Translation: You don't know when it was last changed. And by inference, likely don't know what fluid might be in there. *facepalm*
No issues there! Dex-III is fine.
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722.3 transmission technical discussion
- Thread starter 400Eric
- Start date
I experimented with this a couple of times and found no gains, at least not any measurable, repeatable gains. Not enough for me to pursue a permanent increase in upshift RPM, anyway. Differences of hundredths of a second are not statistically significant, IMO.
I also pulled live data from the AX-22 to see the actual shift RPM's, i.e. what the engine RPM was after the upshifts. The 1-2 upshift dropped to ~4250rpm, the 2-3 also dropped to ~4250rpm, and 3-4 dropped to ~4325rpm. And on my 5.0L dyno graphs, peak torque is right around 4000rpm (very close to the 3900rpm spec).
Problem: The power curve drops off past 6000rpm. If you upshift later, you pick up a little area under the HP curve down at the 4200-4400 shift point, but you also lose some area under the curve at the top end as the power tapers off. On paper, it ends up as a wash... which, interestingly, is exactly what I found on the timeslips. Granted, you are dealing with a 4.2 motor and there could be some minor differences but overall, the 4.2 and 5.0 have VERY similar curve shapes.
I experimented with this a couple of times and found no gains, at least not any measurable, repeatable gains. Not enough for me to pursue a permanent increase in upshift RPM, anyway. Differences of hundredths of a second are not statistically significant, IMO.
I also pulled live data from the AX-22 to see the actual shift RPM's, i.e. what the engine RPM was after the upshifts. The 1-2 upshift dropped to ~4250rpm, the 2-3 also dropped to ~4250rpm, and 3-4 dropped to ~4325rpm. And on my 5.0L dyno graphs, peak torque is right around 4000rpm (very close to the 3900rpm spec).
Problem: The power curve drops off past 6000rpm. If you upshift later, you pick up a little area under the HP curve down at the 4200-4400 shift point, but you also lose some area under the curve at the top end as the power tapers off. On paper, it ends up as a wash... which, interestingly, is exactly what I found on the timeslips. Granted, you are dealing with a 4.2 motor and there could be some minor differences but overall, the 4.2 and 5.0 have VERY similar curve shapes.
MY modded 4.2's peaks are a little higher. Please post my dyno graph again. You have it somewhere. My 4.2's power drops off more gradually than your's does too. Please post your 4.2's dyno graph with mine.
And let's don't forget, I race my M103s too, with their torque peaks of 4400 RPM.
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Wasn't it just the GM Turbo 400s that had an electric kick down switch? I don't remember Turbo 350s having that.
Borg Warner automatics, as used in pre-72 AMCs and Internationals, also had an electric kick down switch.
I did play with this some a while back on B3. Yes, I got some of the results I wanted, but then I got some undesirable ones as well. Like constant downshifts all the time when I didn't want them, holding on to the lower gears (especially 2nd) longer than I wanted it to, even at very light throttle, but yet it didn't seem to change the WOT shift point, which was the one thing I was after the most. Yes, it gave me quick kickdowns more quickly, doing 2 gear kickdowns when before I was only getting a 1 gear kickdown, which I appreciated greatly, but in the end, I ended up putting it back where it was, and instead just worked the shifter manually when a situation called for it, cause the bad effects outweighed the good. There's no question that this cable has an effect!
You really should have made that get together in Georgia, as they could have investigated this further for you. There were some real pros present at that.
Regards,
Eric
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Of course it has an effect. On part throttle shifts! Your experience described above is EXACTLY what I would have expected. The primary discussion here is about WOT upshifts, and once you get past roughly 80-90% throttle travel with a properly adjusted (per FSM) Bowden/control pressure cable, it ceases to provide any further difference. The WOT upshifts assume the Bowden cable is fully pulled out and are based on the kickdown solenoid being energized, along with the VB setscrew which most people never touch in their lifetime. (And selector lever position... most of the discussion above assumes "D" position, keep forgetting to mention that!)
