Transmission Alternatives?

[AGM]

There has been a lot of discussions previously about putting 5 or 6 speed manual in a Q45. I wish to stick with the Automatic but need to "tune" my shift points due to the 4:11:1 gear change.

Level 10 does not make a 'plug and play' for the Q45 Automatic and the JWT TCU upgrade is a fixed point upgrade.

Does anyone have a suggestion on how to modify the shift points?

I am considering pulling out the electronic Q45 Transmission and putting in a 4 speed hydraulic transmission such as a Turbo 700.

A Hydraulic Turbo 700 should be easier to modify and get the shifts right ect.

This may also be a viable alternative to a blown Jatco for stock Q's.

Does anyone see a problem to fitting a Turbo 700?

I would really like a 5 speed, but to the best of my knowledge they are all electronic. BMW have just bought out a 6 speed automatic, but it is electronic.

Your comments are appreciated.

Regards

AGM

[maxnix]

How will it interface with the ECU?

[Q45tech]

Most transmissions I have seen use rpm not speed to shift!However some may use speed in the top 2 gear to lock and unlock the TC clutch.

When you change the diff gearing every shift [speed] just moves down by the ratio of the gear increase.......4.083/3.538= 1.154 or 15%.

To my knowledge [when 4.083 conversion were popular back in 1994] nothing was needed other than the diff change and a new speedometer [speed sensor] plastic reduction gear change [with is available from Nissan for each gear ratio].

The tcu has look up tables for rpm vs load [what position the throttle is depressed broken into 9 different levels......0/8,1/8,2/8..........7/8, WOT=8/8].

Sure errors in engine torque [higher rpm] vs speed [new lower speed] may affect the absolute smoothness of partial light throttle shifts] but once you do mods you have to expect some minor downsides.

All cars are now electronically controlled and you have to expect to get training in Software and electronics if you expect to modify them.

One of the reasons 5/6 speed AT are able to be built lighter [weight and strength reserve] is the engine is controlled by the transmission to avoid excessive torque just before, during, and just after shifts.................so far ZF has gotten it right in high power applications [MB, BMW, JAG, ...etc].

Remember the RE4R03A [as used in the Q,turo 300zx] was a 300 lb/ft unit but since the engine torque FALLS as rpm rises by 6500 rpm it is down to 240>210 lb/ft or less.

The nices thing I've seen is the fact that Nissans new 6 speed is designed to use a 3.538 rear diff ratio wheter the clutch can be made to last with the extra torque is unknown.

[AGM]

MAXNIX

As I would consider it near impossible to interface a transplant transmission with the ECU, I would only go for a hydraulic one.

It may be possible to input RPM and TPS readings, but to get the transmission to reduce torqe just before the shift would be impossible.

Therefore, I would only try and install a hydraulic Turbo 700 and NOT an electronic one.

Q45tech

Before I go any further with the Transmission I will run a self Diagnostic check and then take it to me dealer for a consult check. It could be as simple as a faulty sensor. Chances are my dealer won't have a Consult as there are only about 6 Q45's in this state.

When I first did the Nissan 4.0803 upgrade everything was fine.

The Gremlins crept in when I did a 9" IRS upgrade with 4:11:1 gears. This has made me think that it could be just the sensors.

http://www.harrop.com.au/Produ...1.jpg

Please note this is the same housing as my car (different axle shaft and ABS sensor position) but is not my car.

The feeling the Transmission is giving me, is indecision whether to go up or down in third gear on WOT, resulting in a terrible 'shudder'

Does anyone know of a laptop programable piggyback for an TCU. All the ones I know of are for an ECU.

For all the reasons above, this is why I am considering a hydraulic Turbo 700 with Kevlar clutch packs ect to handle the Torque.

Regards

AGM

[sijoko]

AGM,

At what speed is does this "shudder" occur?

I have the 4.08 and the Level Ten trans w/ 1st and 2nd gear ratios from the pre-94 model Q45.

I have also changed the speedometer gear to correct for the new rearend. So far, the only problem that I have seen is when I am traveling around 70-85 mph and I go to full throttle, the trans hesitates for almost 2-4 seconds. Almost as if it is confused. The stock TCU is expecting to shift down into 2nd but then the engine speed is to high.

I am guessing that the problem is due to the fact that I changed the gears in the trans. and the rearend.

When my car was stock, it would downshift into 2nd even when I was at 70 - 80 mph. The stock 2nd gear (94 - 96 Q) is good up to 84-89 mph (135-143 kph).

When you changed the rear, did you replace the speedo gear?Also, what size tires are running front and rear? I would think that if there is noticeable difference between the front diameter vs. the rear diameter the TCU might be confused.

One other thing that I would check is the output voltage on the throttle position sensor. It should read .4 - .5 volt at idle.

