Downshifting or not with manual transmission in city?

[OILFIELDTRASH]

I mean, the stick moves into and out of the gear very easily when the revs are matched perfectly. (This is all without using the clutch, BTW.) If you are in gear and the revs are not matched, pulling the stick out of gear is hard.... very hard if there is a lot of torque being transmitted through the gearbox. If you match the revs (usually just blip the throttle a bit and then back off immediately while pulling the stick out of gear) then there is no torque being transmitted; the gears are spinning freely at the same rate as the engine. The stick pulls out of gear with no resistance at all.

Same with going into gear. If you are in neutral and trying to shift into gear, if the revs are not matched then it will have a lot of resistance, and if you force it and push hard enough then it will grind the synchros. If the revs are matched then you can push it into gear with no sound and no resistance; it slips right in.

So you have to get a feel for the stick and be able to put a moderate amount of pressure on the stick, enough to be able to feel the resistance but not enough to actually move things and grind the synchros. Any resistance = not matched. Slides right in/out = matched.

The synchros have little teeth on them too. As far as I can tell, this is what grinds in manual transmission cars. The synchros protect the power gears in a sense. The synchros grind, but the power gears don't. Because if the teeth don't line up on the synchro, the power gear is still disengaged.

You sound like you'd enjoy driving a rig. Although there is no synchro so I'm not exactly sure how that changes the equation. A lot of feel stuff you're talking about sounds very familiar to what I do daily. Even blipping the throttle is a feel thing as well. When I first started blipping the throttle I'd either go way too high or not enough. Now it's just kinda natural to give it as much as needed.

 

[OILFIELDTRASH]

I feel for you guys and I try to make it easy for truck drivers trying to merge onto a busy freeway by slowing down and flashing my lights on and off to let them know they can move over into my lane. Usually I will get a flash of the tail lights on and off as a thank you for this.

Yeah I find more helpful people than I do a holes when behind the wheel. We have buttons on the trucks specifically for the thank you sign. Just hit it twice and it flashes twice to say thank you. The driver isn't actually turning off and on his lights.
Just a fyi if you're (not you specifically) merging on the freeway just blow my doors off and get by. I sometimes have people that merge at like 40 and I have to slow all the way down to let them in. I'm basically like a train and when I slow down to 40 it could take me a mile or two just to get back to freeway speed.

 

[JulesMaximus]

Yeah I find more helpful people than I do a holes when behind the wheel. We have buttons on the trucks specifically for the thank you sign. Just hit it twice and it flashes twice to say thank you. The driver isn't actually turning off and on his lights.
Just a fyi if you're (not you specifically) merging on the freeway just blow my doors off and get by. I sometimes have people that merge at like 40 and I have to slow all the way down to let them in. I'm basically like a train and when I slow down to 40 it could take me a mile or two just to get back to freeway speed.

I did not know that. :biggrin: Learned something new today. :thumbsup:

I never pull in front of a truck if I'm going way slower than they are or if I have to stop quickly. And by the time I get to the top of any on ramp I'm going at least as fast as traffic is moving.

 

[exdeath]

The synchro just matches the gear speeds in the transmission so the gears don't crunch, it doesn't match engine speed to the gear being selected.

The synchronizer just eliminates the need for double clutching.

Not double clutching when you should...

 

[exdeath]

I've driven home with a broken clutch cable. It's not bad at all. More worried about the battery dying in traffic if I have to stop too many times.

 

[Zenmervolt]

I really don't see the benefit of rev matching a car transmission. I'd imagine there is much more wear when you don't rev match perfectly and you grind your stuff. Or does a car tranny not grind?

The benefit is that you're not dumping the clutch and putting a huge jolt through the drivetrain when you re-engage the clutch after the shift is complete.

If you don't rev-match a downshift you either have to let the clutch out very slowly and let the slippage bring the engine up to speed or you cause a significant jolt as the clutch suddenly reconnects the wheels to the much-slower-spinning engine and the chassis balance goes all pear-shaped for a moment. A non-rev-matched downshift is sort of like the inverse of dumping the clutch; instead of a rapidly-spinning engine being abruptly connected to a much more slowly spinning drivetrain, the rapidly spinning drivetrain is abruptly connected to a much more slowly spinning engine.

