Quick Q about downshifting

Read the FAQ and still not sure about something? Want to shift faster? Post here.
Wes7523
Junior Standardshifter
Posts: 8
Joined: Wed Nov 28, 2007 1:11 am

Quick Q about downshifting

Post by Wes7523 » Wed Nov 28, 2007 1:17 am

Hi guys, I have a quick question about downshfiting.

For example, if I'm driving at 40 mph in 5th gear and want to downshift to 4th gear, do I have to rev-match? I've heard of riding the clutch, and everytime I downshift when I'm @ low rpms (~1000 rpm), the car kind of pull a lil bit unless I slowly let off the clutch and accelerate. My question is, do I have to rev-match also whe I'm doing this?


I also have a question about double-clutching downshift (I think it's what I'm doing right now). Basically, I downshift going up a hill if my car doesn't have enough torque.

This is what I do:
1. Clutch in
2. Neutral
3. Blip the throttle but still having the clutch in
4. Downshift to desired gear

Is this what's considered double-clutch downshift?
For #3, do I have to let off the clutch when I blip the throttle? I keep it all the way in the entire time.

Thanks!

User avatar
eaglecatcher
Master Standardshifter
Posts: 9441
Joined: Fri Jun 23, 2006 2:04 am
Cars: '90 300ZXTT 5MT
Location: Ithaca, NY

Post by eaglecatcher » Wed Nov 28, 2007 1:22 am

If you are single clutching, then there is no need to really shift to neutral. Just blip the throttle as you are shifting to the next gear.

If you are double clutching, then you must fully shift into Neutal (clutch in, shift to N, clutch out) and then rev, then clutch back in, shift to desired gear, and clutch out.

When you're at low rpms, sometimes rev matching can do more harm than good. There are times when my downshifts only raise the revs 200-300rpms or so, and any blip is gonna be at least that much (usually a little more) and so that means you're going to be farther off after blipping if you can't do a really really small blip, so sometimes its just better to let the clutch pull the engine up.
Z1 Intake
Z1 2.5" Test pipes
HKS 65mm Hi-Power Exhaust
AMS Short Shifter
SZ Subframe Spacers
HKS Vein Pressure Converter
DDM Tuning 6000k HIDs

User avatar
VTECaddict
Master Standardshifter
Posts: 1875
Joined: Mon Nov 15, 2004 9:41 pm
Location: San Jose, CA

Post by VTECaddict » Wed Nov 28, 2007 1:24 am

what you described is a single clutch rev match downshift.

a DCRMDS will be letting the clutch out in before blipping the throttle, then clutch in again to shift to the lower gear. you press the clutch down twice during the process, hence the term double clutching.

5th to 4th at 40 mph should be a very small RPM difference (like a few hundred RPM), so its up to you if you want to rev match that. not rev matching wont cause any significant wear at all since the RPM difference is so small.
2006 BMW 330i 6MT

Wes7523
Junior Standardshifter
Posts: 8
Joined: Wed Nov 28, 2007 1:11 am

Post by Wes7523 » Wed Nov 28, 2007 1:32 am

Alright, also when I'm slowing down, can I downshift as well without rev matching? Sometimes I hear cars' rpm go up while they're slowing down, so I guess they're rev-matching while slowing down?

User avatar
VTECaddict
Master Standardshifter
Posts: 1875
Joined: Mon Nov 15, 2004 9:41 pm
Location: San Jose, CA

Post by VTECaddict » Wed Nov 28, 2007 2:20 am

you dont need to downshift when slowing down, unless you are approaching a turn. in that case, you should downshift into the appropriate gear you need to be in to take the turn (usually second), and you should rev match because it will be a big RPM difference from whatever gear you're downshifting from.

and when you hear RPMs go up when slowing down its what is called "heel toe". you use part of your foot to brake, and another part of your foot to blip the gas while still braking (typically brake with the toes/ball of your foot and blip with your heel). this lets you do rev match down shifts while braking. it takes a lot of practice to get right (i still cant do it). and it doesnt really matter if you actually use the toe and heel, or heel and toe, or left/right side of your foot. whatever works best for you and your car.
2006 BMW 330i 6MT

