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 Post subject: Skip Shifting
PostPosted: Thu Jun 09, 2011 6:59 pm 
Junior Standardshifter

Joined: Tue Apr 05, 2011 10:03 pm
Posts: 59
Cars: 2011 Mazda2
Is it ok to skip shift? I skip 3rd in my car all the time, because 2nd gets me to a good crusing speed in town for 4th gear. No need for 3rd.
I found 2 opposing points of view though: a bulletin below from Honda which says it's bad, and a 2011 forum discussing mustangs that have an automatic skip-shift feature on their manual trans cars, so they can't possibly think it's bad since they built it into the car.

This is from the January 2006 Honda ServiceNews:
"Skip Shifting Is Brutal on Synchronizers"

Gear ratios in 6-speed manual trannies are spaced
close together so you can keep the engine speed
in its optimum range for max power and
acceleration. Shifting to the next higher or lower
gear in a close-ratio tranny causes small changes
in engine speed.
Shifting a close-ratio tranny through its gears by
the numbers puts a very small load on the
synchronizers since they only have to make small
changes to the speed of the mainshaft and the
clutch disc.
Some drivers, though, like to skip shift so they
don’t have to work the clutch pedal and shift lever
as much. They like to accelerate in 1st gear, then
pop it into 3rd gear, then into 5th or 6th. Skip
shifting, though, is really brutal on synchronizers;
it puts a higher demand on them than they were
designed to take. Skip shifting can cause
premature synchronizer wear that can cause the
gears to grind when you shift up or down.
If you’ve got a vehicle in your shop for repeated
damage to the synchronizers, go for a test-drive
with your service customer to see if he or she is
guilty of skip shifting. If that’s the case, remind
him or her skip shifting can be an expensive habit
to break. Any repairs due to skip shifting may be
reviewed and debited by your DPSM."

From the Mustang forum:Quote:
Originally Posted by jbsixer
not to sound clueless, but i am...whats skip shift?

If, while driving a manual, you're below a certain RPM (not sure of the number) the car will force you to shift from 1st directly to 4th rather than a normal 1, 2, 3, 4. Can be quite annoying for those who don't like to get on the throttle after every stop.

Also on a Camaro:Q: What does the skip shift do on a manual 99 camaro z28?

A: It locks out second gear so you shift from first to third gear. It was supposed to save fuel and give you better gas mileage. If you are driving ‘easy’ on the gas pedal, it will light up on the dash with ’skip shift’ and then lock out second gear. It can be frustrating if you don’t realize it.

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 Post subject: Re: Skip Shifting
PostPosted: Thu Jun 09, 2011 7:55 pm 
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Joined: Tue Apr 05, 2011 10:03 pm
Posts: 59
Cars: 2011 Mazda2
I think that Honda document was in regards to the S2000 which revs to 9000 rpm, so maybe for a car which isn't so extreme it's not a big deal.
Here's another post I found explaining the S2000 problems he has seen:
I am the woodwork and I work for American Honda.
I am writing this to hopefully help S2000 owner/drivers understand the importance of shifting properly to minimize the damage to 2nd gear synchronizer rings. I'm not the Warranty Police but will from time to time quote warranty policy when I read things like "Shifting without the clutch".

My overall objective being in the woodwork is to keep S2000 owners from hurting themselves and hurting their cars. Everytime a transmission or engine gets replaced in an S2000 I get the part. I've seen a lot of damaged transmissions.

Before flaming me please read this and keep an open mind.

You have an engine that revs to 9000 RPM. That means that the transmission mainshaft and clutch disk are also revving to 9000 RPM. When you disengage the clutch (push in the pedal) to shift from first to second the engine and the transmission are disconnected. The engine will slow down from compression when you lift off the throttle. The mainshaft of the transmission is not connected to the engine any more so it is freewheeling in the transmission. Given enough time the mainshaft will slow down but not as fast as the engine. The countershaft is connected to the rear wheels and the speed stays constant during the shift.

When you shift into 2nd gear the synchronizer of the 2nd gear must SLOW DOWN the transmission mainshaft to match the speed that the engine WILL be going when the shift is completed and the clutch is engaged.

The transmission mainshaft and the clutch disk together weigh 19.75 lbs. (not including the pressure plate and flywheel that are connected to the engine) When you shift from 1st to 2nd at 9000 RPM the engine speed drops to 5900. That means that the little brass synchronizer rings have to push on the 2nd gear to slow the mainshaft from 9000RPM to 5900 RPM. It not only has to slow down the mainshaft it has to do it in the time that it takes you to shift. So if you have a tendency to shift fast you may be making the sleeve blow past the synchro rings before it has a chance to do it's job and it will smash into the 2nd gear.

The early '00 cars needed a little change to the sleeve to make the synchros work a little harder. That is what the new parts in the service bulletin are for. Cars after VIN YT006255 already have the new parts. Grinding in a car produced later than 6255 is possible if the synchros have been damaged and now are not able to slow down the mainshaft properly.