I'm looking at them! I've been looking at them! I never lost them! The problem is I do not have them in digital form.
You superimposed my best graph with your 4.2's best graph, and then posted them. I'm only asking where did you do that?
If we can see that graph, we'll see why it is beneficial for me to hold onto my lower gears longer. And it sure would be nice to have the trans do it instead of me having to do it manually every time. That would help consistency too! You might even see me make a bracket race attempt if I could have that!
Back to that valve body screw for a moment, guys, is there a rough formula that one can go by, say, a quarter turn equals about a hundred RPM, or something like that?
You superimposed my best graph with your 4.2's best graph, and then posted them. I'm only asking where did you do that?
If we can see that graph, we'll see why it is beneficial for me to hold onto my lower gears longer. And it sure would be nice to have the trans do it instead of me having to do it manually every time. That would help consistency too! You might even see me make a bracket race attempt if I could have that!
Back to that valve body screw for a moment, guys, is there a rough formula that one can go by, say, a quarter turn equals about a hundred RPM, or something like that?
From what I've read of the discussions, everyone has this thing pretty much figured out. Here's some of the important things to remember:
When theorizing or experimenting with these things, think of their usage as designed. For example, it's easy to think of the engine braking "locked in first gear / "B" position" function as being achieved by the electrical switch in the shift gate energizing the kickdown solenoid. With a little further thought we remember that this is not true, and that "B position" is actually achieved by energizing of the kickdown solenoid combined with the shift range selector valve in position 2.
Similarly, it is easy to think of kickdown shifts and kickdown upshift points as being achieved by the energizing of the kickdown solenoid, and this is not true. The kickdown condition is achieved by application of the kickdown solenoid combined with full throttle positioning of the control pressure valve via the cable from the throttle linkage.
While the previous parts of this discussion may seem elementary, my experience has been that we frequently confuse ourselves by not thinking of these individual elements within the larger environment in which they actually function.
An example of this was seen recently as we discussed our way through a diagnosis process on Oakland's transmission. If you don't remember, the problem was that his transmission shifted particularly late. That is to say it required to high a vehicle speed to produce a given shift, and when it finally did shift, it did so in a somewhat bizarre manner. Some of us theorized that the kickdown solenoid was improperly being engaged (powered) at low throttle loads. Others theorized that this was not likely because the transmission did in fact upshift. They were thinking that energizing of the kickdown solenoid alone would prevent any upshifting. This thinking did not allow for the consideration of what could possibly happen when the solenoid is engaged but the control pressure is relatively low, as would be the case in this failure scenario. When thinking of these things singly, it's easy to imagine that that kickdown solenoid has full authority over the upshift points. It is most especially easy to think this when one knows that in a properly functioning system the kickdown upshift points are realized by an electronic control element briefly disconnecting the power from the kickdown solenoid.
The problem with Oakland's car did turn out to be a stuck kickdown switch apparently.
Here's why I went through this: We've had a little controversy as to precisely how much influence this full throttle control pressure adjustment screw could have on kickdown shifts, and indeed if it had any influence on kickdown up shifts at all. In strict theory with a perfectly adjusted system it does not affect the kickdown upshift points. In reality on the street, it sometimes affects them dramatically. Here's how: it turns out, and this is easily verified by experimentation with this screw, that the kickdown function hydraulics via the solenoid are actually a relatively small influence. Far and away the major influencing parameter on the full throttle upshift and downshift points whether under kickdown or not is the full throttle control pressure. As far as the actual transmission behavior goes, the solenoid hydraulics are more or less frosting on the control pressure cake. If the full throttle control pressure is too high the engine will run into the rev limiter even though the power had been disconnected from the kickdown solenoid by the electronic controls at the correct engine speed. Similarly, if the full throttle control pressure is adjusted too low the kickdown solenoid influence is not enough to raise the upshift point high enough that the electronic control element ever intervenes. The transmission will simply upshift with the kickdown solenoid engaged. I have encountered each of these conditions in the field a number of times.
