Raybrant

iTrader: (16)

Honestly it comes with practice and just plain ol' experience... Just keep driving and experimenting and you'll get it sooner or later.

Similar to you, the Z was my first 6spd (been a city boy all my life...) and I knew a tad bit on how to work it being an engineer and watching vids/reading stuff. I've been in that situation where I stalled out in the middle of an intersection and stuff, that was fun... Then I got the hang of it after a week (fast learner) and decided to experiment with downshifting. Started off double clutching and learning the sweet spot per gear/speed to get a smooth downshift (there's no secret formula or number, it's all through feel and guessing) then I moved into heel-toe which is just double clutch downshifting while applying the brakes.

I practice this stuff on the streets. Can't imagine how life would be without rev-matching when you downshift (trannies would be so expensive...).

So my advice is: just keep driving, read/watch stuff, experiment safely and if it suits your interest, do HPDE events or AutoX... teaches you so much more than just civilized driving on the streets.

Pikes 350

im right there with you at stalling at intersections but yea ill just keep practicing cause the last thing i need is to replace the tranny

Raybrant

iTrader: (16)

Just don't go all F&F taking corners at 30 mph and you'll be fine.

Your parents would be disappoint if you totaled the Z and had to go back to the Oldsmobile.

plusONETEN

iTrader: (1)

You know how the gear lever is harder to push into gear when the revs aren't matched, and its easier when they are close or almost perfect? Your car is talking to you.


For fast driving:

Depress clutch
Blip throttle
gear lever becomes easier to push into gear when revs are almost matched
by the time the lever is fully engaged, your revs are matched perfectly
release clutch just as engine RPM is matched to vehicle speed


If you need to brake hard, do the same exact thing, but heel toe it.


For least wear:

if you wait a split second longer to move the lever until the revs are matched 100% perfectly, you can put the gear lever in to position with very little synchro wear - however if you want to do this and shift perfectly you kinda have to maintain the engine at the right RPM for a brief period (during both lever movement and clutch movement)

some people may be able to double clutch faster than this, but i cant... and if the RPMS are matched when you put it in gear, you're not wearing out the synchros anyways so i find double clutching excessive.

The method i listed first is easier because you kinda "catch" the engine at the exact right RPM as you are releasing the clutch instead of having to maintain the RPMs there.






Psychologists have shown that if you heel-toe in traffic, although you think that people are aware of your prowess, they actually think you are an idiot who doesn't know how to drive. Despite what you perceive, they won't notice that your brake lights are on while you are revving your engine, and if they do, they will assume it is because you are driving an automatic and accidentally pressed the gas and brake at the same time. Its called the Illusion of Auto-Transparency. ...maybe?

Jennifer 2

I get what you’re trying say with your post PlusOneten, but I think you misspeak a little with the first part of your description. Once you push down the clutch pedal you completely disconnect the transmission’s input shaft from the engine. All the throttle blipping and revving you do while the clutch is disengaged, will not be noticed by any of the transmission gears or synchros as they go about their job of gear changing.

My dad could shift gears in a tractor-trailer truck without using the clutch. Once he got moving from a stop in first, he would bump the shift lever into neutral (no clutching). Pausing for a second until the engine revs dropped down enough to match the correct road speed for second gear, he would then nudge the shift lever into the second gear position. And-so-on for the rest of the gears. Downshifting would be similar, but now after bumping the lever into neutral he would throttle the engine speed up to match the road and engine speed for the lower gear before shifting.

He claimed shifting like this, (although slower and more deliberate than using the clutch every time) was much easer on the transmission gears and especially the synchros. Also since every shift perfectly matched the road and engine speed there was no driveline shock at all.

Rev matching when downshifting a sports car is not about making the life of the synchros easer. It’s about preventing driveline shock when releasing the clutch pedal. If you’re cornering at the limits of traction while downshifting, the driveline shock from releasing the clutch without enough engine revs will upset the car.

If instead you want to prevent all synchro wear, you must either double clutch or learn the delicate art of clutchless shifting.

I have done the odd clutchless up-shift on my Z. If you want to try it, use the shift into 5th gear, as it being a one to one ratio will be the easiest. Drive along in fifth gear at exactly 35 mph and take careful note of the exact rpm on the tach. Now, next time your driving along in fourth gear, adjust your speed to about 37 or 38 mph and let off the gas pedal. In that short window between accelerating and coasting, when the driveline goes slack, bump the shift lever into neutral without using the clutch. Wait for the car to coast down to 35 mph, bring the engine speed up to the exact rpm you previously memorized and pop the shift lever into fifth. Since the relevant gears will be exactly matched in speed, the shift will be effortless, and the synchros won’t have to do any work at all.

This is a late night two Scotch (Talisker) write up, so please forgive the fractured syntax etc.

plusONETEN

iTrader: (1)

good point. it is true that the gears in the transmission will still be spinning, but you will only be fighting the inertia of the gears/clutch. That is, however, exactly what the synchros are designed to do.

(Typically only by the speed difference of 1 gear.)

