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Brakes or Downshift to slow down


coolnesss

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I often downshift to slow down a little when I'm driving in hills at speeds under 30mph or so, which I do alot because of where I live.

Another motorhead told me that its better to brake.

I said brakes wear out fast then.

He said: yeah, but automatic transmissions cost 3 grand or more to rebuild.

Are there any opinions on what is the best practice?

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When driving in hills, depending only on brakes may cause the brakes to overheat and become ineffective; in that circumstance downshifting makes sense.

Bruce

2016 Cadillac ATS-V gray/black

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With normal driving in a automatic you should never really have to move out of Drive or O/D.

I drive my manuals and I use them to assist. I dont recommend it with a automatic though unless needed.

The wear on the brakes will not be that much more to really notice.

I would rather change brakes then to worry about damaging or having excessive wear in the transmission.

 

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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One big hill near Birmingham, AL I always shift to a lower gear to keep the brakes from overheating....One big hill in Tennessee too. The hill in Tennessee actually has emergency decel lanes for trucks with failed brakes. 

If your on something like Mount Washington......you better have it in a lower gear.....or you will lose the brakes totally. 

Cars with smoldering brakes on the side of the road are common there. 

Even using a lowest gear....you may still have to stop and let the brakes cool off. 

Some cars are actually banned from driving up. Some Hondas and Saturns included. Honda now uses 'Mt Washington decent' as a standard for transmission design. 

https://mtwashingtonautoroad.com/drive-yourself/auto-road-vehicle-restrictions

Also called 'engine braking'.

 

 

mt washington.JPG

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I should have been clearer ----

So, if the hill isn't long enough to cause the brakes to overheat - as a general rule, does using an automatic transmission downshift to control speed down a hill cause premature wear?  I'm driving a 2016 ATS V6 Coupe.

Approximately 1/3 of my driving is done in hills, and typically I'm going down a hill more or less 5 or 7 blocks long, not on long grades.

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I would not be adverse to using the transmission to slow and maintain my vehicle speed on an extended downhill section though I would think this would be an exception rather than the rule if braking was adequate and not sustained.  (kind of what is stated in most driver's manuals; sustained downhill should downshift accordingly)  Excerpt from XT5 manual:   • Know how to go down hills. The most important thing to know is this: let your engine do some of the slowing down. Shift to a lower gear when you go down a steep or long hill. 

Chuck

'17 XT5, '04 Bravada........but still lusting for that '69 Z-28

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I agree with Logan's reply above, occasional downshifting to gain control without overheating the brakes is not going to hurt the transmission.  Think about it the torque created from a stand still pulling away from the curb.   The downshift causes the engine to put a drag on the forward motion increasing the RPM.   I would be very careful of 2 things however, 1) be careful that the downshift does not push the rpm up so high that it goes into redline floating the valves causing damage and 2) on wet or slick ground too much engine braking may cause a skid something very easy to do with a manual transmission on wet ground.  

I will say this however, when I am driving aggressively coming into a turn, I will downshift, to gain more control, if I lift my foot, I slow, if I mash the accelerator, I blast out of the turn. It is important to realize that braking this was provides no warning to any vehicles behind you as the brake lights do not illuminate and you could surprise someone and cause an accident.   I have done it with TH350, TH400, 4L60E and 4T80E.  I will not however do that with a questionable high mileage transmission nor do I do it often.  It's part of my WOT procedure 😃

This article echos what Logan stated above:

Driving Downhill

If you’re driving downhill for long periods, it’s crucial that you don’t overuse the brakes to slow the car. As the car gains momentum with the force of gravity, more braking is needed to slow it, meaning that the brakes can start to ‘fade’ through overheating and reduced friction – which is the last thing you want driving down a steep hill.

In this situation, engine braking can be a real lifesaver; that’s why you always see signs at the top of steep hill telling you to change into a low gear. Third or even second gear will help the car stay at a steady speed, and will allow you to just lightly touch the brakes to slow your descent – meaning they aren’t subjected to any punishing wear.

Reference: https://www.holtsauto.com/redex/news/what-is-engine-braking-and-can-it-harm-your-car/#will

Happy and Healthy New Year everybody!

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One more thing I might add.  On the topic of brake fade due to heat.

In 2009 when Bruce and I attended Bob Lutz's CTS-V Challenge, I was shocked how many drivers were having to park their cars due to high temperature brake fade, and how their performance was degraded due to brakes, while the CTS-Vs exhibited no brake fade throughout the entire day while being driven hard by seasoned race car drivers and enthusiasts, with its Brembo system.  

I recently obtained Bob Lutz's contact information and I am in the midst of thanking him for such a wonderful experience.  I was awe struck when I saw him and clammed up tighter than an oyster and regret not walking over and shaking his hand.   I have always admired Mr. Lutz's grit, history, honesty, determination and love of GM and the automobile industry.   I will post a link later to my drop box of a video of Bob Lutz speaking to the press that day, its inspiring.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Lets see if this works, this is a link to a folder in my dropbox of the 2009 CTS-V Challenge, a brief Bob Lutz spot and a few CTS-Vs flying by.   Keep in mind the CTS-Vs had no brake fade all day long

https://www.dropbox.com/sh/d8o3uj5466184yg/AACoOk6Ck_RMc9iSrAQK2P0ga?dl=0

 

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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13 hours ago, Bruce Nunnally said:

yes that worked.  Hard to believe that's been over 10 years ago.

It certainly is

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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