So this is why one can be "correct" in thinking that this adjustment has no influence on kickdown upshift points. In a perfectly functioning and correctly adjusted system, it doesn't. However, the way the system actually functions with the kickdown solenoid controlled hydraulics being a much smaller relative influence than the full throttle control pressure, one can see why Mercedes states that this full throttle control pressure is a potential influence on all shifts occurring at full throttle, whether under kickdown or not.
Note also that not every shift valve in the valve body is influenced in exactly the same relative degree by these pressures. It is not uncommon for example to find a valve body adjusted in such a manner that the 1-2 upshift under kickdown occurs some degree below the electronically controlled power interruption to the solenoid, while the other two up shifts occur at the moment of power interruption. This is a measure against bumping into the rev limiter on the 1-2 upshift under unfavorable conditions. And no, that particular little tidbit is not published anywhere to my knowledge.
Eric, since you asked, there is training literature stating that one full turn of the screw equals approximately a 10 km/h deviation in the full throttle upshift point. Note that one turns the screw in a counterintuitive direction: clockwise will result in upshifts occurring at lower speeds, while counterclockwise results in higher speed up shifts.
Note something else that we have not discussed, yet that can be as important as anything else when trying to get good shift feel and high performance. The same adjustment that gives you higher speed upshift points also gives you downshifts occurring at lower speeds and sometimes with less depression of the gas pedal. It's not uncommon to tweak this adjustment higher for example, and find an a nice tasty two gear down shift in the same conditions where you only got single gear downshift before. Or you may find that you get a downshift of one gear and a more immediate vehicle response where in the same condition before you only got a downshift by depressing all the way down through the kickdown switch. Both adjustment effects are NICE!!
Very handy this little adjustment. The only downside is that you have to take the pan off. The other is that you probably will over do it the first time or two you try it...
When theorizing or experimenting with these things, think of their usage as designed. For example, it's easy to think of the engine braking "locked in first gear / "B" position" function as being achieved by the electrical switch in the shift gate energizing the kickdown solenoid. With a little further thought we remember that this is not true, and that "B position" is actually achieved by energizing of the kickdown solenoid combined with the shift range selector valve in position 2.
Similarly, it is easy to think of kickdown shifts and kickdown upshift points as being achieved by the energizing of the kickdown solenoid, and this is not true. The kickdown condition is achieved by application of the kickdown solenoid combined with full throttle positioning of the control pressure valve via the cable from the throttle linkage.
While the previous parts of this discussion may seem elementary, my experience has been that we frequently confuse ourselves by not thinking of these individual elements within the larger environment in which they actually function.
An example of this was seen recently as we discussed our way through a diagnosis process on Oakland's transmission. If you don't remember, the problem was that his transmission shifted particularly late. That is to say it required to high a vehicle speed to produce a given shift, and when it finally did shift, it did so in a somewhat bizarre manner. Some of us theorized that the kickdown solenoid was improperly being engaged (powered) at low throttle loads. Others theorized that this was not likely because the transmission did in fact upshift. They were thinking that energizing of the kickdown solenoid alone would prevent any upshifting. This thinking did not allow for the consideration of what could possibly happen when the solenoid is engaged but the control pressure is relatively low, as would be the case in this failure scenario. When thinking of these things singly, it's easy to imagine that that kickdown solenoid has full authority over the upshift points. It is most especially easy to think this when one knows that in a properly functioning system the kickdown upshift points are realized by an electronic control element briefly disconnecting the power from the kickdown solenoid.
The problem with Oakland's car did turn out to be a stuck kickdown switch apparently.
