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Manually shifting an automatic

H

Huckleberry

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I was wondering if it is harmful to shift the automatic manually? I have heard some people say that it could be harmful to the transmission. I usually leave it in 3rd(D) around town and put it in overdrive when I get on the highway. But sometimes I do miss shifting and will manually shift the automatic.
 

Ken

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1987 Z51 Silver Coupe
It will not harm it whatsoever. I wouldn't downshift at 9000 rpm though! (Ok, I meant high rpms.);)

_ken :w
 

mxdout165

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I'm sure someone will chime in with a more technical reply, but from all I've read/heard, it's not very harmful to your tranny.

It is good, however, that you drive in D around town and OD from cruising. Driving in OD around town puts stress on your tranny as it tends to shift more.

As to manual shifting, most of the time, if racing or under hard accelleration, it's better to let the Tranny shift on it's own anyway, because under most circumstances, the computer can shift much more precisely than you, in regards to an automatic.

HTH.

T Jay

Edit: :L :L :L I knew Ken would be me to a reply!
 
1

1DOWN6TOGO

Guest
am i reading this correctly?
did i just read that it was safe to shift down manually on an automatic?
i've never heard this before. i've always heard otherwise. but with no real evidence to support.
i must be reading the truth. this coming from the all-knowing seeing eye (that's you Ken! ;worship )

so i'm gonna ask this one question to clear things up in my head.
are you saying it is safe, (in my '77 A-3) to shift from D to 2 at, say, 2500- 3000 RPM, while taking a corner at around 30?

(please say yes, please say yes, please say yes....)
 

Ken

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1987 Z51 Silver Coupe
Seeing as how I prefer a manual transmission, and have never built an automatic for racing - just experience, I'll leave this for the automatic transmission experts to help out here. ;)

_ken :w
 

cntrhub

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North Hollywood, Ca.
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Miss my '62 & '80 4- Sp. Vettes
What better way to shift an automatic Trans but to increase throttle, or lift, than let the Trans do what it was designed for? Generally, when you "lift", the transmission loses pressure, (slower rpm) and "automatically" changes to a lower gear. When you apply throttle, the transmission fluid pressure overrides the spring pressure in the valve body and sends fluid to lock up the (clutch pack) next gear for that pressure/rpm input...generally speaking. You hardly feel any body/chassis movement when the transmission is slowing down. The Torque converter slows down, and thus, moves to the correct gear.
Now, you override the Trans by selecting a lower gear. The wheels are spinning faster than the engine's torque converter! The tires load up and squeal on the pavement. Your upper body moves forward in the seat a little. The driveshaft loads the U-joints, the output shaft, sprag, planetary carrier assembly, band, and clutch plates. They are all trying to catch up with the input shaft, splined inside the torque converter.... i.e., miss-matched rpm/wheel speed.
It's hard enough on the drivetrain, up shifting aggressively. But at least these parts are going in one direction, and know when to shift. Downshifting manually without wheels and rpm matching, (as stated above) twists things the opposite direction.
You would have to physically shift as well as an automatic Trans. That is... know where the rpm and wheel speed is all the time, for that gear.
It will take a lot of practice to shift as well as a transmission that can do it all.... selected in plain "Drive."
 

jstkrsn

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Parrish, FL, USA
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1992 LT1 White Conv.
I have an A4, with 2.59 rear. If I let it shift by itself, it'll shift at about 5200 RPM. If I hold it in 1st till 4900-5000 RPM it'll shift at 5600-5700 RPM. I read in a Motortrend article years ago that if you shift this way it increases the hydraulic pressure somewhere inside the tranny and there is an increased chance of blowing a seal. Don't know how true this is, and I do it anyway.
 

vigman

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88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
The higher.. the bigger

Yes the higher the revs... the more the internal pressure internal to the tranny.


Now It does have a Hi pressure bypass internally... like an oil filter style... but that still dosen't make it OK to wind the POOP out of the engine / trans.

Let the darn thing do what it was designed to do.


Vig!
 

compyelc4

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Dayton, Ohio
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'95 LT1 Coupe, Comp Yell; C6 Roadster, Vel Yell
This all reminds me of the first year I owned my brand new '68 Camaro, 2-sp auto. I use to shift my auto trying to make the creep driving the Mustang in the other lane think I had a stick. That way way cool back then.:cool
 
N

netgearhead911

Guest
There is nothing detrimental about manually shifting an automatic transmission. However, it is the shifting at high RPMS (over 6000) that will eventually cause most stock built transmissions to fail. Stock transmissions are not built from the factory to sustain the high-RPM shifts.

Small upgrades, such as the .500 boost valve, billet servo, 5000+rpm pump slide spring, and Kevlar band will firm up the shifting as well if you are looking for the tightest shift.