Shifting without the clutch, or, shift too quickly and not letting the synchros do their job may permanently damage the gear, sleeve and synchros and make the 2nd gear grind more often.

It makes sense that if shifting at 6000 makes the engine speed drop to 4300 RPM, (1700) into 2nd gear then you should give the 2nd gear synchro twice the time to do the shift from 9000 RPM.

If your car does grind once in a while you may not want the transmission removed, disassembled and a new 2nd gear put in. If it does it quite often, show it to the dealer and have it replaced.

If you hesitate for another 1/2 second while putting constant pressure on the shifter while the 2nd gear synchro does it's job, I'll bet many of your cars would not grind any more. Try it. You might like it.

Added 5-2-03:
Skipping gears:

I have seen many 6th gear sleeves that have been damaged.

The typical story is this: Stop light, 1st gear, engage the clutch, rev to 9,000 RPM, shift quickly to 2nd, rev to 9,000 RPM, same into 3rd, look down and find the car going 80 MPH on a city street and the engine noise is screaming, recognize that any cop is going to write a ticket. Shift to 6th quickly to lower engine noise.

Dragging the mainshaft speed down from 9,000 RPM to 4,000 when going from 3rd to 6th takes time. 6th gear has only a single synchro ring and it doesn't like it. It will grind if you are shifting hard and fast. By shifting hard the synchro ring does not have time to slow down the main-shaft and the sleeve will slip over the synchro and grind the gear. If the sleeve is ground enough in 6th then it will not slide the other way to engage 5th.

So if it is hard to get your car into 5th or 6th it may be because the sleeve is being damaged by skipping gears. Hope this makes sense.

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 Post subject: Re: Skip Shifting
PostPosted: Thu Jun 09, 2011 9:46 pm 
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Joined: Sat Jan 16, 2010 12:46 pm
Posts: 254
Location: Beijing, China
Cars: Peugeot 307 2L
yeah, if you skip shift, you can DC to ease it on the synchros.


Last edited by Reverence on Thu Jun 09, 2011 10:10 pm, edited 1 time in total.

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 Post subject: Re: Skip Shifting
PostPosted: Thu Jun 09, 2011 10:02 pm 
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It's no different than skipping gears for a downshift, except that you might do it much more often. As the others say, double-clutching will certainly eliminate any question about abuse of the synchros.

IIRC the S2000's transmission is prone to premature failure or bad synchros or something, requiring extra care.

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 Post subject: Re: Skip Shifting
PostPosted: Thu Jun 09, 2011 10:16 pm 
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For an upshift, waiting a second or two in neutral before completing the shift should be as good as a DC. If the shifter goes in smoothly with little effort, you nailed it.


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 Post subject: Re: Skip Shifting
PostPosted: Thu Jun 09, 2011 10:31 pm 
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They teach skip shifting in our driving schools as a fuel-saving measure. As paul34 said, take it easy. You're probably skipping a gear or two after you've finished accelerating, so there's no hurry to the next gear.

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 Post subject: Re: Skip Shifting
PostPosted: Fri Jun 10, 2011 8:07 am 
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Skip-shifting definitely puts more wear on the synchros (I thought this was common knowledge among manual trans drivers) than shifting in normal sequence. If a car has a skip-shift feature built in, it is 100% for fuel economy reasons. In most cases, the manufacturer is trying to avoid gas guzzler status (and tax), so they put a skip-shift feature in the car to bring up the fuel economy rating a little bit over the gas guzzler threshold. And of course this also helps keep the manufacturer's CAFE up. Still though, the synchros are definitely working harder when you skip shift. It's basically a trade-off....greater fuel economy for increased synchro wear.

One other thing--I don't know if this is true or not, but manufacturers may specify stronger synchronizers in vehicles that are designed with a skip-shift feature. Probably not, but I'm not sure either way.

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Last edited by Shadow on Fri Jun 10, 2011 8:30 am, edited 1 time in total.

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 Post subject: Re: Skip Shifting
PostPosted: Fri Jun 10, 2011 8:17 am 
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Found this info on an S2000 forum....it's an interesting read:

