Automatic Transmission 2-Speed thru 10-Speed GM Autos | Converters | Shift Kits
Sponsored by:
Sponsored by:

Shifting an auto

Thread Tools
 
Search this Thread
 
Old 12-12-2012, 09:41 AM
  #1  
TECH Fanatic
Thread Starter
 
LS-ONE_DAY's Avatar
 
Join Date: Jun 2007
Location: Westminster, MD
Posts: 1,062
Likes: 0
Received 2 Likes on 2 Posts

Default Shifting an auto

Ok so I've read through many threads concerning manually shifting an A4. Basically the conclusions I have come to are:
-Downshifting is bad
-Upshifting is alright as long as you don't over-rev the engine
-Don't manually shift the auto while racing.
I've never manually shifted my car ever. I'd never do it while racing, I'd leave it in 3 and be done with it (for the camaro guys, I know you have D and OD seperate, on the firebirds it only has 3 and D on the shifter console). Anyway I would be interested in occasionally upshifting it from 1 to 2 to 3 to D if the mood struck, as far as I'm aware that isn't a problem. However I recently read a post in a thread in the racers lounge where the poster recommended engine braking to slow down going down a hill by shifting the auto into a lower gear...wouldn't that be bad? I know my dad shifts his automatic cars into neutral going down hills if the roads are snowy/icey and then puts it back into D/OD but I never feel comfortable doing that so I don't.

My trans is a stock 4L60E btw, no shift kit or anything, I don't recall if we changed any trans settings in the tune, if we did it may have been raising the rev limiter by 100rpm and possibly reducing tq management a little. Don't think line pressure was touched.
Old 12-12-2012, 11:05 AM
  #2  
11 Second Club
iTrader: (18)
 
thunderstruck507's Avatar
 
Join Date: Mar 2008
Location: Northwest AR
Posts: 8,357
Received 21 Likes on 17 Posts

Default

Downshifting under throttle is bad, but if you let off the throttle and then downshift you can use it to engine brake the car.
Old 12-12-2012, 11:45 AM
  #3  
TECH Fanatic
Thread Starter
 
LS-ONE_DAY's Avatar
 
Join Date: Jun 2007
Location: Westminster, MD
Posts: 1,062
Likes: 0
Received 2 Likes on 2 Posts

Default

Gotcha thanks!
Old 12-12-2012, 11:47 AM
  #4  
11 Second Club
iTrader: (18)
 
thunderstruck507's Avatar
 
Join Date: Mar 2008
Location: Northwest AR
Posts: 8,357
Received 21 Likes on 17 Posts

Default

If you do it, you want to be at a reasonable speed for the lower gear to do so though. And do it one gear at a time.
Old 12-12-2012, 12:37 PM
  #5  
TECH Fanatic
Thread Starter
 
LS-ONE_DAY's Avatar
 
Join Date: Jun 2007
Location: Westminster, MD
Posts: 1,062
Likes: 0
Received 2 Likes on 2 Posts

Default

Do you know what the standard speeds are (generally) per gear on a stock 4L60E with 2.73 gears?

I know upshifting from a lower gear is fine when I am ready to accelerate again but if I was to put it in neutral, what speed would be ok to pop it back into D/OD? I'd only do that in the winter with snow/ice on the ground so I'd be going pretty slow I'd assume.

Note: I don't plan on driving the Formula in the snow/ice ever lol but it could be useful to know for my other vehicle.
Old 12-12-2012, 01:01 PM
  #6  
TECH Addict
iTrader: (36)
 
mjs1012's Avatar
 
Join Date: Mar 2011
Location: Stratford, CT
Posts: 2,687
Received 19 Likes on 16 Posts

Default

Sometimes (not too often) ill downshift to 2nd if im gunna do a 40 roll so it won't downshift when I hit the gas but ill up shift to 3rd as soon as I hit it so I don't risk over revving or forgetting to shift. I'm not sure if it makes a difference on abuse because I have a built transmission not a stock one.
Old 12-13-2012, 05:23 PM
  #7  
TECH Fanatic
iTrader: (6)
 
LeanPocket's Avatar
 
Join Date: Apr 2011
Location: Corpus Christi Texas
Posts: 1,122
Likes: 0
Received 1 Like on 1 Post

Default

i downshift into 1st when im doing 25 rolls or lower. I hate rolls with a passion.
Old 12-13-2012, 07:48 PM
  #8  
Registered User
 
