Auto rebuild and strengthen, looong and piccish.

Here's a catalogue of my recent auto transmission rebuild and upgrades. The car is a 1989 2+2 TT, mostly a weekender with a fairly stock engine.
All work internal to the transmission was done by a professional. Everything outside the transmission was done by myself.
Some of my efforts went well, others less so

Rather than gloss over the mistakes and just brag about the good bits, I'm posting the whole lot "warts and all" so that other auto Z32 owners
who are considering a rebuild of their transmission can maybe get some useful ideas and avoid some bad choices.

To make it easier to read and refer back to I'll post it in multiple parts. Here's an index of it all -

1. Shift kit
2. 3,000 RPM high stall torque converter
3. Upgraded lockup clutch
4. Billet servo mechanism
5. Set of 4 OEM solenoids
6. More transmission internals
INTERMISSION
7. External coolers
8. Remote fluid thermostat
9. Temperature and pressure gauges
10. Shift control module reco
11. Wiring & connectors
12. Summary

Guys, this is not so much a "how to do it" or "how stuff works" type of post. It's more about parts choices and my findings about those choices.

Some bits of it are a work in progress, as usual I welcome any useful feedback

And I might as well answer that "hope you don't mind me asking how much" question now.
$4,730.40 so far, mostly for parts, and some of it wasted on bad choices or overkill.

 

Part 1 - Shift kit.

Not to be confused with a SAW / shift-at-will kit.

For some background info on shift kits, THIS THREAD is a good place to start.

I opted for a Stage 2 shift kit from MV Autos in Adelaide, $385.00 plus core exchange charge of $100 ( refunded when you send your
original valve body back to them ) plus 2 lots of freight at around $35.00 each way.

A shift kit is a stock valve body which has been modified internally to sharpen up the gear shifts, make them quicker and firmer.
They're available from many places around Australia. "Stage 2" kits from MV Autos will shift fairly normally at low throttle, shifts get
firmer as you push the throttle harder. Looks like this -

Underside -




Top side -




Looks pretty much identical to a standard valve body. It can be fitted without having to remove the transmission, some workshops
will even fit them while you wait. -






VERY happy with it. All pros and no cons. If you read the thread in the link above, you'll get a fair idea of what to expect from a
shift kit in terms of performance and reliability plus a basic understanding of how they work.

 

Part 2 - 3,000 RPM high stall torque converter.

I searched our Forum for advice on this before deciding to get one. Not conclusive, so I won't link any of the threads I found.

Short version is that most of the other Zed owners who have fitted a 3,000 RPM high stall converter are making decent power and maybe
chasing better 1/4 mile times from their weekender. Some of them posted that they couldn't pick any difference in street driveability
between the original converter and the new high staller, so I figured there was nothing to lose. *polite cough here*

I opted for a 3,000 RPM high stall converter with oversized lockup clutch, from MV Autos in Adelaide.
$560.00 plus $100.00 core exchange charge ( refundable on return of your old converter )
Maybe add freight costs of $45.00 each way if the converter is the only thing you're buying from them at the time.

Apart from the colour it looks the same as the stock converter, all differences are internal. So the pics are a bit boring -




Mounted in the housing -




Personally I find that the 3,000 RPM stall point makes the car feel a little bit sluggish at lower revs when driving normally around town.
I'd soon get annoyed with it if I was driving daily in stop-start metro traffic. The OEM converter is probably better suited for that.

But when it stalls up it's a lot of fun, you do need 'a bit' more throttle to make it stall up. The car is a tad Jeckyl & Hyde now but
I'm not complaining. It warms my soul to see such a polite and well mannered car turn into a psycho hose beast when you floor it :rofl:

So for drag racing or spirited driving it's absolutely brilliant
Plus I live in a country town and don't use the car for a daily driver so it works out real well for me

A caution - now that I'm monitoring ATF temperature I've found that the 3K converter generates a lot of heat while puttering gently around
town, i.e. mostly below the stall point and not moving fast enough to get much airflow through the coolers. So external cooling and
temperature monitoring need to be looked at if you haven't already done so. If you already have an external cooler you may need to upsize
it to cope with a high stall converter.