Hope this helps.

-sijoko

[AGM]

Sijoko,

I'll take the car out again and note more accuratley the point at which the transmission shudders. However, it is a lot lower than 70 - 85 mph.

The sensation that I am getting is simillar to the one that you are describing, in that there is a hesitation, as if the transmission is confused. The problem with my car is that there is a lot of HP pushing on this confusion.

I think you are right in that the look up tables on the TCU could be throwing out the shift point.

The input figures for the TCU are

Throttle Position SensorClosed Throttle Position SwitchWide open Throttle Position SwitchEngine Speed SignalFluid Temperature SignalRevolution SensorVehicle Speed SensorTurbine Revolution SensorKickdown switch

I wonder if JWT can put in new look up figures figures for the revs (Engine Speed Signal)?

Do you think the Revolution Sensor would also be confusing it as the shaft is now spinning faster in relation to both vehicle speed (corrected) and Engine speed (not corrected).

Same might apply to the Turbine Revolution Sensor (not corrected).

What year car do you have? If 94-96 did you put a 90-93 TCU in it?

Yes, I did change the speedo gear. I was actually thinking about putting the speedo gear back in, just to see what happens.

Front Tires = 18/225/40Rear Tires = 18/255/35

How do you find the shift in first and second as a result of the lower gears to both the diff and the transmission.

Thanks for your help!

Regards

AGM

[maxnix]

Quote »I have also changed the speedometer gear to correct for the new rearend. [/quote] I assume you mean the speed sensing gear in the differential was changed to the correct number of teeth for the new differential ratio so the ECU/TCU knows the true actual speed?

Changing the the 1st and 2nd gear ratios (did Level10 do this for you?) could really be messing with the TCU as it is not mapped for those ratios. I wonder if a JWT or stock ECU for a 1993 would cure your problem? It would be helpful to view the map of your current TCU and one for the 1993.
Modified by maxnix at 5:32 PM 5/26/2008

[sijoko]

AGM,

From what you describe, it could be a problem due to the TCU shift schedule being in conflict with engine speed and transmission output shaft speed.

Page AT-10 in the service manual says that vehicle speed is calculated by the TCU from the Output Shaft RPM signal sent by the Revolution Sensor.

According to the service manual, the Vehicle Speed Sensor is a backup in the event of a malfunction with the Revolution Sensor. So putting back the old speedo gear would not affect your situation.

Probably, Jim Wolf can do something about the TCU look-up tables, but I haven't looked into it yet.

There is also a member on this site, AAAComp, who sells his own chip for the ECU, maybe he can do a custom order chip.

You asked about the 1st and 2nd gear swap. When I first drove the car after the LevelTen rebuild, it was like a different car altogether. Acceleration through 1st and 2nd was much better.

Regards,

-sijoko

[sijoko]

Maxnix,

The speedo gear I am referring to is the one on the Vehicle Speed Sensor located on the transmission tailshaft. The gear is made out of plastic and can be replaced to compensate for altered gearing.

As far as I know, the rear speed sensor on the differential is used for ABS application.

The lower 1st and 2nd gearset was installed by LevelTen when the trans was rebuilt.

Regards,

-sijoko

[maxnix]

Yeah, I put the speed sensor at the wrong end of the driveshaft.

That's the one I meant.

[AGM]

I have now spoken at lenght to JWT about my problem. They explained to me that most modern electronic transmissions have an economy mode and a sports mode. You would all have seen cars with this switch. Basically, the economy mode is for every day driving and the sports mode bumps up the shift point to a higher engine rev.

JWT explained to me that in their opinion the Q45 would have been better designed with a switch overide. Apparently the TCU in a Q45 still has a 'sports mode' an an 'economy' mode ie two completely seperate look up tables (maps).

When you put your foot down quickly, the TPS senses the speed of the throttle response and jumps to the sports mode. Please note the default mode is the economy mode.

What happens is that as soon as you back off, or 5 seconds have elapsed, the TCU reverts back to the economy mode.

Apparently 'glitches' can occur when the Q45 TCU automatically switches between the two modes, such as hesitation. Changing the gear ratio appears to have magnified this problem.

What appears to be happening in my car, is that when I am in third and put my foot down rapidly, the cars initial response to change down to second in economy mode map. This is then overiden by the change to the sports mode map,which puts it into first. This is to low and causes the engine to rev its guts out momenterily and the transmission shifts instantaneosly back into second.

So a simple shift to second results in a quick slip into first and then a slam back into second, which is the shudder I am getting.

JWT reccommend I purchase the trimode TCU so that I can leave the TCU as standard for everyday driving and switch to sports mode for aggressive driving. This will keep the TCU in sports mode when I drive aggressivly, hopefully reducing the problem.

