Acceleration lag ?

R

runner

New member
Hi guys,
I'm new to this site and also to Z4's
I bought a 54 plate 2.2l SE about 6 weeks ago. Really pleased with it but I've noticed that when I pull away
in 1 and then into 2nd, unless I'm doing the pedals really slow, it's difficult to pull way smoothly.
I told a mechanic friend who said it was probably clutch judder but upon driving it he thinks it's lag with
the acceleration. It's only subtle but annoying.
Any ideas as to what would solve it ? tuning maybe ? or am I being too critical and is the same with all Z4's ?

Many thanks in advance for any advice.

James
 
The pull and real power is usually a bit higher into the gears normally... I found you have to learn to drive these more then any other car I've given so with time and practice you'll get in tune with the car much. More.

Have you tried driving with the sport button on? That provides more pull towards the lower ends of the gears and sharpens the throttle response which is much better to drive (I drive in sport probably 80% of the time)

Sent from my Samsung Galaxy S3 using Tapatalk.
 
I am also new to z4's but I think it' the clutch delay valve ( if you have one fitted)which stops you dropping the clutch quickly ( for very good reasons) so it feels like the clutch is slipping hence acceleration drag. Someone who knows more than me will confirm / deny
 
Ste - I would gladly press my sport button but unfortunately I don't have one :)
You may be right about not being used to it but I'm sure when I bought it wasn't like this, maybe my imagination.

Sootydog - I had read about people removing their CDV but not sure, need expert advice.
 
Up to you whether you remove the CDV but let's assume for arguments sake that the BMW engineers developed a fantastic engine developing loads of power and torque then ran out of money and couldn't develop a drive train to handle the power. So they looked for a cheap solution and came up with the CDV. I have no idea if this is anywhere near what happened but being an engineer myself I wouldn't design something into a system if it wasn't required. Your choice.
 
^^^^Eh?!?!?


The Clutch Delay Valve (CDV) is a one-way restrictor installed by the factory between the clutch slave cylinder and clutch master cylinder. It "delays" the engagement of the clutch, much like old record players use 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. But in practice, all it does is prematurely wear out the clutch and turn experienced drivers into people who, despite years of practice, cannot shift smoothly. During parallel parking maneuvers, the delay can be infuriating, causing constant clutch slippage. And during hard acceleration, the slippage can greatly shorten the life of your clutch. During normal, sedate driving, the shift from first into second gear is often jerky, leading passengers to question your skill.

Interestingly, BMW did not install a CDV on the E39 M5. The terrible shifting behavior would be unacceptable to these high performance customers


* taken from a CDV removal site - zeckhausen racing.


@OP... it's pretty certain it's the CDV causing the issues, it's not needed, easy to remove and the car is much better for it.
 
The CDV is designed to stop you damaging the clutch. You are unlikely to damage the clutch if you take it out but be warned. I keep meaning to do mine but I am getting used to he car now.
 
not fans of it, or the possible reason for it on the M3 forums.... :rofl:

http://www.m3forum.net/m3forum/showthread.php?t=224189
 
the cueball said:
Interestingly, BMW did not install a CDV on the E39 M5. The terrible shifting behavior would be unacceptable to these high performance customers


* taken from a CDV removal site - zeckhausen racing..
Click to expand...
Nothing 'interesting' about it. It's simply that BWW weren't using CDVs when the e39 first came out, so it was probably just something new fitted after a certain date.

If it wasn't acceptable to these 'high performance customers' the why did they put it in the e46 M3, e6x M5/M6, etc?

I've not got a problem with mine and it's coming up to 90k miles, so I can't really agree that it shortens the clutch life :P

You've just got to shift really slowly, or really quickly - anything in between or half-hearted and you may get a bit of kangarooing.
 
don't come back at me, speak to the website I mentioned.... I didn't find anything interesting about it either, just posting what professionals who know about these things are saying... ;)

:rofl:
 
the cueball said:
don't come back at me, speak to the website I mentioned.... I didn't find anything interesting about it either, just posting what professionals who know about these things are saying... ;)

:rofl:
Click to expand...
I know, that's why I left the Zeckhausen name on the end of the quote :thumbsup:
 
hahahaha.... sorry, never clocked that... :o

I can't say mine bothers me either... well that much... every now and then I get a judder, but still not enough for me to rip it out...yet..

;)
 
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