Long time 5speeder, 1st time auto owner

[bgilbert]

Joining the auto-lazy man, put it in D and go club. Just bought a early 91 W250 with a rebuilt A727 3sp auto, 3. 07's 140K miles. The rebuild was 50K miles ago. transmission fluid, filter was changed about 5K miles ago. Shifts super fine and smooth, no harsh clunks when moving the gear selector. So I'm asking fellow members, for a daily driver, no trailer pulling, what can I expect out of this transmission? Yes I know I havent read any previous posts or 'best tips for 1st gen' but I will, maybe someone can share knowledge on this transmission? How bad will my fuel mileage be with those high revs on the highway? Bill -off to reading archives. .

 

[RGT]

I don't think your mileage should suffer too much, with turbocharging you pick up some efficiencies, you also have better torque converter lock up. My experience with various vehicles in the past has been that od is nice for engine noise..... but that it takes tha same ammount of fuel to push you along at a given speed...

 

[jdurham]

I have the same setup, used in much the same way. The truck has 130K on it, never been rebuilt, and it still pulls fine. The only problem I am having is that it doesn't stay in second gear very long, almost like it tries to skip it, which from past posts is an adjustment I can have a transmission shop adjust.

 

[tugboatphil]

Bill,



I was a gear grinder for many years also, but both my CTD's have had autos. The first thing I had to do was to stop flailing my left foot in mid air, searching for that "other" pedal that wasn't there.



With my age and the work I do now, I'm happy with the auto. Winter driving is where I miss it most. We had ice on the road and I let off the brake pedal at the stoplight and started spinning. Would have been nice to start from a higher gear.

 

[dpuckett]

RGT- not to split hairs, but there is no lock up in the 727 or 518 (727 with an OD added).



I think with your 3. 07 gears, you can expect about the same as if you had an OD with 4. 10s. FIne for local 55-60 mph driving, but you will want an OD at highway speeds. Mom has my old auto w/3. 55s. At 50-55 (her speeds), it gets better mileage in 3rd. At 60+ it does better mpg wise in OD. Top speed in 3rd is 72.

WIth a diesel, you have more low end torque, thus driving at 1800 rpm will net better efficiency than running at 2800 (near gov). It takes fuel to make power, and it takes fuel to make RPMs. the lower you can run it, the less fuel you will use, to a point. There was an articel in the magazine (issue 37?) about torque curves and BSFC. Overall, I think you can figure 1 mpg less than if you had a stick. Take 2 off for lot of intown driving. Still ought to be in the high teens;19-20 hwy.

 

[RGT]

yeah, I realize we don't have electronic/positive lockup on our converters, but they still gain hold at higher rpm's

 

[phoekema]

RGT,

I agree with you. I had a '93 auto before the '98. 5 I have now and in my opinion the old non-lockup converter had a substantially lower stall ratio than the new stock lockup style. In stock form, my new one had more 'slippage' when just driving around and not locked up. My guess is they did that to get more use from the torque converter at lower speeds, but it seems to have cut the over all efficiency. I solved my problem by installing a ATS converter and valve body.

I don't know if anyone else noticed this or not when comparing the two, but I just think the older non-lockup converters were 'tighter' than the newer ones when in fluid coupling mode.