Transmission for the 2JZ/MA7 hybrid conversion

As stated earlier there are a few options when selecting a transmission for your 2JZ hybrid project. First of all you have the option of selecting a manual and an automatic transmission.

Manual transmission

I'll keep this story short, as I'm going with the automatic transmission and I want to show you pictures! For the manual you can choose for the W58, the R154 and the V160. If you're getting the W58, you need the bellhousing off the 2JZ-GE engine. If you're going with the R154 (standard Supra 5 speed) you need the bellhousing of the 1JZ-GTE manual. If you're going with the Supra 6 speed, you need too much custom work (making the tunnel bigger, fitting the rear diff. Custom drive shaft etc.)

Automatic transmission

Depending on the available hardware and options, fitting the automatic transmission can be 'easiest'. Easiest in this case means: Not much custom work and no big investments in bellhousings etc. If you haven't bought your 2JZ engine with the transmission, you need to buy the bellhousing anyways. I highly suggest to buy the engine complete with automatic transmission, as the transmission is stronger and the electric control is slightly different, although both transmissions are 'A340E'. Let's make a complete overview of what is exactly different.

• Bellhousing

The bellhousing for the 2JZ mates up to the JZ family of engines, while the 7M bellhousing fits the 7M. Easy modification; you just swap the bellhousing and you're done!

• Output shaft

The left picture is the output shaft of the transmission from the 7M engine and the right picture is the output shaft of the 2JZ-GTE engine. Note that the normal aspirated engines of the 2JZ series have about the same type of transmission as the 7M engines; these output shafts look the same and the propeller shaft is of the 'slide in' type as well. Only the turbo models have the upgrades transmissions with the 'bolt on' type propeller shaft. If you would go with the output shaft in the right picture you would have to make a new propeller shaft. This is not really difficult, but unnecessary. Furthermore, there are more differences among the two output shafts. The shaft for the 7M engine has two devices connected, one gear for the speedometer cable and one 'gear' for the rear ABS sensor. If we would go with the output shaft in the right hand picture, we would loose these signals and had to made them ourselves! The picture in the right hand side has two 'other' signals, that are used in the JZ series. One connection is for the speedo signal sender, which is now an electrical signal and one signal is for an additional speed sensor, used by the ECT. This speed sensor is called 'Speed sensor No. 2'.

I would highly prefer the two signals from the 7M output shaft, over the signals from the 2JZ shaft. The speedo signal can easily be extracted from the No 1 speed sensor in the 7M dashboard. This speed sensor converts the speed from the speedo cable to an electrical signal. Furthermore the ABS signal is very handy if you want to keep the stock ABS system. I do, as I don't want to screw around with the brakes and brake system too much. Somehow we have to 'fake' the extra speed signal from the No 2. speed sensor. If you take a close look at the sender for this signal in the next picture, you see it sends four 'pulses' every revolation of the output shaft.

The speed sensor no 2. sender mounted to the output shaft. You can see that every revolation four little pieces of metal will pass the speed sensor, resulting in four signals per revolation. It should not be 'undoable' to get this type of signal out of the 7M rear ABS sensor or the 7M stock speed sensor. Note that this signal is only for the ECT control module.

• Extension housing

As the output shaft is completely different, the extension housing is different as well. I wouldn't care that much about the output shaft, but the mounting points for the transmission to the body of the car are connected to the extension housing as well, as shown in the next picture.

Here you see the difference in extension housing. We don't care that much about the extension housing, but the mounting points for the transmission are quite different. The width of the mounting bracket is substantially wider on the JZA8 body (Left bracket). It would be great to use the extension housing of the MA7 body (right housing in the picture), so the transmission bolts straight up to our MA7 body.

• Electronics

We've already discovered some slight difference in the electronics at the output shaft (speed sensor etc.), but there is more difference among the two transmissions. On the 2JZ transmission there is an extra speed sensor, measuring the speed of the Overdrive direct clutch. This speed sensor is bolted into the transmission almost at the front of the housing. It would be very handy if we can use this speed sensor, as it is very hard to 'fake' this signal using some other signals in the car. Another 'electric' difference is the neutral start switch, mounted to the shift lever of the auto transmission (see picture). 

