Contour Enthusiasts Group Archives Forums General General Down Shifting

I am somewhat new to driving a manual and wanted to know what is the proper way to down shift smoothly?
An example of this would be cruising on the hwy in 5th and then getting onto an off ramp shifting into 3rd or even 4th. If I just let off the clutch, as it engages the car throws you forward. I have been tapping the gas right before I let off and it shifts much smoother. I know this is similar to heel and toe shifting, but it is difficult in our cars the way the pedals are arranged and seems like alot of work for just casual driving.

Am I doing this correctly? What techniques do you guys use in this situation?

rev match to the correct rpm's. simple enough.

I've gotten into the habit of braking with the ball of my foot on the top right hand corner of the brake pedal. Makes it easier to rev with the heel or side of the foot.

These cars are hard to heel and toe in so thats my method. Its a lot of fun too. Off-ramps, stop signs, red lights, I'm constantly doing this. Downshifts are almost butter smooth now.

-R-

What you really want to know is "how to double-clutch." First of all, you should only really down shift if you are not coming to a complete stop. If you are stopping, leave the car in gear as you brake until the rpm's are down to 1500 or so, then press the clutch, put it in neutral, let off the clutch and keep your left foot away from the clutch pedal until it is time to go. Down shifting puts wear and tear on your clutch and synchronizers and it costs a lot more to fix these than to replace brakes.

Before you learn to double-clutch, you can learn to match revs. This just means that when you down shift, you rev the gas a little when the clutch is depressed. If you are down shifting from 5th to 4th, you only rev a little. If you are down shifting from 5th to 2nd, you will need to rev a lot. For example, you can coast down to 35 mph in 5th gear and you'll be turning about 1000 rpm. If you down shift to 2nd, you will need to rev it up to about 4500 rpm or so. But don't try to watch the tachometer when you do this. It's all done by feel and practice. When you match the revs to the car speed, you won't feel any push or pull when you let the clutch out. This means less wear on your clutch and less abuse to the drive train (the car will still feel "tight" after 50,000 miles.)

Now double-clutching: it's exactly as described above but as you shift from 5th to 2nd, you let the clutch out in neutral for a split second as you rev the engine, then press the clutch back in and shift from neutral to 2nd. This is all done in one, smooth motion. When you let the clutch out in neutral, you are connecting the gears in the transmission to the engine so that the gears are revved up too. This way, when you shift to 2nd, the gears speeds are matched and your synchronizers don't have to do much synchronizing and thus don't wear as quickly. In the old days, some cars had no synchros so double-clutching was mandatory. Most cars still don't have synchros for reverse (I think that some BMW's do). That's why it is sometimes hard to get your car into reverse and why you should always be stopped when you shift into reverse. Double-clutching probably won't feel any smoother than matching revs but it will make your synchros last forever.

Also, you will find it much harder to down shift smoothly into 1st or 2nd as compared to 4th. That's because the shorter gear ratios of 1st and 2nd basically amplify the force of the engine.

Good luck!

One more thing - heel-and-toeing is just matching revs while braking. For this, you really need three feet. Personally, I would rather have a bad down shift than a collision. So I tend not to mess with heel-and-toe stuff. If I am braking, I wait until I am done slowing down before I down shift. This won't win you any auto-cross races but then again, any clown with a V6 Altima and an automatic will probably beat you no matter what you do. Uh-oh, here we go ...

Dave - 98 SVT

well, let me use this chance to ask a few questions I've always wondered about relating to this topic...


first off, does it matter how the car is in neutral? is there a difference between just having the clutch in, and having the shifter between gears? if not, then why wouldn't you just do all your rev matching and such with the clutch in...why would you:

depress the clutch-put it in neutral on the shifter-let the clutch out-rev match-depress the clutch again-put into gear

doesn't seem like that'd be all that fast in a race...seems like it'd be easier to just hold the clutch, shift, rev match and let out the clutch...am I missing something...?

With the clutch engaged (pedal out) and the transmission in X gear; engine, transmission and driven wheels are all connected, spinning at given speeds for RPM and ratio.

