For some reason I'm always worried about "using up" my brake pads, so I ofen shift into lower gear with my AT for compression braking. I've heard people say this is bad for the transmission, and I've heard people say it's no problem. So which is it?
Compression braking: good or bad?
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Applying the brakes uses up friction material. Changing gears uses friction material also.
One is designed to be changed regularly, and with relatively little fuss. The other requires a few thousand bucks for an overhaul.
If you are descending a long hill, use engine braking.
If you are slowing for lights, use the brakes.
One is designed to be changed regularly, and with relatively little fuss. The other requires a few thousand bucks for an overhaul.
If you are descending a long hill, use engine braking.
If you are slowing for lights, use the brakes.
I agree Shannow.
If you like engine braking, get a manual trans. I have about 85,000 miles on my brakes and there's still almost 50% pad left! And I don't even downshift that much - never lower than 4th.
If you like engine braking, get a manual trans. I have about 85,000 miles on my brakes and there's still almost 50% pad left! And I don't even downshift that much - never lower than 4th.
Originally Posted By: Shannow
Applying the brakes uses up friction material. Changing gears uses friction material also.
That's what I've been thinking - but doesn't it shift from 1-2-3-OD after every stop anyway?
Applying the brakes uses up friction material. Changing gears uses friction material also.
That's what I've been thinking - but doesn't it shift from 1-2-3-OD after every stop anyway?
Brakes are cheaper than clutch bands. When your AT "downshifts" as you slow, it does it at a speed when it may be imperceptable...and therefore: minimal wear to the AT parts. It's not the shifting that wears out the friction material quickly, it's shifting under load...either accelerating or deccelerating, it doesn't matter...the load during the shift is what matters.
Don't do this on normal stops. Do use a lower gear instead of brakes if you are going down a long downgrade and would have to keep applying brakes to keep the speed under control.
Don't do this on normal stops. Do use a lower gear instead of brakes if you are going down a long downgrade and would have to keep applying brakes to keep the speed under control.
The AT loads the bands/guts more for compression braking than what it otherwise does coasting.
If you want to feel this, accellerate to 10 mph or just enough to stay in 1st gear, with the selector in drive. Then slam it down into manual 1st, you will feel the car start slowing down even without shifting.
OT, it's a federal safety standard to have engine braking avialable in ATs. If one's car goes OD-D-1, D may or may not do it, but 1 definately will. If you stick it in 1 at a high speed, you'll usually get 2nd by default, so if you lose your brakes on a mountain pass, go for the low right away. When it slows down to about 40 mph and hits 1st, it'll be suprising.
If you want to feel this, accellerate to 10 mph or just enough to stay in 1st gear, with the selector in drive. Then slam it down into manual 1st, you will feel the car start slowing down even without shifting.
OT, it's a federal safety standard to have engine braking avialable in ATs. If one's car goes OD-D-1, D may or may not do it, but 1 definately will. If you stick it in 1 at a high speed, you'll usually get 2nd by default, so if you lose your brakes on a mountain pass, go for the low right away. When it slows down to about 40 mph and hits 1st, it'll be suprising.
Titan and Shannow+1
Brakes are for slowing down, down shifting is for maintaining speed for more than a few seconds.
Brakes are for slowing down, down shifting is for maintaining speed for more than a few seconds.
The ATs in the three Taurii have anti-engine braking as they accelerate when going downhill so you're always on the brakes. The diesel in the pickup has some engine braking with the manual tranny (not like the +200 bhp with the exhaust brakes that are available), enough to get some plowing in snow / tire squealing on roads when down shifting as desired, which helps to overcome some of the limitations of ABS in certain conditions.
It is always good to be in the proper gear.
Engine braking with gasoline powered cars is only an emergency help, IMO.
You have 4-500 HP brakes, and 2-20 HP engine braking. $40.00 pads last 3 years. Trannys and over revved engines are thousands.
Engine braking with gasoline powered cars is only an emergency help, IMO.
You have 4-500 HP brakes, and 2-20 HP engine braking. $40.00 pads last 3 years. Trannys and over revved engines are thousands.
Kestas
Staff member
Don't try dropping it in first at high speeds with a Mercedes. There's no high-speed lockout and it's a sure way to grenade the transmission.
Using the transmission to stop the car on either an automatic or a manual is foolish and silly. Every shift causes wear on the clutches and synchronizers, and if you burn out the clutch or the transmission itself it costs thousands of dollars. If you go through 3 sets of $30 brake pads a year for 20 years you still won't be approaching the cost of a new transmission or a clutch on a modern car.
The only time I downshift is when I'm headed into a corner or know I'll be maintaining speed for a while, and when I do, I double-clutch it going down to save wear on the synchronizers. If I'm using 2nd, I'll double-clutch going up as well, since its an old transmission and the synchronizers are already quite worn. Often, if accelerating on level ground, I'll skip 2nd and go right to 3rd.
The only time I downshift is when I'm headed into a corner or know I'll be maintaining speed for a while, and when I do, I double-clutch it going down to save wear on the synchronizers. If I'm using 2nd, I'll double-clutch going up as well, since its an old transmission and the synchronizers are already quite worn. Often, if accelerating on level ground, I'll skip 2nd and go right to 3rd.
