FAQ 2.0! <- New Members Read First

Synchros shot? Weird noises while shifting? Not sure what needs to be replaced?
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jomotopia
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Postby jomotopia » Mon Jul 17, 2006 11:50 am

How do I move the shifter from one gear to another?

Author - jomotopia
Submitted by - jomotopia


Examples for a 6 speed, left hand drive car:

Upshifts:
1-2: Pull straight down with a little pressure towards you
2-3: Push straight up, no horizontal pressure, the stick will center itself, straight up into 3rd
3-4: Pull straight down, no horizontal pressure
4-5: Up, right, up
5-6: Straight down with a little pressure away

Downshifts:
6-5: Straight up with a little pressure away
5-4: Down, no horizontal pressure so it centers itself, straight down
4-3: Straight up, no horizontal pressure
3-2: Down, towards you, down
2-1: If you must, straight up with a little pressure towards you
2013 Subaru Impreza WRX in Orange

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Postby Johnf514 » Tue Jul 18, 2006 9:52 am

Double Clutching

Author = Johnf514
Submitted = Johnf514

Double clutching is a technique used most commonly on big rigs and manual transmissions without syncros. When you double clutch, you allow the transmission speed to sync up to the engine speed, which is what syncromesh gears do in most stick passenger vehicles.

Here's the process:

Situation - in 4th at 45 MPH at 2200 RPMs, downshifting to 2nd

1. Clutch in and hold
2. Shift into neutral
3. Clutch out
4. Rev to roughly 4400 RPMs
5. Clutch in
6. Shift into 2nd
7. Clutch out

Double clutching can also be used for upshifting, and therefore may not require the rev-match in step 4 if completed in a timely manner.
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Postby jomotopia » Tue Jul 18, 2006 11:27 pm

Slipping the clutch is bad, right?

Author - jomotopia
Submitted by - jomotopia


Nope! :D The clutch is designed to slip. That is its purpose, and slipping the clutch is required for starting from a stop in 1st and reverse. The clutch smooths things out and reduces shocks through the rest of the drivetrain.

Any time the clutch is not fully engaged or disengaged when the car is running, it is slipping against the flywheel. As the clutch comes up and reaches the friction point it begins touching the flywheel, and they are spinning at different speeds. They must sync up and during this time the clutch is slipping. When it is slipping it is wearing. The clutch is designed for this purpose and it is designed to wear. But excessive and unnecessary slipping will reduce clutch life. Longer slips of the clutch and higher rpms produce more clutch wear.

It seems to be a general consensus on this forum that people worry about their clutch more than they need to.
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Postby jomotopia » Wed Jul 26, 2006 9:13 pm

Detailed explanation of clutch release.
And why you don't need it

Author - Prodigal Son
Submitted by - jomotopia

Prodigal Son wrote:The reason that your mother can still do it after 15 years, and can't explain how she does it, is muscle memory, which is a way of saying that the knowledge of how to do physical tasks (walking, shifting, releasing the clutch) gets transferred from the conscious mind to the cerebellum, which is the bit at the back of your brain that is responsible for all the things you do without thinking about them. The cerebellum never forgets. But it is not part of your conscious brain, so it can't express what it knows in words.

Now, why are you continuing to have problems? In a nutshell, your conscious mind is not letting go. You are thinking about it to much. The only way I know to help you with that is to really give you something to think about. So pull up a chair and get comfy and let's review every stage of the release of the clutch pedal, starting from when it is pressed all the way to the floor and moving all the way through until it is full engaged and your foot is fully off the pedal.

Stage 1: Full disengagement to the friction point
As you begin to bring up your foot, you release a spring that pushes the clutch plate toward the flywheel. The point as which they first touch is called the friction point. The friction point is always at the same place in your car, no matter what gear you are in or how fast the engine in revving. (It may change slightly over time as the clutch wears, but too slowly to notice.) Not a lot happens at the friction point. You may hear a slight drop in the engine note. You may see a slight dip in the tach. You may feel a slight vibration in the clutch pedal. However. the car will not move.

Why does the car not move? Because there is not yet enough friction between the clutch and the flywheel to transfer enough torque to the wheels to overcome the inertia of the car.

You can complete step one as fast as you like as long as you do not overshoot the friction point. Once you learn where the friction point is, this step will be virtually instantaneous.

Step 2: Friction point to catch point
As you continue to release the pedal, the pressure between the clutch and the flywheel increases until the friction is great enough to transfer enough torque to the wheels to overcome the inertia of the car. The car then starts to move.

So, where is the catch point? It depends. The catch point is the point at which enough torque is being transferred to move the car. Where that is depends on a lot of things. If you are on a hill, more torque will be needed to move the car than on flat ground. If you have four people in the car, more torque will be needed than if you were alone. On the other hand, the amount of torque available at the flywheel depends on how high you rev the engine. So, the location of the catch point is different every time depending on the weight of the car and the speed of the engine.

This means that you can't learn where the catch point is. You have to feel for it. Because the amount of gas you give changes the catch point, you can also move the catch point forward and back with the gas pedal.

You can't go too fast through this step because, although the car is not moving, you are feeling for the catch point. Over time you will get better at feeling it and you will be able to find it faster.

Step 3: Catch point to sync point
When the car starts moving, the clutch is still not fully engaged and is still slipping against the flywheel. You have to keep letting the clutch out until the you reach the sync point, where clutch and flywheel are travelling at the same speed. As you do so, the amount of torque being transferred from the flywheel to the clutch increases, which means that the car accelerates. Just as with the catch point, you can change were the sync point is with the gas pedal. If you give more gas, the sync point will move outwards and the clutch will slip longer. If you let off the gas (or if you move the clutch too quickly, the clutch may sync up abruptly) causing a bump.