Automatics can be custom built for manual shifting with the TransGo Reprogramming Kit. These can be found on the web for $85-$100. We charge an additional $110 parts/labor for the installation of this kit. This will allow you to upshift/downshift your automatic at any RPM.

For more technical information and blowup diagrams, visit:

http://www.netgearhead.com/700r4.asp

For those who didn't know, we still are doing the $100 off any remanufacturing/high-performance building on any 4L60E / 700R4 transmission through our nationwide remanufacturing service.

While we are on the topic of transmissions, here is a nice tidbit of information. Heat is the biggest killer of automatic transmissions, that is why it is very beneficial to have an auxillary transmission cooler installed. The approximate life expectancy of an automatic transmission at various temperatures is as follows.

Degrees/Miles
175 - 100,000
195 - 50,000
212 - 25,000
235 - 12,000
255 - 6,000
275 - 3,000
295 - 1,500
315 - 750
335 - 325
355 - 160
375 - 80
390 - 40
415 - Less than 30 minutes

---
Corey Turner
NetGearHead - Transmissions & Automotive
http://www.netgearhead.com
 

RS84Syr

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Jan 12, 2002
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47
Location
Syracuse, NY, USA
Corvette
1984 Red/Graphite Auto 66k Z51
Huck-

This is a great question.
I think the technical parthas been answered
quite well. When I got my 84 I desperately wanted
a manual tranny. When I saw my car, I could not pass it
up it was that good. It was an auto. I could find
no decent manuals.

A friend of mine who raced Formula V
turned me on to some really fun things to do with an
automatic though, and I was really surprised that you
really could drive it like a manual (almost). There's another trick
where the tranny will downshift when applying the brake
with the gas also - great for keeping the Rs up going
around a corner. Not quite as much fun as a stick, but better
than simply keeping it in D all day... boring.

Perhaps this is the near equivalent of the "heal and toe"
technique. Any racers out there?

RS
 
H

Huckleberry

Guest
Racing! Now you're speaking my language!

I use to autocross quite a bit, did one ice race(on a lake) in Wisconsin, and a road race at Blackhawk Farms (paid $700 for the weekend) in Illinois. Never raced with an automatic. I eventually became pretty good at the heel and toe technique.

I haven't raced in about 7 years now, but have thought about getting back into autocrossing. I probably won't race the Corvette, just because of the cost of extra tires and wheels needed.

I may try the brake and accelerator method. I'll practice in a parking lot first though.
 

Zektor

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United Kingdom
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1982 Silver Coupe (Sold!), New C5 in 3 weeks!
Mmmm!

Ok then guys... I'm not a whizz when it comes to auto's... but here's an expericence and a question.

I used to have a Rover 2.6 ltr 3-speed auto about 10 years ago. I was flying up the road at about 30mph when I accidently pushed the shifter into reverse... The wheels gave an almighty screeching sound as they locked up in an attempt to go backwards!!!!! Oops! Shifted into D and carried on. There didn't appear to be any problems after doing this.

That's the experience out of the way... now here's the questions...

Supposing I do this.... Stick the auto into N, hold the gas pedal at about 4000rpm and then shift into D. Is this a good way to kill your tranny or will it take it, similar to lifting the clutch on a manual tranny? Basically, I'm just interested if auto's are designed to cope with this type of abuse!!!

What is the redline of an '82 Corvette 5200 or 5700???
And why does my tranny shift to the next gear before the tach even gets into the orange????

Cheers
Dazza
 

Edmond

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Louisiana
Corvette
2003 Z06
Re: Mmmm!

Zektor said:
Ok then guys... I'm not a whizz when it comes to auto's... but here's an expericence and a question.

I used to have a Rover 2.6 ltr 3-speed auto about 10 years ago. I was flying up the road at about 30mph when I accidently pushed the shifter into reverse... The wheels gave an almighty screeching sound as they locked up in an attempt to go backwards!!!!! Oops! Shifted into D and carried on. There didn't appear to be any problems after doing this.

That's the experience out of the way... now here's the questions...

Supposing I do this.... Stick the auto into N, hold the gas pedal at about 4000rpm and then shift into D. Is this a good way to kill your tranny or will it take it, similar to lifting the clutch on a manual tranny? Basically, I'm just interested if auto's are designed to cope with this type of abuse!!!

What is the redline of an '82 Corvette 5200 or 5700???
And why does my tranny shift to the next gear before the tach even gets into the orange????

Cheers
Dazza

In my Toyota one time, I was in a fury of playing air guitar and knocked the shifter in N. I didn't even think about popping it back into D while I was going so I just pulled off to the side of the road and put it into D while I was stopped. I'm not an expert by any means, but I don't think auto trannies are built as well to take the abuse that manuals are. That's just my opinion, I could be wrong though.