A Honda engineer indicates the problem with skipping gears is the same as shifting from first to second very fast and making it grind. There are Double cone synchros in 1, 3, 4 and a single cone synchros in 5, 6, R plus a triple cone in 2nd. If you shift quickly from first to second and you don't give the 2nd gear synchro time to slow down and the 19 pound main shaft to match the next engine speed, then you will grind the sleeve as it contacts 2nd gear. All you need is constant pressure and ½ second on 2nd gear. If you put too much force you don't give the synchro time to slow down the main shaft before the sleeve hits the gear. The same is true for skipping gears. Honda does not recommend it but if you are going to do it any way you just have to give a little more time for the synchro to do its job. Double clutching on an up shift is good, if it is done correctly it will slow down the main shaft. It probably takes as long to double clutch as it does to just wait for a half second and let the synchro do its job. Beware if you like to skip 5th Gear: Pointy is good, Mushroomed is bad when it comes to the syncros. The usual customer complaint is that the transmission won't go into 5th gear. In the 5-6 shift sleeve, when it slides one way, the transmission is in 5th gear. When it slides the other way it is in 6th gear. The cause is driving the car high RPM in 1st, shift into 2nd, then high rpm into 3rd. At this time the engine is screaming it's song and the driver usually feels the need to bring the engine RPM down so he (she) shifts into 6th gear and drops the RPM 3 or 4,000. The problem is that 6th gear synchro isn't made to work that hard. (What is 5 to 6 RPM change? About 800 RPM? When that happens the sleeve slides past the synchro that is over worked and grinds into 6th gear. This will mushroom the "Dogs" on the 6th gear and on the sleeve. When the clearance between the sleeve and the hub that it rides on is small enough then the sleeve won't slip backwards into 5th. More comments on why not to skip gears: This tranny is designed differently than most trannies. Two things were done in the design to "ensure an exhilarating and quick shifting performance that meets the drivers spirited operation". (1) Normal manual transmissions have a gear reduction prior to transmitting the power to the gear selection, thus reducing the rotational speed of the gears and shafts and synchros. The S2000 transmission has the gear reduction after the gear selection. Thus the gears and shafts and synchros have a higher rotational speed. So skipping gears will be harder on the synchros of this transmission than most. (2) The S2000 transmission was designed to keep the number of number of synchro cones to a minimum. "It is impossible to ensure gear-shift exhilaration only by increasing the synchronizer capacity through the use of a multi-cone, because the shift knob load is not reduced to a satisfactory level". The engineering of this transmission put a higher emphasis on exhilarating feel and quick performance rather than making it bulletproof (and I'm glad they did). Quotes are from SAE (Society of Automotive Engineers) Technical Notes "Development of a new six-speed manual transmission", by K. Kitajima, Engineering Development Department 4, Honda R&D.

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 Post subject: Re: Skip Shifting
PostPosted: Fri Jun 10, 2011 10:49 am 
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While the synchros might wear faster in skip shifting, do they wear out because of that especially if you're not skip shifting aggressively? After all, most cars never need synchro replacement...

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 Post subject: Re: Skip Shifting
PostPosted: Fri Jun 10, 2011 11:04 am 
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When you skip a gear and let the next gear's synchro do all that work, and therefore put more wear on that synchro, you also put less wear on the skipped gear's synchro. Here's a thought: If you alternate which gears you skip, does that completely even out the wear difference?

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 Post subject: Re: Skip Shifting
PostPosted: Fri Jun 10, 2011 11:22 am 
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theholycow wrote:
When you skip a gear and let the next gear's synchro do all that work, and therefore put more wear on that synchro, you also put less wear on the skipped gear's synchro. Here's a thought: If you alternate which gears you skip, does that completely even out the wear difference?


Hmm...never thought about that. Seems logical to me.

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 Post subject: Re: Skip Shifting
PostPosted: Fri Jun 10, 2011 12:02 pm 
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I sometimes skip-shift, but to minimize wear, I either double-clutch, or I shift through the gears sequentially while holding the clutch down until I reach the desired gear. An example of the latter, let's say I'm just putting along in city streets, and want to shift from 2nd to 4th: I step on the clutch and hold it there, move the stick from 2nd > 3rd > 4th, release clutch. That way, I am still skip-shifting as far as the engine, clutch, and wheels are concerned, but spread out the synchro wear.

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 Post subject: Re: Skip Shifting
PostPosted: Fri Jun 10, 2011 12:12 pm 
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That's really clever, six! I wouldn't have thought to do that.

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 Post subject: Re: Skip Shifting
PostPosted: Fri Jun 10, 2011 10:03 pm 
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Shadow wrote:
theholycow wrote:
When you skip a gear and let the next gear's synchro do all that work, and therefore put more wear on that synchro, you also put less wear on the skipped gear's synchro. Here's a thought: If you alternate which gears you skip, does that completely even out the wear difference?


Hmm...never thought about that. Seems logical to me.

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 Post subject: Re: Skip Shifting
PostPosted: Fri Jul 15, 2011 8:50 pm 
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I know that the last post in this thread is a month old, but I'm curious about which is better for fuel economy: skip shifting or short shifting? As most of you know, I am still very new to driving a manual and want to make sure it lasts as long as possible, but I also want to maximize fuel economy as much as possible. I have not mastered any of the skills you, more experienced drivers, discuss in order to prevent undue wear on the synchros and the clutch plate, and have to drive accordingly. I know my dad was surprised when I drove with him last and was shifting at 2500rpm. He said to me to listen to the engine and shift with the sound of the engine and that I was "shifting too soon." He also couldn't believe that I was using all 6 gears in the city.

I apologize if I ask too many dumb questions.

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