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Discussion Starter #1
My son and I have had an ongoing discussion about downshifting when coming to a stoplight/sign etc. I downshift through the gears trying to rev match as much as I can before I brake to a stop. What is the general consensus on this? Have I been doing this wrong all these years? Should I hit neutral and brake? Just wondering.:confused: Jarrell
 

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My son and I have had an ongoing discussion about downshifting when coming to a stoplight/sign etc. I downshift through the gears trying to rev match as much as I can before I brake to a stop. What is the general consensus on this? Have I been doing this wrong all these years? Should I hit neutral and brake? Just wondering.:confused: Jarrell
A five or four speed transmission was made to do that. I guess I never thought about it before, but yes, I downshift before applying the brakes. Saves on the brakes too.

Bob
 

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Mark Donahue used to say that the engine works hard enough doing what it is supposed to do, that it should not have to be used as a brake as well. At Skippy School (Skip Barber), they teach you to brake before and going into a turn, then downshift through and to the proper gear for acceleration out of a turn. Of course, they do not have stop lights and railroad crossings during races, so the situation is a bit different.
 

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Discussion Starter #5
Mark Donahue used to say that the engine works hard enough doing what it is supposed to do, that it should not have to be used as a brake as well. At Skippy School (Skip Barber), they teach you to brake before and going into a turn, then downshift through and to the proper gear for acceleration out of a turn. Of course, they do not have stop lights and railroad crossings during races, so the situation is a bit different.
I do that of course, did in fact tonight when I wanted to check my lights for the Nationals trip. (had a blast too.) I always downshift before the curve so I have ample RPMs to power out, or slow down. I was just speaking of rev matching to stop at lights/stop signs etc. Thanks for the reply, Jarrell
 

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Über Genius
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Brakes are easier to replace than clutches or thrust bearings.
 

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I would argue that being in the proper gear at all times when surrounded by distracted drivers is just driving defensively. Twice I have accelerated out if an accident that happened next to me. Once was in NY brothers brand new Boxter when a stopped police car was rear ended by a drunk driver.
 

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Just Some Dude in Jersey
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Brakes are made for slowing and stopping, engines are made for moving and accelerating. Just because you CAN use your engine to slow down, doesn't mean it's a good idea.

One thing I have noticed over the 12 years I've been on this site is that when someone finds a long lost GT in a barn that is a manual, the engine/gear box/rear axle is often shot, whereas if it was an automatic the engine/tranny/rear axle is usually in pretty good shape.

When you are in gear with a manual tranny, every part of the drive train is dead locked together with no slippage. The main potential source of friction or resistance is the compression. That compression works directly on the pistons/rings/valves/head gasket. Metal on metal is a lousy braking surface and those parts are cumbersome to replace. Brake shoes are easy to replace.

With a manual, every road bump gets transmitted straight to your pistons/gears/rings. There's no buffer to deaden that force, like there is with an auto tranny. With a manual, every time your foot eases off on the gas pedal, even just a little bit, the forces in the drive train get reversed and the leading edges of the various parts, that normally only experience load in one direction, now experience friction and force against their trailing edges. That means more wear where you least want it.

It's different with tractor trailers with diesels. A trucker and I were talking about his recent engine rebuild and he said that it should last 1,000,000 miles and if it doesn't it was a bad rebuild. Diesels have massively more resistance due to much more compression, compared to gasoline engines. The air being compressed is taking the lion's share of the load when engine braking. Diesels are also constructed much more strongly than gasoline engines and can handle much more load.

But I still don't think that trucks should engine brake either. I work in an industrial park next to a major highway and I hear trucks engine braking to enter the area all day. Some guys engine brake, some guys don't. Just listening to the sound of a tractor trailer engine braking tells me that it can't be a good thing. Rpms surge, gears grind, and all sorts of pops and bangs come out the exhaust. That can't be a good thing.

:veryhappy
 

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Mark Donahue used to say that the engine works hard enough doing what it is supposed to do, that it should not have to be used as a brake as well. At Skippy School (Skip Barber), they teach you to brake before and going into a turn, then downshift through and to the proper gear for acceleration out of a turn. Of course, they do not have stop lights and railroad crossings during races, so the situation is a bit different.
Keeping in mind that at Skippy School the gearboxes are different from your road-going machine, requiring that you double-clutch on the downshift while you are doing the heel-and-toe braking routine. Now that is fun to practice while you are slowing down for the traffic light!
 