Rev-matching is not synonymous with "floating the gears," which is shifting without having to use the clutch. In order to float gears, you do have to rev-match, but you can rev-match in many situations that do not involve floating gears.

Double-clutching (which also involves rev-matching) reduces the amount of work the synchros have to do and, since you're still completely disengaging the clutch when the shift is actually happening, you don't get grinding because even if you're a bit off, the synchro will take care of it. Now, if you try to float a gear and you don't disengage the clutch, yes, a synchronized automotive transmission will still grind.

Of note, floating gears with a synchronized transmission is EXTREMELY bad for the synchros because it places far more wear on them than they are designed to take (remember, they're only designed to spin up/down the input shaft, not the entire engine, which they will try to do if you get a float slightly wrong with a synchronized transmission). Shifting a car without a clutch is not something to do outside of an emergency.

ZV

 

[Zenmervolt]

The synchros have little teeth on them too. As far as I can tell, this is what grinds in manual transmission cars. The synchros protect the power gears in a sense. The synchros grind, but the power gears don't. Because if the teeth don't line up on the synchro, the power gear is still disengaged.

Those teeth aren't part of the synchros. Those are just regular old dog teeth like in any other constant-mesh transmission. Even semis have that sort of setup.

Synchros consist (speaking simply here) of cone clutches made out of brass or other relatively soft metals. These little clutches begin to rub against one another before the dog teeth even begin to engage and it's the friction of the little cone clutches that speeds up or slows down the input shaft so that the dog teeth can engage smoothly.

Other parts of the synchro design actually resist engaging the gear until the revs match well enough. If you put a lot of pressure on the gear lever, you can overcome these "baulk rings" and force the tips of the dog teeth to come into contact before synchronization has occurred, which is what you hear when a synchronized transmission grinds.

Synchros are also wear items (since the cone clutches do wear out over time), so older cars, or cars that have seen abusive shifting, may not have fully functioning synchros anymore, which will also cause grinding as the gears with worn-out synchros (typically 1st and 2nd gear) will begin to behave more and more like non-synchronized transmissions.

ZV

 

[kitatech]

My last MT (99 Altima) needed a new clutch @ 180k miles...the previous 94Alti was sold @ 172K miles with the original clutch...

Odd that the Camry's 1st owner needed a new one by 90k...I often mull and wonder how many more miles I can get out of this, the dealer-installed-for-resale THIRD clutch (the 2nd install being a botch)...

 

[dbk]

I only downshift for a corner where I will be turning without stopping or if I am in very slippery conditions. If all I'm doing is stopping, and there is no issue of compromised traction I just put the clutch in and brake. Once the car is stopped, I am in neutral until it's time to start moving again.

I do this most of the time but only because I'm a noob at driving stick. I can watch a bunch of videos explaining rev matching, heel-toe etc but I chicken out all the time in real time. Honestly, though I don't often find the need to do so in my daily commute.

 

[railer]

Hello all,

I hear sooooo many manual drivers debate over whether you should downshift to a stop or use your brakes to stop? Clutch kit vs brake pads being worn out debate as well.

Specifically, what is the proper way to stop and go city driving and driving under 30mph speed limit more or less?

I would just use the brakes, as that's what they are there for. I would imagine 95% of the normal human population does the same.

 

[PeeluckyDuckee]

I've always coasted in whatever gear I'm in, until I hit about 1500rpm then throw it into neutral and apply the brakes if by the time I get to the intersection it's still red. Or when it turns green, I throw it into whatever gear I feel is necessary for the situation.

 

[thedarkwolf]

I've driven home with a broken clutch cable. It's not bad at all. More worried about the battery dying in traffic if I have to stop too many times.

Amazing how strong those little starter motors are. I've had to drive without a clutch multiple times in my miata, wonderful clutch hydraulics. You can get moving on a pretty damn steep hill just using the starter.

 

[JulesMaximus]

Amazing how strong those little starter motors are. I've had to drive without a clutch multiple times in my miata, wonderful clutch hydraulics. You can get moving on a pretty damn steep hill just using the starter.

