Perfect shifting?

slavic98tj · #1 (**permalink**) 07-02-2008, 03:43 AM

At sea level, on a level street... no incline
lets say freeway as an example.

With a 1998 TJ wrangler, 4.0L, Inline6, (1,2,3,4,5,R) manual transmission

What are the perfect RPM i should be shifting at?

ADvise and tips ?

David · #2 (**permalink**) 07-02-2008, 08:51 AM

It doesn't seem to me that there's an objective answer to this question. It all depends upon how much you value power over gas mileage (or vice-versa), how quickly you need to get up to speed, what you're trying to do, etc. My old YJ used to have a light that came on telling me when to upshift; I don't know if the TJs do or not. It seems a bit silly to me. You should feel when to shift, not rely on an instrument panel. Just off hand, for an I-6, I'd think the shift points would be anywhere between 2.5Gs for economy up to 4+ for power. Having said that, I haven't driven one in forever, and I don't pay attention to the tach. You know when to shift by listening and feeling.

Bounty__Hunter · #3 (**permalink**) 07-02-2008, 09:22 AM

Shift with the light for best mileage, lately I've heard 2000rpm recommended.

slavic98tj · #4 (**permalink**) 07-02-2008, 02:00 PM

2000 rpm is what I've been doing for a while just for the best mileage possiable.
I was just wondering if you all did the same.

thanks

jfrabat · #5 (**permalink**) 07-02-2008, 02:07 PM

Quote:

Originally Posted by Bounty__Hunter

Shift with the light for best mileage, lately I've heard 2000rpm recommended.

I dont think the light will help if you have changed any parameters; I have 31's and the stock out 4.10, so it keeps telling me to shift at about 1,500RPM's, and there is no torque at that level. When it is windy, I get better mileage ignoring the light and driving in 4th than shifting to 5th (which ussually means a WOT to maintain speed).

slavic98tj · #6 (**permalink**) 07-02-2008, 04:12 PM

Quote:

Originally Posted by jfrabat

I dont think the light will help if you have changed any parameters; I have 31's and the stock out 4.10, so it keeps telling me to shift at about 1,500RPM's, and there is no torque at that level. When it is windy, I get better mileage ignoring the light and driving in 4th than shifting to 5th (which ussually means a WOT to maintain speed).

Ahhh Thank you for this post!

I failed to mention that i also have 31's on with stock 4.10 differentials.
Without recalibrating my gauge cluster or computer, i get the same exact problem.

Well it isn't much of a problem now... like the posts above says, all i need to do is feel / hear and that perfect shifting right there.

Thanks for all the input!

jfrabat · #7 (**permalink**) 07-02-2008, 04:40 PM

If you have not recalibrated the speedo, you are loosing efficiency! A correct speedo will improve mpg... The computer uses the speedo infor to calculate the fuel curve.

slavic98tj · #8 (**permalink**) 07-02-2008, 05:38 PM

Should i just go to AAA and have them recalibrate it or is that an Eazy fix?

Wrangl3r93 · #9 (**permalink**) 07-02-2008, 06:55 PM

38 Tooth Speedometer Gear for 93-06 Jeep® Wrangler YJ & TJ - Quadratec

And ten minutes of your time

jfrabat · #10 (**permalink**) 07-03-2008, 08:13 AM

Quote:

Originally Posted by Wrangl3r93

38 Tooth Speedometer Gear for 93-06 Jeep® Wrangler YJ & TJ - Quadratec

And ten minutes of your time

X2... You only need to take out one screw! Just make sure that the orientation of the module is correct for the tooth count you are using (it is marked on the module).