Rev Match On or Off

[maranelloboy05]

I have never heard that argument in my life, and it doesn't make sense anyway.

Holding the clutch pedal in is what causes wear on your throwout bearing.

Downshifting to first implies that you're still moving, and that you are releasing the clutch pedal. Same as any other downshift. The speed the throwout bearing moves at is locked to engine speed, not gear speed. So the throwout bearing doesn't know the difference between a 6th-5th downshift and a 2nd-1st downshift.

Which is what I do, I coast to the stop sign with the clutch pressed and the gear selector in first. I know its not great but I doubt I'll change my habits anytime soon.

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[Deleted User 3888]

If I’m in 4th and I can see I’m coming to a red light. I just coast then eventually go into neutral and eventually come to a stop at the light

why are people shifting down just to come to a stop?

first just gets U moving and great for parking lots. This car is geared in such a way, even at 1200rpm in second there’s no issue

 

[Spart]

why are people shifting down just to come to a stop?

If I’m in 4th and I can see I’m coming to a red light.

Answered your own question: what color does a red light change to next?

Also, coasting in neutral gives you no authority over the speed of the car. You can't quickly speed up to get out of a bad situation, and you can't use the engine to slow you down either.

In some states, coasting in neutral is actually illegal for this reason. Your state is one of those states.

 

[Deleted User 3888]

Answered your own question: what color does a red light change to next?

Also, coasting in neutral gives you no authority over the speed of the car. You can't quickly speed up to get out of a bad situation, and you can't use the engine to slow you down either.

In some states, coasting in neutral is actually illegal for this reason. Your state is one of those states.

If the light turns from red to green while I’m coasting in neutral there’s literally nothing stopping me from looking at my speed. Choosing the appropriate gear. Kicking the gas pedal and accelerating as I’m off the clutch. The whole operation can be performed in less than a second.

U mean to tell me there are people that will see a red light and will down shift into each and every gear until they’re in first and then neutral to stop?!?

you people are psychotic.

 

[PNEUMA]

...a synchronizer which is perfectly capable of spinning up the input shaft on a downshift.

It's a bit of internet lore that downshifting to first always equivocates to being hard on your synchronizer.

Talking specifically about the FL5/DE5, when you're sitting stopped in neutral with the clutch engaged and you need to press the clutch in and select first, the first gear synchronizer has to slow the input shaft down from ~800rpm to 0rpm.

When you're going 10mph in second gear and you want to downshift to first to avoid lugging the engine when you go under 10mph, the fist gear synchronizer has to speed the input shaft up from ~1100rpm to ~1900rpm.

Our cars can handle this just fine, they have a relatively tall first gear befitting a sports car. The difference in input shaft speed handled by the synchro is the same in both situations.

The kernel of truth in the lore is that there are transmissions where downshifting to first is a really bad idea for not just the synchronizer, but also the clutch.

Many of us are old enough to have driven trucks (meaning passenger trucks, not commercial ones) where first is often referred to as "granny low".

If you downshift to first in those vehicles at too great of a speed, not only will you give the synchronizer (if there is one) a very hefty load to handle, but you risk spinning your clutch disk faster than it's capable of being spun without coming apart. As in, the clutch disk will literally explode from the centrifugal force due to being over-spun without you ever needing to "complete" a money shift by letting the clutch pedal out. Merely selecting the too-low gear destroys the clutch disk.

This is easy to do on some of those vehicles, because 3mph could be "just right" to downshift into first and 6mph could be "too fast."

On many of these older vehicles, first gear was actually unsynchronized. So you would need to double-clutch to shift into first, and it would have been an extremely tricky gear to double-clutch downshift into, given how fast the RPM would change relative to road speed. In this scenario, it's good advice to never downshift to first gear while moving, because second gear would not lug the engine. On most of these vehicles, if you weren't hauling anything you might start in second gear anyway.

There's a whole spectrum of this, from granny low at one end to the transmission you see in a Hellcat that can do 0-60 in first gear. Our cars are over halfway to the Hellcat in this spectrum.

TL;DR: you can downshift to first. The car can handle it just fine.

Well said. My lore comes from well before the internet was even a concept. But you touched on those vehicles in one of your paragraphs.

 

[Spart]

If the light turns from red to green while I’m coasting in neutral there’s literally nothing stopping me from looking at my speed. Choosing the appropriate gear. Kicking the gas pedal and accelerating as I’m off the clutch. The whole operation can be performed in less than a second.

Yeah, you're fumbling around trying to get in gear for a second or two while everyone else around you is trying to accelerate. You're impeding traffic because you don't have control of your vehicle.

Since the discussion was steered towards synchronizer wear, what you're describing doing also has the bonus effect of causing far more synchronizer wear than most other operations do.

When you coast in neutral with the clutch out, the input shaft is spinning as fast as the engine's idle. Just like when you suddenly put the car into gear when sitting stopped after having been in neutral, the synchronizer must change the speed of the input shaft to match the road speed.

But unlike shifting into first at a dead stop, this speed difference can be quite a large one. And you are almost certainly picking a gear to accelerate in, meaning you're going to have a large speed difference.

Large speed differences are what wear synchros the most, it puts the most heat and stress into them. You feel this through the increased shift effort any time you do something like what you've described. When synchros are used efficiently and able to cool between uses, they live a lot longer.

So for anyone out there trying to make their gearbox live longer, don't do what apl360 does and break the law against coasting in neutral in your state, and then react like this when called out:

you people are psychotic.

 

[Deleted User 3888]

Yeah, you're fumbling around trying to get in gear for a second or two while everyone else around you is trying to accelerate. You're impeding traffic because you don't have control of your vehicle.

