Scylas

Does it do any harm?? just asking, cuz I do it a lot....

Mike T.

But some people maintain that if you downshift a lot to get the desired engine braking, you will prematurely wear out your synchromesh and clutch disc. Neither of these are true if you do a double-declutch maneuver, however.

Even descending the Grossglockner pass in Austria towards the north, it should be possible to roll a C down in neutral, using only the brakes and not have them overheat and fade away to nothing, as happened to a Renault 5C I drove through there in 1986 (and I was using engine braking TOO!!).

My own rule of thumb is: engine brake/downshift only when not coming to a stop, for example when slowing for a corner and then intending to re-accelerate right afterward, or descending a very long hill.

I never downshift for engine braking when approaching a stop light or sign on a more or less level road.

viper

I don't think you can cause a problem. These vehicles are pretty robust in their internal construction and if there were problems in doing this regularly the owners manual would have lots of warnings.

SoCal240/6

Depends on how long you plan on keeping the car.

If you plan on a long time (100K miles plus), its a bad idea, because it WILL cause your clutch, synchros, etc. to wear faster then they normally would, and these are items that are normally replaced within 100K miles (maybe not the synchros, but at 100K, the synchros tend to get a little slower). It also causes more wears on the clutch slave and master cylinders, etc., which have a determinate life that will be reached if you keep the car for a reasonably long time.

These are just normal wear items that can be extended for longer life without the NEEDLESS downshifting to slow the car down. Every clutch, syncro, slave and master, etc. has a limited number of shifts in them. Every time you needlessly downshift, you are needlessly using one of them up.

Other items are also subjected to increased wear: Dshaft, differential, dshaft center bearing, clutch box, etc. etc.

If you plan on keeping the car for only a few years, it doesn't really matter, I guess.

Mike T.

You've got to learn how to double-clutch my friend, for if it's done properly there will be zero wear on the synchro rings and zero on the clutch disc. Only the release bearing and its mechanism gets a bit more of a workout, and I emphasise, a bit - well within their capability unless the car is poorly engineered.

About clutches lasting only 100,000 miles ... that's total nonsense, unless you have a habit of slipping the clutch a lot on takeoff, have unclean upshifts and those nasty downshifts that use the clutch lining and synchro rings to bring the engine up to drivetrain speed. A clutch on a well-driven car should be good for well over 150,000 miles unless the rear main seal or front gearbox seal spring a leak.

And since you may be wondering, my present French car has over 171,000 miles and still has the original drivetrain and clutch linings, and the synchros are all fine too.

Most gearboxes, well driven, will last indefinitely, well beyond the engine's lifespan. Trivia: my front brake pads last about 60,000 miles, and the rotors twice as long. The rears last twice as long as that!

fernrod

240,000?

Mike T.

No, I mean that I changed the rear brake pads for the first time at 200,000 km (124,000 miles) - they last twice as long as the front ones did.

Sorry for the confusion.

whitecar2003

I'll chime in on the downshifting theme. My old car was a '90 Civic Si, and after downshifting at every stopsign for 12 years and 160K miles, it still had the orginal clutch and showed no signs of wearing out.

I've often heard the argument... brake pads are cheaper than clutch discs. Personally I think that if you know what you are doing (i.e. not abusing the clutch by shifting eratically or with excessive slip) you shouldn't worry about using the engine to slow you down.

PoonerElRay

Mike:

Correct me if I'm wrong but I don't think double-clutching would have a beneficial effect on this. The C230 has syncros like you mentioned therefore there's no need to double clutch.

Accord

They do this a lot in Formula One, this is why a lot of drivers have automatic upshifts and manual downshifts.

Mike T.

You're both incorrect and correct. You are right in that there's no need to double clutch on downshift due to the gearboxes synchros, which are like little dog-clutches. But the point I was making is that if you double-clutch, your gearbox's synchros will not be used at all, therefore making them last a lot longer than they would otherwise.

PoonerElRay

I've seen a lot of import magazines advertising those billet colored clutches, flywheels, and syncros.

Are those actually durable? safe? made to last? or are they ****tier than stock?

taylor192

I learned the hard way on my last car. If you're expecting to get a long life out of your car then don't downshift unless neccessary for corning, change of speed due to slower traffic/speed limit, ect..., don't do it to brake to a stop.

Sure you'll be saving your brakes, but do the math, brakes are a lot cheaper than clutches and transmissions. When the 3rd gear syncho went in my Camry they wanted $900 to fix it, so I just learned to double clutch, which is something I would recommend to everyone with a manual.

Double clutching is great, less strain on drivetrain components, but also a smoother ride once you become good at it. Try it, double clutch to downshift into a corner rather than just downshifting, you'll notice the difference.

MarkL

I had posted this site as a separate thread, but some may find it interesting here. It's a site I found some time ago discussing rev-matching, double-clutching, etc...

http://www.waycoolinc.com/z3/essenti...e/shifting.htm

SoCal240/6

Most driver's don't get 100,000 miles from a clutch. Some do, and some get more, but 100,000 is above average.

Double clutching will help your synchros, but then you get other wear, too. Like double wear on your clutch master and slave cylinder, etc.

Plus, double clutching is simply a waste of time in a modern car. You don't need to do it to downshift. And, if you are double clutching to downshift as you come to a stop at a red light, you are REALLY going through a lot of extra work for nothing. Just put on the damn brakes and stop the car. Save the nonsense.

The bottom line is this: No matter what mileage you can get out of a clutch, synchros, etc., you'll get a hell of a lot MORE mileage out of them if you don't engage in the unnecessary and boy-racer habit of downshifting when you are coming to a stop in street driving. Its goofy, unnecessary, a bad habit, and the sure sign of someone with little mechanical knowledge.

BlackC230Coupe

what is double clutching, i dont have a manual and never did. i also never drove one. but i have heard people talking about double clutching and never knew exactly what it was. can someone explain what it is and why someone would do it?

thanks

Mike T.

Right you are. But I don't think anyone on this thread has said that they like to downshift when approaching a stoplight or stop sign. That is truly unnecessary and wasteful of fuel.

However, when you imply that no-one with mechanical knowledge would choose to double-clutch while driving, that seems to betray a breathtaking lack of mechanical knowledge on your part. Or did you intend your barb for only those "mechanical know-nothings" that downshift while approaching a stop?

Either way, thanks for your opinion

revstriker

Scan up the thread to MarkL's post. He listed a link to an explanation.

BlackC230Coupe

i knew i should have clicked that, thanks.

mdp c230k

The colors are just 'disco dressing', it is really just anodization which can be done in lots of colors. Anodization 'hardens' the surface of the aluminum to make it more durable. Anything made from a billet is stronger than the same cast piece as it is more homogenious as the metal cooled at the same time rather than a casting which can fracture where the metal cooled unevenly causing a change in the grain pattern of the metal (it looks like a dull band or uneven shine in the metal). Billets must be machined which is expensive and wastefull (all the removed material). In short, they are better but unless you race you won't see a difference except in you wallet! Especially since the parts you mentioned are inside the tranny!