This is the neutral start switch and gear indicator from the 7M transmission. The JZ transmission switch is very much alike, although more signals are given as output. While the M transmission has signals for 'P', 'R', 'N', '2' and 'L' the JZ transmission has all signals, including 'D'. As a detail we note that the connector is different as well.

• Control (Electronic Control)

A complete explanation of the auto transmission is currently beyond the scope of this article, but to get a long story short: the automatic transmission is controlled by 'pressures'. Normally you have 'line' pressure, 'throttle' pressure and 'speed' pressure. At the 7M transmission, throttle pressure is controlled by a manual throttle linkage. This is a cable you connect to the throttle body, so the more 'gas' the more pressure in the transmission. Other pressures are regulated in different manners. For gear selection the 7M transmission uses 'solenoids'. These solenoids are used as actuators for hydraulic valves to control shifting and lock-up timing. The M transmission has three of these solenoids. One solenoid is used for 'Lock Ups' and with the other two solenoids you can select one of the four gears (two on/off switches, four combinations).
The JZ transmission has the same amount of solenoids for the gear and lock-up mechanism. These solenoids work in exactly the same manner as the M transmission. However, the JZ transmission does not have a manual throttle linkage. Instead of this mechanical way of regulating pressure, the JZ transmission has two extra solenoids. The first solenoid is the "SLT" solenoid, regulating the line pressure. The second solenoid is the "SLN" solenoid, regulating the Accumulator pressure. It would be nice to adopt this new control unit in our automatic transmission for the 2JZ project.

• Clutches & Brakes

Yes people, I said clutches. Although most of us associate a clutch with a manual transmission, the automatic transmission has clutches as well. And loads of them! Furthermore there are brakes in the transmission also. These are used for preventing various parts in the transmission from turning either clockwise or counter clockwise. Let's make an overview on what is available in the transmission.

As you can see in this table, only the Forward Clutch (C1) and Direct Clutch (C2) both have one disc more in the 2JZ transmission. This will result in a 'stronger' transmission so whenever possible it's best to use these discs.

Recap

What we want to have is a transmission with the output shaft of the MA7, so we can use the propeller shaft of our car, the ABS and speedo hookup. Then we want most of the internals of the JZ transmission (preferably all) including the speed sensor of the overdrive direct clutch. Then we use the control unit of the JZ transmission as well, so that we have the five solenoids and the right neutral start switch. Right? Well, LET'S START!!!

