this about the clutch pressure line swap? Did I miss something while I was building my home theather room and not watching the forums? I've done the CDV but I'm all for anything that makes this thing drive more like it should... can someone point me to a URL?

Thanks!

The S54's do not have the CDV as do the other Z models. Their pressure clutch line has built in restictions via smaller diameter fittings. By swapping out the OEM clutch line from the S54 to the non S54 line (standard Z part#), it accomplishes the same result as removing the CDV in the standard Z pressure clutch line. I think that's an accurate answer. Ron, care to elaborate further?

Originally Posted by beachbuggy

The S54's do not have the CDV as do the other Z models. Their pressure clutch line has built in restictions via smaller diameter fittings. By swapping out the OEM clutch line from the S54 to the non S54 line (standard Z part#), it accomplishes the same result as removing the CDV in the standard Z pressure clutch line. I think that's an accurate answer. Ron, care to elaborate further?

Z4 S54 has a CDV

Originally Posted by inTgr8r

Z4 S54 has a CDV

+1. Mine definitely had one... for about a week.