Here's why I went through this: We've had a little controversy as to precisely how much influence this full throttle control pressure adjustment screw could have on kickdown shifts, and indeed if it had any influence on kickdown up shifts at all. In strict theory with a perfectly adjusted system it does not affect the kickdown upshift points. In reality on the street, it sometimes affects them dramatically. Here's how: it turns out, and this is easily verified by experimentation with this screw, that the kickdown function hydraulics via the solenoid are actually a relatively small influence. Far and away the major influencing parameter on the full throttle upshift and downshift points whether under kickdown or not is the full throttle control pressure. As far as the actual transmission behavior goes, the solenoid hydraulics are more or less frosting on the control pressure cake. If the full throttle control pressure is too high the engine will run into the rev limiter even though the power had been disconnected from the kickdown solenoid by the electronic controls at the correct engine speed. Similarly, if the full throttle control pressure is adjusted too low the kickdown solenoid influence is not enough to raise the upshift point high enough that the electronic control element ever intervenes. The transmission will simply upshift with the kickdown solenoid engaged. I have encountered each of these conditions in the field a number of times.
So this is why one can be "correct" in thinking that this adjustment has no influence on kickdown upshift points. In a perfectly functioning and correctly adjusted system, it doesn't. However, the way the system actually functions with the kickdown solenoid controlled hydraulics being a much smaller relative influence than the full throttle control pressure, one can see why Mercedes states that this full throttle control pressure is a potential influence on all shifts occurring at full throttle, whether under kickdown or not.
Note also that not every shift valve in the valve body is influenced in exactly the same relative degree by these pressures. It is not uncommon for example to find a valve body adjusted in such a manner that the 1-2 upshift under kickdown occurs some degree below the electronically controlled power interruption to the solenoid, while the other two up shifts occur at the moment of power interruption. This is a measure against bumping into the rev limiter on the 1-2 upshift under unfavorable conditions. And no, that particular little tidbit is not published anywhere to my knowledge.
Eric, since you asked, there is training literature stating that one full turn of the screw equals approximately a 10 km/h deviation in the full throttle upshift point. Note that one turns the screw in a counterintuitive direction: clockwise will result in upshifts occurring at lower speeds, while counterclockwise results in higher speed up shifts.
Note something else that we have not discussed, yet that can be as important as anything else when trying to get good shift feel and high performance. The same adjustment that gives you higher speed upshift points also gives you downshifts occurring at lower speeds and sometimes with less depression of the gas pedal. It's not uncommon to tweak this adjustment higher for example, and find an a nice tasty two gear down shift in the same conditions where you only got single gear downshift before. Or you may find that you get a downshift of one gear and a more immediate vehicle response where in the same condition before you only got a downshift by depressing all the way down through the kickdown switch. Both adjustment effects are NICE!!
Very handy this little adjustment. The only downside is that you have to take the pan off. The other is that you probably will over do it the first time or two you try it...
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Wish I could have made the meet as had a bad weekend with some thing that caused a flare up of the AS I'm fighting in my ankles at the end of last week ( this stuff http://shelf3d.com/i/ankylosing spondylitis and TRUST me it sucks!!!). I'm just now getting back to walking normally rather than doing the Tim Conway Mr Tudburry shuffle.
Your right the old 400 had the electric kick down and the vacuum mod. The 350 used the throttle cable to control pressure and a vac mod like the 722-3 but no electric kick down. Been a few years since I built one of ether. Still the throttle cable being properly adjusted on these cars with this tall gear is super important in the real world drivability. Much more so than both the vacuum mod and the valve body screw on a 722-3. With the throttle cable regulating internal pressure would not just shortening that cable with a simple adjustment not do what you guys are talking without the risk that set screw posed in screwing up WOT shift points? From what I see after looking at the internal design here seems like the Vacuum mod can be adjusted to firm a shifts a little then use the cable to raise part throttle shift points a little to make the car more drivable around town. Would not be as silky smooth but seems like it would be more fun to drive so why no mention of the simple throttle cable cable adjustments?