It's all about the gear ratios. Starter motors turn a very small gear very fast which drives a very large gear slowly... kind of like a granny gear on a mountain bike.

 

[MrWizzard]

When was the last time you replaced a clutch?

I've always heard about this "brakes are cheaper than a clutch".
Since I've never replaced the clutch my experience is that I've spent more money on brake jobs than I have on clutches.

Rev matching, or just easin out the clutch (prior to learning how to goose the the throttle for rev matchin) is better than "tossin it in nuetral".

If the driver is to lazy or un involved to figure out how to downshift properly, they might as well drive an automatic.
This way they can have a hand free to put on makeup or hold a phone or something.

Last year it was a little over 8K. Which isn't that bad considering the car. The car is 17 years old. 1st change. I still stand by breaks are usually cheaper. IDK what you are talking about with the whole lazy thing. Even if you know what you are doing. Clutches are more. Try to get more life out of them. Also some cars ONLY come in manual.

 

[pauldun170]

Last year it was a little over 8K. Which isn't that bad considering the car. The car is 17 years old. 1st change. I still stand by breaks are usually cheaper. IDK what you are talking about with the whole lazy thing. Even if you know what you are doing. Clutches are more. Try to get more life out of them. Also some cars ONLY come in manual.

What car did you spend 8K on a clutch job?
Is that 8K of what currency?
How many miles are on that 17 year old car?

 

[lavaheadache]

I shudder at the thought of needing a clutch on my 997

 

[nerp]

Downshift if you have some distance to go and want to slow down gradually. But it doesn't matter.

The one thing to learn about clutches is don't hold the damn clutch in at a light. Leave it in neutral. If there's an emergency, you should be able to shift into first and go quickly. That's better than getting hit and letting go of the clutch in gear because you're injured and the car decides to buck around. Also, holding in the clutch while stopped causes more wear than anything.

The other thing is to not downshift into first while moving. There's a reason why it's stiff and unpleasant to do. Downshift to second, then N, stop, then slide back into first right when you need to go.

So many myths about driving, especially manual transmissions. And nothing grinds my gears than someone who rides the clutch or can't manage a stick without bucking the hell out of the car. A passenger shouldn't be able to tell if it's a manual or stick if their eyes are closed.

 

[_Rick_]

The other thing is to not downshift into first while moving. There's a reason why it's stiff and unpleasant to do. Downshift to second, then N, stop, then slide back into first right when you need to go.

If you give it enough revs, it's sweet and easy to go even into first. But the window for a good shift is quite tight, so it requires a bit more practice, and a bit of clutch slip usually, as well.

For all other downshifts, it's usually enough for me to give a single tap at the accelerator pedal, but for first I jab it twice, because I need more revs, and a short tap makes it easier to predict the plateau of the rev-up.

 

[pauldun170]

My last MT (99 Altima) needed a new clutch @ 180k miles...the previous 94Alti was sold @ 172K miles with the original clutch...

Odd that the Camry's 1st owner needed a new one by 90k...I often mull and wonder how many more miles I can get out of this, the dealer-installed-for-resale THIRD clutch (the 2nd install being a botch)...

We both have the same generation Camry with a stick. Mine is a 2002 with 70K.

Quick trip to forum land revealed quite a few folks with early clutch failures. According to those that looked up the rate, its in the system as 10 hour job so for Camry's it pricey. the reason why its a 10 hour job is that the book calls for removing the engine.
However, its known that removal isn't required and their are several mechanics out their who figured out that you can get it done in 4 hours without dropping the engine.

The Camry is a fairly light car for its size and the gearing isn't exactly the type thats going to require a lot of slippage in first. Maybe the typical Camry driver just sucks with clutch work. Perhaps they could not get accustomed to the fuel delivery.

meanwhile, some owners claim close 200K on original clutch.

 

[NutBucket]

The problem is the Camry has zero clutch feel. But of course my folks got one that's even worse to replace their Camry!

Want to know what a proper clutch/shifter should feel like? Drive a Honda. Nobody else is close for a comparable price/vehicle.

Oh yeah, as for the original question. Typically I won't downshift unless I'm anticipating not coming to a stop. That is, if a light is ready to turn green or traffic is just slowing ahead. Although with the hybrid it wants you to downshift for max regen.

