Shifting Question

[Khronik]

ive read too many different "opinions" on downshifting that im wondering if anyone really knows wtf theyre saying...

the clutchless shifting, is whak... go buy an auto

but with down shifting I see people saying to hit rev and down shift (they are not saying to rev match, just to tap the gas)
other say rev match, heel & toe, etc

and then there is, "synchros do not require rev matching (just dont downshift into a redline) on new vehicles", saying the heel & toe was needed on older cars due to lack of synchros

so is the real answer to this?
ex: im 4th going 40 and pop into 3rd which would prob put me at what 3k rpms?
or lets say going 50 and go into 3rd which is prob 4-5k
is that going to damage anything?

[es.biggs]

When you shift to a lower gear, push the clutch in and rev up to where you think the RPM needs to be, then let the clutch out. That's probably the best way to do it - it will cause the least amount of stress on your drivetrain.

Heel-toe from what I've gathered over the past few years is a technique that utilizes engine braking to assist in slowing a car down. Its used a lot in racing. When you downshift you cant just move the shifter and let off the clutch - you really need to rev match or it will cause a lot of wear on a lot of parts of the vehicle. So heel-toe keeps the brakes depressed and it allows one to press the throttle so they can downshift.

Rev-matching is just getting the engine RPM to match the speed of the input shaft on the transmission. Your clutch is attached to the input shaft. When you shift into a lower gear, the input shaft speeds up. If you don't speed up the engine (RPM) then your clutch and your flywheel will be smashed together at completely different speeds. That's just two of the many things that will wear out faster when you don't rev-match.

The thing about synchros vs no synchros. Synchronizers, in very basic terms, act like a clutch to keep the two shafts inside the transmission spinning at the same speed. That way you can go straight from one gear to the next, with no grind. Older (way older) transmissions don't have synchronizers. The reason they are different is because the two transmission shafts spin at different speeds, and there is nothing to keep them "in mesh" with eachother. When you downshift in an unsynchronized transmission, you have to do what is called double-clutching. You clutch in, shift into neutral, clutch out - this allows the input shaft (where the clutch attaches to the transmission) to speed back up to the same speed as the engine. Here you want to rev match while you're in neutral, before you shift into the gear you are downshifting into. Then you clutch in, shift into the desired gear.

It's a lot harder to avoid grinds in an unsynchro'd transmission. Does double-clutching sound easy? LOL exactly.

That's my .02. Modern transmissions are very easy to drive and the only part that is challenging is the rev-matching. It gets easy when you learn the car though.

The stuff I put above is all very generic...transmissions are hard to understand. If you really want to learn how they work you really have to get inside one with somebody who knows about them. It's hard to understand how it works without actually seeing it.

[Khronik]

ok so heel-to-toe still helps but is more for use of having to break and then wanting to accelerate quickly right after?
or brake/rev matching quickly?

rev matching a downshift is required regardless of synchros unless you want to destroy the drivetrain?
(usually dont down shift because I find it easier to pop neutral and coast in casual driving, putting less strain on the clutch.
prob bad practice but hey it works...)

[bmxer300zx]

if ur doing 60 and go into 2nd ur rear end will lock up so u wont be wearing down ur brakes. it also adds as a level of fun and excitement

[DCaff300ZX]

I suppose that heel/toe and rev-matching can have minute benefits to trans life, but is not why they came about as far as I know.
Rev-matching to my knowledge really is not about clutch/pressure plate life but is more about trans gear cuts which do not mesh as neatly as other styles, but last longer. Rev-matching allows them to mesh easier under spirited driving.
Heel/toe is for better control of your car in competitive racing scenarios, and not necessarily a BETTER way to shift...just necessary for drifting and some tracking needs.

The OP asks whether it's "good" or not to downshift- I've always felt it's beneficial to have deceleration pressure on your engine, and engine braking does save brake pads slightly in the long term...

[DCaff300ZX]

if ur doing 60 and go into 2nd ur rear end will lock up so u wont be wearing down ur brakes. it also adds as a level of fun and excitement

This is true...

[Khronik]

if ur doing 60 and go into 2nd ur rear end will lock up so u wont be wearing down ur brakes. it also adds as a level of fun and excitement

i tried this.
flew out my windshield and died but it was fun

[car nut]

Rev-matching to my knowledge really is not about clutch/pressure plate life but is more about trans gear cuts which do not mesh as neatly as other styles, but last longer. Rev-matching allows them to mesh easier under spirited driving.
Heel/toe is for better control of your car in competitive racing scenarios, and not necessarily a BETTER way to shift...just necessary for drifting and some tracking needs.

Yes.

rev matching a downshift is required regardless of synchros unless you want to destroy the drivetrain?

No.

[es.biggs]

Are you saying downshifting without rev-matching doesn't create excessive wear on the drivetrain?

