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Synchros shot? Weird noises while shifting? Not sure what needs to be replaced?
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Postby Tiamat » Wed Oct 04, 2006 7:09 pm

PSIG - pounds per squar inch, gauge (meaning that the reading is relative to atmospheric pressure) Most of the readings you'll see here are PSIG, I'm just mentioning this for accuracy.
PSIA - PSI, absolute (this one is relative to zero)
NOX - any of various pollutants with the chemical representation NxOx (those x's would be subscripted if I could)
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Postby jomotopia » Fri Oct 06, 2006 10:27 am

What to do in an Emergency Stop

Authored by: SteveUK, Prodigal Son
Submitted by: jomotopia


SteveUK wrote:Emergency Stop with ABS.
Press the brake as hard as you can and keep your foot on it.
Both hands on the wheel.
Foot on clutch at last possible moment to prevent a stall.

With this way you get the full ability from your brakes, plus some passive engine braking. You will be able to steer around obsticles.

Emergecy Stop without ABS.
Press the brake as hard as you can.
When you feel the wheels locking up, release then instantly back down on the brake. Repeat until the wheels no longer lock.
Both hands on the wheel.
Foot on the clutch at the last possible moment to prevent a stall.

You will have less control during steering becuase you cannot "pump" the brakes as quickly as the ABS system can.

Thing you must not do
NEVER change down (downshift) in an emergency stop. You are not in full control of your car when you need to be in the most control you can be.

I have 12 years of manual driving experince, plus my racing licence, my advance driving licence and my pursuit driving licence. I have to have a formal 2 week requalification every 12 months and a at least 4 refresher days in that 12 months.

There is a link in another topic (Link Added) about the UK driving advice. In that there is an emergency stop. Yes, it is for the test, however, this is one move that you will always do the same whether it is in your driving test or not. Driving on a race track is completely different to driving on a public road.

I am in far more danger in my job than when I am on a race track. I have to take in to account other motorists, pedestrians and other things also. I drive at my limit, but NEVER past it. I don't want to kill someone or more importantly me! The average driver (so 99% of those here) should do the following.

ABS - Stomp and Steer
No ABS - Pump and Steer


Prodigal Son wrote:Unnecessary elaboration will get you killed. Modern brakes are very good. In an emergency, keep it simple: brake and steer.
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Postby Nychold » Mon Nov 13, 2006 3:33 pm

OBD(I,II) -- On-Board Diagnostics

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Postby jomotopia » Tue Nov 14, 2006 8:20 pm

Brakes - what you use to slow down your car.

Breaks - what a twig does when you bend it too far.
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Postby JackBauer » Tue Nov 21, 2006 5:19 pm

ECU: Electronic control unit
ECM: Electronic control managment
TPS: throttle positioning sensor
TB: throttle body
HB: harmonic balancer

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Postby Brass » Wed Jan 10, 2007 2:14 am

DP Dot Point.............................................................As in what I'm doing now.
^^^ Also stands for "Double Post"- the same user posts 2 replys in a row in one topic. Frowned upon in some forums.
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Postby jomotopia » Fri Feb 02, 2007 11:20 am

Does revving my engine up hurt it?

Authored by: jomotopia
Submitted by: jomotopia


No. It doesn't. Your engine is designed to operate in any range below redline. As long as your car is well maintained (keeping up with oil changes, not running low on oil or coolant, etc) revving your engine up will not hurt it. It will burn more gas, and will put a minimal amount of added wear on the engine, but this wear will be negligible in the grand scheme of things.

Even if you rev past the redline, you will hit the rev limiter. The rev limiter is designed to prevent engine damage from revving too high. So even hitting the rev limiter will not hurt your engine, just don't go bouncing off of it repeatedly.

The only thing that is really worth worrying about as far as actually damaging the engine is a forced mechanical over-rev by shifting into too low of a gear for your current speed. In this case the rev limiter can not help you.
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Postby jomotopia » Fri Feb 09, 2007 6:03 pm

How do I know if my clutch is worn out/nearing replacement?

You may notice the engagement point moving higher in the clutch pedal travel as the clutch wears out. But until the clutch is actually slipping when fully engaged, you don't need to replace it.

