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  #1  
Old February 20th, 2004, 14:56
lapaul lapaul is offline
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does downshifting with an auto trans to slow or brake hurt the trans

Does downshifting with an auto trans to slow down on steep hills, or even to help stop suddenly with large (say 35') tires do any damage to auto transmission
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  #2  
Old February 20th, 2004, 17:54
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nitrogt101 nitrogt101 is offline
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I'm not sure, but I want to know too because I do that in traffic that way I'm not slamming on the brakes all the time.

BTTT for ya.
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Old February 20th, 2004, 17:56
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imma honky imma honky is offline
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Maybe I'm just stupid, but how do you downshift on an auto?
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  #4  
Old February 20th, 2004, 18:16
kirby kirby is offline
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You gotta be kidding me?



Quote:
Originally Posted by imma honky
Maybe I'm just stupid, but how do you downshift on an auto?
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  #5  
Old February 20th, 2004, 19:38
lapaul lapaul is offline
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You move the lever from drive to third or to 1-2, it revs the engine and slows you down

the question is does it do anything bad to the transmission when you do it at speed that revs the engine or can the trans absorb shifting under any conditions

]Maybe I'm just stupid, but how do you downshift on an auto?[/QUOTE]
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  #6  
Old February 20th, 2004, 19:40
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imma honky imma honky is offline
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Quote:
Originally Posted by lapaul
You move the lever from drive to third or to 1-2, it revs the engine and slows you down

the question is does it do anything bad to the transmission when you do it at speed that revs the engine or can the trans absorb shifting under any conditions

]Maybe I'm just stupid, but how do you downshift on an auto?
[/QUOTE]
Thats what I thought you meant....but I've never heard of anyone doing that in an auto to slow down...
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  #7  
Old February 20th, 2004, 20:57
PaulJ PaulJ is offline
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In general, things wear out when they are used for slowing down. I'd rather concentrate more of that wear and tear in the brakes than in the tranny. Brakes are simpler and cheaper to refresh. If you're dealing with a long downhill grade that is going to overheat the brakes, then it becomes desirable to take advantage of engine braking.
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  #8  
Old February 20th, 2004, 21:00
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RichP RichP is offline
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I have, I've done it with military 5 tons carrying heavy loads and a trailer behind me going down hills when I want to creep around an approaching corner or ford a stream/river. I have also done it in M113 APC's and M2 bradleys a time or two. Personally in a car it's a PIA to me BUT my wifes olds has 1-2-D-OD and when heading for the interstate I keep it in D, once on the interstate it goes into OD and then back into D when going back on local roads. When it's in OD it hunts too much between D [3rd] and OD [4th] on local roads.
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Old February 20th, 2004, 21:20
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Out here when the roads are covered in snow I'll downshift alot going down hills so I dont lock up the brakes and go through the red lights. I've been doing this for about two years now and haven't had any tranny problems.

I did read somewhere though that this will prematuraly wear out the clutch packs inside the tranny. I dont doubt this but from what I've heard, at least about AW4s, is that it would take an aweful lot of abuse to wreck one.

Dean
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  #10  
Old February 20th, 2004, 21:51
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Dropping from OD (4th) back to 3rd for compression braking on downhills isn't going to harm anything. In fact, the auto tranny in the new V-8 Grand Cherokees is programmed to do this without user intervention.

As for dropping back to 2nd, that should only be done when vehicle speed is within the range when you would normally be in 2nd gear. If you drop down into 2nd at highway speeds, it has to be rough on the tranny. If you're talking about crawling along a trail at 5 MPH, by all means use low gear to get compression braking. In fact, there are several conversions floating around Jeep forums for a simple switch to lock the AW-4 into 1st gear specifically for this purpose.
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  #11  
Old February 21st, 2004, 02:48
Mercenary Mercenary is offline
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This is neither here nor there, but I bought a 79 Chevy 3/4 ton pick-up where the owner would downshift all the time in order to slow down. That tranny is still going strong (turbo 400) and its still the original. So, I dont think downshifting your tranny to slow a bit will hurt anything at all as long as you arent being silly like throwing it into 2nd at 50 mph. 4th-3rd at speed= no big deal.
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  #12  
Old February 21st, 2004, 04:23
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Hawaiian Style Hawaiian Style is offline
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I'll agree. Downshifting from D to 1-2 at reasonable speeds is fine. It's great for going down steep hills and such.
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  #13  
Old February 21st, 2004, 08:26
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massxj massxj is offline
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with most newer auto trans they wont let you down shift to soon they will hold out til you slow down or till the presure in the tran drops a bit my old f250 would let you drop into 2nd till you slowed down you could shift it but it would wait
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