[Thescout13]

Originally Posted by KevinM

Well damn. My M5 doesn't have a CVD and I removed it from my Z4M when I bought it on principle. I was driving an F80 M3 for three years before the M2C, and didn't think that had a CDV; the M2C shifts the same to me. Maybe the F80 M3 also has a CDV? The thing is, I find the shifting feel of the M2C fine, so now I'm torn because I know the CDV is there...

F80 is the same. Shifting on the M2C is fine-ish until you get the UCP, then you really notice the CDV.

[2020M2Competition]

Originally Posted by Poochie

Damn, say it ain't so; I was looking forward to this mod but if it's going to make the clutch pedal feel drastically lighter, that's not something I would appreciate.

I know bleeding a BMW slave cylinder can be a chore, so I suggest you reserve judgment until you're sure it's done properly and there is no air left in the lines..

Keep us updated..

Went back to the shop this afternoon to have the clutch and brakes bled again

Clutch pedal has firmed up considerably

It now feels just a tiny bit softer than stock, but with greater sensitivity and consistency

Will need more seat time to evaluate further

Fortunately, I have a track day on Sunday

[2020M2Competition]

Originally Posted by Thescout13

Yeah I think the UCP will make a difference. The center spring location is makes more stuff and you can even take off one of the two springs to make it even stiffer. I would imagine with the stock pedal it may feel different like your experiencing.

Thanks for the input

I definitely think the UCP could help and will more than likely try to order one

[Poochie]

Originally Posted by VTBoss302

Went back to the shop this afternoon to have the clutch and brakes bled again

Clutch pedal has firmed up considerably

It now feels just a tiny bit softer than stock, but with greater sensitivity and consistency

Will need more seat time to evaluate further

Fortunately, I have a track day on Sunday

I figure that would help since the clutch and brakes shares the same brake fluid reservoir, so when you replace the slave cylinder, it can introduce air bubbles into the entire system, not just the clutch line.

Your shop did the right thing by bleeding the brakes and slave together, into order to eliminate any possible air from the complete system.

Beware DIYers, it's a total bitch if you vehicle is not up on a lift and you have no one to assist with the bleeding process..

[AndrewC1989]

Originally Posted by VTBoss302

Went back to the shop this afternoon to have the clutch and brakes bled again

Clutch pedal has firmed up considerably

It now feels just a tiny bit softer than stock, but with greater sensitivity and consistency

Originally Posted by Poochie

I figure that would help since the clutch and brakes shares the same brake fluid reservoir, so when you replace the slave cylinder, it can introduce air bubbles into the entire system, not just the clutch line.

Your shop did the right thing by bleeding the brakes and slave together, into order to eliminate any possible air from the complete system.

I did this mod recently and went for my second drive today since the install. I didn't notice it the first time but today when I first pushed the pedal in to start the car I thought that it felt a tiny bit lighter than normal. Not sure if this is all in my head but I could swear it did feel a little less firm. Nothing alarming or terribly obvious and during driving it felt totally fine. It's only something I can really notice when going from neutral into 1/R. I'm wondering if the cause for the added lightness is not related to improper bleeding or air in the system but rather inherent to the lack of a restrictor in the new slave. Perhaps it's causing less backpressure so the pedal feel is less firm as a direct result? Seems logical.

Anyway, even though the clutch pedal seems a tad lighter, the way the car shifts compared to the way it used to is night and day and I've noticed the benefits of the mod even more today. The car doesn't jerk around and buck sometimes like it used to. Up and downshifting is smooth as hell. It's a BIG difference that I didn't notice as much the day I got it installed when I drove it from the shop back to the house. For me, this is one of those mods I wish I'd done sooner. It's made the car so much more enjoyable to drive.

[Poochie]

Originally Posted by andrewc89

I did this mod recently and went for my second drive today since the install. I didn't notice it the first time but today when I first pushed the pedal in to start the car today I thought that it felt a tiny bit lighter than normal. Not sure if this is all in my head but I could swear it did feel a little less firm

When you get a chance, maybe have a shop vacuum bleed the slave cylinder and all four corners again and see if it stiffens up the clutch pedal.

Vacuum bleeding consist of connecting a hose to the nipple of the slave/caliper's bleed valve and other end submerged in brake fluid. Then pump but keep the reservoir filled with fluid, allowing it to circulate. This pushes fluid through the lines and eliminates any air pockets.

If afterwards it still feel light-ish, then I guess maybe it's just the MO of an unrestricted slave..

It's hard to say without testing it myself and making my own hypothesis but what you're concluding sounds logical, that the lack of resistance would make the pedal feel lighter.

I'm also only making this assumption because you're the third person to mention a pale feedback, so there might be something to that.