There are a couple of tests you can do to determine if your clutch is worn to the point of needing replacement:

1> Get moving and put the car in 3rd gear or higher and low rpms, where you normally do not have enough power to accelerate quickly. Floor the gas. If the revs shoot up but the car doesn't go, you need a new clutch. If the engine bogs and the revs raise relative to the car's acceleration, your clutch is fine.

2> From a stop, put the car in 3rd gear or higher and drop the clutch. If the car doesn't stall, you need a new a clutch.

scionkid wrote:Go to a freeway on ramp doing about 10 mph. Have the car in 3rd and floor it until it reaches maximum speed in that gear. If the clutch slips, you'll hear the engine noise go up unproportionally to vehicle speed. If that happens, start saving up some money for a new clutch.

I don't agree with the 5th gear clutch drop because the engine may not be making enought torque for a bad clutch to slip. But you won't know the clutch is, indeed bad, until you go up a steep hill with no power to go up and no room to hang a U turn.
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Postby jomotopia » Sat Feb 10, 2007 3:11 pm

Full throttle and short shifting for fuel economy

Authored by: scionkid, Standardshifter, Prodigal Son, Johnf514
Submitted by: jomotopia


scionkid wrote:Generally, the less power you use to accelerate, the more fuel you'll save. There are 2 ways to limit the engine's power output. The universal way is to tread lightly on the throttle and this limits the amount of air an engine can aspirate. The 2nd way is to use a high gear and WOT. Since the high gear limits engine speed, this limits the number of air intake.

The theory is that WOT is somewhat more efficient because the engine doesn't have to burn extra fuel to suck in air through a small throttle opening. However, it burns more fuel per engine revolution, which means more heat is transfered to the cooling system, and you need to keep an eye out for the temperature gauge.

I can see my mileage go from 31 to 33 using the short shifting and WOT technique. And I don't go WOT during shifts. I ease off the throttle, double clutch the shift, let the clutch completely out, then go deep on the throttle. Even when I go WOT, there's not much power going through the transmission because the engine speed is quite low.


Standardshifter wrote:Ideally, WOT and short shifting will give best mileage. Most cars switch to set fuel tables that usually are a bit richer than the feedback loop model at part-throttle, so real-world mileage might not reflect the savings.


Prodigal Son wrote:Yes, it's an interesting theory, but as you say, not necessarilly applicable in practice. There are all sorts of factors that make it a less than practical or economical practice in the real world. Like for instance, traffic. And then there is the considereation of what happens if you try to go WOT in first. Burn-outs are not necessarilly efficient. And how do you shift in a smooth and equipment-preserving way at WOT? If you blend the throttle in and out to achieve a smooth shift, there goes your WOT. If you bang the shifter through the gates to get a quick shift, there go the synchros. The stuff you are wearing out (and potentially breaking) will probably cost more than the gas you are saving.

The thing is, when it comes to optimization, you have to look at the system as a whole. You do not optimize a system by optimizing the individual components of the system. You have to look at it as a whole and configure each component in a way that contributes to the optimal performance of the system as a whole under real world conditions. This frequently means that the individual component is not optimized for its own most efficient operation.

Not only does economical driving require a systems approach to optimization, economy is also part of a broader systems calculation that factors in safety, comfort, convenience, and time along with economy in the design of both cars and roads.


Johnf514 wrote:Some folks promote WOT short-shifting, which essentially consists of using full throttle and shifting very quickly at low(er) RPMs. In theory, this is a great idea, as it minimizes or negates any pumping losses or inefficiencies that come from accelerating. However, it is absolutely impractical and nearly impossible in everyday driving, and most things don't as work well in reality as they do in theory. Instead, I recommend accelerating slowly and shifting early. Usually between 2000-2500 RPMs will yield good MPG.
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Postby Johnf514 » Tue Feb 13, 2007 10:45 am

How do higher RPMs affect engine output and wear?

Written by: mdocod
Submitted by: Johnf514


RPMs do not translate *directly* to wear. overall work load does. Work load includes the work required just to turn over the engine. (an engine idling, is a work load, but it is a very small work load)...

