928 S4 91 start first gear
02-24-2021, 02:37 PM
#16
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If you look at some of the MB cars that featured the same 722.3 transmissions, there's a good chance you'll find a sport-mode switch next to the base of the gear lever. Sport mode does effectively the same thing as the downshift solenoid by dropping control pressure slightly all the time. Mercedes suggests that economy and comfort are sacrificed with first-gear starts and higher shift points, but even in comfort mode you can force the lower control pressure via the kickdown solenoid we retain in the Porsche installations.
Greg, do you see the same front planetary damage in the early S4 cars with always-first-gear-start as you see in the later cars with the downshift solenoid activated all the time? I suspect that folks who do the shift solenoid mod di it because they like to take more advantage of the hard launch capability.
There was a MB specialist in Van Nuys who was working on a "smart" module for MB cars that would cause shifting similar to what the GTS cars have. They offered me one for free for testing and market exposure. It read throttle position and RPM and manifold vacuum, along with MPH via the differential pickup, and gives a few options for shifting firmness, first-gear launches, and higher shift points. Interesting concept but, in my '89 car anyway, forcing the downshift solenoid doesn't on its own cause a first-gear launch every time. I've ridden in some other S4's that have a 'parallel kickdown switch' always engaged, and while it might be fun for a short while, perhaps on a winding road or something, the car just seemed too frantic all the time. For those critical sections, I could just 'drive' the gear lever really.
I wonder if Bill Ball ever got into the original gearbox in his '89. He had well over 250k of mostly supercharged fun driving, almost all with first-gear launches and manual shifting. Would be interesting to know what finally let go and forced replacement.
Greg, do you see the same front planetary damage in the early S4 cars with always-first-gear-start as you see in the later cars with the downshift solenoid activated all the time? I suspect that folks who do the shift solenoid mod di it because they like to take more advantage of the hard launch capability.
There was a MB specialist in Van Nuys who was working on a "smart" module for MB cars that would cause shifting similar to what the GTS cars have. They offered me one for free for testing and market exposure. It read throttle position and RPM and manifold vacuum, along with MPH via the differential pickup, and gives a few options for shifting firmness, first-gear launches, and higher shift points. Interesting concept but, in my '89 car anyway, forcing the downshift solenoid doesn't on its own cause a first-gear launch every time. I've ridden in some other S4's that have a 'parallel kickdown switch' always engaged, and while it might be fun for a short while, perhaps on a winding road or something, the car just seemed too frantic all the time. For those critical sections, I could just 'drive' the gear lever really.
I wonder if Bill Ball ever got into the original gearbox in his '89. He had well over 250k of mostly supercharged fun driving, almost all with first-gear launches and manual shifting. Would be interesting to know what finally let go and forced replacement.
02-24-2021, 05:18 PM
#17
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Originally Posted by dr bob;17255025
If you look at some of the MB cars that featured the same 722.3 transmissions, there's a good chance you'll find a sport-mode switch next to the base of the gear lever. Sport mode does effectively the same thing as the downshift solenoid by dropping control pressure slightly all the time. Mercedes suggests that economy and comfort are sacrificed with first-gear starts and higher shift points, but even in comfort mode you can force the lower control pressure via the kickdown solenoid we retain in the Porsche installations.
in my '89 car anyway, forcing the downshift solenoid doesn't on its own cause a first-gear launch every time. I've ridden in some other S4's that have a 'parallel kickdown switch' always engaged, and while it might be fun for a short while, perhaps on a winding road or something, the car just seemed too frantic all the time. For those critical sections, I could just 'drive' the gear lever really.
I wonder if Bill Ball ever got into the original gearbox in his '89. He had well over 250k of mostly supercharged fun driving, almost all with first-gear launches and manual shifting. Would be interesting to know what finally let go and forced replacement.
in my '89 car anyway, forcing the downshift solenoid doesn't on its own cause a first-gear launch every time. I've ridden in some other S4's that have a 'parallel kickdown switch' always engaged, and while it might be fun for a short while, perhaps on a winding road or something, the car just seemed too frantic all the time. For those critical sections, I could just 'drive' the gear lever really.
I wonder if Bill Ball ever got into the original gearbox in his '89. He had well over 250k of mostly supercharged fun driving, almost all with first-gear launches and manual shifting. Would be interesting to know what finally let go and forced replacement.
Nigh on 20 years go I figured that the MB560 SEC "B" gate on the shifter panel could only work by energising the solenoid full time but never managed to confirm such- as noted earlier a friend of mine with a beautiful 560 SEC told me about this feature when I was whinging about the 2nd gear start which I absolutely hate.