 

Part 3 - Upgraded lockup clutch.

The upgraded lockup clutch came with the high stall converter described in part 2. It can also be fitted to a standard rebuilt converter.
It's inside the torque converter so no pic, sorry. Here's a generic diagram instead -




The above layout is similar to our own Jatco transmissions. Here's a modified pic from page AT-7 of the Z32 factory service manual -




Michael at MV Autos says that they upgrade the clutch for longevity more so than performance. Keep in mind that the clutch only
engages when you're already cruising or you're accellerating gently in 3rd or 4th. It should never stay engaged while you're accellerating
hard or stepping on the brakes or even coasting for that matter.

The original friction ring face is 35 mm from inner to outer lip, the upgraded ring is 65 mm and made of a tougher carbon based material.
Also, the MV Autos shift kits include a modification which applies more hydraulic pressure to the ring to reduce slippage and frictional wear.

Can't really give yous a comparison between old and new because the original lockup clutch wasn't working properly.
But now, when the new clutch locks up ( way below the converter stall point ) you can really feel it. Revs drop by 400 ~ 500 RPM, feels
as firm as another gear change up to fifth. Nothing vague about it, you really notice when it kicks in

But maybe that's not just because of the clutch being bigger or better, more to do with the fact that it actually works now

All in all, VERY happy with it

 

Part 4 - Billet servo mechanism.

From MV Autos in Adelaide - $440.00 Add freight of approximately $20.00 if this is all you are buying at the time.

This part of the rebuild might be overkill in my case but it seemed like a cool idea at the time

Custom billet servo set on the left, OEM servo set on the right -






I won't pretend to be an expert on the workings of auto transmissions. Here's my limited understanding of this part -

The custom made servo is designed to clamp the flex band faster and harder. So the available hydraulic pressure in the transmission is put
to better use. The result being that you get much firmer shifts into 2nd, and less frictional wear on the flex band.
That's as much as I need to know about it, other Forum members might be able to explain the operating principle a bit better

From a driver's point of view? It feels wicked, even at just 12 psi. The whole car twists now on upshifts to 2nd at WOT
Might have to get the kevlar flex band backed off a bit, it's pretty harsh at present. But jeez it's fun

 

Part 5 - Set of 4 OEM solenoids.

From CONCEPT Z PERFORMANCE - $325.00 USD. They're not listed on Coz's site as of April 2011. Nissan's part number is 31940-41X13






They mount on the upper side of the valve body -



So the valve body needs to come out of the transmission to get at them. If you're fitting a shift kit, it's a good time to replace the solenoids.

Why replace them? Well it's not mandatory. But the originals are up to 22 years old now. I'd already had the line pressure solenoid fail.
Replaced it with a used generic one, a few months later that one started acting erratic. Not trying to frighten folk into spending money here,
but new solenoids seemed a good idea in my case

You can buy a set of aftermarket solenoids as low as $200.00 from several places in Australia, remember that the Nissan Patrol and Ford
Maverick of the same era use the same Jatco transmissions as our Z32 so there's a healthy aftermarket trade for transmission parts.
But the advice from the Forum is that the OEM solenoids are more reliable than the aftermarket ones.

 

Part 6 - More transmission internals.

From ATS AUTOMATICS BENDIGO ( not itemised seperately )
Kevlar flex band
Bushes and bearings
Steels and heavy duty frictions
Thrust washers
Torrington bearings
General overhaul kit, seals etc.
Labour.
TOTAL - $1850.00




Labour didn't directly include removal and refit or set up of external cooling and monitoring.
Adam mostly just concentrated on this ugly lot -




His labour did include some hours of non hands-on work which I was more than happy to pay him for;
helping to diagnose and confirm the faults, patiently answering a heap of stoopid questions, helping to choose parts, test thrashing the car
before and after, and much more besides. He encouraged me to do as much of the work as possible, sometimes under his direct supervision.
Gave me access to his hoists and tools. Put me onto parts suppliers. Just generally made sure I did things right.

