Technically, you can rev it up, and at the point where it would be revving had it been in gear, you can dump the clutch. The speed of the flywheel and the halfshaft will be the same and no jerk, even though the instant you dump the clutch you're still accelerating.

In practise though, it's really an imprecise technique. You just know where it should be, and you give it a good blip with your right heel. Most times you're doing it under braking so your speed will be decreasing rapidly as well. You just do your best as to not upset the weight distribution of the chassis.

 

Correct me if I'm wrong.

If I can up shift fast enough that the rpm droped down to the ideal point in gear at the specific speed, then there is no need to rev match. Rev match is only necessary if the rpm droped below the ideal point. Am I correct?

 

Rev matching, when done with non syncro gears (older cars and certain types of race cars), requires that you find the RPM that matches the speed before a tranny will go into the given gear. If by "ideal point" you mean the RPMs fall perfectly to match the speed while shifting, you're correct, and that is a common practice. But rev matching is done when downshifting, since the RPMs will need to go up and not down.

 

awd also means more drivetrain loss through friction so when u let off the gas....you'll slow down quicker then a FWD...hence the jerkyness

 

That's all the head bobbing is, especially with my wife. It has nothing to do with rev matching or anything like that, it's the loss of acceleration when you let off the gas to shift. If you drive like I do then it's at least 3/4 pedal all the way till next gear then a semi-quick shift. Passenger's head bobs forwards when I clutch in and bobs back when I clutch out. They could always walk if they don't like it . The 'plateu' that has been discussed is a likely fix for the situation. In other words, stop accelerating before you change gear.

 

Thank you,
Yes, that's what I meant. I know Rev matching is mostly for downshift. Haha, It is very weird for me, I can downshift smoother than I upshift.

 

I am just wondering, if I clutch in and clutch out very slowly, then wouldn't the acceleration slowly decrease, and slowly increase again? Can this fix the head bobbing situation? I know this will KILL our clutch, but I am just wondering...

 

I learned on a 3 on the tree 327 chevy.

I have been driving standards for close to 28 years.

Not every shift I make is smooth. If you ease off the gas right before you put in the clutch and then shift, you will reduce the jerk that you feel.

The guy with the physics has it right, by easing off the gas right before upshifting you reduce your accleration and that makes the shift seem smoother. By easing off the gas you allow the rev's to begin to drop. Since you are going to shift to a higher gear, you need less rpm's to move at the same speed, so by easing off you start the process of rev matching.

For maxmium power you would not want to do this, I am talking about around town don't spill the coffee type driving.

The more you drive the better you will get, you pick it up by trial and error.

 

Oh, I get what you mean by plateauing.

The head bobbing is caused by the weight transfer due to the change in acceleration. When you accelerate, the car throws the weight rearward and press you into the seat. When you disengage the clutch to shift, the car stops accelerating. The suspension throws the weight back to the front as the acceleration is suddenly stopped.

Then when you shift and engage the clutch again, the car begins to accelerate again and throws the weight to the rear.

Hence, the head-bobbing effect.


He's absolutely correct. Before you shift into the next gear, find the position on the throttle where the car will hold its speed without accelerating or decelerating. I guess he calls this letting the revs "plateau." Then you can go ahead and shift. The car will not throw the weight around because in steady cruising, the weight is set; there is no acceleration, hence no weight transfer.


This shows you the importance of throttle position on weight transfer. You can transfer weight front and rear depending on how you control the throttle.

 

All of the above advice is good.

A couple other points:

Having shoes that fit well, with firm but thin soles, can make for smoother throttle modulation.

Also, it may be psychosomatic, but since I installed my shift cable bushings and heavy shift knob I'm finding my shifting timing to be a bit better (I can just "feel" it better).

Another smooth throttling tip I picked up from someone on this board: butt the right side of your right shoe up against the center console when you want to artificially dampen your foot movements for smoothness (e.g. when going over bumps at low speed, taking u-turns, etc.). Our cars can be pretty jerky opening and closing throttle in low gears.

 

All of this is really good stuff

When you're starting out, it's best to use those shoes that will allow you to feel the pedals well.

With time, I was able to wear any shoes and still feel the car respond. Now I can drive with bare feet, flip flops, snow boots, etc. You name it. No problem

The shift feel is highly subjective. Some prefer it hard, some prefer it notchy and loose. I feel like you have to adapt to the car. But in general I dislike short shifters because of the increased shift effort that's required. Bushings will help stiffen up the feel a lot.

Excellent tip about the jerking in low gears. If you're not smooth on the throttle, the car will buck like crazy.

I find that if you brace your entire leg: calf, knee, thigh, butt against the console, it helps stabilise your throttle foot, especially under high cornering load. It takes a lot of practise to develop precise control of the throttle. Sometimes I would feel soreness in my right quadricep after a long drive because I have to control the throttle with a delicate touch for a prolonged period.

 

practice shifting and driving smoothly by putting a cup of water in the cup holder, prevent the water from spilling it :P

 

haha yes like fujiwara takumi.
oh and to address the question about
automatics. those transmissions are
completely different from a standard.
i read up on it a while back on
howstuffworks.com

 

Rev matching or feathering the clutch in 2nd and 3rd gear, but doing this will kill the clutch early. A short shifter will also help in quicker shifts between gears, but all in all it just gonna take practice. just my .02

 

Btw, has anyone ever installed one of these:http://cgi.ebay.com/ebaymotors/ws/eB...category=33730

any input would be greatly appreciated.