just curious if it will hurt anything crusing around town at 45mph in third gear ? the speed shouldn't matter i would think as long as i stay out of the redline and keep the rpms low.

 

I do it all the time and its actually been recommended to my by many transmission folk that you want to leave it in 3rd until you go over 45 or so depending on your application. The reason being so it doesnt slip in and out of OD and burn something up. Plus, third is fun

Car running better?

-Dustin-

 

It won't hurt anything

Frank

 

car runs perfect.... great tuner and had to replace my fuel pump. hey if you are free meet me and my buddies at chilis on saturday. a bunch of fbodies guy will be there and GTO guys. the car runs like a monster..

 

It puts a major hit on fuel mileage, and wears the engine and trans out faster. Transmission rebuilders love it when you do that. OEM engineers don't.

Anyone recall the oil consumption problem with early LS1s due to ring flutter at about 4000 with very little throttle opening? Anyone remember why GM missed that? Basically automotive engineers aren't dumb enough to run around at basically closed throttle in 2nd gear in a Vette or Camaro @ 4 grand in traffic on a regular basis. Unfortunately they assumed customers were brighter than some actually are.

A long time a go, as an OEM engineer we had a saying about that type of customer. Unfortuantely it can't be repeated here.

Most folks who cruise in the lower gears at closed/part throttle won't believe this, but that's their problem, not mine.

Please don't let this thread degenerate into a "lugging" topic. Oh yeah, be sure to change your oil @ 3000 miles no matter what the OEM recommends. What do they know?

My highly-opinionated $.02

 

the car manual says for around town use u can use third gear. they wouldn't give you the option to shift from 1-2 D OD if it wasn't good to drive in any of those gears.

 

On a stock car they give you the option to shift 1-2-D OD but no matter which one you shift to it's up to the computer to decide if it will downshift or not depending on the current MPH/RPM so essentially the choice isnt really ours.

 

Here's what the '94 manual says.

https://www.mygmlink.com/pdf/go2cont...1994camaro.pdf

 

what i'm taking bout is not SHIFTING into those gears. i drive around in 3rd gear around town and the manual says nothing bad bout that.

 

Well I suppose it would be like me keeping my Manu in 4th all the time, it would tach about 3k at 55mph I'd have good jump and make a lot of noise but I'm sure constantly running the engine at the high RPM for extended amounts of time would cause excessive wear. While the manual does not say anything I'm pretty sure it would break parts/oil down much quicker, and suck for gas milage

 

Thanks for the link...all 292 pages of it!

Page 61 (expand Features and Controls and select Automatic Transmission if you don't like paging) has some good stuff on using the various gears.

OD(1st thru 4th) "This position is for normal driving"

D (1st thru 3rd) "you never get into overdrive (4th)."

"Here are somtimes you might choose 'D' instead of 'OD':

-When driving on hilly winding roads
-When towing a trailer, so there is less shifting between gears
-When going down a steep hill"


I guess it's all about how you intrepret "normal driving", flu.

 

I use 3rd at the track till the end of the 1/4 mile.

 

I'm always doing over 45.
so I am always in OD.
Come on with our cars you can't feel the road that much well maybe the bumps.
I remember my 79 caprice it rode so good you can be doing 100 and it feels like your doing 50.
But I don't play around in school zones or where kids are.


Chris G.

 

I just ran some controlled tests in my A4 Vette. It has an accurate instantaneous mpg computer. I ran 45 mph in cruise on a level road, A/C off, 75* F. Results:

in OD (4th gear) with torque converter clutch (TCC) locked:

1350 rpm, 37.0 mpg (+/- about 0.3 as road varied slightly

in D (3rd gear) also TCC locked:

1900 rpm, 27.0 mpg (+/- 0.3)

My conclusions:

MPG ratio is very close to trans ratio (27/37 = .73 and 4th is .70:1 vs. 3rd is 1.0:1) RPM ratio is .71

If I went 100 miles this way (not practical but works out on average if you choose 3rd rather than 4th regularly:

Gas cost @$3.00 gallon: $11.11 using 3rd, $8.11 using 4th.

If you did a lot of driving that way, in 50,000 miles the engine would turn an extra 35 million or so revs. OK, not exact calculations, but it gives you the idea.

Disclaimer: Your results may vary. If your transmission does not have TCC lockup in 3rd gear, your 3rd gear results may be even lower than stated above. Contents may settle during shipping.

 

As a GM tech in the period around 1988 when the 4 speed autos came out I can tell you if you constantly let your car shift from d to OD everytime you let up it shifts in OD and when you try to accell it shifts back down you will wear your trans faster. for those of you with 2.73 gears at a guess I would think your 3rd gear is pretty close to a guy in 4th with 3.42's I cant be sure on that without doing the math and I aint gonna do it. It was recommneded by the factory that you run in d until you get over 45 MPH to cut down on the amount of trans that GM had to replace.