Best thing I can do to explain this... is to give an example:
Lets say you are pulling a long steady hill. At 45MPH the engine may be capable of chugging along in 5th gear (throttle wide open) at lets say 2000RPM. The car is able to maintain a steady pace but you are loading every stroke of the engine with as much air and fuel as it is designed to take, this produces powerful combustion strokes that transfer a lot of force to the crank per revolution. The engine is turning slowly so the number of strokes is less. In contrast, you could down-shift to 4th and pull the same hill at the same speed around 2400RPM.... but now you can ease back on the throttle because the engine does not need to load every stroke of the engine to the max to do the same amount of work. More strokes means each stroke can do less work but add up to the same total work as was being accomplished beforehand. The strokes in this state are gentler, they are not pressing as hard on the crank.

So... if all things were created equally- it could be said that in either case, the engine wear would be almost exactly the same. But the reality is that some engines have different "sweet spots" than others. Some engines have very specific "power bands" that should be used when pulling a hill or accelerating because they will deliver the best power for the least fuel used and do so with minimal engine wear. Large over-the-road trucks with massive diesel engines that can produce insane torque(over 1000lb/ft), will benefit from the selection of a lower gear to pull a hill (1600rpm with less throttle compared to 1400rpm wide open throttle) spinning that engine slightly faster, but reducing the force on the crank and associated bearings is much better for that type of engine. (keep in mind redline on many of those engines is 1800-2200rpm depending on the engine)
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Postby areben » Fri Apr 13, 2007 5:32 pm

Yes, JDM is Japanese Domestic Market

HFP - Honda Factory Performance (sigh...)
VTEC - Variable Timing and Lift Electronically Controlled
i-VTEC - Same as above + cam phasing
IMHO IANAL - In my honest opinion I am not a lawyer. (already said but I like putting them together)
CBU - Completely Built Up
CKD - Completely Knocked Down

I am super surprised no one has listed:
HP - Horsepower
BHP - Brake Horse Power
TQ - Torque (Torques if you're Jeremy Clarkson) ft-lbs or Nm - foot-pounds or Newton meter
FI - Forced Induction
NA - Naturally Aspirated
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Postby Johnf514 » Mon Jul 30, 2007 10:14 am

Gear ratios

Authored by: hockeystix
Submitted by: Johnf514


gearing is a very simple concept. you take 2 connected gears. spin one, other will spin. depending on how big the gears are, the other gear can spin faster, slower or same speed as the gear you turned. this creates different gear ratios. output gear divided by the input gear is the gear ratio

heres 3 scenarios that i drew up real fast. input is on the left, output is on the right. circles represent the actual gears, size of circles is somewhat proportional to what they would look like in real life. numbers are the number of teeth on that gear. more teeth=bigger (physically bigger) gear.

heres a possibility of a 1st gear.
Image
input gear is connected to the engine, and has 40 teeth on it. output gear has 180 teeth in is. do the math. 180/40=4.5 that is the gear ratio for that gearset. it will take 4.5 turns of the input gear to make the output gear turn a complete circle.
now lets apply that to a real situation. your engine is spinning 3000 rpms and producing 100ft/lb of torque at 3000 rpms.
gearing works on the principle of conservation of energy. you need more torque in 1st gear, so you sacrifice rpms. thus, 3000/4.5 = 667. your transmission output shaft will be spinning at 667 rpms. now, 100ft/lb X 4.5 = 450 ft/lb torque.
now we know that if you are in 1st gear and your motor is turning 3000 rpms and making 100 ft/lb torque at the crank, your transmission output will turn 666 rpms and have 450ft/lb torque. you traded rpms for torque. this is why your 1st gear has great acceleration but runs out of rpms very fast. 1st gear is a very short gear.

now for 2nd gear. not as drastic jump.
Image
input gear has 60 teeth, output has 100. now, it takes 1.66 turns of input gear to turn the output a comlete circle. lets plug some real numbers in.
3000 rpms /1.66 = 1807 rpms at the output shaft
100 ft/lb X 1.66 = 166ft/lb at the output shaft
now you dont have as much torque at the output shaft, but you have more rpms. this is why your 2nd gear lasts much longer than your 1st gear. 2nd gear is a taller gear.

now lets jump up to 5th gear thats most likely is a overdrive gear
Image
now your input gear has 60 teeth and output has 50. it takes .83 turns of the input to turn the output a complete circle. now for the numbers
3000 rpms / .83 = 3614 rpms at the output shaft
100ft/lb X .83 = 83 ft/lb at the output shaft
now you have almost no torque. but with having no torque, your output shaft also spins faster than your engine. now your wheels can spin faster while the engine turns slower. in the environment where you dont have fast acceleration and dont need a lot of torque (highway) overdrive gears will keep engine speeds lower and wheel rpms faster.

