I actually see few lights. Most of my driving is highway. But still, there are stop lights. The post by XS650 made it seem like keeping the clutch in for long periods of time would be detrimental to the transmission. Just wondering why, and how to avoid it.
Double clutching to prevent synchros wear
- Thread starter kilou
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That's, er, what I always do.
About 120k miles on a Metro, still no clutch problems.
Not the transmission, the throwout bearing. The throwout bearing is only under load when you have the clutch pedal depressed. Keeping the pedal down is also more wear on the pilot beariing.
And, as TallPaul said, if something goes wrong you are more likely to end up in cross traffic if you are in gear with the clutch pedal depressed.
I often double-clutch a cold transmission in the 1-2 shift, and sometimes the 2-3. Dunno how much synchro wear it saves, but I can't stand the sensation of trying to make a transmission do what it doesn't seem to want to do. Can't be good for it.
When warm, I'll often upshift without declutching. It's much easier to do smoothly in the higher gears than in the lower.
I nearly always heel-toe on the downshifts, using the clutch; if I had a beater to practice on, I'd try to get good at downshifting without the clutch, but I don't want to sacrifice my existing transmissions.
When warm, I'll often upshift without declutching. It's much easier to do smoothly in the higher gears than in the lower.
I nearly always heel-toe on the downshifts, using the clutch; if I had a beater to practice on, I'd try to get good at downshifting without the clutch, but I don't want to sacrifice my existing transmissions.
That makes sense. Fortunately I haven't had to go into the bottom end of a car engine if over 20 years so haven't seen that.
I prefer not knowing how to read rather than slipping the clutch on purpose! If you slip the clutch, therefore you're not transferring all the power of your ""blip"" to the input shaft. Moreover if the clutch is still partially engaged you're still in a gear (i.e. not in neutral) so your engine is still transferring power to the wheels........not very good for a quick blip... This means you'd need to rev up the engine by tons of rpm to barely increase the input shaft speed all the energy left being wasted in clutch slippage.........and additional unecessary wear! If racers want to do that it's their problem and they are certainly not concerned with premature failures. Perhaps this is good on a racetrack for far different purposes but please I'm not a racer, I want to prevent synchros wear as much as possible and the only way is to properly double clutch which means setting the box in neutral with clutch pedal FULLY released.
Thanks to others I think I know have more information than needed. I won't double clutch on upshifts but will try to apply it on downshifts (especially 4 to 3 which is a bit grindy sometimes probably due to a worn synchro). However I'll have to install a gas pedal pad and learn how to heel and toe.....which seems really cramped but it's probably only a matter of habit.
Thanks to everyone
JHZR2
Staff member
If youre driving for economy and smoothness, youll likely not need to heel and toe. Just double clutch on the downshifts and get that down so you cna do it quick.
Personally, I can heel and toe, but I dont like the feeling I have when doing it, like Im not 100% in control of the modulation of all pedals.
JMH
Personally, I can heel and toe, but I dont like the feeling I have when doing it, like Im not 100% in control of the modulation of all pedals.
JMH
never knew this about clutch part wear, I always have the clutch depressed at a light - unless it's going to be an obvious long wait like construction then i'll just go to neutral, and set my e-brake
never once allowed myself to become distracted - if someone allows themselves to become so distracted that they launch themselves forward at a light unintentionally, they need to hand the keys to someone else and forget what a car is.
must be a habit for me I guess...
question - what is the difference in wear when it comes to keeping the pedal depressed v.s releasing the clutch, neutral, re-engage the clutch ? just the clutch pedal itself?
edit: off topic a bit - anyone notice that when you downshift to a light others fly up on you ? it's as if they don't know that you are downshifting and this is why you are slowing without brake light - as if it's a big mystery to them how you did that.
never once allowed myself to become distracted - if someone allows themselves to become so distracted that they launch themselves forward at a light unintentionally, they need to hand the keys to someone else and forget what a car is.
must be a habit for me I guess...
question - what is the difference in wear when it comes to keeping the pedal depressed v.s releasing the clutch, neutral, re-engage the clutch ? just the clutch pedal itself?
edit: off topic a bit - anyone notice that when you downshift to a light others fly up on you ? it's as if they don't know that you are downshifting and this is why you are slowing without brake light - as if it's a big mystery to them how you did that.
Race car drivers usually do not do a true double clutch; they just blip the gas via their heal as they put the clutch pedal in and make the downshift (which is like a half double clutch because it will speed up the input shaft/ constant mesh gears to about the output shaft speed/dogbone gear - if you do it all simultaneously and really slip the clutch a bit). I just blip the gas a bit to the rpm that the motor will be at in the lower gear when I downshift. No need to truely double clutch; ie shift to neutral, let clutch out, blip the throttle, push clutch back in and downshift. Give me a break! I'm not driving a 1960 semi with an unsynchronized 10 speed! I think I'll agree with toocrazy here...