Here's one of Adam's toys, his HR Holden burnout ute NUMNUTZ -






Powered by a blown 202 with a dash of NOS -




Some of Adam's customer's cars -





It's good fun going to his workshop, he's always got some good eye candy in there

 

INTERMISSION. Need a break? CLICK THIS for some pleasant intermission music. Maybe you'd enjoy some POPCORN too

 

another excellent write up .. they are pouring in ... many thanks, MICK.

AND even comes with intermission music ... top stuff ....

 

Mate, sweet write up thus far!

My TT 89 has an Auto box and the car stock as a rock. Would be somewhat keen on one of these rebuilds! Really explains how much fun an Auto trans can be!

Personally I would rather convert to a manual though.

Top stuff!

 

More to come baz, but I need to upload some better pics of the coolers tomorrow

Intermission - we're showing our ages here baz, cinemas outlawed the concept donkey's yonks ago

 

Haha nice job Mick!

 

Thanks mate

The manual versus auto debate is a fun topic, guaranteed to give folk a laugh

Here's some text I'd deleted because I didn't want to stir up the debate again -
---------------------------
As to the manual versus auto debate? I owned none but manual cars for 29 years. Wouldn't look twice at any auto car, wouldn't even bother
to piss on one if I was busting and couldn't find the dunny, dum dah de dum, please sing along if you know the words to this old tune

And to be honest, the stock Z32 TT auto didn't do much for me. It's only saving grace was having a VG30DETT engine bolted to it.
But since the repairs and upgrades I wouldn't have a manual conversion even if it was offered for free, so ner ner ner
-------------------------

But we're not here to argue about manual v auto this time. We're here to help educate the auto owners about parts choices
and to shake our heads in sympathy or disgust about how much I spent on my transmission rebuild :rofl:

 

Part 7 - External ATF cooling.

HERE is a good recent thread on ATF temperatures.

I opted for 2 x Tru-cool LPD coolers, 4" x 11" x 3/4" Part # LPD4451 from MAKCO USA - $157.64 for the pair, delivered.
These are the slimline supposedly high efficiency type. Most sizes are readily available in Australia but the 4" high ones are scarce.

These next pics show my first attempt at mounting the coolers. The plan was to duct cold air into them from underneath and take the hot air
up and away via a custom vented centre panel rather than sending the heat into the engine bay through the radiator. I thought that mounting
them almost horizontally like this would also encourage passive air flow while stationary in stop-start traffic.






Viewed from above -






I ended up swinging them down to a vertical position after running out of time and patience. I still think the almost horizontal
mounting would work well with properly made ducting and centre panel. And the stock airbox would have to go. Will have another
go at it in the future. Meanwhile, this is how they're mounted at the moment -







The stock ATF heat exchanger in the radiator has been bypassed. The coolers are plumbed in paralell. Have also cut the ends off the
ATF hardpipes which come forward from the transmission, at the the point where they narrow down.
Then flared the pipes and used 8.7 mm I.D. hoses all the way.



ATF temperature with this setup averages approximately 83*C at ambient temps of 11 ~ 18*C with normal driving. Gets up over 100*C pretty
quick with a bit of hooning. That's higher than I expected given the surface area of the coolers. Probably because of the high stall converter.
A stock converter would likely show much lower temperatures. I plan to keep on tweaking the placement but the final test will be a spirited
run through some hills in summer. Might need to upsize the coolers, we'll see.

Another aspect of these type of coolers ( according to the advertising blurb so it must be true ) -




Didn't fully understand it at the time. After trialling the coolers I have a clearer picture of what the blurb was about.

ATF is thicker when it's colder, like any other oil. So it is less able to flow through a smaller opening. And it will flow better
through a larger opening, obviously. These coolers have some plates which are larger internally than the rest of the plates.
So when the ATF is cold and thick, more of it passes through the large plates in a hurry and doesn't get cooled much.
When the ATF gets hot and thin, it is more inclined to flow through the thinner plates and get cooled more.

