Compression braking: good or bad?

[mstrjon32]

Originally Posted By: 1sttruck
"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.


You're right, I should have qualified that with "under ideal conditions". There are times it is useful to downshift solely to slow down, such as for the reasons you stated. Although I will say that capable as it is, it takes me more distance to stop my Jeep 4x4 on a slippery/snowy surface by downshifting and intelligently using the non-ABS brakes than it does to just slam the brake down as hard as I can in my ABS Monte Carlo; both cars with all season tires.

I'm sure the newer Jeep models are more user- (idiot?) friendly.

 

[Audi Junkie]

My Hondas downshift automaticly when decending hills.

 

[SHOZ]

I use engine braking all the time in my '97 SHO. But I also consider the tranny a wear item and change them out myself.

FWIW I have programmed the car to maintain the TC locked up and shut off the fuel to the injectors when coasting for more than 4 seconds.

 

[lasmacgod]

Wow. This thread is interesting to say the least. I have never personally seen a manual transmission and/or clutch failure that was caused by down-shifting performed properly. Riding the clutch, resting the hand on the gear shift lever (this applies mostly to trucks with the longer, swept-back shift levers, think 80's four-speed full size trucks), and improper/lack of maintenance. Down-shifting will cause damage when drivers attempt to "float" the gears without knowing what they are doing, or slipping the clutch to slow the vehicle. Depress the clutch pedal, gently change gears, release the clutch pedal quickly and fully - the less time the clutch slips the better off it is. I've heard from some sources (not sure if I believe it, take it for what it's worth) that down-shifting actually increases clutch life by changing the direction of the slippage. Supposedly this keeps the clutch disc fibers "flexible" and prevents glazing. Like I said, take it for what it's worth.

As far as down-shifting being a distraction . . . if you are not used to doing it, maybe so. If you are like me and used to doing it, it is second nature - I don't think about it and don't even realize I am doing it. When I drive a vehicle with an automatic, I'll catch myself reaching for a shift lever that is not there. (This did cause a little issue with the wife . .. she thought I was being sweet/romantic/whatever the first time my hand ended up on her lap while subconciously searching for a shift lever . .. then I suffered an acute dumba$$ attack and told her what really happened. I went from Lucky Me to Not Tonight.)


As far as automatics go . . . I only down-shift those in certain situations. The biggest problem I see with manually shifting an automatic transmission is that the typical automatic shift lever and linkages are not meant for constant use like the shift lever and forks in a manual.

 

[slipperysam]

Brakes are cheaper than trannies

SS

 

[Axe Man]

Originally Posted By: lasmacgod
Wow. This thread is interesting to say the least. I have never personally seen a manual transmission and/or clutch failure that was caused by down-shifting performed properly. Riding the clutch, resting the hand on the gear shift lever (this applies mostly to trucks with the longer, swept-back shift levers, think 80's four-speed full size trucks), and improper/lack of maintenance. Down-shifting will cause damage when drivers attempt to "float" the gears without knowing what they are doing, or slipping the clutch to slow the vehicle. Depress the clutch pedal, gently change gears, release the clutch pedal quickly and fully - the less time the clutch slips the better off it is. I've heard from some sources (not sure if I believe it, take it for what it's worth) that down-shifting actually increases clutch life by changing the direction of the slippage. Supposedly this keeps the clutch disc fibers "flexible" and prevents glazing. Like I said, take it for what it's worth.

As far as down-shifting being a distraction . . . if you are not used to doing it, maybe so. If you are like me and used to doing it, it is second nature - I don't think about it and don't even realize I am doing it. When I drive a vehicle with an automatic, I'll catch myself reaching for a shift lever that is not there. (This did cause a little issue with the wife . .. she thought I was being sweet/romantic/whatever the first time my hand ended up on her lap while subconciously searching for a shift lever . .. then I suffered an acute dumba$$ attack and told her what really happened. I went from Lucky Me to Not Tonight.)


As far as automatics go . . . I only down-shift those in certain situations. The biggest problem I see with manually shifting an automatic transmission is that the typical automatic shift lever and linkages are not meant for constant use like the shift lever and forks in a manual.




I couldn't have said this any better. Totally agree 110% !!!