"manually" shifting an auto
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
96 mph is the top of second for me. 
don't shift manually without a good shift kit for starters. Downshifting while decelerating is plain stupid.
My transmission has 35K on it and the 3-2 automatic downshift has a grind. Manually, its fine, so I don't know how much longer mine is going to last.
I abuse it bad though, accidently went to 1st at 55 mph once, and 2nd at 100mph. oops.
don't shift manually without a good shift kit for starters. Downshifting while decelerating is plain stupid.
My transmission has 35K on it and the 3-2 automatic downshift has a grind. Manually, its fine, so I don't know how much longer mine is going to last.
I abuse it bad though, accidently went to 1st at 55 mph once, and 2nd at 100mph. oops.
Safety Car
Joined: Jul 2008
Posts: 3,966
Likes: 4
From: Made In America
St. Jude Donor '10-'11
The bottom line is, an automatic is made to shift on it's on thus the term automatic. Upshifting is fine once it reaches it's redline but no higher. Downshifting is fine occassionally when going down steep hills or constant braking is needed for winding roads. I upshift mine occassionally just for the feel and the sound. Do it to much and you will be walking. Take my words with a grain of salt. Everyone has a different experience so some will disagree with me. Have fun but don't tear up your tranny unless you have some money ~1500 dollars~ put away for a transmission rebuild.
Thread Starter
Pro
Joined: Sep 2003
Posts: 655
Likes: 2
From: Rio Vista ca.
Thanks for all the feed back, everyone. I guess I'll be doing some up shifting from time to time and avoiding down shifting. It's kind of fun to wind her up a bit in first and second occasionally. Usually if I have to pass someone on the freeway, I just stomp it while in Drive and breeze on by.
Kim
Kim
Max G’s
Joined: Nov 2008
Posts: 2,751
Likes: 78
From: Monroe OH
NCM Sinkhole Donor
I was unaware that c4's had such an issue with speedo's. Wow upper 90's and 100 in second gear, what's the trick? Is it a 1.90 axle ratio or 25" tires? Or maybe the 9,000rpm L98 & LT1 now available. 
Team Owner
Joined: Dec 2007
Posts: 20,974
Likes: 261
I did some serious shifting today, like you guys are talking about, and it kicked really hard when I was up shifting and winding out, way harder than the auto itself. I have done it all the time, but today I pushed it, sucker ran great in 30 degree weather LOL!
Le Mans Master
Joined: Jan 2005
Posts: 6,115
Likes: 3
http://www.kabamus.com/garage/gears.html
...you get 100.99 mph in 2nd gear, and I can personally vouch for this.
Somebody can correct my numbers, but here is what I entered for my '93 LT1 automatic to get this:
Rear wheel diameter: 17"
Aspect ratio: 40
2nd gear ratio: 1.625
Final drive: 2.59
The 2.59s are so dumb... accelerating from a dead stop you'd swear the car was hooked to a 45-foot horsetrailer, and cruising at 70mph with the engine at idle speed is weird. Unless you stomp the gas to make the trans kickdown there is ZERO responsiveness. I've driven an LT1 with no mods save a 3.73 gear and it felt like it had 100 more hp than my car. I know GM did them to satisfy some federal regulation, but I don't know of any other "performance" car that is a contemporary of a C4 that has this feature.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
with a shift kit the operation time is faster than stock reducing heat/ wear because of less slippage time involved.
Same as dropping the clutch v riding it with a stick.
I have a quality shift kit in my rebuilt trans and shift it both up and down when the "need for speed" arises.
Use engine braking on long downhill winding roads just like a stick. Magic
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Brett Foote
Team Owner
Joined: Dec 2007
Posts: 20,974
Likes: 261
rodj, that is good to know, because I used to drive my other one like that, and never had a problem, but in this tame one, I only down shift it like that once in a while, but I love downshifting for a huge curve and pulling right through it!!!
Pro
Joined: Mar 2007
Posts: 595
Likes: 355
From: Mt Prospect IL
2025 C4 of the Year Finalist - Unmodified
One thing nobody mentioned is that you should ALWAYS use manual 1st when racing or accelerating hard from a stop. This applies an extra clutch to make the trans stronger and less likely to fail!!!
That being said, shifting manually or letting the trans do the selection makes no difference in the life of the trans on upshifting, it is a factor of how hard you are driving the car. A/T's build a great deal of heat so a trans cooler gets a real workout when beating on the car.
Downshifting is very hard on the clutches and you are better off using the brake pedal. Much cheaper to put a set of brake pads in than rebuild the trans.
I still downshift on occasion just for the rush and the popping from the pipes! Afterall, it is a sportscar right?