If you're in 5th, however, and you clutch in, and then decide to go into 3rd instead of 4th, you are dealing with a larger speed differential, i feel like this is more likely to cause a gear grind than you would when going from 5th to 4th.



i do cluchless shifting in my honda sometimes just because im bored, lol. I do it the exact same way that you do, i try to note the exact RPM needed. You can also feel the stiffness in the gear lever when the RPMs aren't close, and it gets easier when the revs are matched. You can press lightly and if you rev through the correct RPM slowly, it will go into gear at the correct time without any change of force (assuming you are pressing just hard enough) I usually only do 3rd to 4th or 4th to 3rd though because my fifth gear is annoying, and as you pointed out, lower gears are trickier.


However, feeling with the synchros probably isnt saving them any wear - so you basically have to jam it in at the exact right second in order to get the benefit from this. Actually, if someone has more information on the exact process that causes the lever to be easier to go into place when the revs are matched, im curious to know - i just assume its related to friction in the synchros, but perhaps there is more to it than that. I know poeple always say it is a pain to put a car in first when you are moving, but i never thought there was any truly fundamental difference except the fact that that ratio itself is very low so you need to rev the hell out the engine to match correctly



But you're definitely right - if you can clutchless shift by just popping it into gear without dropping the trans, you will probably not be wearing synchros much at all - because any speed differential low enough that the gears can withstand, the synchros will be almost 100% unaffected by.









Im still trying to improve my technique, this is a cool thread yo.

plusONETEN

iTrader: (1)

also... when you are driving slow, you are probably shifting at lower RPM, so you are going from, say 2200 to 3000 rpm instead of 4400 to 6000 rpm

the fact is that in the first case the synchros are going to have to absorb 800 RPM but in the second case they have to absorb 1600 - so you are going to wear your synchros less when driving slow, even if using the same technique.


My honda has the original synchros on it, and its got 180,000 miles - it has just worn out to the point that there will be a grind just from the gears and clutch intertia in 3rd gear - but only when shifting at very high RPM, and I always figured that it was because at low RPM the differential is low enough that the synchros can absorb it, even with the same exact techinque.

It will grind with a slow and deliberate high RPM shift, but never from a low RPM shift.

pbn85

iTrader: (2)

thanks. I made it mainly because I bought a new transmission and wanted it to last this time. My last transmission had a 5th gear grind upon down shifting from 6th - I never rev matched, but other gears were fine. My question is did the lack of rev matching likely contribute to that transmission going bad? I've been driving stick for 6 years, but the idea of rev matching was unknown to me, and all my previous cars were fine.

I picked up this rev matching technique after the new transmission went in because I heard it was safer on the synchros. Some say it's not beneficial in that sense, but rather the only benefit is that it offers a smoother ride. Others say rev matching will help the synchros last. Just looking for some clarity. I'm still trying to master rev matching, but I noticed it's not necessary on EVERY single down shift.

plusONETEN

iTrader: (1)

read the wiki article on manual transmissions - it explains that the force resisting going into gear is that the dog that selects the gear on the main shaft will not fall into place until the revs perfectly match - so basically the more work the synchros need to do, the longer the resistance will last from the synchros before the speeds are matched - usually its so short you dont notice with low RPM shifts.

AmnCruzie

iTrader: (3)

Lolz at all the talk about double clutching a synchro'ed tranny. And yeah OP, I agree w/ most the guys here. #2 is the way to go, although what you really want is to do it as close to simultaneous as you can, not one or the other. It takes practice and getting used to, but there's a reason most professional racers use the heel-toe method (unless you have one of those fancy f1 style twin-clutch, flappy paddle gear boxes, in which case left foot braking is the preferred method)

Dblock55

iTrader: (4)

Granny shiftin' instead of doulbe clutching like you should

sry, had to do it lol surprised no one beat me to it....


On a serious note, when im on the track its STOMP BRAKES, CLUTCH IN, KEEP TOES ON BRAKE AND HEAL ON THE GAS (BLIP THE THROTTLE) AND SIMULTANEOUSLY DROP GEAR DOWN, CLUTCH OUT. Heel toe might take u a while to get smooth with the braking but once you get it its super simple and effective. good luck

AmnCruzie

iTrader: (3)

^ I wanted to so bad. It was hard convincing myself not to make a Vin Diesel reference

Dblock55

iTrader: (4)

^ unfortunately I do not posses your great powers of self discipline lol

Itzcashew

iTrader: (13)

What i do is out of habit because of my tranny. I can do option 1 from 6th to 5th and 5th to 4th. But if I were to do 4th to 3rd I have to double clutch or else.... ECCHHKKKKK and i have to retry again =[

AmnCruzie

iTrader: (3)

^ Fair enough, double clutching out of necessity because of worn down synchros is one thing (i have that problem too sometimes, my synchros act up sporadically). But honestly, If I hear one more wanna be racer talk about double clutching and granny shifting (especially in the same sentence) like they were in the fast and furious, I'm probably going to bash his face into the hood of his car... I'm not a huge fan of people, people bother me

N80

Agreed. I cannot think of ANY reason to double clutch this car. On the street or on the track. It makes no sense on the street and less sense on the track. If you're doing it to save the synchro......it will last longer if you park it.

