Ok, even though Ive sold my car, Im getting another, but a 3.0 this time and since we dont have 5 speed 4th gens (or 3rd gens for that matter) I am going to continue to pursue this. Read On

What I am wanting to do is to get an aftermarket computer made for the tranny that enables a tip tronic type shifting to be used.
Bear in mind that this is still in the early stages of discussion. I have been talking to an automatic transmission specialist who happens to be an auto sparky as well. He is prepared to donate his expertise in the way of practical mechanical help. What I envisage is may be having a steering wheel (or other convenient place) mounted up down switch to shift gears. Also what I have thought about is having another switch to lock the torque converter in other gears apart from 4th. I know this will take a lot of time and thinking, so heres where I need help. I need you guys to tell me of any problems that you may think will arise, any other suggestions to the idea etc. If you think this won't work at all, please say. I can take constructive critisim.

Thanks all the way from New Zealand. Onwards and upwards with autos!

 

sounds costy..

 

that'd be awesome if that could be done

 

maybe with the price of that project....you can import a 5 speed

 

Its been done on a 3rd Gen so the ideas not completely unreasonable. I can't recall exactly how it was set up but the owner built it himself and it worked well apparently. It was posted about and discussed on 4dsc.com probably 5 or 6 months ago.

 

I imagine a person with good electronics "savvy" could do this. My Maxima is a 5-speed so I have neither the means or motivation to prototype it. Warning... this is "top of the head" (i.e. untested) engineering.

Find the harnesses which emanate from the transaxle. One of them terminates in a brown plastic connector with eight pins. This is connector F42, and is located above the transaxle case and below the black plastic engine air intake ductwork.

Disconnect harness connector F42 and fashion a substitute electrical connector and harness. Run the new harness into the passenger cabin. Connect a multiple plate rotary selector switch to the passenger cabin end of your homemade harness. Wired correctly, you would have five switch positions would control automatic gears 1, 2, 3, 4, 4+lockup.

Viewing the open end of connector F42 with the latch at the "12 o'clock" position you see two rows of four terminals. They are numbered 1-4 (left-to-right, top row) and 5-8 (left-to-right, bottom row). Terminal assignments are:
1 = Shift solenoid B
2 = Shift solenoid A
3 = Overrun clutch solenoid valve
4 = Line pressure solenoid valve
5 = Torque converter clutch solenoid valve
6 = ATF temperature sensor
7 = ATF temperature sensor
8 = ?

The activation schedule for the solenoids is:
1st gear = A and B
2nd gear = B
3rd gear = (none)
4th gear = A
4th gear + lockup = A and TCCSV

The Line valve solenoid would be deenergized momentarily during shifts.


If all of the above works satisfactorily, you may move on to making a slick control mechanism. Mount a rotary solenoid on each end of the rotary selector switch shaft. One solenoid would index the switch to the next higher gear position, the other would index the switch to the next lower gear position.

See that plastic pod on your wheel which contains the Cruise Control buttons? Buy one of those and fasten it to the opposite side of the wheel. On my wheel there is a removable panel as if somebody was planning for it. With some care, this could be made to look "factory". A push on the lower button would mean "shift to the next lower gear" and a push on the upper button would mean "shift to the next higher gear". I like this scheme because
- it's easy to operate
- the driver keeps both hands on the wheel
- the driver keeps his eyes on the road


The foregoing description calls for electromechanical components. This is done for easy explanation and inexpensive implementation. All of this could be implemented with a semiconductor switching network or a rudimentary Programmable Logic Controller. You could also have an 8 pole double throw switch which would allow the driver to select Normal Automatic or Driver Control modes.

 

This is exactlyalong the lines of what I was thinking.

Just one, no two questions Daniel,

1. would it hurt the torque converyter at all if it was locked up in other gears apart from 4th? (assuming that there was some sort of device that stoped it being engaged at a low vehicle speed)

2. Thank you for your reply, This will make people see that this is definitly do-able, but I thought that you didn't reply to these sorts of questions? Or am I wrong slightly.

Anyway, thanks a lot, you are a wealth of information and I respect you for that, everyone does.

