Is it worth changing gears for better MPG's???

[DA BIG ONE]

ART, Just a tire size change to 285/75/16 and your 3.73's will give you a final of 3.42+-

[TurboDiverArt]

ART, Just a tire size change to 285/75/16 and your 3.73's will give you a final of 3.42+-

I wasn't intending on making a big change in tread width. I think increasing the cross section of the tire from 9.6" to 11.2" will probably have a pretty big adverse effect on MPG. Additionally I think it'll be much louder.

If I kept the stock height I was planning on using a 245/70-17 tire.

If I went up I was thinking of using a 255/75-17. I think this brings me pretty close. Might not be down to 3.42's but definitely at least 3.55's. Increases the height of the tire from 30.46

[DA BIG ONE]

I wasn't intending on making a big change in tread width. I think increasing the cross section of the tire from 9.6" to 11.2" will probably have a pretty big adverse effect on MPG. Additionally I think it'll be much louder.

If I kept the stock height I was planning on using a 245/70-17 tire.

If I went up I was thinking of using a 255/75-17. I think this brings me pretty close. Might not be down to 3.42's but definitely at least 3.55's. Increases the height of the tire from 30.46” to 32.06” or 1.6”. I think the ideal height change is probably closer to 2” to get it real correct. Don’t know how precise you can be with correcting the speed sensor.

Not having the converter lock up until 60 MPH is a little bit of a concern for me though. That means that on most state routes around here where the speed limit is 50 MPH I probably won't get the converter to lock up as I usually don't go more than 10 MPH over the speed limit as there are just too many police waiting to give me a ticket. It’s nice that at 50 MPH the converter will lockup. Did know that the 1500 Suburban’s with stock 3.42’s locked up at 60. Does this mean that a truck with 4.10's locks up before 48 mph?

Can someone point me to the article regarding hacking the VSS/VSSB?

In your post above you mention modifying the signal from the VSS (at trans?) as well as modifying the VSSB? I guess I didn’t think that there were two things in play here that could be modified. My thought was to hack the sensor signal (resistor or something) under the dash. Thought doing this would correct for the gearing so that based on output shaft speed the gauges and computer would read speed correctly. Again, I didn't know that this had an effect on how the PCM instructed the transmission to lockup. Does it also have an effect on shift point? I think I'm confused on how this works. My assumption was that you were correcting the speed but the computer still functioned the lockup at the same speed regardless of gearing, 48MPH for 3.42’s through 4.10’s.

Art.

Art, I'm thinking closer to 45mph for od/lockup w/4.10's. I also think using cruse control locks converter too.

Tire width does effect milage, but tread pattern plays bigger role the MT/R's I used made mpg suffer, the SilentArmor is more road friendly and quieter so not as bad.

Your vss is on the t-case along w/2 other speed sensors, 1 for the front drive shaft, 1 for the rear driveshaft. I just discovered the "vss" hack works a little while ago.

Hacking the speed signal from the vss to the vssb will correct the speedo only and leave the 3.73 shift/lockpoints you have now.

Hacking the vssb you modify speedo, shift/lockup to higher mph setting, abs, cruse control. TheDieselPage sells the book showing the hack of VSSB.

I used a commercial VSS re-calibrator to modify vss signal only.

Getting accurate on speedo calibration comes w/hack either way, especially if you measure tire diameter and use this measurement in re-cal.

[LanduytG]

Who's a good source now days for the gear sets?

Greg

[moondoggie]

Good Day!

"I used a commercial VSS re-calibrator to modify vss signal only." Could you be more specific? Jim doesn't mind at all if we mention product names, as long as we're not hawking them.

Hacking the VSS signal looks like it would NOT be a resistor or pot situation - from a quick glance, that signal is a frequency that would have to be multiplied or divided to hack (clarification please).

Blessings!

(signature in previous post)

[DA BIG ONE]

Good Day!

"I used a commercial VSS re-calibrator to modify vss signal only." Could you be more specific? Jim doesn't mind at all if we mention product names, as long as we're not hawking them.

Hacking the VSS signal looks like it would NOT be a resistor or pot situation - from a quick glance, that signal is a frequency that would have to be multiplied or divided to hack (clarification please).

Blessings!

(signature in previous post)

Ok, It is called and "electronic ratio adapter" (ERA) from ABBOTT ENTERPRISES, INC. Just use your divide ratio between changes match it the switch settings (micro-rockers) and your goos to go.

www.abbott-tach.com or www.atrol.com

[TurboDiverArt]

Ok, It is called and "electronic ratio adapter" (ERA) from ABBOTT ENTERPRISES, INC. Just use your divide ratio between changes match it the switch settings (micro-rockers) and your goos to go.

www.abbott-tach.com or www.atrol.com

I assume you put this in series? Meaning you cut the signal wire going from the VSS to the VSSB and put the ERA in the middle? That way the VSSB knows the actual speed as modified by the ERA but thinks the gearing is still stock?

Art.

[TurboDiverArt]

Art, I'm thinking closer to 45mph for od/lockup w/4.10's. I also think using cruse control locks converter too.

Tire width does effect milage, but tread pattern plays bigger role the MT/R's I used made mpg suffer, the SilentArmor is more road friendly and quieter so not as bad.

Your vss is on the t-case along w/2 other speed sensors, 1 for the front drive shaft, 1 for the rear driveshaft. I just discovered the "vss" hack works a little while ago.

Hacking the speed signal from the vss to the vssb will correct the speedo only and leave the 3.73 shift/lockpoints you have now.

Hacking the vssb you modify speedo, shift/lockup to higher mph setting, abs, cruse control. TheDieselPage sells the book showing the hack of VSSB.

I used a commercial VSS re-calibrator to modify vss signal only.

Getting accurate on speedo calibration comes w/hack either way, especially if you measure tire diameter and use this measurement in re-cal.

That

[TurboDiverArt]

Hacking the speed signal from the vss to the vssb will correct the speedo only and leave the 3.73 shift/lockpoints you have now.

Hacking the vssb you modify speedo, shift/lockup to higher mph setting, abs, cruse control. TheDieselPage sells the book showing the hack of VSSB.

OK, reading into your post a little more.

Assuming that from a calibration standpoint the 4.10 VSSB setting does not affect mileage in itself or general health/management of the engine and drive train. Would it make sense, or is it even possible, to set the VSSB to 4.10