Step one. Getting the output shaft from the 7M transmission

	On the left you see a detailed component overview of the A340E transmission from the 7M engine. If you click the image you can view a full-size picture. The snap ring which is in front of the front planetary gear holds the output shaft in the transmission. We need to get to this snap ring by removing all parts that are in front. This starts with the oil pump which is pictured in the lower left corner.
I started with removing all electronics and the throttle linkage cable from the transmission case. If you still have the bell housing and extension housing on the transmission, you should remove these as well.
	When you unbolt the oil pan, make sure you don't turn it over, preventing all the foreign material in the bottom of the pan from swimming around your transmission. There is quite some junk in the pan and you don't want that to go to the transmission. Removing the pan is done by unbolting all the little bolts and then cutting the gasket material with some sharp knife.
When the pan is removed from the transmission you can unbolt the three bolts holding the oil strainer to the valve body.
	These two tubes connect the valve body with the pressure plates for some gears and clutches. Use a big screwdriver to pry them out carefully and remove them.
After disconnecting the three wires that control the shifting and lockup solenoids, and getting rid of the manual throttle linkage, you can remove the valve body from the transmission. Removing is done by unbolting the 17 bolts that hold the valve body to the transmission. Do this in a couple of turns as the valve body is under pressure from springs underneath it.
	Gently remove the check ball body (with the little ball on top) and the spring.
On top of the C0 accumulator piston (the one piston alone, not grouped with the three others) are two springs. Remove these.
	Normally you can just remove the B2 accumulator piston as one piece. There is one spring underneath it. If you cannot remove the piston, you possibly need some compressed air or try to take the piston out in parts.
Removing the other pistons is quite the same procedure. When you are complete you should have the same parts laying on your desk as in this picture on the right. On the top left are the two springs from the C0, then you see the B0 piston with it's one spring. The next two pistons are C2 and B2.
	When you remove the seven bolts holding the oil pump into the transmission, you find two holes with extra thread tapped in. Use two bigger bolts to screw into these holes and gently push out the oil pump by screwing these big bolts completely in. Use even passes for the bolts so the oil pump comes out straight (and not diagonal or something).  If you are so fortunate to have the special puller from Toyota available (SST 09350-30020 or 09350-07020) you can use this one.
If you pull the input shaft, the overdrive planetary gear unit with the overdrive direct clutch, one way clutch and the overdrive planetary ring gear will come out as one big assembly.
	Remove the overdrive planetary ring gear from the overdrive planetary gear. Take special care for the bearing and races between the two. If you've laid everything aside, we can continue with removing the overdrive brake pack.
The overdrive brake consists of a couple of clutch plates which are kept in the transmission body by a snap ring. You can remove this snap ring by using a screwdriver (gently please).
	You can remove the overdrive brake disks as one assembly now. The assembly consists of a flange, five plates and four discs and another flange.
On the side of the transmission is a snap ring holding the second cost brake cover in. Remove this ring. It is very likely the cover will not come out yet.
	Getting the cover off the transmission when the snap ring is removed is easy. Just blow some compressed air into the oil hole and remove the brake cover, piston assembly and spring.
Here you see the whole coast brake assembly. The spring, the piston (with a rod), the dust cover and the snap ring.
	Continuing with the transmission internals, we are going to remove the overdrive support assembly. First remove the bearing with the race which might still be in the transmission (it's possible it came off with the last removal, check that as well).
The overdrive support assembly is bolted into the transmission with two little bolts. Remove these two.
	When you remove the big snap ring (special tool needed, big snap ring wrench), you can pull out the overdrive support assembly using the same methodology as used for the oil pump. Just use two bolts and press it out gently.
Now pull the little shaft inside the transmission. You will take out the direct clutch and the forward clutch as one piece. Take extra care for the bearings and races.
	At the arrow is a little E-ring. You can remove this with a small screwdriver. After removal you can gently pull out the pin. When the pin is removed you can remove the brake band through the big hole in the transmission (front side).
Pull out the front planetary ring gear from the case. Again, mind the bearings and races that might be on / in.
	Take out the last race that's laying on / sticking to the front planetary gear unit.
Now go into the transmission and find a little snap ring holding the output shaft in the transmission. Get your snap ring wrench on the ring and remove it. This is very difficult, but after a couple of tries you will succeed (when you got the right tools). Note; picture might not be exactly as the transmission. I took this while experimenting with two transmissions at the same time.
	When the little snap ring is removed you can take out the front planetary gear.
Now pull out the planetary sun gear with no. 1 one way clutch.
	Now you can pull out the 7M output shaft (from the rear). This is the base of our transmission!