Wes7523
Junior Standardshifter
Posts: 8
Joined: Wed Nov 28, 2007 1:11 am

Post by Wes7523 » Wed Nov 28, 2007 2:30 am

VTECaddict wrote:you dont need to downshift when slowing down, unless you are approaching a turn. in that case, you should downshift into the appropriate gear you need to be in to take the turn (usually second), and you should rev match because it will be a big RPM difference from whatever gear you're downshifting from.

and when you hear RPMs go up when slowing down its what is called "heel toe". you use part of your foot to brake, and another part of your foot to blip the gas while still braking (typically brake with the toes/ball of your foot and blip with your heel). this lets you do rev match down shifts while braking. it takes a lot of practice to get right (i still cant do it). and it doesnt really matter if you actually use the toe and heel, or heel and toe, or left/right side of your foot. whatever works best for you and your car.

Thx a lot VTEC.

How do I rev-match appropriately when downshifting for a turn? Can you please give me the steps? Thanks

User avatar
padauk_dust
Master Standardshifter
Posts: 1497
Joined: Fri Jan 19, 2007 7:59 pm
Cars: '88 Accord, '96 VFR

Post by padauk_dust » Wed Nov 28, 2007 2:58 am

Wes7523 wrote:

Thx a lot VTEC.

How do I rev-match appropriately when downshifting for a turn? Can you please give me the steps? Thanks

Appropriate (desired method, with double clutch+heel-toe) rev-match downshift for a turn:
(Lets pretend we're going 30 in 3rd gear and want to shift into second to get around a tighter curve)

1. Brake to initiate decel
2. Clutch to the floor (continue braking)
3. Shift to N
4. Clutch up (release)
5. Blip throttle to match engine revs to wheel speed in 2nd gear (this is where you can heel-toe it (best method), or stop braking and use your right foot for just the blipping gas and not maintaining braking)
6. Immediate action of clutching in (to the floor)
7. Shift into second as soon as the clutch hits the floor (you can of course, do it sooner if you wish)
8. And as soon as you are in second gear, let the clutch up at a fairly rapid speed while supporting (if needed) with a little (little) gas- if you did it right, you can nearly dump the clutch and you won't notice a jerk.

At least, that's how I do it. It's harder talking/thinking about it than doing it.
'88 Accord DX
'96 VFR750

User avatar
jomotopia
Moderator
Posts: 10230
Joined: Fri Mar 24, 2006 1:01 pm
Cars: 04 STi, 05 Matrix XR (AT)
Location: AWD Turbo Nirvana
Contact:

Post by jomotopia » Wed Nov 28, 2007 10:33 am

you described a single clutch rev match down shift, and there's no reason to stop in neutral. for double clutch you let the clutch out in neutral, then blip the throttle, then clutch in and go to the lower gear.

you don't have to rev match, but it is a good idea if you are doing higher rev downshifts, downshifts for passing, or downshifts at speed when not braking. really the only time i don't rev match is if i brake down to a speed that would be near idle-1k in 2nd, and i just shift to 2nd and let the clutch out slowly while i'm braking.

there's no need to downshift at all when you're slowing down, unless you're going into a situation (such as a turn) that will require to you accelerate again. if you're stopping just brake in gear till the revs get down around 1k, then go to neutral and finish stopping.
2013 Subaru Impreza WRX in Orange

Wes7523
Junior Standardshifter
Posts: 8
Joined: Wed Nov 28, 2007 1:11 am

Post by Wes7523 » Fri Nov 30, 2007 12:46 am

Thanks for all the input.

What's the point of double-clutch downshift when you can just do single clutch downshift way faster?

Also, I tried heel and toe downshift and it is so hard... Im afraid if I blip the throttle I might step on the brake too hard.

