Anyone regret the CDV mod?

[esqu1re]

Getting into 2 is less jerky, but there is some driveline jerkiness when you are accelerating hard and switching gears. I definitely don't regret the CDV mod. Cars like this should not have the CDV <---training wheels.

[Ron Stygar]

Originally Posted by r4gs

ron, clutch was bled via the bleed screw on the cylinder itself. i'm trusting that it's sufficient?

http://www.bimmerfest.com/forums/sho...9&postcount=38

[bdejong11129]

Originally Posted by Caddyshk

One more thing - if you drive it like it's a Toyota Mini Van you may not notice a difference...

I almost choked on my lunch when I read this..Now I have to be honest. and a story will come with this but its worth the read....

I may not have been hard enough on the car while test driving it. One reason is that my wife has always been with me, that I can fix. The other one is that a few months back I was looking at a nice 2003 MSport 540 and while out on a test drive I pushed the gas pedal all the way down and about 3 seconds later I was blessed with a profuse amount of steam coming from under the hood. Turns out the plastic radiator decided to let go at the same time I wanted to feel out the car under full acceleration.

So here I am in a car that is not mine, from a private seller and I have to call him to notify him his radiator is blown and I am on the side of the road. (I pulled over immediately). So I am still a little on edge about really pushing a car that is for one unfamiliar to me and two that I don't own.

Now, the nice part is that I somewhat knew the guy and I did the right thing and helped him remove and replace the radiator that weekend but it still was not a good feeling...

But the next time I am out in a dealer owned car I will be more "sporty" in the driving to see if I notice it.

[mhughett]

Originally Posted by bdejong11129

I almost choked on my lunch when I read this..Now I have to be honest. and a story will come with this but its worth the read....

I may not have been hard enough on the car while test driving it. One reason is that my wife has always been with me, that I can fix. The other one is that a few months back I was looking at a nice 2003 MSport 540 and while out on a test drive I pushed the gas pedal all the way down and about 3 seconds later I was blessed with a profuse amount of steam coming from under the hood. Turns out the plastic radiator decided to let go at the same time I wanted to feel out the car under full acceleration.

So here I am in a car that is not mine, from a private seller and I have to call him to notify him his radiator is blown and I am on the side of the road. (I pulled over immediately). So I am still a little on edge about really pushing a car that is for one unfamiliar to me and two that I don't own.

Now, the nice part is that I somewhat knew the guy and I did the right thing and helped him remove and replace the radiator that weekend but it still was not a good feeling...

But the next time I am out in a dealer owned car I will be more "sporty" in the driving to see if I notice it.

Since I own an E39 and used to be a frequent participant in their boards, I can attest that what happened to you in the 540 is very common. What happens is that the engine shifts slightly when you accelerate hard and it temporarily puts a twist on the radiator hose. If the radiator is a few years old or more, the plastic gets more brittle and the neck where the hose attaches snaps off. If I had a dollar for every time I've read about this story I could probably fund my next set of tires with it.

[Finnegan]

Originally Posted by Finnegan

Zeckhausen addresses any warranty issues....

Originally Posted by Caddyshk

How does Dave Z manage warranty issues?

This was a poor choice of words in attempting to be brief (posting via Iphone).

What I meant was that since the CDV is still on the car (rather than a delete) and the Zeckhausen looks stock, it's not going to raise any red flags at the dealer. I doubt any tech at the dealer would know the difference between stock and Zeckhausen anyway even if they looked.

I've gone back and edited the prior post for clarity.

[Caddyshk]

Originally Posted by Finnegan

This was a poor choice of words in attempting to be brief (posting via Iphone).

What I meant was that since the CDV is still on the car (rather than a delete) and the Zeckhausen looks stock, it's not going to raise any red flags at the dealer. I doubt any tech at the dealer would know the difference between stock and Zeckhausen anyway even if they looked.

I've gone back and edited the prior post for clarity.

[Ron Stygar]

Originally Posted by Finnegan

This was a poor choice of words in attempting to be brief (posting via Iphone).

What I meant was that since the CDV is still on the car (rather than a delete) and the Zeckhausen looks stock, it's not going to raise any red flags at the dealer. I doubt any tech at the dealer would know the difference between stock and Zeckhausen anyway even if they looked.

I've gone back and edited the prior post for clarity.

BMW is aware of Zeckhausen.

[r4gs]

Originally Posted by Ron Stygar

http://www.bimmerfest.com/forums/sho...9&postcount=38

Ron, that was the original thread i had consulted prior to deciding on a cdv swap. i have arranged for a service appointment next saturday and will request a full clutch bleed just to be doubly sure. thanks much for the heads up!

[Ron Stygar]

Originally Posted by r4gs

Ron, that was the original thread i had consulted prior to deciding on a cdv swap. i have arranged for a service appointment next saturday and will request a full clutch bleed just to be doubly sure. thanks much for the heads up!

How I check mine when I do a bleed.

I have a clutch stop set up for the release point a ~half inch from the stop.
If you do a bleed and remove some air the release will go up higher.

[Finnegan]

Originally Posted by Ron Stygar

BMW is aware of Zeckhausen.

Makes sense. But the average tech? Maybe not so much? In any case, my information/reasoning was apparently flawed....

Is BMW flagging cars for just having the Zeckhausen or voiding the power train warranty? It wouldn't make a difference to me as I hate how the car drives with it and I'm willing to pay to play on that one, but I'm sure this might factor into other's decisions.

I guess the core question is whether just having it will flag the car (are they actively looking); or if it might become an issue should clutch or transmission problems occur....

Any insight would be appreciated so we can take appropriate steps....

