hi,
just curious.
is it bad to down shift while stopping?
if it is bad, then why doesn't mb allow us doing that?

 

For the most part, downshifting an automatic is useless....it just over works your engine, transmission and rear axle. Essentially, the auto was designed to do all this for you.
Manual downshifting is highly recommended as it helps to save brakes, slow the car for turns and control the vehicle (something the auto does without human intervention). While it takes practice to get it right, the other benefit is less brake dust...and thats always a good thing.

 

so is it bad for the engine or anything else?

 

mb does control it to a certain extent, you're not gonna be able to shift into first at 60mph, but in certain situations it's nice to be able to downshift and have that extra power.

 

Is it within the break-in period that manually downshifting is sorta frowned upon?

Sometimes while in traffic I keep the gears low just because it's easier to speed up and slow down with traffic that way.

Around turns (you know, when the traffic light's yellow), it's good to jam it into a lower gear and slam on the accelerator. If I don't make the tires squeal at least once a week, it's not a good week.

 

Even with a manual, it's not a good idea to slow the car by downshifiting (as opposed to using the brakes). Brake pads are relatively cheap, and the brakes can be applied relatively smoothly by even the most beginning driver.

On the other hand, slowing the car by downshifting puts additional wear on the clutch and drive train components, and if not done very will, will impart the dreaded 'head bob' on all passengers, with each shift.

In short, it's much more economical to use the brakes to slow the car, and it's easier on the passengers. Downshifting can be a help if the brakes fail, but even in this case, applying the parking brake will slow the car faster than downshifting.

Typically, the reason that you would downshift WHILE braking, is to ensure that you are in the correct gear to exit the approaching corner. Downshifting while braking for a stop sign is a waste of energy and clutch material.

 

There's the answer right there. This applies to both automatics and manuals.

 

Oftentimes I'll downshift on a long highway off-ramp. Though I'm not using the brakes, the car is slowing down. I'll gently hold the gas to keep the RPMs from falling, clutch in (though usually not needed), shift into 5th or 4th, and clutch out. This works so smoothly that it's not even felt (especially 6th to 5th becuase they are so close).

 

This is just SO amazingly wrong, I can't believe I'm reading this. I'm guessing you've never driven a manual trans car in a mountainous area or on a highway where slowing is more gradual.

Downshifting a manual trans car is an act of physics. If you slow from ...say... 65 to 45, would you use the brakes and bog the engine in 6th rather than downshift to 5th then 4th? When going down hill, you should never rely on only the brakes to maintain speed, but downshift to keep a constant control of the vehicles speed.

Even on a racetrack, downshifting is more desirable than braking into a corner.... you can throttle up as you approach the apex in a lower gear...and beat the guy that hits the brakes....every time.

 

I have to respectfully disagree with the last post.

If you read the first post, the question is: 'is it bad to downshift while stopping?' Not, 'is it OK to slow the car by engine braking?'

Of course, no answer is correct for all situations. When racing, downshifting is always prefered - but for the purpose of being in the proper gear when you reapply throttle, not for the purpose of braking.

Downshifting acts only on the rear wheels (on MBs), and can only slow the car at the rate of engine braking - limited by rear tire traction. When braking hard (as when racing), approximately 80-90% of the work is done by the front tires. This means that the most braking that can be done by downshifting is 10%-20% what is done by using the brakes normally. Not the best way to beat the next guy to the apex.

In your mountain example, I would both brake, AND downshift. Yes, holding a lower gear (to avoid riding the brakes) is preferential in the mountains - however MB supplies brakes on their vehicles intended to slow the cars repeatedly from 200kph speeds on the autobahn. The brakes will not fade slowing from 6th to 4th gear.

No flames here, only clarification of my comments. (Yes, I do downshift when driving a manual - but again, not for the purpose of slowing the car)

 

Compared to a clutch brakes are cheap. The brakes are designed to bring the car to a stop. They are not designed to be used for miles and miles on a downhill, this is where a downshift is used. If you are racing around you would also downshift into a turns apex to use engine power out of the turn. Don't waste the clutch if you don't have to. You also wear the rest of the drivetrain.