E90Post
 


Extreme Powerhouse
 
BMW 3-Series (E90 E92) Forum > BIMMERPOST Universal Forums > General Automotive (non-BMW) Talk + Photos/Videos > Clutch drops and general MT questions - Help a noob!



Reply
 
Thread Tools Search this Thread
      06-25-2007, 01:46 AM   #1
GewoW
#thatsanicemovebro
GewoW's Avatar
Greece
198
Rep
3,920
Posts

Drives: E92 M3 LSB/Black 6MT
Join Date: Mar 2007
Location: Montreal, Canada

iTrader: (4)

Garage List
2011 BMW M3  [9.34]
Clutch drops and general MT questions - Help a noob!

I am a noob...at least when it comes to driving MTs...I have a 335 MT and would like to know everything wrong with something that I'd like to do before I would actually go ahead and do it. For that, I have a few questions, and as nooby as they are, having them answered would be greatly appreciated. I mean, how else would I learn?

Now, I know the 335 has a CDV, thus delaying the clutch engagement for noobs like me that would drop the clutch. Without it, I hear that it's easy to modulate the clutch and that shifts are more seamless.
So, questions:
1- What is dropping the clutch? Is it the fact that you reengage the clutch while still giving the engine power?
2- For a 335i w/ a CDV (I know...all MT 3s have one..), would a quick shift from 1st to 2nd still produce a jolt, even if the clutch is completely engaged before flooring it again?
3- That nice little smell from the engine bay after some hard driving, might that be the clutch getting raped because of excess slip?
4- W/out a CDV, would a quick shift from x to x+1 still produce a jolt if the clutch is completely reengaged before power delivery? The fact that your driveline is not protected as much, does that mean you can't drop the clutch with fast shifts? Is the delete mod geared towards the normal drivers or for the eager ones?
5- What is the advantage of a CDV delete and what does the CDV do to protect the driveline at the expense of the clutch.
6- How bad is it to shift quickly, as compared to smooth shifting, with moderate clutch "riding" or slipping.
7- Is there any way to remove that jolt from 1st to 2nd shift (@ high RPMS) while still having a CDV?
8- What are the downsides to shifting @ high RPMS (ex. hard acceleration w/ 7000RPM shifts) and are these surmountable?
9- With revmatching, when you would press on the throttle while having clutch disengaged to match revs of the lower gear that you are shifting into, isn't that really really bad for the clutch? Is it better to blip?

If I have more, I will post them.
Really sorry for all this guys, but I've done a lot of research and have found a lot, but there are still these lingering questions in my mind.

Help a noob out!

P.S. Mods, I didn't know the best place to put this, so move it anywhere you think is better.

Last edited by GewoW; 06-25-2007 at 02:37 AM..
Appreciate 0
      06-25-2007, 04:53 PM   #2
GewoW
#thatsanicemovebro
GewoW's Avatar
Greece
198
Rep
3,920
Posts

Drives: E92 M3 LSB/Black 6MT
Join Date: Mar 2007
Location: Montreal, Canada

iTrader: (4)

Garage List
2011 BMW M3  [9.34]
Anyone?
Appreciate 0
      07-03-2007, 12:35 PM   #3
Bones Justice
New Member
United_States
0
Rep
18
Posts

Drives: Shopping for an i8
Join Date: Apr 2007
Location: Weehawken, NJ

iTrader: (0)

I'm a bit of a MT n00b myself, so I'd be interested to hear the answers as well .
Appreciate 0
      07-03-2007, 06:08 PM   #4
spacedogg
Colonel
spacedogg's Avatar
Canada
194
Rep
2,816
Posts

Drives: Debadged
Join Date: Aug 2006
Location: Vancouver, BC

iTrader: (0)

Quote:
Originally Posted by mstrobel View Post
I'm a bit of a MT n00b myself, so I'd be interested to hear the answers as well .
+1. This is my first MT car...so I would be interested in the answers of some of the more well versed "pros". Let me try answering some of your questions as I understand them...I'm sure someone else will correct me if I'm wrong.


Quote:
Originally Posted by GewoW View Post
1- What is dropping the clutch? Is it the fact that you reengage the clutch while still giving the engine power?
Dropping the clutch, as I understand it, usually refers to letting out the clutch out too fast at or around the point of engagement. This usually happens when you are getting lazy with your shifts and you are somewhat smooth in letting out the clutch but at the last inch or so of letting out the clutch you abruptly let off the clutch rather than smoothly bleeding off the clutch.

You are usually reengaging the clutch while still giving engine power...remember you bleed off one pedal as your are gradually/bleeding on the other pedel

Quote:
Originally Posted by GewoW View Post
2- For a 335i w/ a CDV (I know...all MT 3s have one..), would a quick shift from 1st to 2nd still produce a jolt, even if the clutch is completely engaged before flooring it again?
Probably. All I know is that when I had the CDV, I could never get a smooth shift when I wanted to do a "quick" shift. It always felt jerky, especially between 1st and 2nd.

Quote:
Originally Posted by GewoW View Post
3- That nice little smell from the engine bay after some hard driving, might that be the clutch getting raped because of excess slip?
Umm...could be. Dunno. Are you sure it's not your brakes?