 

[kitatech]

Paul/Nut:
I'm gonna go with ineptitude as the cause of clutch failure...okay, maybe just minimal competence....true, the Camry clutch has ZERO feel, so one has to learn to shift based on peddle DISTANCE and engine impact to judge the proper rpms for shifting...once having done that, the Camry's shifting is smooth as silk...

As for cost of replacement...the salesman told me as I pulled out from the lot on the test drive that it was a new clutch replaced at a cost of $2400...that seemed high but it did include the master and slave cylinders as well as the accumulator...but even that would be a $1200-1400 job at an indie shop, so the $1000 would amount to 10 additional "book" hours...
[it was nice to hear that "cost" as it gave me an idea of how much the dealer likely deducted from the trade, and an idea how low I can without lowballing the buy...and indeed it saved me $1000 off their lowest advertised price.]

As for downshifting...I don't until nearly stopped...around town, third gear has enough engine braking from 40 to 15, 2nd from 20 to 0+ (just barely rolling)...that, just cruising to a stop saves BOTH clutch AND brakes.

 

[skyking]

with the diesels, I do 5-4-3 down to 15 or so, kick it in neutral and brake to a stop that is inevitable. If there is a chance I'll get to roll it, I get second. I can roll from almost stopped in second, thanks to the torque.
My big beef when teaching clutch operation is riding the clutch. I'd rather have somebody stab the clutch, select neutral and GET THE FOOT BACK on the floor, rather than dink around with foot on pedal.
I'm not concerned about the throwout bearing, more about bad habits like hill holding with the expensive parts. I worked with a guy who did that while I was in the truck. GAH!
Ironically I just sold that truck, I had purchased it from my former employer. They had paid me to replace that clutch

 

[master_shake_]

down shifting was a great idea back before power disc brakes, when cars had all brake drums you'd get alot of brake fade.

now that we have power disc brakes down shifting is unneeded. blocker rings are made out of brass and get upset when you use them to stop your car.

 

[pauldun170]

Paul/Nut:
I'm gonna go with ineptitude as the cause of clutch failure...okay, maybe just minimal competence....true, the Camry clutch has ZERO feel, so one has to learn to shift based on peddle DISTANCE and engine impact to judge the proper rpms for shifting...once having done that, the Camry's shifting is smooth as silk...

As for cost of replacement...the salesman told me as I pulled out from the lot on the test drive that it was a new clutch replaced at a cost of $2400...that seemed high but it did include the master and slave cylinders as well as the accumulator...but even that would be a $1200-1400 job at an indie shop, so the $1000 would amount to 10 additional "book" hours...
[it was nice to hear that "cost" as it gave me an idea of how much the dealer likely deducted from the trade, and an idea how low I can without lowballing the buy...and indeed it saved me $1000 off their lowest advertised price.]

As for downshifting...I don't until nearly stopped...around town, third gear has enough engine braking from 40 to 15, 2nd from 20 to 0+ (just barely rolling)...that, just cruising to a stop saves BOTH clutch AND brakes.

If my clutch goes, knowing the 2.4s rep for stripped head bolts I'd probably just get a car I really want rather dump that amount of cash into a clutch job.
I bought my Camry for station car duty. 2400 bucks buys me another station car.
My car is 12 years old and I'm ready for my midlife crisis mobile

 

[kitatech]

If my clutch goes, knowing the 2.4s rep for stripped head bolts I'd probably just get a car I really want rather dump that amount of cash into a clutch job.
I bought my Camry for station car duty. 2400 bucks buys me another station car.
My car is 12 years old and I'm ready for my midlife crisis mobile

Yeah, $2400 is a chunk of good money thrown at bad...which is why the previous owner of my Camry traded up...this AND the fact that the 1st clutch was replaced and botched, so my Camry is on its THIRD clutch....still....
Assuming the job was done correctly by a competent indie, it would be a much more reasonable $1200 or so....about what many other major (10 years' of use) components cost to replace, e.g. A/C, struts...

....and as for that history of headbolt failure....well, the only history I've ever been concerned about when deciding whether to throw money into my cars is the history of MY ride....with fingers crossed...always...