Transmission Question

long_tall_texan · **Posted:** Mon Sep 30, 2013 5:03 pm

I've been away from the forum for a while. I've had my hands full with life in general. Inherited a new toy and have been enjoying driving it a lot too - 2007 black Corvette Z06.

But as always, when I have a question about my KJ, I always come back here to LOST. I searched and did not find any answers for this one, so if it has already been discussed, just point me to the right post. For those that don't know me, I have a 2007 KJ, 2WD, auto tranny, OME/Skyjacker Lifted, JBA Arms, 4.10 Gears, running 265/75-16 on Moabs.

So Here's my problem. Noticed recently when I am running at TX highway speeds of 75 MPH, that when I let off my accelerator and coast, the engine RPMs don't drop significantly. I actually acts like a standard tranny and somewhat does an engine-brake and decelerates much more quickly than a free-coasting. I even tried this today going downhill. I actually sowed down from 70 to 55 pretty quickly while going down a grade that should have kept up my speed, and maybe increased my speed if coasting. It's not my imagination that the Jeep should not act this way, right? Any ideas as to the problem? I have 98k miles on it. Tranny filter and complete fluid change around 40k miles. Since then, I have done a drain-and-fill of trans fluid every 6 months with quality ATF+4.

Here's a recent pic of my KJ...

And Here's my new Z06 too...

dgeist · **Posted:** Tue Oct 01, 2013 4:36 pm

I know my highway coasting behavior changed a bit when I went from the stock muffler to straight-pipe. Granted, the CRD doesn't really NEED a muffler, but the back-pressure factor may still be valid. Any chance your exhaust system has become overly restricted? Are you getting comparable mileage now to before you starting noticing the coasting behavior? There could be other friction items at play, too (brakes, bearing, drive shaft joint, etc.). The "engine" itself could be a red herring.

Dan

long_tall_texan · **Posted:** Tue Oct 01, 2013 4:47 pm

Thanks for the reply. Not noticing any coasting effects at lower speeds under 50 MPH. I've been driving the vette and my wife's Suburban more than my Jeep over the past month or so. Maybe I just got used to the coasting of a 0.5:1 6th gear in vette or the smoothness of the Suburban. I guess it could just be the effects of having 4.10 gears that I didn't notice before because the Jeep was all I ever drove.

BTW, brakes are good. U-joints too. May look into exhaust.

Sent using the FORCE on my SGS4.

John3:17 · **Posted:** Tue Oct 01, 2013 5:21 pm

Is there a chance you have turned the overdrive off with the button on the shifter?

long_tall_texan · **Posted:** Tue Oct 01, 2013 6:01 pm

Good call on over drive switch, but no, that's not it. Verified it is working too. It's not stuck in 3rd.

Sent using the FORCE on my SGS4.

STINGN · **Posted:** Tue Oct 01, 2013 6:23 pm

that z06....woof

djr8505 · **Joined:** Sun Feb 17, 2013 6:43 pm **Posts:** 44

Maybe your TC is not getting the signal to unlock when you begin to coast? Or if it is unlocking you may have old fluid in there which is not allowing it to slip correctly?

Transmission Question

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