Since the discussion was steered towards synchronizer wear, what you're describing doing also has the bonus effect of causing far more synchronizer wear than most other operations do.

When you coast in neutral with the clutch out, the input shaft is spinning as fast as the engine's idle. Just like when you suddenly put the car into gear when sitting stopped after having been in neutral, the synchronizer must change the speed of the input shaft to match the road speed.

But unlike shifting into first at a dead stop, this speed difference can be quite a large one. And you are almost certainly picking a gear to accelerate in, meaning you're going to have a large speed difference.

Large speed differences are what wear synchros the most, it puts the most heat and stress into them. You feel this through the increased shift effort any time you do something like what you've described. When synchros are used efficiently and able to cool between uses, they live a lot longer.

So for anyone out there trying to make their gearbox live longer, don't do what apl360 does and break the law against coasting in neutral in your state, and then react like this when called out:

Me? Impeding traffic? If only Honda used a system that will allow me to skip a bunch of steps and get into an acceleration ready state

oh yeah. Auto rev match. Slowing down in neutral. Oh no the light turned green? Throw into second and let go of the clutch and add gas. Boom. Done


I’ve literally done it like this for over 30 years. So have my kids too. No one’s ever blown a tranny or banged up a synchro. Not saying you’re wrong. Just saying I have not seen it. Maybe the wear is super minute. I dunno. I do know I’ve never met anyone that literally downshifts over and over into each gear to come to a stop. Never heard of them losing a synchro either

I’m not slowing traffic down. At all. Trust.

I forgot what state it was. I think it was Florida? But anyways, you legally can’t tie a giraffe to an electric pole in Florida (again. I think it was Florida). Just because something’s a law doesn’t mean it’s a good law. Or it makes sense.

if anyone wants to be a thug and break the law and not rev match downshift like 4 times in a row to come to a stop. Go for it. Or not. Whatever.

 

[ctechauto]

 

[menikmati]

Sigh, when another thread falls apart before my eyes...

 

[Deleted User 3888]

Man I’m just saying. Why cite a stupid law that states U can’t go in neutral when driving down hill? Might as well cite a law 99.99% of us can’t afford to break, like tying a giraffe to an electric post

like. When I learned how to drive I was simultaneously being taught stick too. And back then the damn thing needed to be double clutched. So I can see why you’d want to stay in gear as long as possible before you’d want to come to a complete stop.

but my mopar stage 3 srt4 acr (with turbo toys) made it to 220k miles before I gave it to my son and it never had a synchro issue ever. And my son stops like me. And he had the srt4 till almost 250k till he sold it. No synchro issues either

I’m not calling bullshit on stressing the synchro. But it sure as hell doesn’t seem like a big deal if true

edit: called this cat from wiwi transmission in Miami Florida. Then I called a friend who literally owns his own shop and does side work for pfi on occasion

they both told me that is not how transmissions work. Once in neutral with the pedal out. The synchros aren’t engaged or stressed. Except they said it in Spanish.

they did agree with the fact that I am wasting my brakes. And they did agree with U, what I’m doing is unsafe. But the trans is fine.

i swear man. Some Honda people can be so full of shit. It’s like old wives tales stacked on top of old wives tales with some of y’all

I remember when some of y’all were cutting off the curved tip on your spark plugs to give the d motors an extra 10whp

 

[shijima_ending]

on for me, its really good. The pedal box on this car is aweful for hell toe as well, not that I would still have it on, I want to focus on driving when I am at the track, just shifting gears is enough of a "another thing to do".

Fun to heel toe but not something that I need to enjoy any car.

Is this car's pedal box actually bad for heel toe? Not my first manual car but my first car learning how to heel toe in - so I don't have much for reference

Sometimes I'm really nice with the heel toes and other times i botch them. Always thought it was a skill issue. Am I nerfing myself by not getting a pedal spacer?

 

[Deleted User 3888]

Is this car's pedal box actually bad for heel toe? Not my first manual car but my first car learning how to heel toe in - so I don't have much for reference

Sometimes I'm really nice with the heel toes and other times i botch them. Always thought it was a skill issue. Am I nerfing myself by not getting a pedal spacer?

If you’re in Colorado near Denver we can meet up and U give it a try. For me and my size 10.5 feet it feels perfect.

 

[Spart]

if anyone wants to be a thug and break the law and not rev match downshift like 4 times in a row to come to a stop. Go for it. Or not. Whatever.

This is literally what a DCT will do, because the DCT knows better than to break the law, leave you without options to make evasive maneuvers, and raw-dog the synchros.

So yes, I follow the law and I drive defensively by keeping the car in gear while it's rolling to keep my options open in emergency situations.

I’ve literally done it like this for over 30 years. So have my kids too.

I met a guy one time that always drove in the left lane doing like 5mph over the limit and taught both of his girls to do the same thing.

How embarrassing.

 

[shijima_ending]

If you’re in Colorado near Denver we can meet up and U give it a try. For me and my size 10.5 feet it feels perfect.

Sadly I am not. but for reference I am a size 12 and i use the foot rollover method since I cannot tweak my heel over like the real drivers can.

 

[MooMoo]

Is this car's pedal box actually bad for heel toe? Not my first manual car but my first car learning how to heel toe in - so I don't have much for reference

Sometimes I'm really nice with the heel toes and other times i botch them. Always thought it was a skill issue. Am I nerfing myself by not getting a pedal spacer?

To me it is, compared to my last 2 cars which was a VW and a BMW M2.

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