Karl

 

In my opinion the TC lockup clutch could be used in all four forward speeds, but there is no benefit in doing so. Its purpose is to improve fuel efficiency and there is not much savings to be had in the lower gears. I believe that is why the Nissan Transmission Control Module enables TC lockup only in 4th gear, only when the ATF is warm, only above a certain threshold speed, only below half throttle, etc.

I don't care much for mods, but this one stimulated my imagination. This subject has been explored in this forum once or twice before. I think Level 10 is (or was) developing this kind of device. See http://forums.maxima.org/showthread.php?threadid=20627

 

Wow, I'm certainly impressed - but slightly lost. Well COMPLETELY lost on the technical but slightly lost on the concept. My question is WHY? Would this yield any different results than simply manually shifting the automatic? With my G-Tech experimentation, I have noticed a 0.30-0.50s 1/4 mile reduction time by manually shifting. Would this improve on that or just make it more convenient or safer for the transmission or...??? Thanks.

 

Nobody said this was for drag racing. It isn't. The benefit is to give the driver full control over which gear is being used and when shifts should be made. It would be helpful in everyday driving situations. For example, sometimes you want the tranny to shift down right now, not when the Transmission Control Module gets around to doing it.

 

I must say this is very interesting indeed. I must bow to you guys to have the intuition and knowledge to think up of such a project. This will definitely give more driver interaction with driving without having to mess with the clutch pedal. One question or suggestion, is it possible or available to have a high stall torque converter on to help with launching? I know this was not intended for drag racing, but it would be beneficial to those who are. Also, those with SC with autos would perhaps have an advantage to those with 5sp in that you don't have to lift off the throttle to keep the boost up, right? I know the gearing makes a difference but maybe it can make the difference up. Just a thought.

Good luck.

 

Wow this mod seems like it will be intense. How long would somethign like this take??

SuDZ

 

Maybe 6 weeks if I went about it in my spare time.

 

The way I see it, this mod could benefit people in different ways.

1. Controlled downshifting.
2. Controlled upshifting.
3. Control of the line pressure which will result in quicker tranny shifts.
4. Will work well with those trannys that have had a VB done.
5. For those 5 speed wannabes (like me), having the torque converter locked up in other gears would make drivability like a 5 speed. This would result in a higher vehicle speed for a particular gear.

 

I believe that Level 10 did such a thing for an old member i30krab a couple years ago.

 

good luck, hope everything goes well.
oh btw, just one thing.....will there be a fail safe built in???
like something that will force a shift so you don't cook your trans driving it in one gear (in case the control switch fails)

 

That would be pretty cool.

 

I would be interested in a computer mod that would allow engagement of the torque converter clutch in 2nd and 3rd gears.

Assuming that the transmission ECU doesn't command the convertor clutch to disengage, does that clutch have enough holding strength to take the full torque of the engine at lower RPMs?

I personally belive that if the torque convertor clutch would stay locked up at all RPMs in all gears (with exception of shifting and <10MPH), the car would accelerate faster and get more economy. --- regardless of "stall speeds" and valve bodies, etc.. etc.. etc..
3rd gear does lock-up but only above 3000RPM. 4th gear locks up but it takes only mild throttle application to unlock it... which is rather annoying.

 

i think that is a good idea. could it be possible to move a switch on the steering wheel like another cruise control switch on the other side?

 

They alrady have this mod on Maximas, its called a manual transmission.

 

 

I think this could be done without a computer mod. My Maxima is a 5-speed so I have neither the means or motivation to prototype it. Warning... this is "top of the head" (i.e. untested) engineering.

Cut the wire which goes to pin 5 of connector F42. Connect both ends of this cut wire to a long pair of new wires. Run this new two-wire harness to a a double pole double throw switch mounted in a convenient location in the passenger cabin.

Wire one position of the 2P2T switch such that the two wires are connected.
Wire the other position of the 2P2T switch such that...
- current from the Transmission Control Module passes through a 15 ohm resistor and then to ground.
- a fused 12 volt "ignition on" supply passes through the wire which leads to the TC clutch solenoid control valve inside the tranny.

The idea is that in one switch position the TCM operates the TC clutch in the normal manner, and in the other switch position the TCM is fooled into thinking it is still controlling the TCCSV but in reality you are.

