teomcdohl

To the people who drive a manual transmission:

Do you downshift to assist with braking? Ex. Driving 50 mph, and downshifting to 2nd or 3rd to help slow down.

Figured I'd just throw it out there with a poll.

Is there any danger to the transmission to doing this?

princelybug

iTrader: (16)

I always coast in neutral. This topic has been brought up before, and someone said, "It is alot cheaper to replace break pads than it is to replace engine parts."

Now...downshifting to pass someone is a different story....

CanopyFlyer

You never down shift to slow the car (PERIOD THE END).

Down shifting is only for making sure you have enough engine power available at lower speeds. If you want to keep it in a lower gear (not down shifting) while going down a long grade, fine. Also you should match the engine RPM to the lower gear and speed while down shifting.

The brakes are made to slow the car, not the engine, CV joints and transmission.

Not just my two cents, but the facts.

FiveLiterCheater

^^ Exactly...I never got why people downshifted to slow the car down lol...and the best excuse is "it saves the brake pads" LOL i think its cheaper to swap out some $100 pads than risking thousands of dollars in engine/tranny repair!

Winnipeg

Nothing wrong with down shifting to keep the rpms up. Not braking though, under normal conditions at least.

SouthernBoy

I would not recommend downshifting at 50 MPH to 2nd gear. Third is Ok if needed from this speed, though. As for the rest of it..

Does downshifting hurt the engine, transmission, and/or clutch assembly? No, not if it is done correctly. Yes, if done incorrecting for items two and three in the list.

Should you ever downshift just for braking? See the above. As a general rule, it's best to coast down to a manageable speed, then when slow enough, just go into neutral (assuming you're coming to a stop). Downshifting for braking effect is not bad IF it is done correctly AND there is not a great disparity in wheel speed versus engine speed.

modificata3

when i drive manual i just use the gear I'm in til the rpms get low and then pop into neutral

teomcdohl

Thanks for all the replies. Seems that everyone here has the general consensus that throwing the engine into high RPMs in low gear to downshift is bad, especially when brakes can be replaced cheaply while the engine/transmission take the brunt of the damage. Now, for extra credit , where does the line come down? For example, in my original post, I said 50 to 2nd - in reality, that would be pretty high rpms - but, where does it go from being safe to being dangerous? I'd probably guess less between 3-4kpms.

Now, for all those who don't downshift, at what rpms do you like to re-engage your transmission? For those who do downshift, the same question.

betep

80% of my cars were manuals - I do use th engine to brake when I need to stop really fast, or I'm racing someone and need to slow down, but have to be ready to floor it at any sec, also How many extreme stops in a short period of time can You make with brakes only before they start fading?!? If You use engine+brakes, it's at least 1.5-2times more.

As for coasting in neutral - is wrong for 2 reasons:
1 - In neutral You have no control over the car - period.
2 - You waste gas when coasting in neutral.

Re-engaging:
Again - If I find myself in N, and I'm not in a rush I engage the top possible gear to meet ~1K rpm.
If I need to floor it - the lowest possible gear to get engine in it's sweetest spot ~3500rpm, hittig the accelerator before releasing the clutch to get the engine closer do desired speed.
So @50mph - in the first case would be 3rd gear and second 6th.

Just my opinion.

BEAR-AvHistory

Downshifting to save the brakes on the street it a boy racer wanna-be thing like the 150mph guys in the how fast thread.

Back in the bad old days when brakes & brake fluid were much less technically advanced, both in material & design, it was necessary on race cars to give the brakes less work load to help keep the brakes cool to reduce fade & keep the fluid from boiling. This ate up clutch & internal engine parts, thrust bearings, synchros ETC, but it did not matter as the engine would be torn down on a regular basis anyway.

For street operation the "pads are cheaper & easier to replace then clutch/engine parts" is the way to go.

