Do you get better mileage tweaking shifter position on 4L60 tranny?

[Rockhounder]

Just did my sixth tank of gas, to confirm, but it seems that my shifter is touchy about the position it is resting in, while in OD. It clicks into the nearly proper orientation on the OD symbol, but a little to the left. Always put it there as long as I have been driving this suburban (88 4x4, 1500). I got religiously 12-13 mph on the highway if I drove very conservatively, drafting semis, etc.

Then one day when shifting I noticed that if you bump it a little more to the left, almost touching the "N" symbol, the sub still drove like it was in OD, but my tranny oil temp dropped from around 160 degrees to 120 degrees. I thought that was a little weird, but kept driving, and then noticed the fuel gauge was dropping slower than usual. Ends up, with the shifter in this position, I can now get (averaged over 6 tanks of gas) 16.5 mpg.

Has anyone here have an answer to why this is? Or has anyone else noticed this? It would explain why the older subs sometimes seem to not be able to get past the 10 mpg mark, perhaps there is some cable adjustment that stretches or shifts with age, so there is a partial mis-match in the actuator valves linked in the shifter, making more resistance? (just an uneducated guess)?

Anyone ever encounter this before? I am now definitely driving with the shifter in this altered position.... engine seems to run with less need for pedal.... just don't want to be doing something potentially harmful.

 

[1stDeuce]

Sounds like your shifter is out of adjustment... As far as temps, must be that when it's not quite in OD, the torque converter isn't locking up. But that should sound about like it's in 3rd... ??

 

[rayra]

sounds like only now are you actually in OD. Consider either fiddling in the dash to adjust where the indicator displays, or slightly bending the connecting rod on the shift linkage on the trans so it actually goes into the gear you think you are putting it in.

eta and I'm pretty sure the torque converter lockup has nothing to do with what you do at the dash indicator and everything to do with where the actuator on the side of the trans gets moved to.

 

[ExpoMike]

IIRC, the indicator is driven by a small cable hooked to the shift column. There is a small amount of adjustment at where this attaches to. I believe you loosen a screw and move the mounting tab and align with the marks on the dash.

 

[1stDeuce]

Yes, to clarify, the indicator on the dash has nothing to do with how the transmission works, but there are detents in the column shifter that can influence it if the linkage is adjusted incorrectly. There should be an adjustment on the linkage IIRC... You put the trans in park and the shifter in park and set the linkage there. ?? It's been a long time since I messed with an old auto trans shifter...

Anyway, once the shift detents on the column agree with those in the trans, your issue should be resolved. At that point, the indicator on the dash can be adjusted to agree. BTW, In the body style you're running, I think you actually have a 700R4 trans, not a 4l60e, though they are pretty much the same I think, just that one is electronically controlled and one is not. ??

 

[Rockhounder]

Yes, to clarify, the indicator on the dash has nothing to do with how the transmission works, but there are detents in the column shifter that can influence it if the linkage is adjusted incorrectly. There should be an adjustment on the linkage IIRC... You put the trans in park and the shifter in park and set the linkage there. ?? It's been a long time since I messed with an old auto trans shifter...

Anyway, once the shift detents on the column agree with those in the trans, your issue should be resolved. At that point, the indicator on the dash can be adjusted to agree. BTW, In the body style you're running, I think you actually have a 700R4 trans, not a 4l60e, though they are pretty much the same I think, just that one is electronically controlled and one is not. ??

Yes, you are right, it is the 700R4.

In response to some of the other posters, I do not think that the previous driving was in 3rd, as the rpm's have not changed, with my 33's I was doing around 2200 rpms at 55 mph. That has stayed the same....... although, if I keep my foot now really off the gas, and am drafting semis, now it drops to a ridiculously low 1500 rpm's at freeway speeds sometimes. I am barely keeping my foot touching the throttle (If I was in neutral and put the same throttle level, the engine would rev at around 3k rpms)

 

[NevadaLover]

The adjustment is under the gauge cluster bezel and attaches to shift column with a little clip, take the outer bezel off the gauge cluster and you can pry the clip loose with a screwdriver, then slide it one way or the other until the pointer is aimed correctly then push it back on the shift cover and put the bezel back on!!

 

[ExpoMike]

Yes, you are right, it is the 700R4.

In response to some of the other posters, I do not think that the previous driving was in 3rd, as the rpm's have not changed, with my 33's I was doing around 2200 rpms at 55 mph. That has stayed the same....... although, if I keep my foot now really off the gas, and am drafting semis, now it drops to a ridiculously low 1500 rpm's at freeway speeds sometimes. I am barely keeping my foot touching the throttle (If I was in neutral and put the same throttle level, the engine would rev at around 3k rpms)

You didn't mention what gears you have in the axles (my guess 4.10) but your given info, of ~2200 RPM at 55 MPH with 33" tires, equates that you were running with the transmission at 1:1 ratio, i.e. 3rd gear. Dropping down to ~1500 RPM calculates out to being in Overdrive (.70:1). That said, if you have to use almost no throttle input, your TV cable is likely out of adjustment. With everything correct, you should be able to use the pedal to 1/2 throttle before it kicks out of Overdrive. With your throttle wide open (at the TB, not the gas pedal), the TV cable should be drum tight. If not, there should be a button on top of the cable where it mounts to the TB bracket. Push and slide housing back. Then push the TB lever to full open, which should ratchet the housing forward. This is the correct adjustment and the cable should now be tight.

 

[Rockhounder]

You didn't mention what gears you have in the axles (my guess 4.10) but your given info, of ~2200 RPM at 55 MPH with 33" tires, equates that you were running with the transmission at 1:1 ratio, i.e. 3rd gear. Dropping down to ~1500 RPM calculates out to being in Overdrive (.70:1). That said, if you have to use almost no throttle input, your TV cable is likely out of adjustment. With everything correct, you should be able to use the pedal to 1/2 throttle before it kicks out of Overdrive. With your throttle wide open (at the TB, not the gas pedal), the TV cable should be drum tight. If not, there should be a button on top of the cable where it mounts to the TB bracket. Push and slide housing back. Then push the TB lever to full open, which should ratchet the housing forward. This is the correct adjustment and the cable should now be tight.

I have 3.42 gearing (tow package). I did not have a tach on the sub, but just going by "ear" to guess the rpm's. I will get a tach and see what the rpm's really are doing, then I can give you good info on the revolutions.

I count the gears as I go through them, accelerating onto the freeway, and definitely count 3 definite shifts (starting from 1st, going into 4th). Then occasionally, it shifts down from that when I take the throttle almost all the way off, seeming to drop the rpm's by near half.

I do have the proper adjustment on the throttle I think, as it downshifts when I put throttle to at least 50% position.

 

[justcuz]

From what you are describing you may be feeling converter lock up and thinking it is a gear change. Your engine RPM will change 200 to 300 RPMs between converter locking and unlocking.
To adjust your shifter, park your truck and block the rear wheels. Looking at your firewall where the steering column comes out you will see the shifter arm. It has a clamp with a nut on it. If you loosen that not you can adjust the position of the shifter arm. You can tell if you need to adjust the arm by shifting the truck with the ignition unlocked but not running. You should feel very detent for each gear, P R N OD D 2 1. If you don't you don't feel each detent adjust your shifter. If you feel each detent then remove the screws and cover under your steering column and you will see a flat clip with a little cable. That cable goes to your indicator needle and it can be adjusted by moving the flat clip.