That being said, shifting manually or letting the trans do the selection makes no difference in the life of the trans on upshifting, it is a factor of how hard you are driving the car. A/T's build a great deal of heat so a trans cooler gets a real workout when beating on the car.
Downshifting is very hard on the clutches and you are better off using the brake pedal. Much cheaper to put a set of brake pads in than rebuild the trans.
I still downshift on occasion just for the rush and the popping from the pipes! Afterall, it is a sportscar right?
Safety Car
Joined: Jul 2008
Posts: 3,966
Likes: 4
From: Made In America
St. Jude Donor '10-'11
Max G’s
Joined: Nov 2008
Posts: 2,751
Likes: 78
From: Monroe OH
NCM Sinkhole Donor
I know it's hard to comprehend, but the speed is a factor of the oddball 2.59 final drive that some ***-head at GM came up with to satisfy some CAFE standard. When you plug the numbers into this speed calculator-
http://www.kabamus.com/garage/gears.html
...you get 100.99 mph in 2nd gear, and I can personally vouch for this.
Somebody can correct my numbers, but here is what I entered for my '93 LT1 automatic to get this:
Rear wheel diameter: 17"
Aspect ratio: 40
2nd gear ratio: 1.625
Final drive: 2.59
The 2.59s are so dumb... accelerating from a dead stop you'd swear the car was hooked to a 45-foot horsetrailer, and cruising at 70mph with the engine at idle speed is weird. Unless you stomp the gas to make the trans kickdown there is ZERO responsiveness. I've driven an LT1 with no mods save a 3.73 gear and it felt like it had 100 more hp than my car. I know GM did them to satisfy some federal regulation, but I don't know of any other "performance" car that is a contemporary of a C4 that has this feature.
http://www.kabamus.com/garage/gears.html
...you get 100.99 mph in 2nd gear, and I can personally vouch for this.
Somebody can correct my numbers, but here is what I entered for my '93 LT1 automatic to get this:
Rear wheel diameter: 17"
Aspect ratio: 40
2nd gear ratio: 1.625
Final drive: 2.59
The 2.59s are so dumb... accelerating from a dead stop you'd swear the car was hooked to a 45-foot horsetrailer, and cruising at 70mph with the engine at idle speed is weird. Unless you stomp the gas to make the trans kickdown there is ZERO responsiveness. I've driven an LT1 with no mods save a 3.73 gear and it felt like it had 100 more hp than my car. I know GM did them to satisfy some federal regulation, but I don't know of any other "performance" car that is a contemporary of a C4 that has this feature.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Team Owner
Joined: Dec 2007
Posts: 20,974
Likes: 261
I went to the site and input the numbers. It isn't your fault that the dumba55 that created that data calc used tire diameter instead of radius in his equation. I know what the 2.59 will run in second, because I used to have the gear until last year. I have a tuned chip in my car and slight intake mods and can get to around 6800 rpm and would hit close to 80mph in second. Plug in for tire diameter in that calculator (8.5in) and look at those results and then get into your car and put it in second gear and see what it will do. I'm not calling anyone out, we just need to keep it real.
wind out quite a bit longer than us, but I have done like 90 in 2nd gear with a stock tpi going through curves with a 4+3 3.07 rear end tpi car chasing me, and I garuntee he was well into third:o
What gears do you have now? what is 2nd peak?
Last edited by pologreen1; Feb 15, 2009 at 01:35 AM.
Safety Car
Joined: Jul 2008
Posts: 3,966
Likes: 4
From: Made In America
St. Jude Donor '10-'11
Melting Slicks
Joined: May 2007
Posts: 2,171
Likes: 1
From: Warwick RI
I think that this is quite common for high torque builds. If I remember correctly my guy did the same when he built mine to handle 500+ ftlbs
Instructor
Joined: Sep 2007
Posts: 192
Likes: 0
From: Waynesville North Carolina
I want 500+ ftlbs too.
Racer
Joined: Nov 2007
Posts: 386
Likes: 0
From: Cicero IN
[QUOTE=9340Ruby;1568943165]Downshifting is very hard on the clutches and you are better off using the brake pedal. Much cheaper to put a set of brake pads in than rebuild the trans.
Downshifting would be be harder on the 2-4 band then the clutches. The "extra clutch" that was mentioned is the overrun clutch. It is appied in all manual gears. You can increase the number of friction and steels in the 3-4 clutch for more holding power.
No, it does not hurt the transmission to manually upshift or downshift. Just use common sense.
Downshifting would be be harder on the 2-4 band then the clutches. The "extra clutch" that was mentioned is the overrun clutch. It is appied in all manual gears. You can increase the number of friction and steels in the 3-4 clutch for more holding power.
No, it does not hurt the transmission to manually upshift or downshift. Just use common sense.