then, after all that, is the final drive gear, but for the simplicity, i wont get into it. its just another gear that once again cuts down rpms and increases torque some more. whatever your output shaft numbers are, feed them thru the final drive and you will have your wheel numbers. this would be true for a perfect mechanism, but since thats impossible, you will always have drivetrail losses.

but thats the idea behind gearing. and understanding how this all works in a manual transmission is a huge part of becoming a high end stanardshifter.

hope this helps and isnt too confusing.

and for changing gear ratios, it involves taking the transmission apart and replacing the gearsets inside the transmission.
or your could put in a different final drive and alter all of your gears at the same time. but for stuff like making your 2nd gear a little shorter or making 5th a little taller, thats replacing the actual gears.
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Postby jomotopia » Thu Aug 16, 2007 10:00 am

(Pulling a) Terrence

eaglecatcher wrote:(Pulling a) Terrence:

Inspired by a member who beat his car so thoroughly, that the transmission was destroyed, his front tires (FWD car) had only half tread after a couple thousand miles and the rears were normal, etc.

Ok heres the story I got a 2007 VW Jetta 2.5 Manual in Jan. I had no miles on it when I got it. I was ok with it the first 2 days until I found it had a seatbelt defect. Then they took my car for 4 days to fix it while me having a 07 Jetta automatic loaner. I got it back then days later realized my tire sensor light stayed on I took it back again. They said the stem on the tire was defective so they took the tire out my back and put it on my car until they get a new one. So I leave the lot and 5 min later took it right back because my check engine light was on and then started blinking meaning undrivable but I drove it anyway. They discovered that my car had a hole in the intake manifold. They replaced it under warranty after quality inspectors looked at it. Then I later discovered my air intake was broken and then I asked them to order one. So the next week later I was driving and shifted at redline to 2nd and 2nd didn't engage what I got was a loud phsstttttt clunkish sounds until all kinds of noises and noticed I had no more 2nd. I took it back and the dealer was like well no 2nd. They replaced the shreaded gear under warranty. Then 3 days later my check engine light was on again. They said that I had overrev codes in my car and then they reset the computer and also said my intake manifold is about to break again. So then 5 days later my 3rd gear goes pshtttt then I take it back again then after quality inspectors looked at it this time because it would be the 2nd time working on the tranny, they denied my warranty. They said I have to pay $2,300 dollars for a rebuild or $3,700 dollars for a new tranny and they will give my warranty back. This happened on March 2 or something and it is now almost May and I still have to pay my $400 car note. I want to know why did that happen considering this never happen in my Mustang GT 03 or my 2.4 Camry 03 or even a 95 pickup truck as long as I drove it.


go here to see what pulling a terrence means in original context.


in other words, if a forum member tells you that what you are doing is terrence like, or any other form of the word terrence that is directed at you or your car, means you should stop immediately and seek proffessional help.
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Postby jomotopia » Tue Oct 30, 2007 7:29 pm

Do I have to push the clutch all the way to the floor?

Authored by: jomotopia
Submitted by: jomotopia


While you can technically get away with not going to the floor, as long as you get the clutch fully disengaged, it introduces the chance for human error. If you push the clutch all the way to the floor, barring mechanical problems, you know the clutch is fully disengaged. If the clutch is not fully disengaged then you will cause much increased wear to both your synchros and your clutch.

So, yes, push the clutch all the way to the floor. If you find this difficult, you are probably sitting too far back. You should adjust your seating position while you have the clutch floored.
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Postby jomotopia » Wed Oct 31, 2007 1:55 pm

Glazed (glazing the) Clutch - a clutch gets glazed by heating it up too much (by slipping it for a long time at higher revs) so that the rough friction surface gets "glazed" and is then smoother and harder, giving it less ability to grip.

i like to use pottery as an example. a piece of unfinished pottery (after it's made and dry but before it goes in the kiln) is rough. then you put a glaze on it and put it in the kiln and it comes out smooth.

if a clutch gets glazed, the car will drive weird and it may feel like the clutch is slipping. a few days of normal driving will usually wear away the glazed surface of the clutch and return it to normal.
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