[Chattzx]

it does put strain on the drivetrain components if you do not rev match when downshifting. I always downshift otherwise its too jerky.

[DCaff300ZX]

Are you saying downshifting without rev-matching doesn't create excessive wear on the drivetrain?

Any damage possible is mostly to the synchros, which have a certain cut that is harder to mesh "on the fly".
To answer your general question best, for the Z32 rev-matching is not required for a comfortable drive where a Z33 and other performance Nissans like GTR will shift better/easier if your rev-match when you shift.
The newest GTR and I believe 370Z have a rev-matching setup for the trans to address this issue with shift smoothness and to help synchro life.

[car nut]

Are you saying downshifting without rev-matching doesn't create excessive wear on the drivetrain?

It creates wear on the drivetrain, but this is wear the components were designed for. So no, I wouldn't say it creates excessive wear.

[es.biggs]

I thought, when you slide the gear shifter into gear, you are in gear - synchros are meshed with the gear. From that point you want to rev match to whatever gear you selected. Otherwise it's similar to "dropping the clutch" right?

If you are in 5th gear going 60, I'm not sure but lets just say you are cruising at 3200 rpms. You want to downshift and pass somebody, so you put it in 4th. At this point, you are rolling in 4th gear at 60 mph, the clutch is disengaged, and the engine rpm has dropped to around 1500.

In order for a smooth transition into 4th gear, you would need to rev match at around 4400 or so, right?

If you let the clutch out without giving it some throttle to rev up, it will most definitely wear the clutch and flywheel more than normal - because the difference in rotating speed between the two components.

[Khronik]

some good controversial info here, ill throw it around some and see what works

[es.biggs]

Yeah I mean I'm not trying to start a big argument or anything, I'm just trying to make it all make sense in my head. Car nut knows his stuff - so I'm curious as to whether or not I've been wrong about it for so long lol

[Khronik]

i hear ya, im trying to figure out whats going to do the least amount of wear and tear while being able to have fun with it
(first standard.....)

[car nut]

Yeah I mean I'm not trying to start a big argument or anything, I'm just trying to make it all make sense in my head. Car nut knows his stuff - so I'm curious as to whether or not I've been wrong about it for so long lol

You're sort of right but not entirely. Yes, rev matching does make it easier on your drivetrain but it does not cause unnecessary wear. It is wear that the drivetrain was engineered to deal with so I wouldn't call it unnecessary. This is what synchros were designed for.

Really, it's more an issue of being smooth. In the above situation of going from 5th to 4th, if you make a smooth, quick downshift and don't just bang the shifter in or wait incredibly long, you're synchros will do their part and you should have a relatively clean, smooth downshift.

i hear ya, im trying to figure out whats going to do the least amount of wear and tear while being able to have fun with it
(first standard.....)

Then double clutching is your thing. Tons of fun, especially if you're making some good power.

[DCaff300ZX]

I thought, when you slide the gear shifter into gear, you are in gear - synchros are meshed with the gear. From that point you want to rev match to whatever gear you selected.

If you are in 5th gear going 60, I'm not sure but lets just say you are cruising at 3200 rpms. You want to downshift and pass somebody, so you put it in 4th. At this point, you are rolling in 4th gear at 60 mph, the clutch is disengaged, and the engine rpm has dropped to around 1500.

In order for a smooth transition into 4th gear, you would need to rev match at around 4400 or so, right?

You have things basically laid out correctly, but need to look further into what is going on mechanically to understand the effect of rev matching and whether it's necessary or not. Only transmissions with steeper cut angles on the leading edges of the gears need rev-matching of the crankshaft and the drive line speeds, while most modern transmissions have gear cuts that make rev-matching and double-clutching unnecessary when shifting in either direction under speed.
Rev matching and double clutching is done only to ease the gears meshing together smoothly, and to my knowledge and as carnut said has no positive or negative effect mechanically on the rest of your working drivetrain.

If you let the clutch out without giving it some throttle to rev up, it will most definitely wear the clutch and flywheel more than normal - because the difference in rotating speed between the two components.

You put FAR more stress on the clutch and pressure plate (not flywheel) each time you start from a stop than during gear shifts at speed, because from a stop you add moving a weighted object (you and your car) into motion to the process- so I doubt that there is any real "gain" to clutch/PP life from rev-matching when downshifting or upshifting at speed because there are not the same stresses on the transmission components unless under severe circumstances such as dumping the clutch into a low gear at high speed as bmxer300ZX joked.

[Khronik]

double clutch rev matching.... wanna make sure i got this right..
clutch-in, neutral, clutch-out, hold rev at match, clutch-in, downshift, clutch-out

[CrazedZ32Owner]

yeap thats double clutching...

i rev match regardless... or just ease off of the clutch pedal