I am dealling with JWT at the moment on my specific application and will inform of the results.

My understanding of the JWT Trimode TCU, is that it allows you to leave the TCU with OEM features or set and hold in sports mode or hold in each gear.

Are other members happy with their Trimode JWT TCU.

Regards

AGM

[sijoko]

AGM,

I have heard about the Jim Wolf Tri-Mode TCU. Does it still allow you to manually shift to 1st at low speeds? From what I heard, it will not allow the shift into 1st like the stock TCU.

I shift manually quite a bit and would like to know if this feature would remain with the Tri-Mode. Also did JWT say anything about the shift schedule being adversely affected by the lower rear?

Thanks.

-sijoko

[AGM]

SIJOKO

Which did you do first. The 4.08 gears to the diff, or the lower two gears to the transmission, or did you do them both at he same time.

If you did them seperatley, what was the difference whem you did the other.

Am I right in assuming you sent a 1994 Transmission to level 10 and had them put in the lower first two gears.

Even with a speedo pinion change, wouldn't the speedo be out in first and second but right in third and fourth?

For acceleration from a standing start, I see three options in terms of gearing, being 1. lower diff gears. 2. lower first and second gears and both 1 and 2.

Obviously, the best way to find out definitivley is to try all of the above, but this is a hassle to keep pulling the dif and trans out.

Are the 4.08 gears and lower 1st and 2nd tooooo low for the car and it wants to get out of first and into second straight away, or are you very happy with the combination and would do it agian in an instant.

I am concerned that both the lower gears in the diff and the transmission will result in three transmission gear changes before hitting the quarter mile mark, which will reduce my quarter mile times.

I am looking for maximum acceleration from a standing start, with only one transmission gear change before I cross the quarter mile line.

Another good thing about the JWT Tri-Mode TCU is that they build it from scratch, so you won't need to take your car off the road to have your OEM TCU reworked.

My understanding is that the manual shift mode allows you to put the car into each gear manually, including first, unless your speed is to high.

As they make the Trimode from scratch, I assume they can make the appropriate look up table to accomodate the lower rear end.

I am waiting for a response to quite a lenghty and detailed Email I have sent to Ben at JWT.

I will update you when I get a response.

Regards

AGM

[Chally]

AGM, It doesn't matter what ratios are in the gearbox, as the speed is taken from the output shaft. ie: the one that drives the tailshaft.

[maxnix]

AGM,

I am wondering with your supercharged engine and its torque characteristics if the lower (numerically) 1st and 2nd ratios of the 1994-1996 transmissions would not indeed offer better acceleration than the higher (numerically) 1st and 2nd gear ratios of the 1990-1993 transmission running the 4.08 gears.

It would be interesting to see what you calculate. There might just be too much torque for the lower first and second gears, and the closer ratios of the latter transmission might keep you in the power band better. It all depends on the area under the torque curve between your shift points.

[911/Q45]

I have a JWT trimode TCU and am happy with it. I bought it through Stillen and they supplied the core, so there was just a core charge and refund, no down time. I shift manually into first to climb my steep driveway, but I'm going very slowly when I do it. The first mode is bone stock-start in second gear. My wife likes it because it's not so snappy off the line. The second mode, which I use, starts in first, holds shifts, and downshifts more readily, especially at part throttle. The third mode appears to perform very much like mode 2, but the transmission malfunction message is always on at the trip odometer, whereas mode 2 just has it at WOT.

[QShip]

AGM,

It would be interesting to see what you calculate. There might just be too much torque for the lower first and second gears, and the closer ratios of the latter transmission might keep you in the power band better. It all depends on the are under the torque curve between your shift points.

I recall SD saying the supercharged Q would accelerate better if it started in 2nd gear due to the amount of torque.

[sijoko]

AGM,

The 1st and 2nd gears were changed by LevelTen at the time of rebuild.

I did the 4.08 differential upgrade about 6 mos. later.

I think the 94 - 96 Q needs both upgrades. It is a heavy car .

As far as the 1/4 mile is concerned, there would be a shift into 3rd. But since you have a LevelTen trans. it should not slow you down too much.

If you are aiming at 12 sec. times, then you will be in 3rd gear anyway at the end of the 1/4 mile.

I am on the waiting list for the B.A.D. supercharger. Even with the extra torque, I think that the 4.08 rear would work fine.

-sijoko

[AGM]

JWT advise the following in respect to their Trimode TCU.

The JWT Trimode TCU still allows you to perform a self diagnostic check.

It should not cause any fault codes to appear on the dash.

Cost is $650.00

No core is required as it is manufactued from scratch.

The switch/wiring comes with the TCU.

The cable is 6 feet long so you can place the switch were you like.