Consider yourself half way of the hybrid conversion. Now let's disassemble the A340E transmission of the 2JZ. As the transmission is about the same in design, I'm only showing the real differences.
The valve body of the 2JZ transmission looks substantially different than the one from the M transmission. This valve body contains the 5 solenoids and some other control stuff. Remove it carefully. No oil pipes are attached. The body is very big.
	In the Japanese mkIV transmission I found this little 'dampener' at the first discs (the O/D discs). This little device was not present in my mkIII transmission.
One note on pulling the output shaft from the mkIV transmission; my transmission had the bolt at the end screwed up so I was unable to remove the extension housing from the transmission. I ended up pulling the extension housing with output shaft together. Not a bad solution anyways. So let's build our hybrid transmission. You have two transmissions in parts laying on the work bench, so let's start quickly. We take the A340E of the 2JZ engine as a base. There are still some parts in. First we should compare these with those of the M engine, to make sure we don't have any differences or so. The parts that are inside the transmission are: Rear planetary gear. This gear is the same in both transmissions (assuming both transmissions are from the turbo cars), so we can have this one in place No 2. one way clutch. This clutch is the same in both transmissions. So no change necessary. 1st & rev. brake pack. These clutch plates are slightly different, but as the unit is one assembly we can keep it all in the transmission. These clutches don't interfere with the newly installed output shaft either, so no need to go back to original. Both transmissions contain 7 clutch disks here. Second brake Drum. Another part which is exactly the same on both transmissions! Keep it there. Second brake pack. I cannot trace if these are different among the two transmissions, but as the rest is the same, we can keep these disks from the 2JZ without any problem! So first throw in the No. 1 one-way clutch, which came out of the transmission together with the planetary sun gear. Both these items are the same on the transmissions (although the 2JZ got a redesign after may 94). To be sure, just drop in the unit from the 2JZ. If you can't make the unit in the transmission, you have to remove the complete brake pack, but I wouldn't do so. (well, I did, but if I had to do it again, I would NOT).
Now you can install the planetary sun gear. Again, these units are EXACTLY the same on both transmissions. At first glance, I thought they were different but that was just a slight detail. The electronic parts catalog mentions both units have the same number.
	Now gently slide in the output shaft of the 7M transmission and stand the transmission on this output shaft. I used a small table to stand it on.
Now things get tricky! As you can see in the picture on the right, the front planetary gear units are not the same. The left unit is from the 7M transmission and the right unit is from the JZ transmission. As this unit mounts to the output shaft, we need to make use of the M unit. The M unit comes with it's own bearings and races so use these as well. Mount the unit in the transmission.
	Now put the snap ring on the output shaft. Quite a difficult work this is, but trust me: Getting it off is more difficult than putting it on! Don't forget the race on top of the planetary gear assembly!
Now we have to create a unit which needs to be mounted all together inside the transmission. The problem we're facing here is that the unit needs to be mounted on the 7M front planetary gear unit. As these units are different we cannot use the unit for the JZ, so we are stuck with the 7M unit. The unit I'm talking about is the front planetary ring gear, highlighted in this picture.
	The next 'problem' we're having; as the front planetary ring gears have different dimensions, is we need to make use of the forward clutch for the 7M as well! Ahh, that's a pity as the JZ engines come with a forward clutch with 7 discs, while the M engines are equipped with 6 discs. I haven't found a solution to install the 7 discs yet, but with some custom work on the size of the flange you can get quite far. But I wanted to get my car driving BEFORE CHRISTMAS, so I decided to put in the 6 clutches. I did replace them with the JZ clutch discs, as my M engine was completely worn out because of the previous abuse (400+ bhp). The clutch discs have different order numbers so I currently don't know if the replacement of the discs was a good idea! Otherwise I need to go back to new M clutch discs.
Now there was some good news. This assembly does fit the direct clutch drum of the 2JZ. So we can use the direct clutch discs out of the 2JZ transmission, resulting in one disk more than the M transmission! These discs did look most worn in my transmission, so very important to upgrade! The picture shows the complete assembly to be put into the transmission.
Getting the assembly into the transmission is quite easy. You need to keep the transmission case with the big opening facing downwards. Then you can put the assembly into the case. This is different than what we did before, when we put everything from top into the case. Before you can install the assembly, you need to put the second coast brake band in. These are different in the two transmissions, so I have put the JZ band in.
	When you have installed the assembly inside the transmission, you can turn the transmission over again and install the rest. This includes the second coast brake piston, the overdrive support assembly, all other O/D related parts, the oil pump and the valve body.
This should be the result. A complete hybrid transmission with the output shaft of the M engine and only the number of forward clutch plates being the same as in the M engine. The rest is all from the JZ engine. Let's hope it works!!!! Otherwise we have to take the transmission apart again.