SnakeyesTx
05-16-2008, 09:29 PM
What a difference two production years make!
Cars in question : My 97 540/6 (built 7/96) and my friend's 98 540/6 (built 7/98)
When I bought my E34, I had help coax a friend into buying one about a month later (as seen in my sig pic). When I bought my E39, it only took a week for another friend to buy one just like it :D
Every day since he bought his last Saturday, he's been asking me about these "noises" he hears... I dismissed most of them as 'new owner fears' which several of them were. One gripe in particular I swore was nothing but driver error but he swore that his car doesn't shift as good as mine does.
Initially I considered the dreaded CDV (clutch delay valve) and how they were different across various models (I assume maybe different between production years of the same model as well). This valve is also known as the 'idiot proof clutch valve' which I think is just ridiculous because it really does the exact opposite of its intended purpose. M5's don't even come with these because people would complain about the performance loss and the lack of clutch sensitivity and response most of us are accustomed to or demand from our 4-door rockets.
Anyway, tonight something peculiar happened. I was in the middle of changing his plugs and ... well... there was 7 in the box instead of 8. So I send him to the parts house for some NGK 2288's (same as my E34 used) in my car. When he came back some half an hour later, he went on and on about how much tighter my car felt and how much more responsive my clutch and transmission felt. We're both equipped with Getrag 420G's so this didn't make much sense to me.
After changing out his plugs (and finding 3 O-ring leaks >.<) I decided to take his car out for a spin and launched it hard... like really hard. In first gear his car spun up to 5,000 rpm pretty quick like mine does, and I work the clutch and get her into 2nd and the rev's stay near 5k... so I take it up to third... still near 5k. Car's not really accelerating OR decelerating, and I don't really feel any torque whatsoever. It feels almost like clutch slippage, but to be honest, I can't even feel 2nd or 3rd engaging whatsoever. I drove it back to his house just normally... kinda short-shifting around 2,500 and it engages all gears just fine.
*edit* No clutch smell when we got out of the car at all...
So, with that sensation fresh in my mind, we hop in my 540. I launch pretty much identical to the way I drove his, and ... lets just say we were pinned down in our seats between gears. I could clearly feel the clutch working, the shifts are crisp, and the torque jumps are sharp and pronounced, and the traction control light kicked on (2nd gear scratch too!). It feels .... wonderful... as it should.
So, I guess the major question here is, what would cause his to feel ... disconnected so bad? My first theory was that maybe they used a different and more interrupting CDV compared to mine which was built 2 years earlier. My other theory was maybe that his clutch system isn't giving the disc enough pressure against the flywheel, again the valve maybe restricting the flow too much giving me the lack of torque and the engagement I desire compared to mine.
This is honestly my first higher performance car with a manual and I've never really experienced what a "failing clutch" or a bad clutch master or clutch slave cylinder would feel like so I couldn't honestly say "well it could be one of those" since I've never had one fail before. Being this is a manual... I'm really looking for a little guidance by some of you 5 and 6-speed guys that may have ever experienced this before. JonK .. I'm looking at you on this one since you're pretty keen on manuals! :D
Cars in question : My 97 540/6 (built 7/96) and my friend's 98 540/6 (built 7/98)
When I bought my E34, I had help coax a friend into buying one about a month later (as seen in my sig pic). When I bought my E39, it only took a week for another friend to buy one just like it :D
Every day since he bought his last Saturday, he's been asking me about these "noises" he hears... I dismissed most of them as 'new owner fears' which several of them were. One gripe in particular I swore was nothing but driver error but he swore that his car doesn't shift as good as mine does.
Initially I considered the dreaded CDV (clutch delay valve) and how they were different across various models (I assume maybe different between production years of the same model as well). This valve is also known as the 'idiot proof clutch valve' which I think is just ridiculous because it really does the exact opposite of its intended purpose. M5's don't even come with these because people would complain about the performance loss and the lack of clutch sensitivity and response most of us are accustomed to or demand from our 4-door rockets.
Anyway, tonight something peculiar happened. I was in the middle of changing his plugs and ... well... there was 7 in the box instead of 8. So I send him to the parts house for some NGK 2288's (same as my E34 used) in my car. When he came back some half an hour later, he went on and on about how much tighter my car felt and how much more responsive my clutch and transmission felt. We're both equipped with Getrag 420G's so this didn't make much sense to me.
After changing out his plugs (and finding 3 O-ring leaks >.<) I decided to take his car out for a spin and launched it hard... like really hard. In first gear his car spun up to 5,000 rpm pretty quick like mine does, and I work the clutch and get her into 2nd and the rev's stay near 5k... so I take it up to third... still near 5k. Car's not really accelerating OR decelerating, and I don't really feel any torque whatsoever. It feels almost like clutch slippage, but to be honest, I can't even feel 2nd or 3rd engaging whatsoever. I drove it back to his house just normally... kinda short-shifting around 2,500 and it engages all gears just fine.
*edit* No clutch smell when we got out of the car at all...
So, with that sensation fresh in my mind, we hop in my 540. I launch pretty much identical to the way I drove his, and ... lets just say we were pinned down in our seats between gears. I could clearly feel the clutch working, the shifts are crisp, and the torque jumps are sharp and pronounced, and the traction control light kicked on (2nd gear scratch too!). It feels .... wonderful... as it should.
So, I guess the major question here is, what would cause his to feel ... disconnected so bad? My first theory was that maybe they used a different and more interrupting CDV compared to mine which was built 2 years earlier. My other theory was maybe that his clutch system isn't giving the disc enough pressure against the flywheel, again the valve maybe restricting the flow too much giving me the lack of torque and the engagement I desire compared to mine.
This is honestly my first higher performance car with a manual and I've never really experienced what a "failing clutch" or a bad clutch master or clutch slave cylinder would feel like so I couldn't honestly say "well it could be one of those" since I've never had one fail before. Being this is a manual... I'm really looking for a little guidance by some of you 5 and 6-speed guys that may have ever experienced this before. JonK .. I'm looking at you on this one since you're pretty keen on manuals! :D