Mode 1= 2nd gear start with standard origional program

Mode 2= 1st gear start with high shift (shifts a little higher RPM)

Mode 3 = Snow mode (hold you in the gear you are in when activated but you can still go up or down gears)

A diff upgrade should not negativley affect the shift points as the TCU uses the driveshaft speed to determine the shift point.

They sell an identical Trimode for the 1st and 2nd generation Q45.

You need a JWT ECU as well, as the shift points are done by output shaft speed (the driveshaft) If you use the origional unmodified ECU for the engine, then there might be a problem with the Trans controller letting the RPM getter higher and holding with the Rev limiter. If you use the upgraded JWT ECU there will be no problem.

Hope this info is useful.

Regards

AGM

[Q45tech]

90-93 1st gear [x 3.538 diff] is 9.85 total gear multiplication [plus adjusting for different tire rolling circumference [-4, zero, to +4%]...a 26" tire is depressed up to 1" by weight on tire].

A 94-96 1st gear x diff is 9.05 total gear multiplication.........a 4.083 [15.4%> than stock] diff = 10.444 or 6% more multiplication than a stock 90-93.

So your 1st gear choices are 9.05, 9.85, 10.444, 11.367 mix and match..............this is still a long way from current 5-6 speed AT optimized for best zero to 30 mph time where the ratio would be 13-14:1 so that the shift occurs at 32-34 mph.

I think you'll find the built in speed vs rpm vs gear tables will give you downshift fits [if you change the diff] since the TCU thinks the TC is slipping once you deviate too much from the existing program.

I have had the trimode since late 1993 on stock diff and 3 different trannies.........it always stays in "Power 1st gear start" position except a few times in snow.

It is just not cost effective [read owners won't pay $5,000 -$10,000 for the time required to decompile the TCU tables and write new ones and experiment to get it close].

[AGM]

I spoke to sam at Level 10 yesterday. He advised that they are developing a 'plug and play' computer upgrade for the Q45 transmission which should be available before June 30.

I wonder who's car they will test it on!

http://www.levelten.com/products_2.htm

Regards

AGM

[sijoko]

AGM,

How much is the LevelTen product?

Thanks.

-sijoko

[AGM]

sijoko

The level 10 upgrage is $1,098.00

Regards

AGM

PS: Since you are already a level 10 customer, they might offer it to you cheaper, especially if you use your car for R&D. Might sort out your shift delay at high speeds wheb trying to kick down. Just a thought!

[AGM]

Does anyone know if the JWT trimode has an inbuilt Automatic Line controller.

If not, does the 90-96 Z32 have the same TCU, so that you can plug in the HKS automatic Line controller interface as well.

http://members.tripod.com/chrispounds/hks_alc.htm

Regards

AGM

[Q45tech]

Since time the dawn of drag racing time there has always been ONE correct gearing for the quarter with a V8, supercharged , turbocharged or Nitrous fed or stock...............Asssuming that the terminal speed is not inexcess of say 105 mph.

First shift at 30-35 mph, 2nd at 60-70 mph, and finish the quarter at [just below] redline [revlimiter] in 3rd gear .....manual or automatic.

You mix and match your gears, diff, tires to accomplish this.

With Nitrous any 1st gear is too much because of the inverse way Nitrous produces power [constant amount per unit of time] so the lowest rpm [where you activate produces the most torque and its down hill from there]...........any wheel spin [is bad] increase your time.

[sijoko]

AGM,

The LevelTen TCU upgrade is almost twice as much as the JWT Trimode. I wonder if it is worth it?

I don't want to be the guinea pig just to save a few hundred dollars and risk tearing up the car. Besides, I am about 1500 miles from LevelTen's facilities.

I will wait to see if LevelTen product pans out.

-sijoko

[AGM]

Q45tech,

The current set up on my car as follows is : -

Tires = 255/35/18

Transmission = 1994

Gears = 4:1:1 (Ford 9")

I don't want to change the tires.

After a lot of consultation with JWT, I believe I have founda way to fit a 1990 Transmission if it is beneficial.

Based on the available choices, 1. either a 1990 or 1994 Transmission and 2. any ford gear I like, what do you think is a likley combo to get me the first shift at 30-35 mph and 60-70 mph in second?

You help is much appreciated!

Regards

AGM

[sijoko]

AGM,

Here is a cool site that allows you to play around with different gear ratios:

http://www.geocities.com/z_des....html

Just manually enter in the ratios.

The stock ratios for a 94 Q45 are: 2.57, 1.48, 1, .69

-sijoko

[AGM]

The HKS link for the Automatic Line Controller is

http://www.hksusa.com/products/?id=641&rsku=o

Does anyone know if it will suit the Q45 RE4R03A.

Regards

AGM