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RunOpel
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A very interesting topic to discuss, thanks Jarrell. I would agree with the others about less wear on the engine and easier to replace brakes. With that said though, it is fun :yup: to go through the gears IMO.
Dan
 

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Discussion Starter #14
A very interesting topic to discuss, thanks Jarrell. I would agree with the others about less wear on the engine and easier to replace brakes. With that said though, it is fun :yup: to go through the gears IMO.
Dan
Dan, Gordo, and all, you are right. There will be less wear on the engine and it is easier to replace brakes. I'll have to give this one to my son. Use the brakes and not the engine to slow down. Gordo, your explanation was really spot on and I had never looked at it in such a manner as you pointed out. Just curious about how others felt and got some great replies. Thank you all, Jarrell
 
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Discussion Starter #15
An interesting discussion, I wonder if you put the car on axle stands too after use to avoid flat spots and take the stress away from the springs and shocks ?:veryhappy
Now this is a topic for another late night discussion.:D Does make sense for long term storage. Jarrell
 

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I can see the argument for less driveline wear but in my 45 years of driving sticks I've never broken any part of a driveline or even worn out a clutch. But then I also have never abused drivelines by burning rubber or dropping clutches. Seeing someone intentionally doing burnouts is somewhat distressful. Must be the engineer in me not liking equipment being abused.
 

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Just Some Dude in Jersey
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An interesting discussion, I wonder if you put the car on axle stands too after use to avoid flat spots and take the stress away from the springs and shocks ?:veryhappy
Why as a matter of fact I do! I also glue old tires onto my new tires so that I don't wear out the tread. And if the sun is in my eyes when I'm driving, I drive backwards so that I don't wear out my sunglasses. I also keep my engine running 24/7 so that I don't wear out my starter.

:lmao:
 

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Opel Rallier since 1977
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The compression braking torque on the drivetrain for these engines is tiny compared to the accelerating torque from the power. Plus any wear on things like rod bearings and gears and wear surfaces in the trannie is going to be on different areas of the components than for acceleration.

You're putting more wear on the shifter linkage and synchros than anything else. But you will put more wear on those parts if you live in an urban area and have to shift a lot. IMHO, don't worry about it.
 

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Just Some Dude in Jersey
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I can see the argument for less driveline wear but in my 45 years of driving sticks I've never broken any part of a driveline or even worn out a clutch. But then I also have never abused drivelines by burning rubber or dropping clutches. Seeing someone intentionally doing burnouts is somewhat distressful. Must be the engineer in me not liking equipment being abused.
Where I live, you'd have to shift 150 times just to go 5 miles. Clutch, shift, rev, feather the clutch, lock in, accelerate, repeat 150 times. Sheesh! I prefer: Accelerate, slow, stop, repeat. I've got beers to drink, I don't have time to work all those pedals and levers, I might spill my beer!

:lmao:
 

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Brakes are made for slowing and stopping, engines are made for moving and accelerating. Just because you CAN use your engine to slow down, doesn't mean it's a good idea.

One thing I have noticed over the 12 years I've been on this site is that when someone finds a long lost GT in a barn that is a manual, the engine/gear box/rear axle is often shot, whereas if it was an automatic the engine/tranny/rear axle is usually in pretty good shape.

When you are in gear with a manual tranny, every part of the drive train is dead locked together with no slippage. The main potential source of friction or resistance is the compression. That compression works directly on the pistons/rings/valves/head gasket. Metal on metal is a lousy braking surface and those parts are cumbersome to replace. Brake shoes are easy to replace.

With a manual, every road bump gets transmitted straight to your pistons/gears/rings. There's no buffer to deaden that force, like there is with an auto tranny. With a manual, every time your foot eases off on the gas pedal, even just a little bit, the forces in the drive train get reversed and the leading edges of the various parts, that normally only experience load in one direction, now experience friction and force against their trailing edges. That means more wear where you least want it.

It's different with tractor trailers with diesels. A trucker and I were talking about his recent engine rebuild and he said that it should last 1,000,000 miles and if it doesn't it was a bad rebuild. Diesels have massively more resistance due to much more compression, compared to gasoline engines. The air being compressed is taking the lion's share of the load when engine braking. Diesels are also constructed much more strongly than gasoline engines and can handle much more load.

But I still don't think that trucks should engine brake either. I work in an industrial park next to a major highway and I hear trucks engine braking to enter the area all day. Some guys engine brake, some guys don't. Just listening to the sound of a tractor trailer engine braking tells me that it can't be a good thing. Rpms surge, gears grind, and all sorts of pops and bangs come out the exhaust. That can't be a good thing.

:veryhappy




I don't agree with this statement at all. How many people do you know have had their engines blow up (newer or older vehicles) because their transmission where manuals and not automatic? Matter a fact I know of many, many, many automatics that have prematurely failed and very few manuals that have. Obviously their alot of variables in this, but all in all, a manual transmission does not mean much more potential driveline failure. Just my 2 cents.
 
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