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Comment by dotancohen | Hacker News Reader

And that downshifting involves a clutch operation, moving the engine into a higher RPM. That most certainly wears down the clutch, talking as someone who's replaced quite a few of them.

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I've seen an interesting A-B test with this seeing the difference in clutch wear between the Ferrari F1 transmission in the 599 and 612 and the DuoSelect transmission which is essentially the same box in the Quattroporte. The shifting strategy and technique is more of a controlled variable here because the shifting is automatic though it's a somewhat traditional manual gearbox with hydraulic actuation. The QP is a bit heavier but the Ferraris make a lot more power. From what I saw the cars that fared far worse were the Quattroportes, and those that ate the most clutches by far were the ones putting around the city, especially in San Francisco, Marin, Los Altos Hills, etc. where people are slowly creeping into parking spots on hills. On the Ferraris that are weekend warriors that get driven hard the clutches could go 30k+ miles no problem, Quattroportes would come in with smoked clutches in a few thousand miles sometimes.

Sorry, ain't native: Which car use downshifting to help braking? Cannot wire in my brains whether this example is pro-downshift braking or not.

I think their point is that you eat clutch when you slip it e.g. when you’re getting in and out if parking on hills, or in city stop and go traffic. When the clutch is fully engaged there’s little wear even hard-driving, and doing a straight in-and-out does not bother clutches much.

Hence Quattroportes eating clutches like nobody’s business while the harder-ridden higher-power Ferraris don’t.

As such downshifting would not wear clutches much.

And anecdotally I’ve never suffered from or heard of engine braking causing clutch issues.

I semi-daily drive a DuoSelect Quattroporte, but usually in light traffic. The clutch-eating problem is sorta inherent to the car. First off, it uses extra clutch to smooth out shifts in non-sport mode, and you don't always want sport mode because it stiffens the suspension a lot. But even in sport, you can't always get it to behave predictably. So given an experienced driver with both cars in city traffic, the DuoSelect will eat clutch faster than a stick. Some install an aftermarket box (Formula Dynamics) to improve this, but still.

Idk how the Ferraris are different. They're lighter at least. Think they also have a different version of the "Superfast" software.

Anyway... I do engine-brake it. The real brakes appreciate not having to stop that limo by themselves.

Forgot to clarify, there is a clutch-eating problem when driving the car properly, but it's not THE clutch-eating problem people talk about where it dies in 10-15K miles from treating the car as a regular automatic.

Everything on the QPs was always breaking.

I've never driven an automatic Ferrari or paddle shifted Ferrari to compare, but the QP that I drove (Ferrari V-8, I think that it even said Ferrari on the valve covers maybe) didn't have anything outstanding about the transmission that I remember. I thought it was a regular hydraulic automatic with a torque converter, so they really did tune it nicely. The robotic Toyotas I could feel. Maybe had they not tuned it so nicely it might have lasted longer?

Only the 2004-2006 and maybe some 2007 QPs came in automated manual. Anything after was regular automatic w/ torque converter.

I didn't quite get if you think changing gears for the purpose of engine braking wears the clutch more than normal or not. Are you using the force from the clutch to force the engine to go from a low RPM to a high RPM? In cases like that where the difference in RPM is significant, I would press the clutch pedal, then speed up the engine by pressing the gas pedal, downshift, then release the clutch. Rev matching, basically. It does wear the clutch a teeny tiny bit, but not more than any other gear change.

If your comment wasn't meant to imply that engine braking wears the clutch more than normal gearing, if you just want to avoid gear changes as much as possible, disregard this comment. (Although... I'm not sure that that's a valid worry, modern clutches last a LONG time when used properly)

You might not execute the rev-match perfectly every time, esp if you're doing a heel-toe. I think it's also harder on the synchro.

Sure, and I definitely don't rev-match close to perfect every time. I'm just saying you don't have to use the clutch to accelerate your motor all the way from minimum RPM, which it sounded like my parent comment might be suggesting

I think that suggestion was that you're holding the clutch pedal in longer while you bring up the RPMs, compared to upshifting which is faster. The clutch does wear a bit even when "fully" disengaged. But I don't think it matters enough here, just don't leave it like that during a red light.

Are you really shifting so much that your clutch slip in the middle of the shift effects clutch lifetime?

My 300k km Volvo S60 still runs on its original clutch, and I changed the brake pads only once. Engine braking is the way.

Clutch wear occurs when the clutch is slipping so you always want to minimize the slipping time.

Most of clutch wear comes from making it slip, while accelerating from a standstill.

You don't make it slip when shifting gear.

The clutch wear on a standard downshift must absolutely negligible when compared to accelerating from a full stop and especially when compared to slower-that-idle operation, i.e. parking.

Also, I have never ever had to replace a clutch, and I drive my cars way past 100k miles.

Yes but actually no.

It wears the clutch but clutch wear is massively dominated by starts from a stop or other cases where you actively slip it any noteworthy amount so just rowing the gears up and down doesn't do much.

It's a negligible amount, especially if you (or your car) does rev matching. My last car (BMW 328) made it to 300k miles on the original clutch.

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