Updated automatic trabsmission

Rudy3.0CS

Rudy3.0CS

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Revisiting auto gearbox upgrades for the E9...
I know that the ZF 4hp22 is a significant upgrade from the 3hp with a locking torque converter and 4th gear. I was wondering if anyone has used a Compushift stand alone controller for the ZF. You use the electronic version of the 4Hp22. The controller allows Bluetooth adjustment of all shift points, the quality of the actual shifts and when the torque converter locks up. It will work with any stand alone throttle position sensor or the output from the engine ECU if it's an injected car. It also can have 2 preprogrammed modes like cruising or sport. I used one of these in a Jag Mk2 and it was a remarkable upgrade from the 700r which was impossible to tune.
I am not looking for anyone to try to convince me to that I need a 5 speed. I can easily go that way if I feel the need. But my car is already an auto and thinking I might make this swap when the B35 engine gets swapped in. Once the car is dialed in the way I want it performance wise, Mario at VSR will blow it up and restore it.
Just looking for any real world experience doing this swap.
 
Two questions are not clear to me:
1) How easy is it to transplant a ZF4HP22 into a carbed E9.
2) What does the Compushift do that you cannot do by shifting the 4HP22 manually.

I converted the E9 to 5-speed at the time because I had no answer to 1).
I have a perfect 4HP22 in my E24, and the sport mode never enters 4th gear, so I ended up re-gearing the differential (to operate at higher revs and more power when cruising). Now, the shift points are a mystery to me, they are neither speed nor rev deterministic, they depend on how you get there. The lockup algorithm is fine, it seems like a plain delay function.
Algorithms are always too smart for their own good if you ask me, but that argument takes you to a manual...

If you go the 4HP22 route I recommend the use of a dedicated transmission oil radiator and not go through the normal radiator, as they are not what they used to be, when they fail you are in for a transmission rebuild.
 
So your issues with the E24 are exactly why the Compushift exists. Read the article below. It allows you to chose exactly the shift points you want regarding RPM. You can dial in how the shifts actually feel. Shift more aggressively for sport use. Smooth for touring. Choose when you want 4th to engage for overdrive. Choose when you lock up the torque converter. It's just modern sophisticated technology. My bet is that your gearbox is the manual version with the 2 wire harness for kick down. The electronic version has a 9 pin plug. The gearbox will mount directly to an M30 block. I am fairly sure you need to select the right bell housing to avoid modifying the tunnel.
I have made this exact swap on a Jaguar Mk 2. Literally transforms the car.
 
Rudy3.0CS said:
So your issues with the E24 are exactly why the Compushift exists. Read the article below. It allows you to chose exactly the shift points you want regarding RPM. You can dial in how the shifts actually feel. Shift more aggressively for sport use. Smooth for touring. Choose when you want 4th to engage for overdrive. Choose when you lock up the torque converter. It's just modern sophisticated technology. My bet is that your gearbox is the manual version with the 2 wire harness for kick down. The electronic version has a 9 pin plug. The gearbox will mount directly to an M30 block. I am fairly sure you need to select the right bell housing to avoid modifying the tunnel.
I have made this exact swap on a Jaguar Mk 2. Literally transforms the car.
Click to expand...
Rudy3.0CS said:
So your issues with the E24 are exactly why the Compushift exists. Read the article below. It allows you to chose exactly the shift points you want regarding RPM. You can dial in how the shifts actually feel. Shift more aggressively for sport use. Smooth for touring. Choose when you want 4th to engage for overdrive. Choose when you lock up the torque converter. It's just modern sophisticated technology. My bet is that your gearbox is the manual version with the 2 wire harness for kick down. The electronic version has a 9 pin plug. The gearbox will mount directly to an M30 block. I am fairly sure you need to select the right bell housing to avoid modifying the tunnel.
I have made this exact swap on a Jaguar Mk 2. Literally transforms the car.
Click to expand...
Rudy3.0CS said:
So your issues with the E24 are exactly why the Compushift exists. Read the article below. It allows you to chose exactly the shift points you want regarding RPM. You can dial in how the shifts actually feel. Shift more aggressively for sport use. Smooth for touring. Choose when you want 4th to engage for overdrive. Choose when you lock up the torque converter. It's just modern sophisticated technology. My bet is that your gearbox is the manual version with the 2 wire harness for kick down. The electronic version has a 9 pin plug. The gearbox will mount directly to an M30 block. I am fairly sure you need to select the right bell housing to avoid modifying the tunnel.
I have made this exact swap on a Jaguar Mk 2. Literally transforms the car.
Click to expand...
Forgot one thing. The carved engine just requires a throttle position sensor. You wouldn't need any input from the engine ECU. That was how my Jag is set up. Under $100 for the TPS
 
Intriguing - checked Compushift site and they only show as applicable to the late 4HP22EH with seven pin harness. Not applicable to the early 8 pin version which would be found in 5, 6 and 7series before 90's (?). Ran across that issue when I was looking for a transmission for my 91 735i.
I installed a 3HP out of a 633 in my 3.0 after frustration with the Borg-Warner and that conversion was pretty straightforward. (anyone need a BW one?)
 
