Newbie question: Downshifting

[zoom_x2]

Hi all,


I'm new to this forum, and new to driving a standard :)

My question is, how do you figure out what rev it should be when downshifting? I heard that it has something to do with the gear ratio and stuff, but is there like a formula or something that explains it?

Right now I just do it by guessing... which ends up in lugging most of the time :P

Thanks in advance!!


zoom_x2

[Gonthro]

when you stop then you downshift, brakes are cheaper than a tranny.

[JustinL]

Start with aiming for 1000-1500 RPM differences in the low RPM ranges and 2000-3000 RPM above 4000RPM. Every car is different so just take your time and get a feel for it. It will get more acurate as you get used to it. Be careful dropping 2 gears at a time though.

Don't stare at the tach when you should be watching the road.

Edit: I just re-read your post... are you sure you didn't mean upshifting?

[tsi_neal]

the only real time you should down shift while driving is if youre trying to get more power

example crusing on the highway in 5th at 2500rpm and you want to pass someone, most cars wont have the power to quickly pass at 2500rpm, so if you drop it into 4th youre revs will jump to probably just over 3000rpm, a bit more power there. or if you down shift to 3rd your revs should be a bit over 4000rpm LOTS more power there to quickly pass on the highway.

example 2 cruising at 60km/hr and the speed limit drops to 30 your in 3th gear at 60 but at 30 your revs are low and you dont have any power and your lugging the engine youll downshift to 2nd to bring the revs back up to an ideal cruising rpm. once the school zone is over youll accelerate back to 60 and shift back to 3rd.

there is no formula, its all about where and how much power your car makes and how much power you need for the situation that dictates the gear. well i suppose if you had all the info and wanted to do the math you could calculate the ideal gear for a situation. but doing it by driving feel is what everyone else does

[sabad66]

you bought a 2004 rx-8 6spd and you dont know how to drive standard??:poosie:

[GTS Jeff]

watch in-car vids of racecar drivers and mimic their movements

[Kid_a]

Originally posted by Gonthro
when you stop then you downshift, brakes are cheaper than a tranny.


I've heard its better to do both at the same time, downshift while braking.. not true?

[GTS Jeff]

Originally posted by Kid_a



I've heard its better to do both at the same time, downshift while braking.. not true? depends.

pros: ure in gear so u can gas it right away in an emergency., tougher to stall, ready to accelerate instantly, fun

cons: wastes gas, scares pedestrians, jerky ride if u dont do revmacth well

engine wear and tear from downshifts would be negligible if u knew anything about anything.

[hjr]

if you match properly then there is very little extra wear on the engine or trans, but you are wearing the clutch a bit more (simply by using it more)

as for rev-matching properly, its all practice. i have been doing it for 3 years and im not perfect. just keep trying it, generally at lower rpms until you know how much gas to give it, then work your way up. also, make sure you release the clutch very soon after you have blipped the throttle.

[GTS Jeff]

Originally posted by hjr
also, make sure you release the clutch very soon after you have blipped the throttle. :angel:

[THREE40SEVEN]

No rev matching, no blown trannies, no warn clutches and i downshift all the time on all of the cars i've owned.

[Kid_a]

Yes, but last time I checked corn infested turds have pretty bullet proof trannies.

[Skyline_Addict]

basically you downshift (when driving normally) when you are slowing down significantly or when you're coming to a complete stop.

hold down the brake and the clutch until you reach your desired speed, engage the correct gear for that corresponding speed range, and you're off.

as tsi_neal pointed out, there is no formula. you need to learn to understand how your car works and just get used to it. don't recklessly downshift as it can ruin your tranny. your vehicle manual should tell you the reccommended speed ranges for each gear. keep those in mind when you downshift.

[GTS Jeff]

no one has mentioned that u should be doing heel-toe, not just letting it out in a lower gear. (THAT is not good)

[THREE40SEVEN]

Originally posted by Kid_a
Yes, but last time I checked corn infested turds have pretty bullet proof trannies.
I've owned a 2.3 turbo crapi, an 87 pulsar, a 4cyl ford ranger, and of course "the turd"...
My father has 145000km on his original talon tsi clutch, and its still fine..

[rice_eater]

Originally posted by THREE40SEVEN

I've owned a 2.3 turbo crapi, an 87 pulsar, a 4cyl ford ranger, and of course "the turd"...
My father has 145000km on his original talon tsi clutch, and its still fine.. :werd: i downshift my car every time i stop and have been doing so for 3 years...i have just pulled off the original clutch (car is 8 years old) and other than a little wear and tear it looks perfect. Never slipped and never had a problem with it.

