# Downshifting to slow down in a diesel - Is it hard on components?



## MRO1791 (Sep 2, 2016)

I use low gear all the time, big trucks rely on it. My Dodge truck has the exhaust brake and it's recommended to be used. I would say as long as you are not going fast, like over 30, and shifting to 1st, you should not be doing any harm. This transmission has been used on many other cars and has a solid reputation, the engine should have no issues. Hope that helps.

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## au201 (May 18, 2013)

Not a problem. The computer won't let you do anything harmful to the engine or transmission. 


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## boraz (Aug 29, 2013)

its fine, i have a 10% 7 mile long hill on the way to work

3rd gear, 4000 rpm hold me at 100kmh no brakes


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## Cruze2.0TD (Feb 12, 2014)

Thanks guys!  I figured it wasn't harming anything, but thought I'd make sure.


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## jblackburn (Apr 14, 2012)

Just don't go to 1st downhill to help you stop. 2nd is fine; the 2->1 shift is typically pretty rough on the internal clutches.


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## Cruze2.0TD (Feb 12, 2014)

jblackburn said:


> Just don't go to 1st downhill to help you stop. 2nd is fine; the 2->1 shift is typically pretty rough on the internal clutches.


Yeah I dont ever use it to help me stop.I really just use it to maintain speeds on a steep hill or slow down a bit if I'm coming down a hill and the speed limit is dropping.


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## ChevyGuy (Dec 13, 2014)

Downshifting for hills - fine
Downshifting because you enjoy feeling like Speed Racer - just remember, racers typically rebuild their cars every season. If not every race.


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## ChevyGuy (Dec 13, 2014)

BTW, I'm not sure about the Diesel, but on my Cruze, I've noticed that after about 5-7 seconds of significant braking, the automatic transmission will downshift by itself.


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## justin13703 (May 2, 2016)

ChevyGuy said:


> BTW, I'm not sure about the Diesel, but on my Cruze, I've noticed that after about 5-7 seconds of significant braking, the automatic transmission will downshift by itself.


It will, but this is because the converter is locked and by slowing down the rpms go low enough to make the car want to downshift. The op is asking about using the engine at the same time as or before the brakes, to remove wear from the brakes. Which is completely fine and works relatively well on a diesel.


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## CruzeDan (May 17, 2015)

au201 said:


> Not a problem. The computer won't let you do anything harmful to the engine or transmission.
> 
> 
> Sent from AutoGuide.com Free App


Bingo. The computer will deny shifts that will cause harm to the engine. You will get a beep and a message on the DIC: SHIFT DENIED.


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## Cruze2.0TD (Feb 12, 2014)

CruzeDan said:


> Bingo. The computer will deny shifts that will cause harm to the engine. You will get a beep and a message on the DIC: SHIFT DENIED.


Yeah I know the computer will prevent you from damaging the car, I was more so wondering if it'd cause premature wear. I'm not nearly as concerned about instant damage, but the general consensus seems to be that it's fine todownshift to slow the car down


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## LiveTrash (May 24, 2015)

justin13703 said:


> It will, but this is because the converter is locked and by slowing down the rpms go low enough to make the car want to downshift.


Not sure about the gassers, but even without the RPM's being at the bottom end, if you're going down a hill and begin slowing down, it will detect it and, in my experience anyway, downshift even if the RPM's are at 1500 or more to assist in slowing down. I really enjoy driving the car because of things like this. Makes it unique.


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## justin13703 (May 2, 2016)

LiveTrash said:


> justin13703 said:
> 
> 
> > It will, but this is because the converter is locked and by slowing down the rpms go low enough to make the car want to downshift.
> ...


Well another thing that it seems like they do, at least on the diesels, is change upshift and downshift points depending on how you are driving the vehicle.

For example, when I've been driving the car pretty aggressively, it does seem very quick to downshift when on the brake. But when I've just been cruising, it doesn't do this nearly as soon.

Either way, he is wanting to use the engine to slow the vehicle before using the brake. Which won't hurt anything.


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## jblackburn (Apr 14, 2012)

LiveTrash said:


> Not sure about the gassers, but even without the RPM's being at the bottom end, if you're going down a hill and begin slowing down, it will detect it and, in my experience anyway, downshift even if the RPM's are at 1500 or more to assist in slowing down. I really enjoy driving the car because of things like this. Makes it unique.


My Toyotas did that, but I did notice that driving a Gen 2 Cruze through the mountains that the transmission programming is awesome about downshifting when you're on the brakes - sometimes 1-2 gears if needed. Maybe the first gen automatics did that too, never noticed.


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## diesel (Jun 8, 2013)

I've always used the transmission to slow the car down since day 1. Doesn't seem to have hurt anything, however I am not sure if that contributed to the cold flaring on the 2-3 or 4-5 shift I have now. I would tend to think that was more of a lack of timely fluid changes than the downshifting.


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