 

Yeah I know --
The manual transmission is such a wonderful modification!!

I just feel that there is a lot of room for improvement in automatics (not just Maximas but all cars) in terms of efficiency.

I read that the upper end Mercedes cars are soon coming out with 5 speed automatics that keep the convertors locked up at all times except for shifting and at low speeds in 1st gear.

But most Americans are too lazy to drive a stick. They need their hands free for cell phones and eating burgers while driving.

 

I truly don't know. The torque curve of the VQ30DE engine is fairly flat. The torque at lower engine speeds isn't very different from the torque at higher engine speeds.

I don't share your opinion. My reason is that the Torque Converter is more than a simple fluid coupling. It might properly be called a Torque Multiplier. If you lock the TC clutch you are denying yourself that fluid "gearing" advantage. For more information on the workings of the Torque Converter, please see http://www.transmission-crafters.com...TC%20Works.htm .

Are you sure of this? I'm not saying you are wrong, but the factory service manual leads me to believe otherwise. Here is a quote...
The torque converter clutch solenoid valve is activated, with the gear in "D4", by the TCM in response to signals sent from the vehicle speed and throttle position sensors.

 

I dont beleive that the t/c locks up in 3rd. It would seem strange that it did above 3000 rpm when doing that you would be actually accelerating with enough force that it would disengage itself.

 

Just digging up some old DBM posts (trying to kill time). Did this idea ever go anywhere? Pretty neat concept for us Autotragics.

 

Hello NZ Max:

I have some experience driving Maxima clones overseas.
In Korea, I can get either a 2.0VQ 6 cyclinder or a 2.5VQ 6 cylinder.

What I think would be even cooler is getting their shorter final drive ratios that are offered on those engines. For example, taking the stock 3.6 ratio thatis used in the US Maxima models (only come with 3.0Liters) and dropping in a 4.0 or 4.4 final ratio in the transmission might be nice.

I think I read somewhere that the lock-up clutch disengages easily because it can only take so much torque (not a lot). Just enough for cruising but not enough for real acceleration. Full lock-up in all gears with all throttle applications would probably require a nice new and serious torque converter that when locked up could handle teh full torque of the engine.

 

Yes I do have such a unit and I use it every day! It is a small box with 4 buttons, a TC lock-up switch, and a toggle for computer or manual. In computer mode I get a very quick hi line pressure gear change. In manual, I can really screach the tires and it shifts very fast. For racing in manual, I was told by Pat at Level 10 to wind the gears all the way up before shifting. I use the TC lock up in 4th gear over 55mph. This helps spray more tranny fliud back on the spider gears causing the tranny to run cooler and also drops the rpm about 250. I must switch off the ignition before toggling between manual and auto shifting. It is a very useful modification.

 

I miss DBM.

 

Hey man, I'm all for it. Since I know that my tranny is going to perish eventually, I'd wear it out in style like that

That is an awesome mod. Get it working right, and you've got yourself a buyer here...

 

im sorry for this stupid question. is this for an auto? you guys can make fun of me lol.

 

You did read the thread title, right?

 

so whatever happened with this?

 

need4speed is working on this right now

 

Damn thats a good idea but seems like ALOT of work

 

Damn.... sounds sweet as hell. Wish someone made these, most likely make some good money.

 

correct me if i'm wrong, but this has been done....the manumatic i think it was called...it let you contol the gear changes with the cruise control buttons...all it did was tap into the tcm, and let you tell the tranny when to shift...someone on the .org might still have it...they went for around 300 bucks..i was going to buy one, but the guy that made them stopped making them.

 

That is correct, heres the link for the 4 speed manumatic setup. Maybe this guy could even help you out as far as getting the fifth gear.

http://www.rcreations.com/manumatic/

 

Good luck if anybody can get in touch with him.. I tried emailing him when I was selling mine a couple months ago, but no dice. It was a pretty great mod, but not for anybody who is scared of wiring. Try searching thru the for sale forums, the guy I sold it to couldn't wire it correctly but i'm not sure if he had any luck selling it again.

 

good luck with all that, post what u got when u find out.