2000CS said:
Intriguing - checked Compushift site and they only show as applicable to the late 4HP22EH with seven pin harness. Not applicable to the early 8 pin version which would be found in 5, 6 and 7series before 90's (?). Ran across that issue when I was looking for a transmission for my 91 735i.
I installed a 3HP out of a 633 in my 3.0 after frustration with the Borg-Warner and that conversion was pretty straightforward. (anyone need a BW one?)
Click to expand...
Can't comment on that as I haven't gone down that road. But you can easily source those boxes fully rebuilt. Wasn't actually sure where they came from. In my mind the newer the better technology wise. I have never heard of an 8 pin harness for a 4hp22.
 
Rudy3.0CS said:
Can't comment on that as I haven't gone down that road. But you can easily source those boxes fully rebuilt. Wasn't actually sure where they came from. In my mind the newer the better technology wise. I have never heard of an 8 pin harness for a 4hp22.
Click to expand...
Worth calling their customer support. They are very responsive. Curious if it would matter as I think that the 8th pin a reverse lockout of some sort.
 
I have the electronic version of the 4HP22, its was very odd to re-gear the differential expecting all shift point to move up in revs by the new ratio, and not being able to ensure that. If the sensors are the same, and the actuators are the same, I have a hard time calling a new firmware load configurable through an iPhone "modern sophisticated technology" :). I may be jaded by test driving a bunch of SUVs for my wife with 8-speed transmissions and even CV transmissions and they feel like lawn mowers, the harder you push the gas the more noise they make.
 
How exactly is driving an 8 speed SUV or CV car remotely applicable to what I am talking about? This is no different than having a better and more modern fuel injection ECU. The sensors are nearly the same. It's the brain that is telling the system when to shift, how to shift etc. the sensors have nothing to do with it. Would you feel better if you plugged it in to your laptop? Are you offended by adjusting a 123 distributor with a phone? Your comment is analogous to wondering why some people can drive way faster on a track in the same car than a professional. Same car, different brain.
 
Oh I trust your judgement and experience with the Jaguar. It was just a metaphor showing that it is hard to craft shifting algorithms when the dyno plot of power and torque do not cooperate :), these new cars have the processors and programmers yet the result is a jerky downshift and turbo boost. My extrapolation is unfair, maybe this product on the M30 and ZF combo works great. Apologies for my skepticism, I have seen videos where DSG clutch transmissions have better times than stickshift.
 
And yes, Don installed a Pertronix distributor in my E9 and I asked him to go back to stock as there was no detectable difference. For me, working with computers since I was 16, I am proud to keep the E9 just fuses and relays…
 
Arde said:
Oh I trust your judgement and experience with the Jaguar. It was just a metaphor showing that it is hard to craft shifting algorithms when the dyno plot of power and torque do not cooperate :), these new cars have the processors and programmers yet the result is a jerky downshift and turbo boost. My extrapolation is unfair, maybe this product on the M30 and ZF combo works great. Apologies for my skepticism, I have seen videos where DSG clutch transmissions have better times than stickshift.
Click to expand...
I completely agree with you on modern multi gear transmissions. But keep in mind what the point of them really is. They are entirely geared to extracting every last MPG out of undersized engines. They are not built for performance. They are constantly hunting for the next shit point which has nothing to with driving briskly. Awful.

Contrast that with the auto gearbox in my late model 911. That box shifts blindingly fast. It's brilliant.

What I am trying to do is figure out what will work right behind a strong VSR built B35 with modern fuel injection, that I don't mind driving in NYC traffic when I leave the city. That's why I am going down this road. Not that big of an investment that I can't go with A 265 box anytime in the future. If I can figure out the shift lever to have a tiptronic function so I can row the lever, it might be perfect. Well a 5 speed auto box might be more perfect, but that's way more complicated.
 
Totally agree on the MPG obsession...You have a great goal, if the Compushift were a non-intrusive evaluation I could help answer that question ahead of your build. I will read and try to figure out if I could just hook it up as a "sidecar" to the controller. An even better idea I can offer is to chat with Paul at Mercedes Werkstatt in Mountain View, CA. Paul knows the ZF inside out and has built a test jig for dynamically testing them outside the car. A dyno of sorts but not quite.
 
Rudy3.0CS said:
That would be outstanding if you can do that. Keep me posted.
Click to expand...
No luck getting Paul to answer his landline. One day I will stop by and chat with him about that, but some days I feel it is easier to get Putin on the line than old car mechanics.

By the way, we never discussed the torque converter which does play a role in the user experience...as the lockup happens there. I would make sure that one is designed and dimensioned for minimal lag in transfer, and somehow remove the clack clack knock effect when accelerating/decelerating. That knock alone makes want to go stick shift...
 
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