Its possible to just stick it in gear and let out the clutch going slow but if youve ever done it, it jerks the car. Racing and even driving fast on the street you HAVE to heel toe becasue otherwise the car will lock up the rears and possibly spin it.

 

i downshift all the time, rarely use my breaks, and my gas mileage is great 22.1, i think it only hurts ur gas mileage when you downshift than accelerate, because your rpms are alot higher

 

I do alot of rebuilding motors, NA motors mostly (toyota) that are high rev and most of my customers are Drifters and trust me this guys do alot of down shifting and over rev and this motors are not pretty when opened :)

If you want to keep your motor well over 100,000 i would not down shift much unless you have to. But if you dont care and want to show boat your exhust go for it and enjoy and save some money for new clutch and presure plate.:)

Brakes are cheaper than clutch.
the truck thing trucks has more gears than cars they are made for this (16gears) granny gear is what they use to slow down, but they only use this if they have heavy loads. when empty they try to save there trucks clutch.
This guys are diesel they run cooler and compresion is alot lower than NA so alot less punishment.

If you want to save gas dont pop out the gear when your slowing down and also dont down shift( unless ur to high of gear 6 or 5) leave your gear in and apply brakes and when your closing to stop and feel your rpm is to low then releas it out of gear. This will keep your injector paulse in place and rpm and save gas.

 

I can't believe this post has gone on for 2 pages and no one has mentioned downshifting for a corner.

IF you are coming to a light that just turned red, and you know you are going to come ot a complete stop, just shift to neutral and use your brakes to stop.

If you are, say on a surface street, going 40 mph, and coming to a right hand turn, you need to get into 2nd gear. You need to downshift before your turn, so you heel/toe down to third, then to 2nd (BEFORE the turn).

Make your turn and go.

Downshifting just for the hell of it doesn't make much sense to me, unless you are practicing your technique or you know the light is going to turn green and you need to get rolling soon.

 

First of all, downshifting will not decrease gas mileage unless you rev match. The G (along with most every other car out there) has these things called fuel injectors. The fuel injectors are always supplying the engine with gas with the minimum being enough to keep the engine idling. If you don't press the gas pedal, nothing more than enough gas to keep the engine idling will be supplied regardless of engine rpms.

Those big trucks do indeed downshift to avoid burning up their brakes.

In terms of inertia, if you don't rev match the downshift, then the initial deceleration is the inertial of the engine going from fewer to higher rpms. However, once you're up to the revs in the lower gear, the engine braking is coming from compression, not inertia.

Matching revs on a downshift is not necessary. However it is a good idea. Not matching the revs is taken care of by the synchros as you mention to actually get the car in the lower gear. However, your clutch is the part that is being worn when it gets the engine spinning to the higher revs when you let it (the clutch) out.

Rev matching is the only way you'll lose mpg downshift but it's a very miniscule amount. If you just downshift and let the clutch out, your mpg will be unaffected.

Finally, properly downshifting is not the worst thing you can do to your car. However, it will cause additional wear on the engine.

 

first off, you shouldn't downshift without revmatching, that's stupid, even if the synchros are ther why put stress on em? And you don't need to heel tow unless you're taking a corner. But i have heard that you should downship because you shouldn't be in a gear too tall for your speed. If you're slowing down, you should be shifting down to maintain stability. Is this true?

 

I wouldn't even worry about it unless you really suck at rev-matching/heel-and-toe shifting. Most of us aren't gonna keep the car long enough to experience any negative effects of downshifting. However, if you don't match the revs, you are putting the stress on your drivetrain, and that can cause some problems like worn-out synchros and clutch.

I don't downshift when I'm coming to stop. Whatever gear I'm in, I just brake, and shift into neutral when the rpm falls to about 1000. I do heel-and-toe when I'm taking a corner immediately after braking. If I coast to a corner, I just shift down without heel-and-toe, rev-match, let the clutch out and go.

 

So long as you don't donwshift at too high a speed, it should not affect gas mileage and help braking a lot.
C.

 

You should see no difference in MPG since the throttle body is closed and the engine is not taking in any more air then if you just put the car in netural. Since the injectors are fired based on Mass air flow and throttle position and a few other parameters, downshifting the car with you foot off the gas will have no effect on MPG.

 

Brilliant!
Automatics downshift so why should you not downshift with your standard? You should always downshift but easily, it uses no extra fuel and is not at all bad for your engine... Been doing it since 1978 and still do everyday... getting 25+MPG's with my 04 6MT coup.

Also, my last Supra was given to my little brother at gradualtion and it had 240K miles on only it's 3rd. clutch, 2nd, head gasket, and 4th. full brake service. Very good for 240,000 miles. Always downshifted it since day one!

Had an Isuzu truck with over 200K that I downshifted from day one... Was on 3rd brake job and no engine work besides normal tunes and maintenance.

So downshift your 6MT's, it burns no more fuel and is the proper way to drive a manual.

 

aight so quick question
when you are in MM and coming to a stop from lets say...60mph
according to people saying "i'd rather brake than harrassing my motor," you just brake and let gears change by itself?
i downshift all the time...maybe i should stop doing this.
btw this is for AT w/ MM users.

 

Amen

 

Downshifting won't affect your economy much at all... the only impact that it has to your economy is the additional fuel that is required to blip the throttle to get the engine RPM's up to matching the drivetrain speed(rev matching).

If your engine is spinning at 5000 RPMs but your foot is off the gas(coasting with the car in gear), your car is going to use the same amount of fuel as it would if you were sitting still at idle. Additional fuel is only used when the injectors are pumping more fuel into the engine... and the amount of fuel being pushed into the engine isn't a function of engine RPM's, it's a function of throttle application. If you're accelerating to or cruising at 5000 RPM's.. you're going to use a ton of fuel, but if you are already at 5000 RPM's and let off the gas with the car in gear, it will just decellerate due to the engine-braking effect and not use much fuel at all.

Engine braking by downshifting through all the gears to slow down will increase the wear and tear on your clutch, tranny and even a bit on your engine... but not by that much at all if you do it properly and rev match.

If you don't rev match when you downshift, it will increase the wear and tear on these components by quite a bit more than if you did rev match.... regardless of the fact that the gears are synchronized. The synchros just allow you to get your car into gear, it doesn't prevent what happens once you let the clutch out if there's a huge difference in Engine RPM's vs Driveshaft RPM's.

I generally don't downshift to slow down or come to a stop, although I will occasionally downshift if I'm going down a long steep hill... the reason being, that your brakes can heat up very fast while continually braking down a long hill.. and you could possibly warp your rotors(particularly if you do it when it's raining out and there are puddles on the road) and accelerate the pad wear by a good amount. In normal driving situations, I typically don't downshift too much and just coast and apply the brakes. Been doing this for the past 11 years of driving manual transmissions, and I've never had to replace/rebuild a single clutch, engine or transmission after about 500K combined miles amongst all of the vehicles I've owned.

Hope this helps.

 

There is really no reason on the street to heel toe because you really don't have to be on the brakes and the gas at the same time when downshifting on the street. I have been racing cars for over 30 years and I fully understand heel toe downshifting and rev matching as well as the potential of locking up the rear tires if you dont rev match, but that is on the track. I have never had to heel toe my car in street driving. If you just take your foot off the gas and as the car slowes and you want to go into the next lower gear just blip the gas a little and downshift the car, there is really no reason to use the brakes (while slowing) unless its an emergency if you are paying attention and not following to closely to the car in front of you. Again I agree with you 100% on using heel toe downshifting on the track but it is not necessary on the street.

 

You really didn't say that diesles run lower compression than N/A gas motors did you??