Anyone who is driving a 6 spd with Brembo brakes on the street hard enough to require downshifting to keep them cool is a moron & a danger to everyone around them.

BEAR-AvHistory

I downshift as the speed comes down but not to use the engine as a brake so I am not putting drag on the engine.

I generally want to keep the RPM over a minimum of 2K/2.5K so the engine does not lug when I want to either hold speed or speed up in traffic.

rodneyc77

iTrader: (1)

sh!t... If I had a Manual... I would have the RPM below 4000 at any time...

SouthernBoy

There is no hard and fast rule to any of this. Suffice it to say that under normal driving conditions when downshifting, try to do this only when engine speed in the chosen lower gear will be below 4000 RPM once the downshift is completed. I say this because most people do not know how to properly downshift, so unless you do, avoid the higher RPM ranges.

SouthernBoy

I agree with your #1 and would advise to do this with caution. I do it when coming up to a red light that is not in the process of going green. And even then I wait until my speed is low.

As for #2, I would love to hear this explanation.

SouthernBoy

Barring extreme cases such as towing, racing, or living in a city like San Francisco, if you cannot get at least 100,000 miles out of a clutch, you are doing some terribly wrong. In fact, 200,000+ miles is more in order for this item. The same for synchronizers. Proper downshifting (and upshifting) will place extremely small amounts of wear on synchros.

Most of the boy racers that I see downshifting don't do it correctly anyway.

betep

Ok,
When You are in a gear and let off the gas - the vehicle fuel system shuts off, intil it hits idle rpm, so no fuel is used at all, at that point engine is turning from the wheels, as soon as You touch the gas, the system turns on.

if you put in neutral fuel is needed to maintain idle rpms.

blueracer17

We aren't driving golf carts, I highly doubt your claim on this one. The engine is sill running, therefore fuel is being consumed. When you are in neutral your mpg skyrockets since the car is moving and the engine is idling. If you coast with the engine engaged to the drivetrain you will actually coast less due to engine drag and get less feet per coast (made that one up). I coast down hills all the time. If you have any facts to back up your golf cart like statement, please share.
eric

betep

If You have instant mpg indicator on your car - try to coast in N and in gear and tell me what it shows. I'm talking about manual transmission. If You don't - ask someone who does. Then get back here and post. I'll back it up from there

black label

C'mon Southerboy, every one knows you waste gas when coasting in neutral, that's why when coasting I shut the engine off entirely

SouthernBoy

Ok, that sounds logical. Do you know this to be fact by chance? Just curious.

SouthernBoy

There you go. Solves everything.. all the problems, clutch included.

I hate cars

You have less control of the car when using high rpms to help slow the car. It throws off the balance of the brakes and hinders ABS performance. If your brakes are fading you need better brakes or you need to learn how to drive. Are you actually fading your brakes on public roads? I've driven very hard with the stock auto brakes and never faded them. If this is happening you should turn in your license.

Coasting in gear for long periods of time will get you better mileage than coasting in neutral. My miles to empty count backwards on long hills in gear. The injectors shut off fuel as long as you're abovr a certain rpm threshold, so even though the engine is spinning the fuel is off. In neutral, even though it's not much, it takes some fuel to maintain idle.

geekybiker

I dont downshift to decelerate to a stop. However I will go through the gears when traffic slows. IE on a highway and you'll be up and down in speed alot without coming to a stop.