To get first gear starts everytime the bit you are probably missing is the tightening of the kick down cable by approx 4 turns- even with the kick down configured stock, this mod alone offers first gear starts on part throttle take offs. With both mods active the car is not in the least bit frantic- it is "responsive". It works just as well with gentle throttle openings as it does with loud pedal operation- in essence it works as a 4 speed manual with no gear lever and the car shifts when I want it to simply in response to throttle movements! The right tension on the kick down cable is easy to identify- rolling along at 70 mph you should be able to gently accelerate with light throttle pressure- any more and it is into 3rd and you're going to the races. Nothing frantic about it at all- it is very predicatable across the board.
I was not sure if Bill by passed the kick down switch but have a feeling he did and if he could get 300k miles doing so then I am in good shape as I will be approximately 130 years old when I get to that mileage point!
I fail to see any difference in the operating logic these mods make thus the challenge I set- no takers so far. In fact I reckon that what I have done is actually softer on the system - not harder. With the stock setup you have to mince the throttle while the thing drops into first and it feels somewhat "violent"- with my setup it feels like the tranny is already in first just waiting to go irrespective of whether you take off in a civilised manner or go for it- no thumps, bangs or clangs. If anything it encourages smoother driving.
As I stated earlier, it drives like a 4 speed manual without a gear shift **** and if I want to hold it in either 3rd or 2nd gear I use the shifter.
Emptied the ATF this evening- out came 6 litres of ATF, no discoluration, no funny smells after 30k miles.
Chance favours the prepared mind!
02-24-2021, 06:57 PM
#18
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I've experimented with several different TV cable tension settings, including a little time a 3-turns-tight, and found it not good for my use pattern at the time. Even one-turn-tight and the factory setting was causing unneeded downshifting while negotiating Los Angeles traffic regularly. For the way traffic moved then stopped most of the time there, plenty sufficient torque in the higher gears and lower RPM, no need to shift down. There are cobwebs in the rev counter dial above 4.5k too, and they were even lower when we were in the Los Angeles basin. The car doesn't get raced, and while my idea of performance is big numbers on the speedo, I'm generally not in a huge hurry to get "up to speed". Way different use pattern than what your car sees, Fred. I also hate using the brakes, and enjoy the ability to carry speed through most 'touring' routes without having to bleed much off.
02-24-2021, 10:08 PM
#19
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If you look at some of the MB cars that featured the same 722.3 transmissions, there's a good chance you'll find a sport-mode switch next to the base of the gear lever. Sport mode does effectively the same thing as the downshift solenoid by dropping control pressure slightly all the time. Mercedes suggests that economy and comfort are sacrificed with first-gear starts and higher shift points, but even in comfort mode you can force the lower control pressure via the kickdown solenoid we retain in the Porsche installations.
Greg, do you see the same front planetary damage in the early S4 cars with always-first-gear-start as you see in the later cars with the downshift solenoid activated all the time? I suspect that folks who do the shift solenoid mod di it because they like to take more advantage of the hard launch capability.
There was a MB specialist in Van Nuys who was working on a "smart" module for MB cars that would cause shifting similar to what the GTS cars have. They offered me one for free for testing and market exposure. It read throttle position and RPM and manifold vacuum, along with MPH via the differential pickup, and gives a few options for shifting firmness, first-gear launches, and higher shift points. Interesting concept but, in my '89 car anyway, forcing the downshift solenoid doesn't on its own cause a first-gear launch every time. I've ridden in some other S4's that have a 'parallel kickdown switch' always engaged, and while it might be fun for a short while, perhaps on a winding road or something, the car just seemed too frantic all the time. For those critical sections, I could just 'drive' the gear lever really.
I wonder if Bill Ball ever got into the original gearbox in his '89. He had well over 250k of mostly supercharged fun driving, almost all with first-gear launches and manual shifting. Would be interesting to know what finally let go and forced replacement.
Greg, do you see the same front planetary damage in the early S4 cars with always-first-gear-start as you see in the later cars with the downshift solenoid activated all the time? I suspect that folks who do the shift solenoid mod di it because they like to take more advantage of the hard launch capability.
There was a MB specialist in Van Nuys who was working on a "smart" module for MB cars that would cause shifting similar to what the GTS cars have. They offered me one for free for testing and market exposure. It read throttle position and RPM and manifold vacuum, along with MPH via the differential pickup, and gives a few options for shifting firmness, first-gear launches, and higher shift points. Interesting concept but, in my '89 car anyway, forcing the downshift solenoid doesn't on its own cause a first-gear launch every time. I've ridden in some other S4's that have a 'parallel kickdown switch' always engaged, and while it might be fun for a short while, perhaps on a winding road or something, the car just seemed too frantic all the time. For those critical sections, I could just 'drive' the gear lever really.
I wonder if Bill Ball ever got into the original gearbox in his '89. He had well over 250k of mostly supercharged fun driving, almost all with first-gear launches and manual shifting. Would be interesting to know what finally let go and forced replacement.