BTW when I found out these had the throttle cable on the trans and started looking at the adjustment potential found the plastic adjuster for the actual throttle cable is toast as it crumbled as soon as I messed with it. Looked fine until I messed with it and that was what was likely giving me some of the fits in normal drivability on this car in particular in the wet and I just ordered a new cable.
Off topic I know but how much of a bear is snaking that cable under the brake booster to the firewall on these? Looks like a PITA from what I can see.
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From what I've read of the discussions, everyone has this thing pretty much figured out. Here's some of the important things to remember:
When theorizing or experimenting with these things, think of their usage as designed. For example, it's easy to think of the engine braking "locked in first gear / "B" position" function as being achieved by the electrical switch in the shift gate energizing the kickdown solenoid. With a little further thought we remember that this is not true, and that "B position" is actually achieved by energizing of the kickdown solenoid combined with the shift range selector valve in position 2.
Similarly, it is easy to think of kickdown shifts and kickdown upshift points as being achieved by the energizing of the kickdown solenoid, and this is not true. The kickdown condition is achieved by application of the kickdown solenoid combined with full throttle positioning of the control pressure valve via the cable from the throttle linkage.
Eric, since you asked, there is training literature stating that one full turn of the screw equals approximately a 10 km/h deviation in the full throttle upshift point. Note that one turns the screw in a counterintuitive direction: clockwise will result in upshifts occurring at lower speeds, while counterclockwise results in higher speed up shifts.
Note something else that we have not discussed, yet that can be as important as anything else when trying to get good shift feel and high performance. The same adjustment that gives you higher speed upshift points also gives you downshifts occurring at lower speeds and sometimes with less depression of the gas pedal. It's not uncommon to tweak this adjustment higher for example, and find an a nice tasty two gear down shift in the same conditions where you only got single gear downshift before. Or you may find that you get a downshift of one gear and a more immediate vehicle response where in the same condition before you only got a downshift by depressing all the way down through the kickdown switch. Both adjustment effects are NICE!!
Very handy this little adjustment. The only downside is that you have to take the pan off. The other is that you probably will over do it the first time or two you try it...
Since you state we will likely over do the adjustment and you have done them what's a good starting point say half a turn counter??
Have you tried combining the screw adjustment with a slight shortening of the pressure cable? If so what was the effect?
You are just now starting to understand why I'm right about the Jim F Resistor mod. Underhood heat effs EVERYTHING up! ANYTHING you can do to keep those temps down is worth it!
I've already addressed your other question. Unless your bowden cable adjustment is off, I'd leave it alone. I couldn't stand the constant downshifting, and I couldn't stand the way that it held onto second gear FOREVER, ALL OF THE TIME. Again, if you are in a situation where you need instant throttle response, just hold the gears manually. Old school guys like us know how to do that!
Very handy this little adjustment. The only downside is that you have to take the pan off. The other is that you probably will over do it the first time or two you try it...
That's not a problem, seeing as how Gixxer wants me to change my trans fluid every 3,000 miles anyways!
Thought I said that, control pressure cable is attached to the valve body
Opinion, not fact.
I do not have the Jim F miricle resistor
My throttle cable & bowden cable are fine
Klink, excellent info (all of post 64 above, I won't re-quote it all in the interest of reduced scrolling). Thanks for the details, much appreciated. I had forgotten to mention the selector lever position until post 58, and that is a very good point. I had a similar weird high-upshift thing happen when my electronic FGS box acted up, for the reason you explained, the solenoid was energized but the selector lever was in a different position.
On a related note, I tried adjusting that VB setscrew out nearly three turns on my 124.133 and it only increased WOT upshifts by maybe 200rpm at best. (Not sure what gear the factory had in mind with their 10kph spec, since 10kph is a lot bigger difference in 1st compared to 4th gears).
