My dream come true, External transmission control

[Q45tech]

Why not secure a oem resistor from a junker or TWO. Then you have 6, 12, 24, 36 or 18 ohms?

Only the no longer available JWT TriMode TCU was really worth the money.The current First year start is really just that a First gear start with no tweaking. Better than swapping in a 94-96 TCU but not much since only the shift vs speed is corrected.Ideally the First gear start 1993 TCU is best on a 90-92Q.

[jonseyq45]

I may have the 93, what skew am I looking for on the TCU itself. I started out with a 50 ohm resistor plus the 25 ohm pot but the shifts were a little edgy, though not as bad as no resistor at all. With my current setup I am at 45.8 total load. So I figure that I am almost at the sweet spot or may be there already. I just want look at the 45 to 50 range.

Jonsey

[Q45tech]

The problem is each transmission will be different depending on exact clutch wear, pump pressure vs rpm, ATF brand viscosity vs temperature, and internal leak arounds.

Heck the voltage to the solenoid will be different based on alternator regulator.

If you are trimming to 1.0 ohms expect these variables............you could use a computer to trim just like TCU does with fluid sensor.

Look at solenoid current graph vs time with different ohmatic values as the main purpose of the resistor in parallel with solenoid is TO PROTECT THE TRANSISTOR IN TCU from back emf after the shift when the power is removed from solenoid...........................too high ohms and pow goes TCU!

[maxnix]

So it is correcting the transmission and alternator (charging system) wear issue and the solenoid is there to protect the TCU.

For the later G50, I thought the only benefit of the JWT TCU was to delay shifts till the modified ECU hit the higher redline.

[Infinitiguy19]

Any luck with this project?

But what sucks about this is that every installation needs to be custom done because of all the variable that tech listed.

What kind of "ECU*" can be used to make a universal installation?

*Electronic Control unit

[Q45tech]

The ignition cut and ramp back up is set by tcu so not as much acceleration advantage for faster shifts as many would think................really nothing happens until the advance goes from zero to - 20 degrees or so.

An accel/G meter will show you what is happening during the 1 second interval.

Afterall in quarter mile we are only talking about 1 shift at ~ 50mph as the quarter is over before 7300 redline in second.

Many people do mods which may feel good but accomplish nothing or worse in real world acceleration.I spent a few years fooling myself in mid 90's until I got accurate test /timing equipment.

[jonseyq45]

Latest News:

I have completed it. Reworked some things and have it in place and working. I'll take pictures tonight and explain it further. Not pretty but functional.

Results: Tighter shifts at higher RPM's.

Parts: One from Radio Shack and the other form Harley Davidson, yes you read it right H.D.

More tomorrow.................

Jonsey

[shanec86]

Will be interesting to see what you have come up with. Im about to start somthing very similar, have some 1-10k 5 watt ceramic resistors to have a play with and see whats best suited.

[Q45tech]

I think people need to study a little electronics to understand the back emf that results when the power is shutoff to an energized solenoid.............these spikes can exceed 100 volts with just 13.8 volt power from alternator. The resistor is across the solenoid to cut [damp] this SPIKE down and absorb the excess energy.

Any larger than oem value of substitute resistor makes the SPIKE WORSE!

Obviously the switching transistor is rated for a higher spike [called reverse breakdown voltage] than operating voltage but 50-60 volts was the limit back then.

I guess you could add another transistor between TCU and solenoid that could survive anything ..............something with a 200 volt [reverse breakdown].

A reverse diode can substitute for resistor in absorbing the reverse spike, but doesn't substitute for resistor in fine tuning time of engagement or sppeding up disengagement ................some of each is more ideal.

I would be interested in how cycles the mods survive [months, years]?

[1QIKQ45]

I want!! haha I'm in!!! Ill be watching for your post saying your selling them!That plus Nico Ecu will be fuuuuuuuuuuuuuuuuun

[flyingbrick]

Man all this and all you guys have to do for firm shifts is cut the wire to the line pressure reduction solenoid ? is it not just 0 to 5v with 0v usually fed to the solenoid when you are at full throttle.

[maxnix]

Like Q45tech said, report back at 25K, 50K, 75K... with maintenance schedules and shift times.

[flyingbrick]

who, me?

spending more time with a higher line pressure only does GOOD things for the trans. IT reduces wear on the bands and clutch packs as they spend less time slipping between gears. Because of this there is also a reduction in heat.