There is unique damage to the planetary in all transmissions that have had the kickdown switch jumpered or in the cars where the transmission is shifted manually (as I described above) on a constant basis.
While it is sometimes difficult to tell how a car was driven, over it's life, by looking at the engine pieces (when it is apart), a transmission (manual or automatic) tells all, when it is apart. (Of course, this requires seeing many examples apart, to get a baseline difference between abuse and normal wear.)
Porsche engineers were pretty smart, even back then. They didn't make changes because they ran out of things to do on a Tuesday and needed to look busy until Friday. (Although the GTS engine ventilation "issues" might be an exception to this.)
If they decided to limit the amount of 1st gear starts by making the car start in second (while still enabling the vehicle to use 1st gear, if it was really necessary) and decided that it would be a good thing to retard the ignition timing a bit on the 2nd to 3rd gear shifts, they had a reason.
02-25-2021, 12:25 AM
#21
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and for "comfort". Apparently, MB decided that their mid-sized performance versions had more than enough torque for most driving even with second-gear launches.
The big argument here now is about the effects of altitude on performance. I'm at two-turns-loose right now, down from three.
I have a supposedly-good '88 2.20 no-LSD box here now. I suggested to Greg that I'd like to go through it with him, if he'd let me help. Without getting into Kibort territory, I suspect I'd want the first-gear launches, but will look at total ratios first. Most driving ere now is 'touring', with plenty of mountain scenic drives available. Not as busy as Angeles Crrest Highway was in our previous back yard, more longer easier curves and such, so long as I get out before the summer tourists. ACHis saddled with a 40MPHspeed limit and lots of enforcement especially on weekends. Summer erly weekday drives have few out on the roads, and decent detector helps a lot with the other thing.
Are the earlier first-gear-start 2.20 boxes subject to the same front planetary drive and cage issues? Should I do a teardown and indpect on that one before it goes into the cr, or just put it in, and invest the time/$$ into refreshing the original 2.54 LSD box that came in the car?
The big argument here now is about the effects of altitude on performance. I'm at two-turns-loose right now, down from three.
I have a supposedly-good '88 2.20 no-LSD box here now. I suggested to Greg that I'd like to go through it with him, if he'd let me help. Without getting into Kibort territory, I suspect I'd want the first-gear launches, but will look at total ratios first. Most driving ere now is 'touring', with plenty of mountain scenic drives available. Not as busy as Angeles Crrest Highway was in our previous back yard, more longer easier curves and such, so long as I get out before the summer tourists. ACHis saddled with a 40MPHspeed limit and lots of enforcement especially on weekends. Summer erly weekday drives have few out on the roads, and decent detector helps a lot with the other thing.
Are the earlier first-gear-start 2.20 boxes subject to the same front planetary drive and cage issues? Should I do a teardown and indpect on that one before it goes into the cr, or just put it in, and invest the time/$$ into refreshing the original 2.54 LSD box that came in the car?
02-25-2021, 04:24 AM
#22
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The 89 box is sweet. Even with 2nd gear start, one of those transformed the driveability of my 84 automatic, the Stan Shaw car that needed the transplant years ago.
Maybe the answer is do both! You know you wont be satisfied unless you do!
Maybe the answer is do both! You know you wont be satisfied unless you do!
Last edited by Landseer; 02-25-2021 at 04:25 AM.
02-25-2021, 06:33 PM
#23
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Its all relative...
but...
Why did they make a first gear. ? Its not even advertised on the gear selector.
If they didnt make a 1st gear...and second became first..then it shalt become 1st gear....only prior to second gear..being one prior to third. If one selects a gear 2 prior to third then one has gone to far. ...and all bets are off.
...
but...
Why did they make a first gear. ? Its not even advertised on the gear selector.
If they didnt make a 1st gear...and second became first..then it shalt become 1st gear....only prior to second gear..being one prior to third. If one selects a gear 2 prior to third then one has gone to far. ...and all bets are off.
...
02-26-2021, 02:39 AM
#24
Former Sponsor
and for "comfort". Apparently, MB decided that their mid-sized performance versions had more than enough torque for most driving even with second-gear launches.
The big argument here now is about the effects of altitude on performance. I'm at two-turns-loose right now, down from three.
I have a supposedly-good '88 2.20 no-LSD box here now. I suggested to Greg that I'd like to go through it with him, if he'd let me help. Without getting into Kibort territory, I suspect I'd want the first-gear launches, but will look at total ratios first. Most driving ere now is 'touring', with plenty of mountain scenic drives available. Not as busy as Angeles Crrest Highway was in our previous back yard, more longer easier curves and such, so long as I get out before the summer tourists. ACHis saddled with a 40MPHspeed limit and lots of enforcement especially on weekends. Summer erly weekday drives have few out on the roads, and decent detector helps a lot with the other thing.
