Kupplung prüfen vor einem Tuning? | Posts 16+

gwg wrote:

Otherwise, it will become locally hard (vitrified) due to "radical" crystallization, and it will be prevented from distributing evenly.

Glazing, that's a good keyword...

Under what exact conditions does this actually happen?

When I once tried a full stop with my mother's old car, the deceleration was so incredibly [expletive] that, despite all my force (I thought the pedal might break off), I couldn't get any of the wheels to lock up – even though the car definitely didn't have ABS!

According to the workshop, the brake pads were glazed, even though she, being a woman, tends to drive more gently and brakes less frequently.

Hello Ulf,
Brake pads can 'glaze over' if they get excessively hot; however, they can also degrade if they are simply 'polished' (which likely happened with your mother's brake pads). Otherwise, brakes can also fail if the rotors are heavily rusted.
Best regards,
Günther.

Quote:

Oh dear... how old (in terms of mileage) is the clutch?

The clutch has 27,500 km on it. With the chip, it has approximately 4,500 km. Manufacturing year: 10/02.

It mainly occurs in the 5th and 6th gears at 2000 RPM.

ulf wrote:

Does this durable layer that forms on the flywheel and pressure plate constantly regenerate due to the wear of the clutch disc?

That's right. The surface of a worn clutch disc is slightly darker than a new one, and it remains that way. The coefficient of friction is obviously higher than with a brand new disc. It seems that manufacturers of "M" cars only realized the need for a break-in period through experience.

The most stressful factor for the clutch in the M series vehicles is prolonged operation under full load, as it can slip imperceptibly even with a torsional vibration damper (ZMS) under high torque, leading to overheating.

Due to the higher torque fluctuations of a four-cylinder engine (even a tuned one, with higher peak torque compared to average torque), the slight slippage may become even more pronounced.

Best regards,
Christian.

Klima96 wrote:

[The clutch now has 27,500 km on it. With the chip, approximately 4,500 km. Year of manufacture: 10/02.] It mainly occurs in the 5th and 6th gears at 2000 RPM.

Sure, that's where the torque is highest, and that's where you'll most likely notice the discrepancy between RPM and km/h.

Please don't take this personally.
Can you relate the slipping of your clutch to any of the "misdiagnoses" mentioned in the posts here?

Well, 200 horsepower at 4000 rpm is also 'just' 351 Nm.

If the tuner limits the maximum torque, for example, to 370 Nm, then it doesn't necessarily say much about the clutch having huge reserves.


Sorry, but I don't understand that...

'How long have you been focusing on engine speed? The performance of your desired tuning seems completely irrelevant considering your previously posted driving profile ('always trying to stay below 2000 RPM').'

Get a decent clutch and have the engine tuned for Nm (Newton-meters), otherwise you'll be unhappy again...

CU Gremlin.

Gremlin wrote:

How long have YOU been driving with a focus on RPM...? The performance of your desired tuning is completely irrelevant if we consider your previously posted driving profile ("always trying to stay below 2000 RPM"). Buy a decent clutch and have the engine tuned for Nm, otherwise you'll be unhappy again...

Caught in the act...

It should still be a "full-throttle" experience, because I don't want to feel like I'm "consuming something other than just diesel" when overtaking or when occasionally driving on the highway a few times a year.

The same applies to the Nm:
To protect the transmission (and to avoid premature clutch replacement), I'm limiting the torque to a nominal 360 Nm, which is 16% more fuel injection than the standard maximum for a nominal 310 Nm – specifically, a maximum of 65 mg per stroke instead of 56 mg.

I've already been in contact with an (OBD) tuner who will create a custom tuning for 160 horsepower based on his standard software, with a torque plateau of 360 Nm between approximately 1800 and 2400 rpm – and with a TÜV approval certificate.

"And I'm sure I'll definitely feel the 16% more Nm than the stock peak at 1900 rpm, plus the 23% more Pmax, especially since the Nm plateau, as a performance integral, provides more gain than just 16%."

The clutch spring is designed such that its spring rate remains constant as the friction material wears down. This is achieved through the finger-shaped recesses in the spring element.