A lot of good information here, brakes are cheap. When I drive in the mountains with an MT and going down a steep hill, I will use the brakes to slow down, and then shift into a lower gear. The speed I shift into the lower gear is always the appropriate speed for the gear, and the transition is smooth, with little rpm gain. Once the clutch is engaged, the engine and brakes are used to slow the vehicle down, if it starts to rev too much for the gear I step on the brakes. I've driven with guys that will use the clutch to slow the car down, and that's not a good idea.
Frank D
Frank D
I'm not a fan of attention fatiguing down-shifting but I had seen no adverse affects. My THM 125 waits for the proper speed before shifting down, on the manual booklet it states any lower position could be selected at any speed. ATs road to engine torque limit is about x1.5 the engine to road limits (Alldata). So stressing the tranny more than the designation looks impossible. My worry, however, is the engine mounts. The mounts are finer in an AT with a longer stroke.
The freewheeling trannies are for the sole purpose of fuel economy as far as I know, this doesn't imply their reverse loading limits. Also I read sometime, somewhere that the freewheeling prevents sudden (or continuous) rpm changes so accounts for the engine longevity (for what it woths).
Maintaining speed on the longest descends is an art. Pull up the emergency brake one or two clicks if helps with the pedal, with front dip or for keeping the fronts cooler.
After all, I hardly ever downshift. I never do hard downshifts, not just for the egine mounts it is also wiser to brake with four wheels and keep the car suspended as level as possible on all suspension corners, so you'd still have suspension capacity in the fronts if a pothole or unexpected bump shows up.
The freewheeling trannies are for the sole purpose of fuel economy as far as I know, this doesn't imply their reverse loading limits. Also I read sometime, somewhere that the freewheeling prevents sudden (or continuous) rpm changes so accounts for the engine longevity (for what it woths).
Maintaining speed on the longest descends is an art. Pull up the emergency brake one or two clicks if helps with the pedal, with front dip or for keeping the fronts cooler.
After all, I hardly ever downshift. I never do hard downshifts, not just for the egine mounts it is also wiser to brake with four wheels and keep the car suspended as level as possible on all suspension corners, so you'd still have suspension capacity in the fronts if a pothole or unexpected bump shows up.
What about switching off the od?
don't do it unless you coasting down mountain paths. and even in that scenario, use the brake first than down shift slowly and keep it into 3rd as 2nd will be too low a gear for that speed, which will wear out the trans and engine.
brakes is cheap and there are ways to cool down brakes during prolong use. i have been on a same set for my accord since new and it still has 80% life left after 6 years and 70k miles.
brakes is cheap and there are ways to cool down brakes during prolong use. i have been on a same set for my accord since new and it still has 80% life left after 6 years and 70k miles.
"Using the transmission to stop the car on either an automatic or a manual is foolish and silly."
On gravel, snow, ice covered snow, etc., ABS will happily let you blow thru stop lights and signs, unless someone's car is there to stop you. With an auto you typically have to rely upon braking which is ABS controlled these days. Don't count on rear wheel emergency brakes to stop a 7k to 9k lb truck on a hill. A manual tranny and 4wd seem to help when ABS isn't helping at all.
On gravel, snow, ice covered snow, etc., ABS will happily let you blow thru stop lights and signs, unless someone's car is there to stop you. With an auto you typically have to rely upon braking which is ABS controlled these days. Don't count on rear wheel emergency brakes to stop a 7k to 9k lb truck on a hill. A manual tranny and 4wd seem to help when ABS isn't helping at all.
I know a lot of people who grab neutral with an automatic transmission when braking and I just think that is so pointless.
I know on Fusions, you have your choice of L or D, and when you select L, it will start you in second gear, and not shift above fourth and it is supposed to be used for better engine braking/ice takeoffs/etc.
I know on Fusions, you have your choice of L or D, and when you select L, it will start you in second gear, and not shift above fourth and it is supposed to be used for better engine braking/ice takeoffs/etc.
I wouldn't down shift an automatic but I drove tractor trailers combos for years and I did most routine braking with compression. With transmissions like those, you have to match the rpms to down shift or upshift and the clutch generally isn't used except from a stop. Although I do use the clutch in my car, I shift the same way. If you match rpms so there is no wear on the clutch it's all good. My front brakes on my '97 Camaro had over 84K on them and they weren't even 2/3 worn out.
I think what most people are missing is an auto usually freewheels by way of a sprag(one way)clutch when decelerating with the shifter in OD. Doesn't matter what gear it's in, it's as if the engine and trans are not coupled. When you manually downshift, a clutch or a band is applied to give you engine braking.
No way would I use my weak Honda trans for engine braking around town but I do downshift to 4th going down the Grapevine and don't touch the gas or brakes for nearly 15 minutes. Doing this also makes sure I'm in fuel cut so the car uses no fuel for the entire decent.
No way would I use my weak Honda trans for engine braking around town but I do downshift to 4th going down the Grapevine and don't touch the gas or brakes for nearly 15 minutes. Doing this also makes sure I'm in fuel cut so the car uses no fuel for the entire decent.
Originally Posted By: ikeepmychevytoo
Maintaining speed on the longest descends is an art. Pull up the emergency brake one or two clicks if helps with the pedal, with front dip or for keeping the fronts cooler.
Gotta be kidding....!
Maintaining speed on the longest descends is an art. Pull up the emergency brake one or two clicks if helps with the pedal, with front dip or for keeping the fronts cooler.
Gotta be kidding....!
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