Why does your tranny shift before it gets to the orange? That's a good thing, if you're not shifting until you get to the orange, you'd have problems. I believe the latest my L98 auto shifted was at 3200 RPM's or so.
 
P

Piet

Guest
Drop to Drive

I had a 77 camaro that I bought for the front clip.
Was throwing away motor burning blue etc...

so I thought.. what the heck. Let's spin donuts by dropping into drive. ANswered many questions. (Including questions like: What happens when you shift into reverse at highway speed?)

After two weeks of playing... that was mighty black tranny fluid.

Your tranny SHOULD be able to downshift however. This was advised by my driving school when driving in the mountains (The Rockies) and going down hills.
 

Mad-Mic

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Messages
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1987 Redskin Red Coupe
Re: Mmmm!

Zektor said:
Supposing I do this.... Stick the auto into N, hold the gas pedal at about 4000rpm and then shift into D. Is this a good way to kill your tranny or will it take it, similar to lifting the clutch on a manual tranny? Basically, I'm just interested if auto's are designed to cope with this type of abuse!!!
Cheers
Dazza

if you did that at 3000 rpm you'd either A) blow the torque converter and eat up the clutch plates or B) blow a chunk of gear out the rear end or C) Both :L

pressure is pressure is pressure. i blew 4 auto's all rebuilt in a year of street/strip racing in my Z/28 a few years back. dropping gears to redlining isn't a good thing in the long run like the above stated temps suggesting heat kills trannys fast! if you don't monitor your fluid usage and keep it clean it will eat it up real fast. my prob was the tranny was a light trans for a 3500 lbs car. 200 metric 3 speed that was stock in an 82 Z/28. add a trans cooler then a 2800 stall converter (which does what you want like a clutch stalls out at 2800 rpm then hang on!) and maybe a shift kit for hard firm shifts. if you wanna get trick you can rebuild it with manual valve bodies which lets you shift the car like an auto and it'll take a beating much better. with out manual valve bodies you risk the chance of blowing a seal or torching a few clutch disks. or you could make it reverse manual valve body that way you can pull down to shift instead of bumping up and possibly into neutral. drive would be where 1st is and 1st where drive is FYI
 

Zektor

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Joined
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Messages
100
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United Kingdom
Corvette
1982 Silver Coupe (Sold!), New C5 in 3 weeks!
More!!!!

My '82 sounds really agressive when running in 2nd. Quite regularly I will shift it from D into 3 and then into 2. Of course, it loads the transmission whilst it changes into gear... but doesn't seem to have any detrimental effect on the car.

I used to do this all the time on my old car as well. That car never had a problem either.

Regarding the "changing gear before it gets to orange". In my '82 if say in D. If I give it WOT from standstill, it always changes to 2nd and then to 3rd about 3mm before the orange section, which If I remember correctly, starts at 5000rpm. So my car must be changing gear at about 4850rpm. Now, I class the orange section as "watch out your getting close!" or "warning red line approaching!". And the red section, which I think starts at 5700rpm (I'm not in the car so I don't remember exactly at the moment!!!) means "Danger, engine about to explode!!!"... Am I right??? If so, I'm losing performance simply because my tranny changes into the next gear too early!

Incidently, If I engage 2nd... I can hold 2nd until into the orange section before shifting manually into 3.

Will adjusting the TV linkage allow me to raise the WOT shift point to say half way through the orange section???

Cheers
Dazza
 

Mad-Mic

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Messages
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Location
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1987 Redskin Red Coupe
manually shifting up is ok just shift about 500 rpm early so it engages when you actually want it to shift. most cars won't redline in D at WOT my vette shifts anywhere from 4600-4800 rpm. you can adjust the kick down linkage so it kicks down a gear sooner or later depending which way you go. sorry i can't be more help there i never messed with it.

if your tach redlines at 5700 rpm you are good to go. you can even probably squeeze 6000 to 6500 rpm out of it but then the valve train starts to float and you'll hear a spitting and sputtering then you get the boom most of time it just don't go boom unless it was screwed up in the first place. Now i wouldn't recommend shifting at 6500 rpm that is just GM's way to keep you governed for warrenties and such. my Z/28 would pull to 6500 rpm but redlined at 5500 rpm any given time if i let it but anything past 6000 rpm it drops off hp but the shift is way harder on more in the torque curve of the motor. is it worth it to scatter parts because of it? not really just watch your fluids and also touch the fluid. run your fingers down the dip stick to feel for any grittyness if you get grit thats metal and metal isn't good. dropping gears all the time wears out the bands inside the transmission and they end up stretching thats where you get the slippage then eventually it'll just stop grabbing.
 

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