[AndrewC1989]

Originally Posted by Poochie

When you get a chance, maybe have a shop vacuum bleed the slave cylinder and all four corners again and see if it stiffens up the clutch pedal.

If afterwards it still feel light-ish, then I guess maybe it's just the MO of an unrestricted slave..

Yeah, that's a good plan. I'll update when that happens.

[RocketBoots]

Just did this over the weekend. Big thanks to Thescout13

My initial thoughts: If the AutoSolutions SSK is an 8.5, and the UCP is a 6, for me, this is a 6. During the first bit of driving, the pedal was definitely softer, especially when you start the shift. At this point, I'd say it's back to OEM feel.

To me, this mod is kind of like removing a tumor or a thorn in your side vs buying a new watch or suit. The OEM CDV was 'hurting' me at every single shift. The engagement point always seemed unpredictable (except for first). I really couldn't understand why the car wasn't smooth, despite my best efforts. Now, the car is getting more smooth, because I am having to re-learn the muscle memory a bit. But my body and brain are learning very quickly, as the clutch engagement is relatively linear. In contrast, the SSK is like buying a new suit. The OEM shifter wasn't hurting me, and the new SSK really changed the shifting experience much more dramatically. The CDV delete is more subtle, but perhaps more necessary. I know this is so cliche, but the car really should have come from the factory this way. There is NO need for a CDV. There is need of clutch skill.

My guess is that I'll enjoy this more and more as time progresses.

BTW, I already had the Ultimate Clutch Pedal installed, and there were no issues bleeding the slave.

[AndrewC1989]

Originally Posted by RocketBoots

To me, this mod is kind of like removing a tumor or a thorn in your side vs buying a new watch or suit. The OEM CDV was 'hurting' me at every single shift. The engagement point always seemed unpredictable (except for first). I really couldn't understand why the car wasn't smooth, despite my best efforts.

This is a great way of describing this mod. Definitely like removing a thorn.

Originally Posted by RocketBoots

During the first bit of driving, the pedal was definitely softer, especially when you start the shift. At this point, I'd say it's back to OEM feel.

While I do love the predictable engagement and find it pretty life-changing, I'm not super happy with the added lightness. It's not terrible or anything but It's definitely a small step backward. I'm currently having the clutch rebled to make sure there are no air pockets, but a part of me thinks the lighter pedal feel is unavoidable and is simply a byproduct of deleting the restrictor valve. Hopefully it stiffens up a little after a rebleed but even if it doesn't this is a great mod that I am definitely keeping.

[CTSean]

Out of curiosity is replacing the whole slave really easier than pulling the hard line and removing the restrictor like this guy did? https://f30.bimmerpost.com/forums/sh...&postcount=102 It's too cold for me to take a stab at this at the moment so I don't know what it really looks like for clearance under there.

[RocketBoots]

Originally Posted by andrewc89

While I do love the predictable engagement and find it pretty life-changing, I'm not super happy with the added lightness. It's not terrible or anything but It's definitely a small step backward. I'm currently having the clutch rebled to make sure there are no air pockets, but a part of me thinks the lighter pedal feel is unavoidable and is simply a byproduct of deleting the restrictor valve. Hopefully it stiffens up a little after a rebleed but even if it doesn't this is a great mod that I am definitely keeping.

The re-bleed might help. It seems like people that have had this kind of issue had something going on with the bleeding. I had a shop do it, and they've already done a few of these. I was talking with the tech, and he said he had to pump the clutch a bunch of times, and told me to expect it to firm up as I drove it more. Turns out, he was right

Also, if you have an UCP, you could adjust the spring to the more stiff setting. Come to think of it, I may do that...

Originally Posted by CTSean

Out of curiosity is replacing the whole slave really easier than pulling the hard line and removing the restrictor like this guy did? https://f30.bimmerpost.com/forums/sh...&postcount=102 It's too cold for me to take a stab at this at the moment so I don't know what it really looks like for clearance under there.

To me, replacing the whole slave is a no-brainer. It's an inexpensive part, and the cleaner/easier way to go. Just FYI, I had a great shop do mine (shout out to P-Tech!). They'd done a few the 'old' way, and said some of those folks had problems later on. I didn't press further about the details of the problems, but they did say that replacing the whole thing was a more ideal solution.

[Thescout13]

Originally Posted by CTSean

Out of curiosity is replacing the whole slave really easier than pulling the hard line and removing the restrictor like this guy did? https://f30.bimmerpost.com/forums/sh...;postcount=102 It's too cold for me to take a stab at this at the moment so I don't know what it really looks like for clearance under there.