I rev match on the street for two reasons:

1) Low speed and getting resistance to downshifting into first or second. How do I do it? I have no idea. Never thought about it. Listen. Feel. Blip just right and it slides right into gear. Never had to do this on any other car but works just fine.

2) When I'm practicing heel-toe, which gets easier.

I have not learned to heel-toe on the track (will start next in about 2 weeks). So here is how it works without heel-toe:

Throttle on the floor. At braking point, hard on the brakes, clutch in, downshift, at just the right time (I wish) come off the brake, blip throttle, clutch out smoothly, back on brakes if necessary, off brakes, begin turn in. Roll into the throttle then to the floor.

Because you have to come off the brakes to blip the throttle this means you have to brake earlier. This slows you down. With heel-toe, you never have to come of the brakes and can brake later.

The only other option if you don't heel toe is not to rev match at all and I'm told that this can work fine as long as you ease the clutch out slowly at just the right rpms.

If you pop the clutch out with too much of a mismatch in rpms and wheel speed the rear can lock up and spin you.

Edit: If you are struggling with heel-toe, then forget about using your heel to blip the throttle. Just use the outside edge of you right foot. You have to use the right side of the brake to get close enough. I could not do it with my heel to save my life but getting good at it with the side of my foot.

AmnCruzie

iTrader: (3)

^ big toe-pinky toe downshifting FTW! I do that sometimes, when I'm too lazy to fully heel-toe or when I drive the Miata... Pedals feel weird on that for some reason.

N80

I was wrong! There is a recommended use for double-clutching. The 2007 350Z Owner's Manual says to double clutch when there is resistance to shifting into first or reverse. So there, now you Vin Diesel fans actually have a bona fide reason to double clutch.

However, what this really tells me is the difficulty shifting into first is a natural characteristic of this transmission and not a wear issue or malfunction. It is a fault, but not a sign of malfunction.

Jennifer 2

N80, you have a little misconception on how the transmission/power-train functions, obviously you slept through Driver’s Ed. I’m sure if we could subpoena your father he would clearly state that he explained all this stuff to you, but being a teenaged boy you didn’t listen.

When a car stopped a sometimes-occurring resistance for engaging reverse or even first gear, is generic to all manual transmissions. Think about how gears shift in the trans. When the car is not moving the output shaft and all the gears directly connected to it are not turning. Also, even though he engine is running, with the clutch pedal pushed in, all the gears connected to the input shaft are also not moving. When you move the shifter to reverse or first gear, a sliding collar is moved towards the gear, dogteeth on the side of this collar engage corresponding teeth on the side of the gear. Once in a blue moon the gear and shift collar will have come to rest I a position that aligns the points of the dogs exactly head on blocking easy engagement. Returning to neutral and momentarily releasing the clutch will move the gears around a bit, allowing them to come to rest in a better position for the dogteeth to mesh. This is analogous to jiggling the steering wheel to reposition the steering interlock, when the ignition key is hard to turn. The owner’s manual is not speaking to any fancy driving moves here. It’s simply giving you a handy technique for engaging a gear before leaving a parking space.

The other situation you reference about hard down-shifting into first gear is not difficult to understand. Some people here have described feeling a lot of resistance in the shift lever when coasting towards a stop sign and wanting to select first gear at 10 or 15 MPH.

I feel this mostly first thing in the morning before the trans fluid is warmed up. As I push in the clutch coasting towards a stop sign, the viscous nature of the gear oil used in a Z causes a lot of drag on the first gear, its corresponding gear on the lay shaft and the input shaft. This can cause them to stop spinning altogether along with the clutch disk that is splined to the input shaft. As these are all rather large heavy-duty items, it’s a lot of weight for the poor little syncro unit to get moving and spin up to speed.

If I’m slow and lazy on this shift and I suspect that the synchromesh unit is going to have to make up for my sloth, here is what I do. When I’m passing through neutral on my way to first I simply release and reengage the clutch momentarily, just enough for the engine to get the input side of the gear train moving a bit. I’m not trying to consciously match gear speeds or do anything fancy; I’m just taking a bit of the load off of the synchro. Once the trans fluid is fully warmed up (takes a bit of driving) this is no longer necessary.

N80

Jenny, unwad your panties and take a deep breath. And no, that time of the month is no excuse.

Depends on the differential between engine speed and wheel speed. The point is that this car has a greater than normal resistance to downshifting into first. What's normal? Well, again, I've been driving a wide variety of MTs for more than 30 years. I've got an idea how a manual gear box works.

Yada yada yada. Spare me the lecture. The owner's manual recommends double clutching when downshifting into first in a 2007 car. Clearly this is peculiar to this transmission. Other trannys may be like this as well...but not one I've driven. My G was similar.

Yep. I was one of those people. And you're right, it isn't hard to understand. What's your point?

Yep. I said that too. So you're firing personal attacks at me for what reason?

OMG. What is wrong with you? In my very last post I cited the manual describing the same thing!

Just what exactly got your panties all wadded up?