OK, Eric, when you gonna drop you pan and twiddle this screw? Let's get you some 6500rpm WOT upshifts and see if your 034 can hit 13's!!
On a related note, I tried adjusting that VB setscrew out nearly three turns on my 124.133 and it only increased WOT upshifts by maybe 200rpm at best. (Not sure what gear the factory had in mind with their 10kph spec, since 10kph is a lot bigger difference in 1st compared to 4th gears).
OK, Eric, when you gonna drop you pan and twiddle this screw? Let's get you some 6500rpm WOT upshifts and see if your 034 can hit 13's!!
Was mentioned in passing but not a real part of the overall discussion. Am I wrong in thinking that pressure control cable is the single most important part in controlling non WOT shift points on the units? Also what about the vac mod on these? Does it not have a good bit to do with how soft or firm the actual shift is ?
Anybody looked into a shift kit in possibly removing check balls or opening holes in the valve body plate on these units?
It's a common mod on many other units and looking a the design schematics on how this unit is designed should be an effective way to firm the shifts up to tire chirping levels.
Basically, yes.
It has everything to do with it. The vac modulator controls shift firmness (not shift RPM).
Read this thread: http://www.500eboard.com/forums/showthread.php?t=1038
No, it was mentioned in relation to WOT shift points
You were the one that started discussing part throttle
WOT shift points are a combination of kick down solenoid & control pressure cable.
I'm thinking governor pressure has a say in it as well
Go back and re-read from where I mentioned the valve body screw
Post #20
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On a related note, I tried adjusting that VB setscrew out nearly three turns on my 124.133 and it only increased WOT upshifts by maybe 200rpm at best. (Not sure what gear the factory had in mind with their 10kph spec, since 10kph is a lot bigger difference in 1st compared to 4th gears).
OK, Eric, when you gonna drop you pan and twiddle this screw? Let's get you some 6500rpm WOT upshifts and see if your 034 can hit 13's!!
Dave, please, there are some folks on this site who don't know what a 124.133 is. Can we just please say 87 300D instead?
I'm already shifting at 6500! It would just be nice to have the trans do it for me, for better consistency. I mean, why have an automatic if I still have to shift it myself?
Awww, you won't let me have any fun at all.
I agree 100%. The stock setup is pretty consistent with upshift RPM's, if you want higher upshifts, it would be nice to have it equally consistent. I'm curious how consistent the VB can be with upshift RPM when relying entirely on the adjusted setscrew, since the kickdown will still be de-energized at ~5950.
Awww, you won't let me have any fun at all.
We COULD have some fun if you posted those dyno graphs.......
Exactly what I was talking about. Any info on current availability of a kit for the 733-3 variants?
Whatever kit Scotty used, remains a mystery to this day. If the kit was available, I have a feeling it would be a box of parts with no instructions. I've never seen any further info besides what has been posted in that thread. But I bet Eric would sure like to duplicate the results!
Hello guys. I see you are specialist in m119 and 722.3 transmission. So i have a big problem with my tranny after rebuild. The car is w140 with m119.970 engine and 722.370 transmission.
After rebuild tranny the shift point on full throttle with kickdown and without kickdown is 4500 RPM. Before rebuild shift point on full throttle was in the red line.
I am 100% sure is tranny problem because i "block" leverage on 2 position and after change from 1 to 2 shift point was on 4500 and after that went to redline.
My guess is something wit pressure lines or kickdown switch (but it works) Or maybe E/S switch because no change after switch from E to S position. Please help and sorry for my english
After rebuild tranny the shift point on full throttle with kickdown and without kickdown is 4500 RPM. Before rebuild shift point on full throttle was in the red line.
I am 100% sure is tranny problem because i "block" leverage on 2 position and after change from 1 to 2 shift point was on 4500 and after that went to redline.
My guess is something wit pressure lines or kickdown switch (but it works) Or maybe E/S switch because no change after switch from E to S position. Please help and sorry for my english