[Ron Stygar]

Originally Posted by Finnegan

Makes sense. But the average tech? Maybe not so much? In any case, my information/reasoning was apparently flawed....

Is BMW flagging cars for just having the Zeckhausen or voiding the power train warranty? It wouldn't make a difference to me as I hate how the car drives with it and I'm willing to pay to play on that one, but I'm sure this might factor into other's decisions.

I guess the core question is whether just having it will flag the car (are they actively looking); or if it might become an issue should clutch or transmission problems occur....

Any insight would be appreciated so we can take appropriate steps....

It's in the Tech Info mag that BMW throws out. If they don't read it.

[r4gs]

inspecting the zeckhausen and oem cdv's side by side, everything from the number etching to the machining looks almost identical, only difference being the significantly larger bypass area of the zeckhausen one. i'm quite sure that unless a in-the-know bmw tech removes the cdv and spots it to be a zeckhausen, there's next to no way to tell on visual inspection.

[Skelekitty]

Originally Posted by Finnegan

Makes sense. But the average tech? Maybe not so much? In any case, my information/reasoning was apparently flawed....

Is BMW flagging cars for just having the Zeckhausen or voiding the power train warranty? It wouldn't make a difference to me as I hate how the car drives with it and I'm willing to pay to play on that one, but I'm sure this might factor into other's decisions.

I guess the core question is whether just having it will flag the car (are they actively looking); or if it might become an issue should clutch or transmission problems occur....

Any insight would be appreciated so we can take appropriate steps....

Screw 'em. I love the CDV mod. We're not putting it back (and it's my car, so...). SKELEKITTY SAYS, NO CDV!

[dekaliber]

CDV made a night and day difference in drivability, especially for the heavy duty M clutch.

THe notchiness is common on this transmission, and as has been stated, has nothing to do with the CDV. In fact, I can feel it in my ZHP too (same ZF gearbox), but it's more subtle.

[Blind32]

Originally Posted by dekaliber

CDV made a night and day difference in drivability, especially for the heavy duty M clutch.

+1 Noticed it immediately that it felt much much better.

[Ron Stygar]

Originally Posted by dekaliber

CDV made a night and day difference in drivability, especially for the heavy duty M clutch.

What did it do on the heavy duty M clutch?

[r4gs]

curious as well how the cdv may have helped the clutch feel itself. as far as mechanically understood, the cdv delete would only help engage the gears directly and immediately instead of the 'delay' the valve itself is meant to create in order to prevent 'shock' to the master cylinder?

[thekurgan]

Originally Posted by r4gs

curious as well how the cdv may have helped the clutch feel itself. as far as mechanically understood, the cdv delete would only help engage the gears directly and immediately instead of the 'delay' the valve itself is meant to create in order to prevent 'shock' to the master cylinder?

I believe it's there to relieve stress on the driveline, not the master cylinder, but someone correct me if I'm wrong.

[JPWEraser]

Originally Posted by thekurgan

I believe it's there to relieve stress on the driveline, not the master cylinder, but someone correct me if I'm wrong.

A CDV is a valve that delays/restricts fluid delivery (and thus clutch engagement) to help circumvent the possibility of grinding gears and driveline damage due to aggressive or careless shifts.

Prime example - 2003+ S2000s came with a CDV. It was quite a popular mod for people to remove it and while some were ok with the change, others were left with blown rear diffs and damaged gears as a result.

[thekurgan]

Originally Posted by JPWEraser

A CDV is a valve that delays/restricts fluid delivery (and thus clutch engagement) to help circumvent the possibility of grinding gears and driveline damage due to aggressive or careless shifts.

Prime example - 2003+ S2000s came with a CDV. It was quite a popular mod for people to remove it and while some were ok with the change, others were left with blown rear diffs and damaged gears as a result.

Thanks for the better explanation. I didn't know the S2000 had such a unit, is it as easy to replace/remove as the BMW unit?

[JPWEraser]

Originally Posted by thekurgan

Thanks for the better explanation. I didn't know the S2000 had such a unit, is it as easy to replace/remove as the BMW unit?

Depends on how you look at it. The S2000 tranny would accept both AP1 and AP2 slave cylinders (which is where the CDV is in the S2000) so it was popular for folks to buy an AP1 slave cylinder and slap it on. One could also choose to modify the AP2 slave cylinder to remove the CDV. There is a large visible difference between the AP1 and AP2 slaves as the AP1 is black and a little smaller while the AP2 is silver and larger.

I had an AP1 S2000 and I couldn't imagine having that car with one. My S2000 was heavily modified with an aftermarket clutch, pressure plate, built transmission, and built diff.. sooo my opinion of CDVs is a little skewed in that respect. I have contemplated doing the CDV mod in my Z4MR, but I haven't been really that unhappy with its current performance.

[thekurgan]

Originally Posted by JPWEraser

Depends on how you look at it. The S2000 tranny would accept both AP1 and AP2 slave cylinders (which is where the CDV is in the S2000) so it was popular for folks to buy an AP1 slave cylinder and slap it on. One could also choose to modify the AP2 slave cylinder to remove the CDV. There is a large visible difference between the AP1 and AP2 slaves as the AP1 is black and a little smaller while the AP2 is silver and larger.

I had an AP1 S2000 and I couldn't imagine having that car with one. My S2000 was heavily modified with an aftermarket clutch, pressure plate, built transmission, and built diff.. sooo my opinion of CDVs is a little skewed in that respect. I have contemplated doing the CDV mod in my Z4MR, but I haven't been really that unhappy with its current performance.

Agree, it has helped parallel parking and will probably extend the life of the clutch face by reducing the slip, but that's about it. Didn't do much for actual changing of the gears.