auto versus 6 speed

[Glen]

I'm sorry I came late to the thread; I just returned from a trip. But let me say something that seems obvious to an ELECTRICAL engineer.



I often tow my trailer on long trips and want the best fuel economy. That means running about 2000 rpm. All the obfuscation about accellerating aside, the automatic transmission will be locked-up when cruising. That means there are four gears available to set engine speed instead of six for the manual transmission. Or, typically, one instead of two or three. My manual transmission doesn't have to unlock to climb a grade and where I drive there are a lot of grades.

Glen



P. S. I cannot resist a comment about "all the energy that is lost spinning up and slowing down the flywheel". The process is energy neutral.

 

[Matt400]

My manual transmission doesn't have to unlock to climb a grade

That kinda sounds like your implying the auto does.



When I hit a grade in (OD locked) and the load, RPM's & speed are such that I could use a lower gear I then choose (drive locked) for long grades.

Actually letting the transmission do its thing translates into a 7 speed as it makes changes in engine RPM's between the various gears and locked or unlocked modes.



This thread could go on forever I bet. I admit the 5 & 6 speeds are fun to drive but I guess I'm just lazy.

 

[Hohn]

Matt:



In terms of gears and such, the auto basically has these modes, right?



1st gear, unlocked

2nd gear, unlocked

3rd gear, unlocked

3rd gear, locked

OD, unlocked

OD, locked



Am I mistaken? I thought the 48RE will lock in 3rd, but also will allow OD without the TC locked. This equates roughly to six gears. It's the variability of gearing the the TC allows that really makes the gearing of an auto vs manual apples and oranges. There's no set ratio of gearing with the TC when it's unlocked.



Glen, spinning up and slowing down the flywheel would NORMALLY be energy neutral. The problem is, we expend the energy the accelerate the flywheel, but we don't get to reclaim that energy because the clutch is pushed in when the Flywheel is spinning down. When we engage the clutch, the stored flywheel energy that isn't lost already is usually converted to heat as the clutch transitions from disengaged to fully engaged.



A flywheel is only energy neutral if all the other conditions are held constant, and in a manual trans, we aren't doing that.



Hasselbach will back me up on that (I'm not so sure that's a good thing, lol)





True, the auto trans WILL be locked up when cruising. But this does NOT mean there are 4 gears available. First, the TC won't stay locked in all gears. The problem/advantage of the auto trans (depending on your opinion) is that is will unlock and make available an infinite number of ratios between two limits (those limits being stall speed and lockup).



So that auto actually has more available ratios than you could count. The price of this advantage is reduced mechanical efficiency when not in lockup.



As discussed earlier, there's more to overall efficiency than just the mechanical efficiency of the engine/trans connection (BSFC is a huge factor).



Justin

 

[hasselbach]

Yep, Justin is correct with his observations, but one thing I will add. . The TC will lock up in second gear as well. I have confirmed this with my scan tool recently, so it locks up in 2-3 and OD.



And Justin made a very good point about spinning up and down the flywheel, it is not energy neutral as Mr. Electrical Engineer deduced...

 

[Glen]

Of course BSFC is what I am referrring to. This occurs about 2000rpm. As for the flywheel, I stand corrected; it is a minimal loss anyway.



Personally, I don't like AT's, nor does may wife. A truck with an AT is just a car. I also own a car. It took four months to order it from the factory. It was the only way I could get a nice car with a manual transmission!



Glen

 

[Lorenz]

If you add a lock up switch (mystery swicth) itll lock up in 1st as well. The catch in my situation is im not shure of the in's and out's of the switch's proper use. could anybody chime in on the proper use of the switch?



http://www.tstproducts.com/tranny_install.html

A link to the switch from tst... cost is less than $10

 

[hasselbach]

I've talked to Suncoast about the switch, and from what I understand they have a new box coming out for the 48re to control lock up.



I guess if you manually lock it up too soon you might hurt the converter (stock unit) due to the amount of slippage at high loading. This transmission definitely needs a better lock up program though.

 

[Matt400]

Am I mistaken?

Hi Justin, Only thing you forgot was (2nd locked).

True, the auto trans WILL be locked up when cruising. But this does NOT mean there are 4 gears available. First, the TC won't stay locked in all gears. The problem/advantage of the auto trans (depending on your opinion) is that is will unlock and make available an infinite number of ratios between two limits (those limits being stall speed and lockup).



So that auto actually has more available ratios than you could count. The price of this advantage is reduced mechanical efficiency when not in lockup.

uggg... reduced mechanical efficiency? I suppose if you focus on one is slipping where the other is locked that would stand to reason. Maybe we should rename the torque converter to slip unit.

Another view is the one varying the torque is allowing the RPM's to remain steady thus taking advantage of a more steady RPM. Something has to account for the excellent mpg's auto drivers are getting.

 

[BRayls]

Funny all the talk about spinning up the flywheel. You never once mention spinning up the tc,less to worry about but it still is weight. The problem with the variable ratio you feel you have in the tc is ,the power is not locked up. That is wasted power not being put to the ground. Mpg,autos are not getting better mileage than sticks. Sure you can upgrade the trans to be better,but the dollars you spend ,lets just say not cheap. Don't let me stop anyone from buying autos, that keeps me in work, I work in the plant the units come from. I made this easy to read. Better not read many other topics , as they too have many posts like mine. :{ still waiting to see the 60 foot times from your runs hasslebach. I am waiting on buddy to bring et slips to post. now if we had the option of hydrostatic trans,then I would see the variable ratio

 

[hasselbach]

Funny all the talk about spinning up the flywheel. You never once mention spinning up the tc,less to worry about but it still is weight. The problem with the variable ratio you feel you have in the tc is ,the power is not locked up. That is wasted power not being put to the ground. Mpg,autos are not getting better mileage than sticks. Sure you can upgrade the trans to be better,but the dollars you spend ,lets just say not cheap. Don't let me stop anyone from buying autos, that keeps me in work, I work in the plant the units come from. I made this easy to read. Better not read many other topics , as they too have many posts like mine. :{ still waiting to see the 60 foot times from your runs hasslebach. I am waiting on buddy to bring et slips to post. now if we had the option of hydrostatic trans,then I would see the variable ratio

You made this is easy to read? Wow, I would hate to see the uneasy format. :-laf



In any event Mr. Rayls, I've covered your questions in great deal about 100 posts ago, so feel free to review them at your leisure. But to sum it up, the TC is not wasting power, the TC does not work like a flywheel (storing energy and released when clutch engagement) and no, the 6 speed does not get better mileage than the auto. In fact, I've seen the parasitic loss (transmission dynos) of autos equal to or less than 5-6 speeds due to friction losses, high viscosity oils and multiple gear engagement in manual transmissions compared to linear power flow automatics (planetary gears locked up)



The mpg between the stick and auto's in the newer dodges are almost identical from what I have witnessed and personally seen with exact trucks albeit the transmission choices.



Lastly, at LACR recently when my brother and I took our 04. 5's to the track (his is a 6-speed, mine is obviously the automatic). I was faster in MPH and ET than his identical truck, regardless of the driver. Did I say the trucks were identical except for his is leather and a 6 speed. My 60 foot was 2. 5 (leaving at an idle) and 2. 42 (leaving at 1,600 rpm). Bro's was never better than low 3's regardless of launching in 1st, 2nd or 3rd. Either he was too low geared, or had to slip the clutch way too much, or spun the tires and didn't recover. I drove the truck and had the same results. He was a full 1/2 second slower in the ET, and 2-3 MPH less in the traps.

 

[jimk]

I have read several of these post and I have a 95 4x4 automatic. From what I have read in these posts are how really wonderful the convertor transmits torque, my question is has the convertor design changed since 95 model? I can at will flash the convertor to the very high rpms but I dont remember blistering speeds or break away exceleration in fluid coupling. I do remember towing a 50 hp 4x4 backhoe and that was not what I would say as enjoyable. Seveal times I have had a trailer load of 8 inch pipe about 20 foot long and several layers that was very heavy. The pipe had a lot of dirt in them. One thing is for sure I can just about set the rpms about any where I want in fluid coupling. That must be great, but I do not remember the experince that way. Thank goodness I have a 4x4 to backup with to use low range.

My goal is not racing my truck or truck and 4020 JD diesel in tow or diesel backhoe. I just want to have a truck that has more than infinate number of ways to flash the convertor to red line of the tack and finally see the miles an hour increase.

If the flywheel is wasted energy I certainly can live with that problem. If I can let off the clutch and watch the speed odometer move along with the tack that would be a welcome change. I dont care if I get the checker flag or not. I'm for sure not going to jail for racing or killing some one doing that pulling a trailer. JIM

 

[hasselbach]

Well, your 1995 isn't a torque monster to begin with, so even if you had a 10 speed, I doubt you'd feel much acceleration anyway.