Clutch disengaged (pedal in) and transmission still in gear; engine disconnected, transmission and driven wheels still connected (which means the engine can be made to spin any speed, transmission is being spun by driven wheels at X ratio).

Clutch disengaged and transmission in neutral; all three disconnected (which means engine can be spun any speed and transmission will spin freely).

Clutch engaged and transmission in neutral; Engine connected to transmission, driven wheels disconnected (which means engine speed determines transmission speed: use engine to make transmission speed match new ratio to driven wheels.)

Now, to answer your question about missing anything...
As a normal driver, double clutching is most likely a waste of time and effort, and actually puts a little extra wear on the clutch and throwout bearing over just rev matching.

Also, people who are good at double clutching can do it quicker than you can excecute a normal shift, mainly because they are race drivers and have to out of nescessity.

It is easier to just hold the clutch and match revs, but in racing, you have to do that while braking, which is what heel-toeing accomplishes. Double clutching comes down to personal preference. I mean, synchros were invented so we wouldn't have to double clutch any more so why save them from having to do their job?

Now, it seems like theduker is getting ready for a flame. I'm not going to shoot fire, but I am going to send a few sparks his way:

Yes, trying to heel-toe in normal driving is a good way to slip your foot off the brake and rear-end somebody, and to brake and then rev match is a slow way to go about it, but his comment about "This won't win you any auto-cross races" is contradictory because you don't have anybody to run into on an autocross, so you wouldn't have to worry about it, and being good at heel-toe downshifting gives you the edge that is the key to auto-xing.

I'll happily hand any clown in a V6 ATX Altima his a** at the finish line because I can drive my SVT better than he can ham-fist his Nissan. If he does beat me, it'll be because he's a better driver. Auto-xing is about driver skill, not hardwear.

Peace be with you all

Jed

it only jumps forward if you dump the clutch...but obviously thats going to happen if you drop the clutch into 2nd and you're going 50.

Read this article: Heel and Toe Downshifting and then practice!!

I used to dread downshifting before I learned what Heel and toe meant. Now I am getting to the point where I can do it smoothly and quickly enough to avoid jerking the car.

And contrary to what others have said, I feel the contour pedals are set up just fine for heel-and-toe action. (I'm talking about the stock pedals, I've not driven a car with aftermarket aluminum pedals.) Now I am in the habit of braking with the left side of my foot so that I can tap the throttle if necessary for a downshift.

Double clutching, if done right, will eliminate almost all wear on your drivetrain components. However, it really isn't necessary on modern cars with fully synchronized gearboxes.

Also, heel and toe is only necessary if you need to slow down while downshifting (like for taking a corner). Otherwise just hit the throttle when you downshift and match revs for a smooth shift.

98.5_SVT,

Beyondloaded summed it up. Most of the rest introduced other terms that are different, but possibly related or can be used together. The goal is to rev match with every gear change, up or down. The jerking is because the engine speed is not matched to what the selected transmission gears/axle/wheels are turning. This jerking could occur no matter what gear to which you are shifting, up or down. By nature, upshifting tends to be smooth without most poeple not knowing why. Downshifting requires an extra effort, raising the engine speed vs. the speed it was at in the higher gear. You can calculate all the appropriate engine speeds for every mph in every gear so that you cna always know what you need to bring it to, but experience and feel are the only ways to make it smooth. Use momentum of the engine going up or down to help make it smooth, yet minimize clutch slipping. Quick blips of the throttle when downshifting work well, but you must do it by the right amount.

Practice, pratice, practice. Maybe watch some others that are more experienced with rev matching.

Combining rev matching with heal and toeing or double clutching can be very useful to make the shift smooth and/or reduce wear.

Keep in mind that downshifting is not an effective braking tool. Even if you do it "right" and minimize engine/tranny/clutch wear, the momentum of the engine speed is not going to slow you down quicker than the brakes would. In fact, quite the opposite in emergency/racing braking. It is effective in setting you up with a desired gear for maintaining the corner speed and power out of a corner. And for certain vehicle, the sweet sound of the engine and exhaust make it fun.