As for the question that was posted, it doesn't matter what rpm you shift down at...just make sure that when you do downshift your RPMS are about 2000 less than your redline and you wont have a problem :thumbsup:

[T5_X]

Originally posted by GTS Jeff
depends.

pros: ure in gear so u can gas it right away in an emergency., tougher to stall, ready to accelerate instantly, fun

cons: wastes gas, scares pedestrians, jerky ride if u dont do revmacth well

engine wear and tear from downshifts would be negligible if u knew anything about anything.

Downshifting (not double clutch or rev match downshift) wastes no gas. It brings your revs up, but since your foot is not on the gas pedal through the whole process, no fuel is being injected.

The best method is to just coast to stops to slow down, from fairly far back. You are using your momentum to maximize efficiency. No wear on brakes, no wear on tranny/engine. I've driven around on brake pad wear indicators for 10 months like this now :D

[Rockski]

Originally posted by GTS Jeff
no one has mentioned that u should be doing heel-toe, not just letting it out in a lower gear. (THAT is not good)



can you explain this heel toe thing, im interested, cause i have no idea what you mean when you say it and its been said many a time here


Originally posted by T5_X


Downshifting (not double clutch or rev match downshift) wastes no gas. It brings your revs up, but since your foot is not on the gas pedal through the whole process, no fuel is being injected.



arent you using gas because the rpm's are up, for example (bad for car) your doing 80 in second and you take your foot of the gas, the rpm's are still up, but if you were doing 80 in 3rd or 4th your using gas, just not as much. SO, wouldnt you still be using gas even though your foot is not on the pedal if the rpm's are up high enough?

just wondering, im probably wrong

[H4LFY2nR]

Heel-toeing is when you use all three pedals at once. Left foot on the clutch, and right foot on both the gas and the brake. Using this technique when downshifting you can slowdown using the brake while revmatching your downshifts. The sequence is as follows:
brake with the right toe
depress the clutch with the left foot
shift to neutral
while continuing to brake
blip the throttle with the side or the heel of the right foot to raise rpm
shift to a lower gear
let the clutch out
release the brakes
It takes lots of practice so you should be comfortable with downshifting before you start IMO.

[Skyline_Addict]

Originally posted by H4LFY2nR
Heel-toeing is when you use all three pedals at once. Left foot on the clutch, and right foot on both the gas and the brake. Using this technique when downshifting you can slowdown using the brake while revmatching your downshifts. The sequence is as follows:
brake with the right toe
depress the clutch with the left foot
shift to neutral
while continuing to brake
blip the throttle with the side or the heel of the right foot to raise rpm
shift to a lower gear
let the clutch out
release the brakes
It takes lots of practice so you should be comfortable with downshifting before you start IMO.

heel-toe technique is not necessary in anyway for ordinary commute (i.e to work in during rush hour, etc). it's mostly used in racing. it's a neat thing to be able to do though, and takes some practice.

[zoom_x2]

Thanks guys for all the good advice! Basically the way I've been practicing is: clutch, neutral, rev up, shift down, release clutch, sometimes it's smooth, sometimes it lugs, I thought I must be doing something wrong, but I guess I just need more practice.

What are some of the good vids out there?

[Skyline_Addict]

Originally posted by zoom_x2
Thanks guys for all the good advice! Basically the way I've been practicing is: clutch, neutral, rev up, shift down, release clutch, sometimes it's smooth, sometimes it lugs, I thought I must be doing something wrong, but I guess I just need more practice.

What are some of the good vids out there?

practice. get used to the response and sensitivity of both your clutch and gas. the reason your car "lugs" is because you are releasing the clutch/stepping on gas too fast. Remember, release of clutch and stepping on gas must be done in as much unison as possible to stay smooth, most evidently in 1st gear.

[Rockski]

Originally posted by zoom_x2
Thanks guys for all the good advice! Basically the way I've been practicing is: clutch, neutral, rev up, shift down, release clutch, sometimes it's smooth, sometimes it lugs, I thought I must be doing something wrong, but I guess I just need more practice.


thats what ive been doing, oly mine races instead or lugging, guess the revs are too high

[T5_X]

Originally posted by Rockski


arent you using gas because the rpm's are up, for example (bad for car) your doing 80 in second and you take your foot of the gas, the rpm's are still up, but if you were doing 80 in 3rd or 4th your using gas, just not as much. SO, wouldnt you still be using gas even though your foot is not on the pedal if the rpm's are up high enough?

just wondering, im probably wrong

I think your engine is just turning over without making any power strokes, you're not injecting any gas at all until you reach the idle speed which takes over and starts injecting gas. Injecting gas when off the throttle otherwise would just be a waste.