As the poster noted above, from what I read some had leaks in their system doing it the old way (including the guy in the thread I posted in the original post). End of the day is up to you, just wanted to remove that possibility myself.

[Montaver]

This strikes me as one of those placebo mods, and reading between the lines doesn't actually improve anything. The stock clutch feels very consistent to me, if a little long at the very top.

[AndrewC1989]

Originally Posted by Montaver

This strikes me as one of those placebo mods, and reading between the lines doesn't actually improve anything. The stock clutch feels very consistent to me, if a little long at the very top.

Speaking as someone who has owned and driven their car for 3 years on the stock slave/cdv and recently changed it, I feel like I know what I'm talking about here. I'm telling you right now this isn't a placebo and that a very large noticeable positive change has taken place. If it hadn't done anything I'd have stuck the old part back on and returned/resold the new part. But don't take my word for it, go ahead and try for yourself.

[Montaver]

Originally Posted by andrewc89

Speaking as someone who has owned and driven their car for 3 years on the stock slave/cdv and recently changed it, I feel like I know what I'm talking about here. I'm telling you right now this isn't a placebo and that a very large noticeable positive change has taken place. If it hadn't done anything I'd have stuck the old part back on and returned/resold the new part. But don't take my word for it, go ahead and try for yourself.

Fair enough. So what's the actual difference? I have no issue shifting smoothly with the stock setup.

[AndrewC1989]

Originally Posted by Montaver

Fair enough. So what's the actual difference? I have no issue shifting smoothly with the stock setup.

The difference is in the way the clutch engages. It has nothing to do with drivers' skill or error. The way the clutch functions with the delay valve in place will make shifts more rough and unpredictable by nature. I've been driving MT my whole life and this is my 3rd 6MT bmw. This car, in particular, is rough shifting sometimes and the cdv is clearly the cause behind it. If you don't see or have a problem shifting then don't do the mod. I very clearly saw issues with the shifting and clutch engagement in this car regardless of how careful I was and this mod solved that immediately. It's not an expensive mod so if you're curious go do it and see for yourself.

[Daytona_550]

The best way that I can explain it is that, with the unrestricted slave cylinder, the clutch engagement follows the action of your foot at a linear rate. With the CDV, the clutch action lags behind your foot, and not in a consistent or predictable way.

[RocketBoots]

Originally Posted by Montaver

This strikes me as one of those placebo mods, and reading between the lines doesn't actually improve anything. The stock clutch feels very consistent to me, if a little long at the very top.

Nothing to read between the lines; it's definitely not placebo, but it's not as in-your-face (or ass) as getting a +100HP tune. I also think it depends on your driving style/conditions. It's definitely more noticeable if you're a bit of a spirited driver. But even under much more conservative driving, it's hard to be consistently smooth. For example, when I'd go maybe half or less throttle, shifting ~3500rpm, sometimes the car would over-rev, or be smooth, or even buck.

The CDV also makes it nearly impossible to stall out of 1st gear. Perhaps BMW was catering to fledgling 6MT drivers, and wanted them to have a good experience; or if this is your first MT car, and you're learning how to drive MT. As mentioned a few times already, it's a very inexpensive mod, so there's little risk in trying it out and making your own conclusions.

[AndrewC1989]

Originally Posted by Poochie

When you get a chance, maybe have a shop vacuum bleed the slave cylinder and all four corners again and see if it stiffens up the clutch pedal.

Just got the car back from the rebleed and the clutch feels stiffer for sure. Still has that initial inch of slight play right at the beginning but it's only apparent if you're looking for it. Not sure if that existed before the mod or not but either way when you go for a normal clutch press at full speed it's not noticeable. Overall it feels as close to the OEM weight as much as I can remember. Definitely glad I rebled, thanks for the suggestion.

[RocketBoots]

Originally Posted by andrewc89

Just got the car back from the rebleed and the clutch feels stiffer for sure. Still has that initial inch of slight play right at the beginning but it's only apparent if you're looking for it. Not sure if that existed before the mod or not but either way when you go for a normal clutch press at full speed it's not noticeable. Overall it feels as close to the OEM weight as much as I can remember. Definitely glad I rebled, thanks for the suggestion.

That initial inch was the softness I first felt also. It went away after a couple of drives.

[AndrewC1989]

Originally Posted by RocketBoots

That initial inch was the softness I first felt also. It went away after a couple of drives.

Good to know, will keep an eye out to see if it changes over time.

[Montaver]

Alright I'm interested. What's the labor cost and where is the CDV located? One thing I was already considering is the UCP as I think the clutch pedal sits an inch or so too high. Whilst I can shift smoothly there's definitely a 'lag' to the clutch, I definitely have to slow release on the 1-2 but just gotten used to it.