The sync point is also to a certain extent a function of time. If you hold the clutch above the catch point, the clutch and the flywheel may be able to sync up over time without you advancing the clutch. Not recommended, but the point is that the syncing of the clutch and the flywheel depends on time, pressure, resistance, and force. Things sync up when these things even out.

This also means that you can control the amount of acceleration you are getting by manipulating the clutch between the catch point and the sync point. This is often done to control speed while reversing.

This step must be done at a moderate speed if you want the clutch and flywheel to sync up smoothly without jerking. This can actually be done very quickly once you get the feel for it, but it has to be done more slowly while you are learning. Like finding the catch point, this is done by feel, and by a balance between the gas pedal and the clutch pedal.

Step 4: Sync point to full engagement
Once you pass the sync point you can move to full engagement with your foot completely off the clutch. You can do this as fast as you like, since the clutch is already in sync with the flywheel. However, since you have to feel your way to the sync point, and the sync point moves depending on a bunch of variables, you can't simply learn one position where you can jump off the clutch. Once the clutch is in sync, you can jump off the pedal. Learn to feel for the sync point and then release the pedal.

So, what is the point of telling you all this? It is to show you just how complex it is so that you will accept that you can't think your way through the engagement of the clutch. You have to feel it. It's like walking over rough ground. No two steps are exactly the same, and if you think about what you are doing you are likely to fall flat on your face. But leave the job to the cerebellum, and you can walk over uneven ground without even thinking about what your feet are doing. Feel it, don't think it.

So, forget all that stuff, and all the other stuff people have been telling you and just do this: Release the clutch until you feel the car start to move, then use the clutch and the gas to accelerate smoothly until you feel everything hook up. Then get off the clutch.

That's it. Pretty soon your cerebellum will take over for you and it will all just be natural and will seem like a single quick motion.
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Commonly Used Acronymns

Postby jomotopia » Tue Aug 01, 2006 12:58 pm

i thought i'd start this list. everyone please add to it.

WOT - Wide Open Throttle
SC - Single Clutch
DC - Double Clutch
HT - Heel Toe
DCHT - Double Clutch Heel Toe
SCHT - Single Clutch Heel Toe
PSI - Pounds per Square Inch - referring to air pressure of boost from a turbo or supercharger, or air pressure in the tires
NA - Normally Aspirated
FI - Forced Induction, or sometimes Fuel Injected
EFI - Electronic Fuel Injection
DBW - Drive By Wire
ETC - Electronic Throttle Control
CEL - Check Engine Light
ECU - Engine Control Unit - the car's computer that controls everything

OP - Original Post or Original Poster
IANAL - I am not a lawyer
FTL - For The Loss

and i just have to put this one ;)

STi - Subaru Tecnica International
Last edited by jomotopia on Wed Aug 23, 2006 8:59 pm, edited 7 times in total.
2013 Subaru Impreza WRX in Orange

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Postby papyrus » Tue Aug 01, 2006 1:06 pm

FP - friction point
OT - off topic
from now on, we'll take 'here' to mean 'here i am, rock you like a hurricane.' mooninites ftw!

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six
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Postby six » Tue Aug 01, 2006 1:08 pm

NOT - Normal Operating Temperature
ATX - Automatic Transmission
(4,5,6)MTX - (4,5, or 6 speed) Manual Transmission
CAI - Cold Air Intake
SRI - Short Ram Intake
BOV - Blow Off Valve
BPV - Bypass Valve


Others (non-car related Internet terms for forum newcomers):

AFAIK - As Far As I Know
FWIW - For What It's Worth
IM(H)O - In My (Humble) Opinion
IIRC - If I Recall or Remember Correctly
NT - Note Topic or No Text
NM - Nevermind
FTW - For The Win
WTF - What The F***?
OM(F)G - Oh My (F'ing) God
LOL - Laughing Out Loud
BTW - By The Way
(ROF)LM(F)AO - (Rolling On the Floor) Laughing My (F'ing) Ass Off
ROFL - Variation of above
+1 - I agree
PM - Private Message
Last edited by six on Tue Aug 01, 2006 1:38 pm, edited 4 times in total.
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Postby chrono » Tue Aug 01, 2006 1:28 pm

TDI - Turbo Diesel Intercooler
FWD/RWD - Forward/Rear-wheel drive
4WD/AWD - Four/All-wheel drive
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Postby YetAnotherRocky » Thu Aug 03, 2006 3:12 pm

I ANAL?

Sorry. Teenage perversions.

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Postby Coupe31705 » Thu Aug 10, 2006 2:07 pm

GTO-Grand Turismo Omologato
Wanna give me insurance $$$?

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Postby screenname » Thu Aug 10, 2006 2:40 pm

Coupe31705 wrote:GTO-Grand Turismo Omologato


I wonder what Paolo300ZX is going to say about this...

Hey Paolo! Is he referring to the Ferrari, Pontiac, or Mitsubishi? (Don't answer that, Coupe31705.)

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Postby Paolo300zx » Thu Aug 10, 2006 4:13 pm

DIY - do it your self

BMSN - BITE ME SCREENNAME :twisted:

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Postby screenname » Thu Aug 10, 2006 4:15 pm

Paolo300zx wrote:DIY - do it your self

BMSN - BITE ME SCREENNAME :twisted:


The Stig's fingernails have 30 more horsepower than your car.

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Postby Coupe31705 » Thu Aug 10, 2006 4:20 pm

TTAMML-These two always make me laugh
Wanna give me insurance $$$?

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Postby jomotopia » Thu Aug 10, 2006 4:28 pm

let's try not to spam up this thread too much ;)

TTIWWOP - This Thread Is Worthless Without Pics
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