A tale of two 540's ...

[SnakeyesTx]

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

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!

[SnakeyesTx]

I'm happy to say I'm getting around 17 mpg in mixed conditions where his is around 14 but still climbing since we reset his OBC about 2 days ago and his commute involves a lot more stop-and-go and traffic.

[repenttokyo]

what is his fuel mileage like? similar to yours or much lower?

[Paul in NZ]

to test the clutch for slippage try taking off with the handbrake on. if the clutch is good the car will stall...if not the cluth will slip and the car wont stall.immediately...dont over do it though its hard on tthe drivetrain

[SnakeyesTx]

bump for exposure... c'mon manual guys :/

[joshuagore]

Get to cruising speed... 55ish

Shift into 5th... nice and easy

Floor it.. and keep it floored.

As the rpm's rise, try and notice the rpm's. Do they rise seemingly faster than the car is accelerating? I have found it hard to spot bad clutches on hard shifts between 1-2-3. You would think that this is where a slipping clutch would show worst, but in reality cruising speed higher gear acceleration seems to highlight clutch wear.

Josh

[bimmerd00d]

i took my 98 540i/6 to the track, and it roasted the clutch there. 6mos after, the clutch is working perfectly fine, you'd never know anything happened. It sure didn't like to be launched at the track though. I also have had the CDV removed since day 1.

[SnakeyesTx]

That is definitely on my to-do list as well. I'm almost thinking that a different CDV was used on mine (built in 7/96) to his (built in 7/98) since mine feels so much less intrusive. I'll be giving Zeckhausen a ring up here in a day or two for a delete valve though.

[Tiger]

First thing I would do is go to the dealer with both VIN number and ask for equipment spec sheet. It tells you what factory loaded into your cars.

I am suspecting you have the sport package while he doesn't. Sport package has different rear end gear ratio.

I drove a 99 540iA with sport package and man... what a monster with the rear end difference..

[filip00]

okay try this


cruise around 50mph, then shift 4th gear and then put the gas to the floor. if the clutch doesn't slip then, then it should be good.