I have never worn out a cutch MC or slave cylinder in 200,000 miles but have seen a lot of transmissions with worn out syncros with many fewer miles that that.
Throw out bearing wear is more bearing operation time related than number of uses. Chances are a person who double clutches isn't going to cluelessly keep his clutch pedal depressed for 2 minutes at a stop light, so his throwout bearing should last longer than average.
Throw out bearing wear is more bearing operation time related than number of uses. Chances are a person who double clutches isn't going to cluelessly keep his clutch pedal depressed for 2 minutes at a stop light, so his throwout bearing should last longer than average.
When you depress the clutch pedal at a light you put pressure on your clutch hydraulics like master and slave cylinders for nothing. But most important you put the clutch release bearing mechanism under stress like in any gearchange but for a much longer period when you are waiting at a light with clutch depressed. Please correct if I'm wrong or miss something.
makes sense, I burned my clutch pretty good once when I lived in san diego, they have the on ramps setup with stoplights at busy parts of the day and this one ramp did a 180 degree turn and it was like a 45 degree climb through the turn and it was packed with cars, 1 car per green so i did the little clutch little gas thing until it was my turn at the light and when it was time to hit the gas to get on the freeway all i smelled was this nasty **** and it wouldnt shift to 2nd for about 10 seconds! so I can believe it.
You probably burned the clutch friction material by excessive slippage but the release bearing issue is different. If you fully depress the clutch pedal you don't make the clutch slip but you (slowly) wear out the release mechanism if the pedal remains depressed for long periods....and you also wear out your knees
Today double clutching on downshifts worked a bit better....well I can do it faster but the downshift is still not as smooth as with single clutching. I guess I'm wrong with the gas blip probably and cannot achieve the right synchronization of both shafts. But I really can't figure out how to heel and toe with my pedal configuration. I'll leave that for later.
Today double clutching on downshifts worked a bit better....well I can do it faster but the downshift is still not as smooth as with single clutching. I guess I'm wrong with the gas blip probably and cannot achieve the right synchronization of both shafts. But I really can't figure out how to heel and toe with my pedal configuration. I'll leave that for later.
Interesting discussion, driving the family tractor from age 12 on helped me to understand how sticks work, helped me to learn double clutching at an early age as it is impossible to down-shift or up-shift at higher RPMs without synchros on a tractor.
My brother has a 271K Mazda with original transmission and clutch. He does not double shift, but he tells me that he only touches the clutch when changing gears. This means no clutch slipping, or being engaged in first with the clutch pressed. When slowing down for a light he just shifts to neutral and lets the brakes to the job. He says I’d rather change the 30 dollar pads more often then touch the transmission. Looks to be working for him, I have too young of a car to comment on longetivity.
My brother has a 271K Mazda with original transmission and clutch. He does not double shift, but he tells me that he only touches the clutch when changing gears. This means no clutch slipping, or being engaged in first with the clutch pressed. When slowing down for a light he just shifts to neutral and lets the brakes to the job. He says I’d rather change the 30 dollar pads more often then touch the transmission. Looks to be working for him, I have too young of a car to comment on longetivity.
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Heel-and-toe braking/downshifting, yes, double-clutching, no. I'm not racing a Tin Lizzie.
What would be the purpose of doing heel and toe without double clutching especially if you're not racing?? The only benefit I can think of under normal driving conditions is a smoother engagement of the clutch (probably) but there is no benefit for the synchros since you're reving the engine with clutch depressed. My 3rd gear synchro is probably weak now as downshifting from 4th to 3rd grinds sometimes. A weak or worn out synchros is almost like having an unsynchronized gearbox......and this requires double clutching. This has nothing to do with racing...I wouldn't race in an old Volvo anywayquote:
Originally posted by moribundman:
Heel-and-toe braking/downshifting, yes, double-clutching, no. I'm not racing a Tin Lizzie.
You get smoother, quicker stops with heal-toe braking.
Unless a car can be flat-towed then shifting into neutral at speed is bad for the transmission as the input shaft is what lubes the gears, and the input shaft is now spinning really slowly...
If it can be flat-towed then this isn't a problem.
Anyone else ever skip the clutch and just rev-match???
Unless a car can be flat-towed then shifting into neutral at speed is bad for the transmission as the input shaft is what lubes the gears, and the input shaft is now spinning really slowly...
If it can be flat-towed then this isn't a problem.
Anyone else ever skip the clutch and just rev-match???
Can you please make a step by step description of heel-toe braking and rev matching while skipping the clutch?
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