Quote:
Originally Posted by GewoW View Post
4- W/out a CDV, would a quick shift from x to x+1 still produce a jolt if the clutch is completely reengaged before power delivery? The fact that your driveline is not protected as much, does that mean you can't drop the clutch with fast shifts? Is the delete mod geared towards the normal drivers or for the eager ones?
I just got the CDV delete mod done. All I can say is that you should go get yours done as well...shifting is MUCH smoother...especially between 1st and 2nd which usually was quite jerky for me. There has been lots of articles written on CDV and why it is a good idea to remove: http://www.zeckhausen.com/CDV.htm

You probably never want to "drop" the clutch at high RPM...even if you have a CDV installed. As I understand it, the benefits of driveline protection from the CDV is minimal compared to the benefits of removal (particularly longer clutch life).

Quote:
Originally Posted by GewoW View Post
5- What is the advantage of a CDV delete and what does the CDV do to protect the driveline at the expense of the clutch.
From the webpage linked above:

"The Clutch Delay Valve (CDV) is a one-way restrictor installed by the factory between the clutch slave cylinder and clutch master cylinder, as shown in Figure 1. It "delays" the engagement of the clutch, much like old record players used a damped tone-arm to gently lower the needle onto the surface of a record.

Because of this valve, no matter how quickly you lift your foot off the clutch pedal, the clutch engages the flywheel at a constant (slow) rate. In theory, it can save the driveline from shock, were an inexperienced (or immature) driver to dump the clutch at high RPM. But in practice, all it does is prematurely wear out the clutch and turn experienced drivers into people who, despite 20 years of practice, cannot shift gears smoothly. "


Quote:
Originally Posted by GewoW View Post
6- How bad is it to shift quickly, as compared to smooth shifting, with moderate clutch "riding" or slipping.
Done properly, quick shifting is not that bad for your clutch. You should try watching Greg's M5 Virtual Driving School videos: http://www.e39m5.com/VideoDrivingTech.html

I am still trying to perfect my shift...as everyone is... The videos are quite helpful...especially in getting you to listen for immediate pitch changes (from the transmission) which signifies a clean shift vs. a sloppy shift where the pitch sounds like it is winding up and then down.

All us noobs are so careful about damaging our manual trannys--which is a good thing. But I always remind myself that they are not made out of cotton candy...it's a fairly robust/strong unit. Just as long as I don't abuse the tranny ALL the time...sloppy shifts while practicing isn't going really hurt the car that bad. And if I need the replace the clutch prematurely...oh well...part of learning.

Quote:
Originally Posted by GewoW View Post
7- Is there any way to remove that jolt from 1st to 2nd shift (@ high RPMS) while still having a CDV?
Probably. Try letting out the clutch at the same slow rate as the CDV. Likely this isn't going to happen since you are probably at a high RPM because you are driving fast/shifting/clutching fast.

Quote:
Originally Posted by GewoW View Post
8- What are the downsides to shifting @ high RPMS (ex. hard acceleration w/ 7000RPM shifts) and are these surmountable?
Downsides: engine wear and more gasoline being burned?

It seems that done properly, you can likely safely shift at high RPMs without much or if any added stress to your car's drive line or clutch.

Quote:
Originally Posted by GewoW View Post
9- With revmatching, when you would press on the throttle while having clutch disengaged to match revs of the lower gear that you are shifting into, isn't that really really bad for the clutch? Is it better to blip?
Not sure I understand your question. Rev matching usually involves blipping the throttle.



===
Hope this is somewhat helpful and correct.

Others have corrections to make to what I have said?
Appreciate 0
      07-05-2007, 08:30 PM   #5
Cookiemonster
Captain
Cookiemonster's Avatar
16
Rep
791
Posts

Drives: 2010 335XI e92
Join Date: Apr 2007
Location: Jupiter

iTrader: (2)

cdv delete all the way. Been driving manual cars for 15 years. That CDV is way annoying.
__________________
2007 335I sedan (retired)
2010 335xi coupe
Appreciate 0
      07-05-2007, 08:45 PM   #6
achien
AC
Canada
95
Rep
2,387
Posts

Drives: E90 Post Members Crazy
Join Date: May 2007
Location: Toronto, Canada

iTrader: (0)

Quote:
Originally Posted by Cookiemonster View Post
cdv delete all the way. Been driving manual cars for 15 years. That CDV is way annoying.
I am adjusting my driving style around this CDV, I am beginning to think they put this in to prolong the drivetrain from this crazy engine.
__________________
Your Supreme Leader
Appreciate 0
      07-06-2007, 01:01 AM   #7
spacedogg
Colonel
spacedogg's Avatar
Canada
194
Rep
2,816
Posts

Drives: Debadged
Join Date: Aug 2006
Location: Vancouver, BC

iTrader: (0)

Quote:
Originally Posted by achien View Post
I am adjusting my driving style around this CDV, I am beginning to think they put this in to prolong the drivetrain from this crazy engine.
Yeah but they also have it slower cars such as the 323i, 325i and 328i. Presumably they also have it on the European models like the 320i...

I think it was more for protection for the idiots who would rev the engine to 4k+ and dump the clutch...
Appreciate 0
Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 11:45 AM.




e90post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST