Upshifting in an automatic

[Douglas]

All this talk of shifting has reminded me of a question concerning manual gear changes in a Pagoda. When you manually shift up to a higher gear, is it necessary to remove your foot from the throttle during the upshift?

Douglas Kim
New York, NY
280 SL #016220

[DavidAPease]

Doug,

I manually shift my automatic all the time.  With the exception of moving to second to start out in first, it seems that what the shifter does is set the highest gear the automatic will shift into.  What this means is that when you manually upshift, all it really does it move the high limit up (but doesn't really shift, as such).  When I am accelerating onto a freeway in third, with my foot into the throttle, I will move the shifter to 4th without letting up on the gas.  This allows the automatic to shift into 4th when it's ready, often quite a while later.  If I were to let up on the gas when I did this, it would usually shift immediately.  

I hope this makes some sense.

-David Pease
'66 French 230SL

[mdsalemi]

Doug,

It's taken me a little time to get used to effective control of RPM's and torque via "manual" shifting in the automatic, which I have.  My only real shifting occurs from the Drive (4) position down to 3 sometimes; this is because short of flooring it and activating the electric kickdown switch, sometimes you need the power of third gear when the sleepy    transmission decides it should be in forth gear, and you don't need to frighten your passenger or neighbors by flooring it!  This happens after cruising in 4th, and you go to casually pass someone, or casually get on a highway ramp, or something to that effect.  Moving the shifter down to 3 drops the gear down to 3, and when you put it back into 4, the transmission will decide when it should shift into 4th as David noted.  I never move it into 2 nor do I try to mimic the action of the transmission and I don't remove my foot from the accelerator.  Never occured to me to do so.  Also, only once has my car actually been in 1st gear when I decided to see if it really exists.  It is so very low, I'm certain I could tow a trailer up the north face of Everest with it.   With mildly brisk acceleration, my car frequently chirps the tires in the 2-3 shift, so using 1st gear would be ridiculous.  Norton once pointed out that this gear is useless.

Interesting note: I once owned what was called an Austin America, aka Austin 1300 Mk II in Europe with a 4 speed automatic.  It had a gear selector; there was a drive position, as well as 4,3,2,1.  When you moved it from D to 4, it stayed in 4, and wouldn't move.  Ditto for 3,2,1 positions regardless.  So the shifter was actually manually selecting the gears and disabling automatic shifting when out of the D position.  Read more about this unique car:

http://www.seriouswheels.com/1970-1979/1970-Austin-America.htm

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

[Cees Klumper]

This is an interesting phenomenon we are now discussing.

My car used to downshift when I applied more throttle, WITHOUT necessarily having to engage the kick-down switch. In the data manual and/or BBB, there are shift points for the automatic that are within a range for downshifting. Which means that, when you need to downshift because you need the extra torque or whatever, there is a speed range within which the transmission should downshift depending on the amount of throttle applied, however before you need to apply the kick-down switch - this is only necessary when the speed you are driving at is outside the designated range.

Then I installed my rebuilt engine last year spring. I connected all the wires to the auto trans solenoids the same way I was confident I had disconnected them. And the transmission shifts up as it used to, however not down anymore in response to throttle. It only will shift down if I slow down (so that's normal), OR engage the kickdown switch, OR obviously if I select a lower max. gear with the selector. No more downshifts with more throttle applied, as it used to. I double checked the wiring but to no avail. I still want to double-check the operation of the 3-position solenoid, but not sure whether to expect solace from that.

Then as I was tinkering with the ignition timing the other day (see all those other posts) I found that this timing sigificantly affects the upshift points. This would be from the alteration in the amount of vacuum that goes to the transmission from the intake manifold, no?

So maybe the new engine has different vacuum characteristics that the auto transmission needs to be adjusted to, is what I am thinking (probably erroneously, so please help me out!).


Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[rwmastel]

quote:Originally posted by cees klumper

My car used to downshift when I applied more throttle, WITHOUT necessarily having to engage the kick-down switch.

Then I installed my rebuilt engine last year spring. I connected all the wires to the auto trans solenoids the same way I was confident I had disconnected them. And the transmission shifts up as it used to, however not down anymore in response to throttle. It only will shift down if I slow down (so that's normal), OR engage the kickdown switch, OR obviously if I select a lower max. gear with the selector. No more downshifts with more throttle applied, as it used to.

So maybe the new engine has different vacuum characteristics that the auto transmission needs to be adjusted to, is what I am thinking.

Very interesting, Cees!

You are one of the few, if not only, people to experience down shift with increased throttle.  Everyone else seems to need the kickdown switch or the gear selector.

It will be interesting to hear form the transmission experts regarding the adjustments of the transmission to the vacuum properties of the engine.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[waltklatt]

David,
Wonder if the transmission is waiting for a slight pause in the heavy accel to upshift, to avoid a massive flareout in the converter housing.  I also do the same with any automatic, especially when I feel like doing some spirited driving.
Several times with my former 1968 280SL, I would open the throttle wide open to near the redline (fuel starvation problems) to keep the motor going and then shift into gear to go.  Problems were fixed by replacing the injection pump.  But the sheer neck snapping acceleration with the tires spinning in 1st and 2nd was spectacular.
Ahh the younger days....
Walter
1967 230SL-diesel
1963 230SL-for sale

[Chad]

Walter, did you keep the stock differential on your 230 SL after you put the diesel (presumably OM617) into it??  I am trying to imagine it because I have each engine.  I can only imagine that a MBZ diesel runs out of revs with the stock 230 SL differential.

-CD-
1967 230SL, 113.042 10
1983 300TDT, 123.193

[waltklatt]

Chad,
The motor I put into the 1967 230SL is an OM601 4 cylinder 190D 2.2L with the 5 speed manual.  Both came from the same car-1985 190D that was wrecked in the rear.
I currently have a 4:08 rear end in the car, but also have a 3:65 on the side if I want to reduce the revs on the highway.  Might even look for a 280SE 4.5L rear end and switch to disc brakes all around.
I will post the results after driving the car for many miles on the highway.  As of now, it's still in it's primer and waiting for the paint.  Will be out of town for a few days and upon returning I'll drive the car to the painters.
Walter
1967 230SL-diesel
1963 230SL-for sale

[Chad]

Walter, any thoughts of WVO/grease conversion in this Pagodas future??  It may be the only one with clean emissions and smell like french fries!

I've gone that route in the OM617, but mostly just fill the diesel tank only.  Figure it's seen 300k miles of diesel, it might as well see another 300k miles of it.

-CD-
1967 230SL, 113.042 10
1983 300TDT, 123.193

[Cees Klumper]

Any more inputs as to the original topic, upshifting in automatics - should that happen automatically?

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[waltklatt]

Heehee Chad,
Would you like to have an order of fries with that?
Well, not yet going that way.  
But if the prices of diesel and gas going up like they are, I might look into other ways of powering the SL.  Maybe corn or soy power?
Never know what's the next fuel source.
Walter
1967 230SL-diesel
1963 230SL-for sale

[waltklatt]

Cees, I'm sure you have driven with the gear in 2 or 3 position and then upshift to higher gear.  In this case the tranny will hold the gear longer to attain maximum acceleration and power till you want to upshift manually.  Does this answer your question?
Walter
1967 230SL-diesel
1963 230SL-for sale

[Cees Klumper]

No Walter; the question concerns downhifting, not upshifting. I.e. my car used to upshift at certain speeds when I appied more throttle, without engaging the kickdown switch. With the rebuilt engine, it does no longer upshift like that and if I want it to, I have to do it manually by selecting a lower gear (mostly 3 instead of D) OR engage the kickdown switch. So the question was whether other cars also downshift at certain speed ranges, when more throttle is applied (as new cars fitted with an automatic transmission, like my 2001 Volvo C70 convertible) will do.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[J. Huber]

Cees, I think I might know what you mean. Mine will shift to a lower gear automatically by gently applying the throttle in certain situations. For example, if I am coming up on a left turn on a hill, as I slow to turn but am still throttling I feel it kickdown. However, there are those times when it doesn't seem to do it -- and I feel a loss of power -- I then manually drop a gear.

James
63 230SL

[Cees Klumper]

That's it James! So there is at least one more car out there that shifts more user-friendly.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[ja17]

Hello Cees,
I have the factory automatic transmission book in front of me and there is a chart showing up shifts and downshifts at different accelerator positions.

It does appear that the transmission will downshift at other pedal positions. For instance;
in gear selector 4, at partial throttle the automatic will downshift from 4th to 3rd at 30 kph and at around 23 kph it will downshift from 3rd to 2nd.

At full throttle (not kick down) the auto  downshifts are the same as above.

With the selector in 3, no downshifts occur except in kick down at 10-12 kph (2nd gear to 1st gear).

With the gear selector in 2 the auto downshifts occur at 10kph at any throttle position except kick down when it occurs at 23 or 30 kph ( depending on trans version).


Joe Alexander
Blacklick, Ohio

[mdsalemi]

Hi Joe,

OK, I hear you on the downshifting points.  What if the downshifting (4 to 3) is not happening at the proper time?  What does this mean?  Transmission problem or wiring problem?

When slowing and braking for a stop sign or stop light, certainly I am getting the downshifts...whether they are at the right point I'm not certain.

But here IS a scenario I experience...cruising in 4th, and manage to slow down to say 40 kph (25+mph??), according to the book you will still be in 4th.  Should the transmission then downshift to 3rd if you accelerate, but not so hard as to hit the kickdown switch on the floor?

Without all the experience you and others have, I am often trying to figure out if (as the computer software writers say) I have a "bug" or a "feature"!

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

[ja17]

Hello Michael,
Of coarse any change in differential ratios from standard ratio will alter the shift points a bit. These specs would almost have to vary slightly between cars depending on the differential ratio. I guess the question I missed is "will the automatic transmissions ever downshift without hitting the kick down?". We know that the transmissions will shift down when reaching the speed  for shift down. The modulator pressure is affected by accelerator position in that it will changes engine vacuum which changes modulator pressure at the transmission via the vacuum tube from the intake manifold. My guess would be that the change  of the accelerator pedal position in between kick down and idle will cause some MINOR changes in shift up or down speeds because of changing modulator pressure. In this case mandatory downshifts may only be able to be caused by hitting the kick down in most cases. However automatic downshifts will occur when the correct lower speeds are reached which may be influenced by modulator pressure controlled by pedal position (intake vacuum). Just some thoughts. Maybe someone can verify?
 
Michael if your downshift speeds are radically different from the specs you may need a minor adjustment. Before acting I would document the downshift speeds, check your differential ratio, and double check the factory specs for your year and transmission type. I can double check the specs in the Tech Data Books and factory transmission manual if you can provide the other information.
   
 



Joe Alexander
Blacklick, Ohio

[mdsalemi]

OK Joe, here goes.

First, my car has the stock, normal rear axle for a 1969 US Automatic.

I drove a bit today and did quite a few checks.  Everything concerns shift between 2, 3 and 4th gears; 1 does not come into play in normal driving and neither does reverse, so here goes:

UPSHIFTING.
I drove in three different manners, Gentle (very light touch on the accelerator); normal (medium touch) and "spirited" (almost heavy touch).  I did not do "pedal to the metal".  All shift points are in MPH.

Gentle/Normal/Spirited
2 to 3:  20/28/28
3 to 4:  28/45/50

DOWNSHIFTING.
Downshifting was uniform.  The 4-3 downshift is at 20mph, and the 3-2 downshift is at about 10mph....

...and therein lies the question:  From the above downshifting you'll see that if you are cruising in 4th, you'll have to get to 20mph to get into 3rd.  So, you are cruising at 55, and suddenly you slow for a light that's red...you slow down to 25.  You are still in 4th.  You then go to accelerate, because the light went green before you really had to stop.  At 25mph in 4th, acceleration is quite sluggish.  You can put pedal to the metal and engage the kickdown, which works fine.  Or you can manually downshift into 3rd using the automatic's shifter, also fine.

B U T, should the transmission "find" 3rd gear earlier then 20mph on deceleration?  That's the big question.

Comments?


Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

[J. Huber]

Thanks Mike -- just gave me an excuse to go take a ride...(not that I needed one!) But in the name of science, I will see what my numbers are compared to yours.

James
63 230SL

[J. Huber]

Ok. First round of my lab results are in! Just got back from some driving in the name of science...(I am thinking I might need to recreate this experiment at least a 100 more times to make it truly scientific)   ...

On my original 3.75 automatic tranny -- 230SL: (fully warmed up). I had to convert from KPH to MPH -- and I averaged any varied numbers.

      Gentle/Normal/Spirited
2-3:          22/26/26
3-4:          37/44/49

One thing I noticed was the shift points in Normal driving were very consistent. Almost dead on every time. The Gentle and Spirited numbers fluctuated a lot more.

And, to get the car to downshift from 4 to 3 on throttle, I need to be slowed down to 25 MPH. Anything above that was no man's land -- to get back up to speed I either had to ride it out sluggishly or drop to 3rd with the stick. Darn.




James
63 230SL

[ja17]

Hello Michael and Cees,

I have reserched the question of downshifting in my factory transmssion manual and the technical data booklet. It appears that accelerator postition during downshift will NOT cause an earlier or later downshift unless the kickdown is engaged. The 4th to 3rd downshift will occure at about 30kph (20mph). If your car has the 3.92 differential the downshift will happen at a 4% lower speed and if you have the 3.69 differential the downshift will happen at approx 5% higher speed. ( **1969 Tech Data Booklet).

Now since upshifting will be influenced by engine manifold vacumme and rpm, shift variations will occure depending on the accelerator postion and engine load.


Joe Alexander
Blacklick, Ohio

[mdsalemi]

quote:Originally posted by ja17

Hello Michael and Cees,

I have reserched the question of downshifting in my factory transmssion manual and the technical data booklet. It appears that accelerator postition during downshift will NOT cause an earlier or later downshift unless the kickdown is engaged. The 4th to 3rd downshift will occure at about 30kph (20mph). If your car has the 3.92 differential the downshift will happen at a 4% lower speed and if you have the 3.69 differential the downshift will happen at approx 5% higher speed. ( **1969 Tech Data Booklet).

Now since upshifting will be influenced by engine manifold vacumme and rpm, shift variations will occure depending on the accelerator postion and engine load.


Joe Alexander
Blacklick, Ohio

Thanks, Joe!  It appears as if the automatic shifting in my car is working exactly how it supposed to.  It seemed that Cees had described downshifting at a higher speed then 20 mph, without the kickdown, and that had me concerned; I must have misinterpreted his comments, or he has an issue!  At least I know mine is all OK!

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

[ja17]

Hello Doug,

Yes you can keep it to the metal when shifting up manually with an automatic transmission.

Joe Alexander
Blacklick, Ohio

[J. Huber]

Well, as this wraps up, I'd agree that Mike's seems to be right on, mine a bit out of whack. My downshift occurs at precisely 41 KPH -- so either my speedo is considerably off (which I do not think so), or my transmission is old, original, and peculiar because of it. And Cees, as I look at the equation more, I think my downshift on throttle might be a mere a coincidence to the KPH hitting the "shift zone."

James
63 230SL