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Power/comfort transmission switch

Ecomike

NAXJA# 2091
NAXJA Member
Location
MilkyWay Galaxy
What does the Power/comfort transmission switch really do?
 
changes the shift points on the transmission. power is what the newer h.o. rigs are always on. they don't have the choice some renix rigs do. i haven't regeared and run 33 inch tires so i run my '89 on power all the time so it doesn't bog down so much.
 
Any idea how it affects gas mileage in the two positions?

I have one on my stock 4X4 Wagoneer limited, 4.0, 1987.
 
It also firms shifting - which wears the clutches a bit less. Thus, there is a longevity advantage to leaving it set to "Power" - and why ChryCo hardwired it as an option later.

Soft shifts accelerate clutch wear, since they cause vehicle motion to depend upon simple friction longer, rather than the mechanical coupling of a fully engaged clutch.

I switched mine to "Power" a long time ago - and I've been gradually hardwiring them behind the panel as I need additional switches in the IP for add-ons...

5-90
 
i was told it was very minimal. since i have bigger tires, having it on power and not having it bog down so much, improves my mileage and strain on the engine.
 
Thanks!!!!!
 
My light does not come on to show you its in power unless you put it inbetween power and comfort. if the lights not on but the switch is in power is it truely in power or not?
 
mcnamaag said:
My light does not come on to show you its in power unless you put it inbetween power and comfort. if the lights not on but the switch is in power is it truely in power or not?

You've probably got a goofy contact, and may want a new switch. The indicator and switch proper are, technically, two different circuits (the lamp is energised by the load being switched, as I recall, but that's it) so it could burn out entirely but the switch still work normally.

5-90
 
also with the power button on, it is kind of positioned as being in the middle instead of most buttons that when pushed the button goes all of the way to the opposite side. if the light is not on, you can easily tell if it's on or not. stomp on the gas and see if it shifts at a higher rpm or not.
 
My parents had it on our 91 when I was a kid. My dad only ever used it when towing our boat. It works relativley similar in concept to the B&M electronic shift controllers for some GM and Ford trannies.
 
I ran a tank of gas with it on comfort and a tank with it on power. Zero difference in mileage. The torque converter also seems to lockup quicker in comfort as well.
 
On my 89 that switch should be called economy/power.
In power mode I get around 17 in comfort I get better than 20 with my driving style.
If you push it hard I doubt there will be as much difference.
 
langer1 said:
On my 89 that switch should be called economy/power.
In power mode I get around 17 in comfort I get better than 20 with my driving style.
If you push it hard I doubt there will be as much difference.
Langer1,

Verrrry interesting!!!

I do recall switching it from power to comfort while driving, under heavy acceleration (at or near WOT?) one day and the RPM immediately dropped from about 2,400 to about 2000 RPM as it upshifted. It immediatelty switched gears when I hit the Power/ comfort switch, which changing it from power mode to the comfort mode.

Now I am wondering if the gas mileage effect of the two modes does not depend partly on the driving (foot accelearation) style of the driver ( light foot versus heavy foot, as well as trailer towing, hilly areas versus flat). It would certainly explain your getting better mileage in comfort (economy) mode if it stays closer to the 2000 rpm range than the 2400 rpm range for sifting.

Has anyone else run a mileage comparison for the two modes. I assume they just renamed the comfort mode as economy after 1987?
 
Last edited:
My $.02

I have a 92 AW4 transplanted into my 90 Renix which has the pwr/cmft switch in it. When the switch is off the torque converter will lock up at about 30 mph in 3rd gear at light throttle. When the switch is on, the converter will not lock up until 45 mph in 4th gear at the same throttle tip in. Obviously for cruising around town you want the converter to lock up as soon as it can for miles per gallon sake. Having said this, I would say the switch has a major effect on gas mileage, if you're keen enough to notice it that is.
 
OK, now you've done it.

So far I have been able to ignor the fact that I even have a transmision:laugh:, much less other trivial:eyes: questions such as which one I really have:rof:?

So now it begins.

What do you mean "Lock up" when referring to the torque converter. All my experience with torque converters is 1970's hydraulic torqe converters. Never heard of lock up before. I do recall rumors of Chrysler eliminating hydraulic torque converts and going back to mechanical ones in the early 80's.

Please enlighten :sunshine:me!
 
Say you're driving steadily down the road at 25 mph, while lightly pulsating the accelerator pedal you can see the rpm's change accordingly, this would be 'unlocked'. Now say you're traveling steadily at 50 mph, while slightly modulating the accelerator as before you will see that the rpm's will not change so easily as the converter is 'locked up', as it were. Of course taking your foot off the accelerator pedal will cause it to automatically unlock. Locking the converter essentially eliminates all slippage inside the converter providing a 1:1 engine/tranny ratio similar to a manual clutch.

I'm sure there are many thorough explanations of the term 'lock up' regarding converters, so don't take my word for it.:read:
 
Torque converters are still hydraulic, but they (mostly, now...) have a mechanical/hydraulic clutch in them that can change the torque converter from a three-step hydraulic coupling to a single-step mechanical coupling, just like a clutch for a manual.

"Lockup" refers to when this clutch engages, and you then end up ignoring the action of the torque converter elements. This eliminates torque converter slippage (increasing the efficiency of the coupling, and therefore fuel economy,) reduces wear on the fluid (due to heat,) and reduces wear on the transmission internals (due to heat.)

Typically, the transmission controller is programmed to not "lock up" until it sees a steady-state cruise in third gear or overdrive. Once it does lock up (you can usually tell if you pay attention - it will feel like a "soft shift" and cruise RPM should drop a couple hundred points or so...) "breaking cruise" will cause it to unlock ("breaking cruise" being any change in speed caused by a detected action of the brake or foot throttle - not because you're going up or down a grade.)

An early lockup transmission, as I recall, was the A904/A999 - which was an A727 with a lockup converter and hydraulic control circuit.

Lockup torque converters are now very common on vehicles - mainly due to CAFE (Corporate Average Fuel Economy) requirements - this is one of the very few good things that have come out of CAFE regs (bad ones being the Geo Metro and Ford Escort...) They are found in FWD/RWD/AWD/4WD vehicles, and are just about everywhere since 1985 or so.

So you see, the torque converter is still much like you remember - they've just added another part (the clutch) and made some changes in the valve body (hydraulic control circuit) since you were playing with this stuff last... You probably don't notice it because you haven't had to troubleshoot it - and the circuit itself is fairly simple, most "lockup" failues are due to the control solenoid they put in to engage the hydraulic control circuit...

5-90
 
I decided to switch mine to "power" and the only difference that I see is with the TC, it doesn't go into lock up as much or as easy.

Is that normal?
 
Thanks. Now that I know what I am looking for, I can definately feel the lock up, and tell when it is not locked up. Very informative, thanks for bringing me up to speed on this.
 
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