jatco 50 cent trans mod

[slidenyo]

after following chaz's post on patrol4x4 I've switched my line pressure solenoid resistor out with a 50 cent 5w 4.7k ohm one from jaycar.
have to say my 475km old auto just woke up,
it was a little flarey between 2-3 and the increased line pressure does no end of good ,
shifts are all nice and firm whilst remaining smooth enough for daily driving.
torque converter lockup is a bit more positive also.

[Crash bandicoot]

just unplug the wire to the line pressure solenoid , full line pressure by defualt.

[slidenyo]

maybe that's a bit foolhardy I don't want full line pressure through the shifts,
driveline shock is pretty severe with it just 'unplugged'
hate to think how savage it'd be in a newer auto

[darinz]

The valve body I have runs full line pressure all the time and it is pretty harsh on shifts if you're off the gas. At full power it shifts really smooth. It is a full manual VB and has no accumulator piston springs either so a little ore extreme than most.

[Crash bandicoot]

It's not having good line pressure that kills Jatco transmissions as it allows the plates to slip too much between gear shifts. which unfortunatley is what the manufacturer intended for smoooooooooth shifting....you dont need smooth shifting when off road or requiring power to haul your ass up a hill.

Full line pressure won't hurt them and also pretty obviously that it will stop the trans fluid cooking due to high friction/wear in side the trans.

I have run full line pressure on mine(basically ripped out the computer and manualised the trans solenoids) for yonks and the fluid is still rich candy red after well over 100,000 kms

When manualised you have a fair idea exactly when the trans is about to shift( you get the knack after a while) taking your foot of the throttle briefly it will change just as smooth as having the line pressure computer controlled.

[slidenyo]

what you're saying is correct but does move driveline shock into the equation if throttle modulation isn't in time,
I spent a fair few summers in an Allison auto equipped tructor that did break uni's fairly regularly if you were rough ,
saying that it had a ten tonne bin and was only used on the steepest or boggiest country,
and given that a trans service is only $280 and I have a cooler, i'll have the smoother operation.
just my 2c on a 50cent spend

[Weemsy]

Maybe this has already been covered in another thread, but.......

Does disconnecting or changing the resistor on the line pressure make the auto any less of an 'auto'?
I would like to improve the shift on my safari, but the mod that I have been shown is wiring in a switch to lock up the torque converter which does help in drive ability, but with me not having a left arm, means I would have to keep taking my hand off the steering wheel...

I would like to keep the auto as it is, but with better shifts.

Hope this makes sense!

Cheers

[Zooker]

This mod would suit you mate.
Just makes the slush box less "slushy"

Shifts are firmer, quicker and more positive.
No need to touch the lever any more then before the mod.

Cheers

[Weemsy]

Can someone point me toward the wire I need to disconnect again, as I can't find the thread......
Might just be me being tired

[Zooker]

Supposed to be a resistor where the clutch master would be on the firewall if it was manual..
http://www.patrol4x4.com/forum/nissan-patrol-gu-gr-10/line-pressure-solenoid-dropping-resistor-35866/#/forumsite/20678/topics/35866

[slidenyo]

yeah my resistor was mounted to the clutch master blanking plate,
the lockup mod is next on the list which i'll put on a high low dip switch on the footrest.
line pressure mod works well but needed to reset the throttle position sensor again,
as I'd retarded it fully to make it shift earlier due to a flare pre mod between 2-3

[Zooker]

So i'm wanting to do this mod.
I have concerns about my truck being a safari and everyone else is talking patrol..

Ie 24 vs 12 volt.

Do I still use the same ohm resistor.

[slidenyo]

mines a 12 volt safari also, from the research I've done everyones pointed at the tcu being 12 volt feed for either model.
beauty of it is you can try it without changing anything, just drop 50cent on a resistor unplug the existing and plug the pins into the plug for a trial run.
I found I noticed the downshifts when off throttle grab more assertively which aids engine braking but did feel a bit unusual after the slushy coast to a stop .
adjusting the tps seems to give a happy median though

[Zooker]

Bunged a 1 watt 4k7 resistor in mine yesterday.

Night and day difference in shifting. Its awesome.
Feels perfect. Shifts smooth yet quick.

Love driving it even more now. Now some more boost 12psi I think.

[Zooker]

So after a couple weeks with this mod done i have sadly had to plug the factory resistor back in.

It does a funny thing while on decell, only in top gear with overdrive off though.
it sort of pulses the engine braking, pretty violently actually.

Doesn't do it in any other gear.

I'm going to try a lower value resistor and see if that helps, i still like the way it shifts with the 4k7 in but can't put up with the pulsing..

Cheers

[Muzza]

Is this mod applicable for my 92 GQ RE4RO3A or is it for later model GU's as I don't appear to have a resister
Thanks

[Crash bandicoot]

it will muzza just probably not in the usual places, on my mistral it is on the gang plate for all the plugs from the engine/trans loom to main loom thru firewall travel past.

[Muzza]

Yep ! ... found it straight away
Thanks for that Crash .... it was literally right under my nose bolted to the RH inner guard beside the brake master cylinder.
I just have to resolve another issue first that I have as the lockup clutch does not engage unless under hard throttle and I can't get the last part of the self diagnostic routine to start by pressing the throttle to the floor and releasing it.
I suspect it is an issue with the TPS needing adjustment or faulty.

[slidenyo]

mine pulses a little on decel, but my auto has done 480k now,
I've found leaving the od on when dropping 30-50km/h helps or just shift it down 2 second manually.
I'm going to look into it a bit further but I'm pretty sure its just the box trying to downshift too early,
which with the increased line pressure maybe forcing it back into the higher gear momentarily.
having the tps fully retarded may be a factor also.

[Crash bandicoot]

mine pulses a little on decel, but my auto has done 480k now,
I've found leaving the od on when dropping 30-50km/h helps or just shift it down 2 second manually.
I'm going to look into it a bit further but I'm pretty sure its just the box trying to downshift too early,
which with the increased line pressure maybe forcing it back into the higher gear momentarily.
having the tps fully retarded may be a factor also.

that pulsing you feel on deceleration is the over run clutch, it is floating so may pay to check the solenoid is operating properly, i found this out by accident as i thought that particular wire was the T/C lock up as my mistral is a euro and the colours the wires are different.

full line pressure makes the shifts more decisive up aswell as down.

[stovanovich]

Reviving an old post but it's good info regardless so no loss!

I toyed around with this mod yesterday & I too have noticed the little "pulse" on decel between 50-30km/h when OD is off that has been mentioned. Has anyone come across the solution to this of yet or do we just have two options:

1. Revert to factory resistor and live with the crap feel of factory changes

or

2. manually shift to 2nd or decel with OD on as mentioned in an earlier post.

[charlies paj]

Any of these mods apply to Pajero autos
94 3.5 v6?

[Muzza]

I tried it for a short period with the factory resistor disconnected before reconnecting it. Soon after that the over run clutch on Drive stopped working ( free wheels ) but works on the other gears including overdrive. I suspect it is electrical .... any thoughts. Where is the solenoid for the over run clutch and how do you test it. Cheers