Double clutch downshifting or rev matching is almost always pointless in city driving. Good stuff to learn for racing though, and its fun. If you're cheap like me though, just coast to stops, downshifting without blipping the throttle so your only slightly engine braking.

[FiveFreshFish]

Originally posted by zoom_x2
Thanks guys for all the good advice! Basically the way I've been practicing is: clutch, neutral, rev up, shift down, release clutch, sometimes it's smooth, sometimes it lugs, I thought I must be doing something wrong, but I guess I just need more practice.

What are some of the good vids out there?

Here are some excellent in-car videos of shifting techniques done in an M5. Of course the videos apply to any car with a manual tranny. http://www.bmwm5.com/greg/school/

[dkny_stylez]

Originally posted by Skyline_Addict
basically you downshift (when driving normally) when you are slowing down significantly or when you're coming to a complete stop.

why not just pop it into neutral?

[talonboi]

juss let me drive ur car..i'l show u how to down shift:rofl:

[boostfed]

Here's a chart of the gear ratios, etc, for your RX8. The shift point is approx. what the revs will drop to after a shift right at redline. You can use this as a bit of a guideline to figure out what gear you should downshift into and help you with revs.

[T5_X]

Does the RX-8 really go to 300 km/hr? :eek:

[boostfed]

Originally posted by T5_X
Does the RX-8 really go to 300 km/hr? :eek:

It would be gearing limited to 300 clicks, but it is drag and horsepower limited to something lower than that.

[Skyline_Addict]

Originally posted by dkny_stylez


why not just pop it into neutral?

it's redundant. he's asking when he should start downshifting, not how he should slow down. there are a few ways you can slow down a car (besides downshifting). braking while in gear. braking with clutch and brake. braking while in neutral, etc.
obviously, after losing some speed, you've got to downshift to keep your revs up. that's what i was adressing.

[91VTEG]

this is from g2ic but i think it explains it pretty good
Heel-To-Toe

The idea here is to match the engine RPM's to the cars speed in the gear you select, giving you a smooth downshift, & keeping the car's balance. Aftermarket pedal covers make heel-to-toe easier. The clutch pedal cover isn't as important as the brake and accelerator. It can stay rubber, but for the brake and accelerator, you want to have a lot of surface area to work with (a flap on the accelerator is preferred).


This brings the brake & accelerator pedal surfaces closer together, making heel-to-toe much easier.

I'll use a common "downshift from 3rd to 2nd while decelerating before a turn" as an example.

1) Apply Brake
2) Push and keep the clutch down.
3) Take the selector out of 3rd gear.
4) Before you stick-it into 2nd gear, you must rev-match. Since you're decelerating, you have to raise the RPM's slightly because you're going into smaller gear.

*The Heel or the side of the foot, applies the gas. The Toe-side of your right foot applies the brake.* (Heel-To-Toe)

5) Once you've given it the right amount of throttle, move the selector into 2nd gear.
6) Let go of the clutch, then let go of the brake (Be smooth). By this point you should be through with the turn (past the apex) and ready to accelerate.

[zoom_x2]

Thanks everyone for such your comments and advice! I've been practicing while driving around town and get a pretty good feel about it now... I even tried heel & toe'ing a few times (only got it right a couple times tho lol)

You guys have been great just wanna say I really appreciate all the help!

[hjr]

almost everyhting has been gone over pretty extensively so trying doing a search for your answere first, you might be suprised that this topic alone has been discussed multiple times.

[three.eighteen.]

Originally posted by FiveFreshFish


Here are some excellent in-car videos of shifting techniques done in an M5. Of course the videos apply to any car with a manual tranny. http://www.bmwm5.com/greg/school/

of course they show you how to do in it in a bmw...heel-toe is retarded simple in any manual bmw cus of the way they set the pedals up

[moojester]

The best way to know where to rev match too.. (what rpm to have your car in before shifting down.) is to pay attention to the speed and rpm of a particular, lower, gear.

ex:

I watch my car in 2nd at 70km/h.. and mark the rpm at around 4500 say, in 3rd when i'm going 70km/h i need
to rev match to 4500 for 2nd =p. if you make note of
particualr speeds and rpms you'll find it much easier to
quickly figure out a good rpm for each of the gears at
differnt speeds, (by estimating based on known values).

Also..

I think this is missing a step:


"brake with the right toe
depress the clutch with the left foot
shift to neutral


-- Let the clutch out



while continuing to brake
blip the throttle with the side or the heel of the right foot to raise rpm


-- Clutch In again



shift to a lower gear
let the clutch out

My understanding is that you want to be reving the engine when the car is in neutral and the clutch is engaged, if you
don't do this, your only spinning part of the car up. You really want everything to be spiining at the correct speed.

thus.. double clutching.