User avatar
watkins
Master Standardshifter
Posts: 15708
Joined: Sun Jul 01, 2007 12:42 am
Cars: 1999 Saab Viggen
Location: Salem, MA

Post by watkins » Fri Nov 30, 2007 12:51 am

Its more natural for muscle memory to double clutch in a lot of people. One foot up, the other down. For me, its very uncomfortable to be on both the gas and clutch at the same time. My legs just dont want to do it.

Besides, double clutching looks so much more badass
Image

User avatar
Prodigal Son
Master Standardshifter
Posts: 3079
Joined: Fri Jun 23, 2006 11:20 pm
Cars: 2006 Jetta, 2004 Miata
Location: Ottawa

Post by Prodigal Son » Fri Nov 30, 2007 12:53 am

Wes7523 wrote:What's the point of double-clutch downshift when you can just do single clutch downshift way faster?
Not a lot really. Its a hold over from the days before synchronized transmissions. I prefer it because it is a more synchronous motion for doing a rev match -- essentially two single clutch motions in rapid succession.

People will argue that it reduces wear on the synchros, which is probably true but probably not relevant, since they will probably last the life of the car anyway. (If the synchros do wear out, though, you will have to double clutch to get the car into gear.)

Finally, it can let you get into the lower gear a little quicker and a little easier (again because it is doing the work of the synchronizers). But if you don't want to do it, there really is no reason why you should.
Just some guy on the Internet. Heed with care.

User avatar
jomotopia
Moderator
Posts: 10230
Joined: Fri Mar 24, 2006 1:01 pm
Cars: 04 STi, 05 Matrix XR (AT)
Location: AWD Turbo Nirvana
Contact:

Post by jomotopia » Fri Nov 30, 2007 10:25 am

Wes7523 wrote:What's the point of double-clutch downshift when you can just do single clutch downshift way faster?
like Prodigal said, there's not a lot of point to it. but it does also feel like a more natural motion to me. it does save wear on the synchros (though like PS said that doesn't matter much). and a single clutch downshift is really only faster at first. once you get the hang of a double clutch downshift it is quite fast, and can actually be a bit faster because you don't have to wait on the synchro to let you into gear since you're doing its job for it. this is especially noticeable on high rev downshifts or downshifts where you skip several gears.
Also, I tried heel and toe downshift and it is so hard... Im afraid if I blip the throttle I might step on the brake too hard.
you will step on the brake too hard at first. that's really the hardest part to get down with heel toe. but once you get the hang of it you can do it with constant brake pressure. just takes practice.
2013 Subaru Impreza WRX in Orange

Wes7523
Junior Standardshifter
Posts: 8
Joined: Wed Nov 28, 2007 1:11 am

Post by Wes7523 » Thu Dec 06, 2007 12:11 am

VTECaddict wrote: and when you hear RPMs go up when slowing down its what is called "heel toe". you use part of your foot to brake, and another part of your foot to blip the gas while still braking (typically brake with the toes/ball of your foot and blip with your heel). this lets you do rev match down shifts while braking. it takes a lot of practice to get right (i still cant do it). and it doesnt really matter if you actually use the toe and heel, or heel and toe, or left/right side of your foot. whatever works best for you and your car.

Just to make sure, here is the youtube video, @ 0:36: http://youtube.com/watch?v=X49F5XHNg3k ... is this heel and toe braking?

User avatar
Bawked
Master Standardshifter
Posts: 2414
Joined: Wed Aug 29, 2007 12:24 am
Cars: 1991 mr2 sw20 n/a 5 speed
Location: New Zealand

Post by Bawked » Thu Dec 06, 2007 12:47 am

In the comments he says its a A/T
<3 fwd

User avatar
Ecmslee
Senior Standardshifter
Posts: 105
Joined: Thu May 18, 2006 8:14 pm
Location: California

Post by Ecmslee » Thu Dec 06, 2007 12:51 am

There's a better video on this site that illustrates heel and toe. Just go over to the video section and click on the last video- "Footbox video. Lap and a half of Sears Point". Gary Sheehan provides many examples of double clutch heel toe downshifting in that vid.

Post Reply