Tattooed80's Avatar
 
Join Date: Dec 2012
Location: Sanger, Tx
Posts: 15
Likes: 0
Received 0 Likes on 0 Posts
Default

2-1 downshift while moving is never good unless the trans is set up for it.
Old 12-14-2012, 09:58 PM
  #9  
Pontiacerator
iTrader: (12)
 
RevGTO's Avatar
 
Join Date: Nov 2003
Location: Wichita KS / Rancho San Diego
Posts: 6,125
Received 194 Likes on 163 Posts

Default

There's nothing inherently wrong with it, you just have to rev match when downshifting or going into gear from neutral - just like you would with a manual trans.
Old 12-14-2012, 11:20 PM
  #10  
TECH Senior Member
iTrader: (96)
 
01ssreda4's Avatar
 
Join Date: Aug 2007
Location: Turnin' Wrenches Infractions: 005
Posts: 24,240
Likes: 0
Received 79 Likes on 70 Posts

Default

Originally Posted by mjs1012
Sometimes (not too often) ill downshift to 2nd if im gunna do a 40 roll so it won't downshift when I hit the gas but ill up shift to 3rd as soon as I hit it so I don't risk over revving or forgetting to shift. I'm not sure if it makes a difference on abuse because I have a built transmission not a stock one.
This. Understand, the single hardest thing on your transmission clutches during normal operation is forcing them to gear change under full throttle. By doing the above, you have eliminated the 4>2 shift under throttle and have allowed the clutches to fully bite before apply power therefor giving them a better chance of biting and not slipping. Also, you seem to think the shifter is directly connected to the trans operation. It's not. The computer has complete control. Operations are as follows based on your input: 1 or L= 1st gear only with increased holding capacity due to a low roller sprag (or something like that), 2 = 2nd gear only regardless of speed, 3 or D = 1,2,3, Lock-up shifting automatically. 4 or OD = 1,2,3,4, Lockup, full transmission functions. The point of this explanation is simply this.....when you shift from 2 to 3/D you have not shifted, you have simply commanded the computer to run a different set of parameters of going from one gear function to 3 gears and lock-up based on auto shifting tables. The auto is not a manual and never will be, but you two can live in harmony once an understanding has been made.
Old 12-15-2012, 12:11 AM
  #11  
TECH Apprentice
iTrader: (6)
 
GarrettM's Avatar
 
Join Date: Dec 2009
Location: Fort Worth TX
Posts: 314
Received 7 Likes on 5 Posts

Default

^^ very good explanation. Learn something new everyday.
Old 12-16-2012, 12:59 AM
  #12  
11 Second Club
iTrader: (14)
 
Camaro396's Avatar
 
Join Date: Oct 2005
Location: Toledo, Oh
Posts: 5,091
Likes: 0
Received 7 Likes on 7 Posts

Default

Originally Posted by 01ssreda4
This. Understand, the single hardest thing on your transmission clutches during normal operation is forcing them to gear change under full throttle. By doing the above, you have eliminated the 4>2 shift under throttle and have allowed the clutches to fully bite before apply power therefor giving them a better chance of biting and not slipping. Also, you seem to think the shifter is directly connected to the trans operation. It's not. The computer has complete control. Operations are as follows based on your input: 1 or L= 1st gear only with increased holding capacity due to a low roller sprag (or something like that), 2 = 2nd gear only regardless of speed, 3 or D = 1,2,3, Lock-up shifting automatically. 4 or OD = 1,2,3,4, Lockup, full transmission functions. The point of this explanation is simply this.....when you shift from 2 to 3/D you have not shifted, you have simply commanded the computer to run a different set of parameters of going from one gear function to 3 gears and lock-up based on auto shifting tables. The auto is not a manual and never will be, but you two can live in harmony once an understanding has been made.
Sure it will, mine is. Trans Brake valve body FTW.
Old 12-17-2012, 04:37 PM
  #13  
TECH Fanatic
iTrader: (6)
 
LeanPocket's Avatar
 
Join Date: Apr 2011
Location: Corpus Christi Texas
Posts: 1,122
Likes: 0
Received 1 Like on 1 Post

Default

Originally Posted by 01ssreda4
you have simply commanded the computer to run a different set of parameters of going from one gear function to 3 gears and lock-up based on auto shifting tables.
yup x2



Quick Reply: Shifting an auto



All times are GMT -5. The time now is 07:07 AM.