Are the earlier first-gear-start 2.20 boxes subject to the same front planetary drive and cage issues? Should I do a teardown and indpect on that one before it goes into the cr, or just put it in, and invest the time/$$ into refreshing the original 2.54 LSD box that came in the car?
The big argument here now is about the effects of altitude on performance. I'm at two-turns-loose right now, down from three.
I have a supposedly-good '88 2.20 no-LSD box here now. I suggested to Greg that I'd like to go through it with him, if he'd let me help. Without getting into Kibort territory, I suspect I'd want the first-gear launches, but will look at total ratios first. Most driving ere now is 'touring', with plenty of mountain scenic drives available. Not as busy as Angeles Crrest Highway was in our previous back yard, more longer easier curves and such, so long as I get out before the summer tourists. ACHis saddled with a 40MPHspeed limit and lots of enforcement especially on weekends. Summer erly weekday drives have few out on the roads, and decent detector helps a lot with the other thing.
Are the earlier first-gear-start 2.20 boxes subject to the same front planetary drive and cage issues? Should I do a teardown and indpect on that one before it goes into the cr, or just put it in, and invest the time/$$ into refreshing the original 2.54 LSD box that came in the car?
I took a quick look, at this, walking out the door, tonight.
Surprising enough, the 2.54 "shorter" ring and pinion has a lower 1st gear ratio that the 2:20 ring and pinion transmission, which has the taller ring and pinion with a taller 1st.
I'll look at the ratios more tomorrow, but it appears that in '89, they gave everyone a "mountain" climbing 1st gear.
An '89 ring and pinion, with a set of gear ratios from an '87 might be a fun combination!
Last edited by GregBBRD; 02-26-2021 at 02:50 AM.
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dr bob (02-26-2021)
02-26-2021, 03:57 PM
#25
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The other better-for-me option might be my existing '89 box with just the '88 2.20 R&P swapped in. That would offer the longer cruising legs I'm looking for but leave the (a little less...) short first and second for drag racing the Amish buggies. Swapping R&P is a relative walk in the park in the auto box, as the pinion unbolts without disassembling the diff from the transmission case. Need to read more on setting pinion depth for that swap.
But we are straying from the 'first-gear-start' topic...
But we are straying from the 'first-gear-start' topic...
02-26-2021, 09:19 PM
#26
Former Sponsor
The other better-for-me option might be my existing '89 box with just the '88 2.20 R&P swapped in. That would offer the longer cruising legs I'm looking for but leave the (a little less...) short first and second for drag racing the Amish buggies. Swapping R&P is a relative walk in the park in the auto box, as the pinion unbolts without disassembling the diff from the transmission case. Need to read more on setting pinion depth for that swap.
But we are straying from the 'first-gear-start' topic...
But we are straying from the 'first-gear-start' topic...
The original 2.20 transmission has a 2.41 second gear.
The '89 2.54 transmission has a 2.25 second gear.
Seems like is you put the 2.20 ring and pinion into the '89 transmission, you'd end up with a taller second...maybe not ideal for the mountains?
02-26-2021, 09:46 PM
#27
Former Sponsor
The other better-for-me option might be my existing '89 box with just the '88 2.20 R&P swapped in. That would offer the longer cruising legs I'm looking for but leave the (a little less...) short first and second for drag racing the Amish buggies. Swapping R&P is a relative walk in the park in the auto box, as the pinion unbolts without disassembling the diff from the transmission case. Need to read more on setting pinion depth for that swap.
But we are straying from the 'first-gear-start' topic...
But we are straying from the 'first-gear-start' topic...
The original 2.20 transmission has a 2.41 second gear.
The '89 2.54 transmission has a 2.25 second gear.
Seems like is you put the 2.20 ring and pinion into the '89 transmission, you'd end up with a taller second...maybe not ideal for the mountains?
Good luck with understanding the Workshop Manual regarding automatic transmission pinion depth. I've tried a few times and suspect that the guys that did the work explained it to someone who had no clue what they were talking about....or something happened from German to English.
Basically, there's three sets of shims that can change the pinion depth. One under the pinion, one under the pinion bearing carrier, and another set between the intermediate plate and the differential case. It gets really confusing in the Workshop manual, but the combination of the shims needs to adjust the endplay of the transmission, the position of the bearing carrier, and the pinion depth.
Last edited by GregBBRD; 02-26-2021 at 09:47 PM.
02-26-2021, 09:50 PM
#28
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Hello Greg. Please clarify. I thought the A28.07 in my 1986.5 S3 was fundamentally similar to the A28.1* in the later S4 and on 928's.
Thanks!
02-26-2021, 10:55 PM
#29
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02-26-2021, 11:22 PM
#30
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