GIXXERDK

If done right, nothing can really go wrong.. (rev matching)

teomcdohl

First post... welcome to the board! Thanks for your input to the post

gauravp123

I think we should all just drive bicycles.

teomcdohl

sure, but if we all drove bicycles, then i'd be asking the same question in reference to bicycles

GIXXERDK

Thank you, I'm a proud new owner of a TL

stillhere153

iTrader: (1)

well being that my tl is 5speed I can't really comment on the manual tl tranny, but I can say when I had my previous civics (which I learned how to drive manual in) I never used the breaks to slow down simply because I had a big ol canister muffler (apexi n1) and it used to sound crazy loud, so usually what I'd say is downshift only when the rpms drop to the point where you downshift and the car doesn't jerk or a better measure is where the rpms dont spike back up, if the rpms spike way back up trade in your car for an auto

SouthernBoy

If, when downshifting, your car jerks, as in an abrupt reduction in speed as though you just got into your brakes, you are not downshifting properly and need to correct your technique.

black label

I've been thinking about this. If the fuel shuts off (assuming you mean the pump shuts off), the engine would pull the fuel from the line through the engine. I believe this would leave an air bubble in the line which would cause an issue when the pump turned back on.

I hate cars

The injectors shut off.

stillhere153

iTrader: (1)

exactly what I ment

dookie320

I do this sometimes, not sure if it is good or bad...maybe someone can shed some light.

Sometimes as i am braking, lets say from 5th gear, as i get slower, i will push the clutch in and leave it there, shift to 3, then 2 all the while leaving the clutch in, then to N when Im near a complete stop.

Other times i will put it in N as i slow down but feel what if i need to get on it for some reason and im out of gear

Cyberdemon

If you downshift without rev matching you should be slapped. I won't downshift if I know I'm coming to a complete stop, in that case I will leave the car IN GEAR - up until the point that the gear hits idle and then take it out.

You should not need to downshift and bring your engine up to 6k every time you stop, but down shifting is as normal as upshifting - as long as you do it right.

And the person who said your engine doesn't use fuel when off throttle is correct. If your engine kept dumping fuel when you were off throttle you'd have some fun once that spark plug ignited.

I hate cars

We used to rev my friend's old (carbureted) van to redline, shut the ignition off, floor it and then hit the ignition right before the engine stopped. It made for some serious fun until we blew the catalytic convertor and mufflers to pieces.

TLin05

There are few absolutes here, although "coasting in neutral" when stopping the car from speed is absolutely wrong IMO. Doing that just puts undue strain on the brakes.

When cruising at a steady speed on level (or downhill) road, in the interest of fuel economy I am normally in the highest gear possible without "lugging" the engine below about 1,400 RPM. So at a steady 50, I'd be in 6th.

Then, if a stoplight turned yellow a few hundred yards down the road, I'd first let off the gas and coast, then double-clutch downshift to 5th, then possibly to 4th depending on my speed and remaining distance to the light, and then start gentle braking (without further downshifting, but still in 4th or 5th gear with engine braking engaged (i.e. clutch out).

I think this is a good compromise, and proper double-clutching downshifts do not impose any undue wear on mechanical components. This is a technique I only began using within the past two years (after 25+ years of driving manuals!) thanks to Southernboy's excellent descriptions of how to do it. But even without double-clutching, my last three cars (2000 Accord EX 5 spd, 1990 Accord EX 5 spd, 1983 VW GTI) all went well over 100,000 with original clutches and no issues. The VW and '90 Accord also went over 100,000 before needing brake work. The 2000 Accord was an exception in that it required rear disc pads at about 50,000, then fronts at 100,000.

gauravp123

awesome but you also live in centreville, VA....for us who drive in stop & go traffic ALL the time...us so called "new yorkers," cannot have our brakes live that long, no matter how soft you are on them etc

gauravp123

I guess that's what the derallier(sp) is for huh? LOL

SouthernBoy

You pretty much just described what I do most of the time as well. While I tend to consider 55 MPH my "shift-to-6th-gear speed", I see nothing wrong with 50 on a level road where the engine is not taxed.

As for your first paragraph, I worry more about not having control over the vehicle than prematurely wearing the brakes. Coasting at higher speeds can be downright dangerous.

Good for you! Oh, BTW.. I travel through Centreville every day during my work commute (in and out). I work in Fair Lakes. Lived in an apartment in Centreville for a year while I was between houses (sold one - had a new one built).