If you are redlining your motor and not moving, your converter is crap, I'd guess that the sprag is broken and the stator is rotating backward, not transmitting any torque. It occasionally can happen. Call DTT or Suncoast and get a decent converter, it will make a world of difference.

 

[Hohn]

Agreed. The OEM converter is by FAR the weakest link in a stock auto transmission-equipped truck.



I'd like to hear from the DTT guys on the mileage difference between the different DTT converters-- the 89, 91, and 93 "percent" converters.



Reasoning says that the 93 would get the most mileage (slips least), but how does this play out inthe real world?



Haselbach already illustrated how the auto makes for better racing...



I have one pivotal question, though-- which truck burned more fuel to run its quarter mile race? I mean, the quantity of fuel burned over the 1320. The auto, because it has slippage? The stick, because it took longer to run the race?



Inquiring minds want to know.....

 

[Archive]

Quick question for the auto guys ... can you select each of the four gears with the shifter, or does it work like GM or Ford where they won't allow you to select one of them. I almost got my Corvette with an auto, but you couldn't force the selection of third gear, so I went with a manual. I don't like not having control of every gear.

 

[Cummins Pilot]

I think most people buy an auto because its easier and more convienent. Even in downtown driving I don't notice shifting gears. I'm to used to it. And also since I'm a pilot my hands are always busy. When I drive an auto I feel very disconnected. I feel like I'm not part of the process. I guess I'm just used to the work load and have done it enough its like breathing.



But in the end its each to their own.

 

[jimk]

I have never wonted a torque monster so that is fine by me. The truck makes, I am told, around 270 or a little more hp and 650 or so lbs of torque. The more hp I have given the truck the more apparent the convertor is crap. I wish I had more gears an if I dont sell the truck to some one who has to have a automatic I will have six gears.

Even if I had a good convertor the gap between 3 and 4 gear is not what I would consider good for towing. I have considered installing a gear vendor and I have one sitting in my shop floor to have a better gear to tow in. Third gear lockup and gear vendor overdrive. NOT have to put up with a TPS switch has some value, along with a better gear ratio in overdrive is for me = a six speed. I dont mind being in the rear view mirrow. But I would be interisted in watching some one else race their truck. regards Jim

 

[Matt400]

Quick question for the auto guys ... can you select each of the four gears with the shifter, or does it work like GM or Ford where they won't allow you to select one of them.

Well specific settings are a little more than putting the lever in a particular position like a stick but yes you can select 1st, 2nd and 3rd. 4th requires speeds over 45-50 while in the 3rd gear selection.



2nd locked will happen for you while in the 2nd or 3rd gear selections depending on your go pedal position.

3rd and 4th locked will happen for you while in the 3rd gear selection again depending on your go pedal position.



A real nice feature would be an auto/stick like whats in the wifes PT Cruiser.

With hers you can select manual mode and up or down shift + hold any of the gears you want.

 

[Jeremiah]

Well specific settings are a little more than putting the lever in a particular position like a stick but yes you can select 1st, 2nd and 3rd. 4th requires speeds over 45-50 while in the 3rd gear selection.



2nd locked will happen for you while in the 2nd or 3rd gear selections depending on your go pedal position.

3rd and 4th locked will happen for you while in the 3rd gear selection again depending on your go pedal position.



A real nice feature would be an auto/stick like whats in the wifes PT Cruiser.

With hers you can select manual mode and up or down shift + hold any of the gears you want.

All this talk has confused me. I thought automatic transmissions were supposed to simplify things - put 'er in D and go, in other words. Now you guys are making me think I'd need a Ph. D. to operate one properly. Glad I got a 6-speed HO. I just put 'er in the gear I want, when I want it, let the clutch out and go! Don't worry 'bout torque coverters or nothin. ' Ignorance is bliss.

 

[hasselbach]

All this talk has confused me. I thought automatic transmissions were supposed to simplify things - put 'er in D and go, in other words. Now you guys are making me think I'd need a Ph. D. to operate one properly. Glad I got a 6-speed HO. I just put 'er in the gear I want, when I want it, let the clutch out and go! Don't worry 'bout torque coverters or nothin. ' Ignorance is bliss.

What happens when you have to stop? Do you remember to use the brake pedal or is that confusing too? :-laf

 

[Matt400]

All this talk has confused me. I thought automatic transmissions were supposed to simplify things - put 'er in D and go

Sorry for the confusion- my reply was just about how to manually select what you want out of 7 possibilities. You can also just dump it in D and go.