Yes, you still have ATF rushing through the larger plates when it's hot but it all seems to balance itself out.

 

Part 8 - Remote fluid thermostat.

Derale part number 15719, from ONLINE PERFORMANCE AUTOS AUSTRALIA $148.96 delivered. Also available from some US suppliers.
There's a few different types out there, the Derale looked good because it has the largest ports.



I was worried about overcooling the ATF. Read BADZX's findings in THIS THREAD . A remote oil thermostat seemed worth a try.

Installed on the car -





The good news is that the ATF got up to a temperature which enabled overdrive and lockup real quick at ambient temps of around 4*C.
The not so good news is that the thermostat doesn't start to flow fully until 80*C, so that's your minimum ATF temperature after the now brief
warm up period regardless of ambient temperature or driving conditions. Not enough head room for my liking.

Ended up removing the thermostat for now, currently trying to source a lower temperature wax element for it.

Anyway, the thermostat might be redundant with the "self-regulating" type of coolers fitted. Did I mention that some of this is a WIP?

 

Part 9 - Temperature and pressure gauges.

This part is another WIP and maybe a bit of overkill but meh, I enjoy tinkering with this type of stuff

From SCINTEX AUSTRALIA
250 psi pressure sensor - $97.90
K type thermocouple with gland - $88.00
2 x Digital display / controller module - $120.00 each. TOTAL - $425.90 ( purchased a few months ago, prices may have gone up )




The display / controllers I chose can accept inputs from a wide range of temperature or pressure sensors. Scintex also have some
temperature only modules, which have extra output functions. But those ones only accept input from temperature sensors, not pressure.

Here's the sensors mounted on the transmission, temperature on the left and pressure on the right -





Had to get the thermocouple gland welded to the pan. There are other areas of the pan where you could put the gland, but the sides
are a bit close to the exhaust. My pan has no drain bung so I thought to use the gland as a drain too. The pan is higher at the back but
the car would be jacked up at the front to dump the ATF anyway so most of it would still come out.

Also got the gland angled downwards. The plan was to have the tip of the temperature sensor at the same height in the ATF as where the
factory sensor is positioned.

Drilled a hole above the transmission ( from inside the cabin ) and put a rubber grommet in the hole, then passed the
cabling for the sensors through the grommet -




Had to dismount the shifter assembly cover plate for some work room -






Display modules mounted in the lower DIN slot - ( Yes, Delorean time machine spec!! Or old school taxi fare meter spec )



I plan to have some vinyl labels printed up for them, after finalising the choices about which gauges are assigned to what.
The oh so tastefully done labels will go on the lower half of each gauge, covering the existing SET > ^ markings.
Here's how they're assigned at the moment -



The ATF temperature gauge is staying, not sure about the line pressure gauge and lockup clutch indicator. They were put there temporarily
to help monitor some issues which were intermittent and hard to pin down. Those issues seem to be resolved now.

Wiring them up was tedious but straightforward -




These display modules can trigger alarms and cut-offs, so you don't need to be watching them all the time. The whole collection is
usually covered by the BOSE grille. If one of them squeals I just pop the grille off to see what's upset -




Not everyone's cup of tea from a styling point of view. But they work well and don't clutter up the cabin

 

Part 10 - Shift control module reco.

Also known as the ATCU, or auto ECU. Reconditioned by INJECTRONICS MELBOURNE via local Repco - $150.00 at mates rates.
Injectronics don't deal direct to the public, you have to go through one of their agents such as Repco.






The Injectronics Tech who worked on the ATCU rang me direct to discuss the job. He told me it had bench tested OK for main functions,
then asked for more info on what sort of faults I was having and under what conditions.
Short version is, I asked him to replace all of the electrolytic capacitors, check the voltage regulators, and re-solder the boards.

Ever seen the innards of an ATCU? Here's a pic taken while troubleshooting a non-existant TPS fault, before the ATCU was overhauled -



I always get nervous when I see sub-boards soldered at right angles to main boards, especially when they're subjected to vibration.

Why bother overhauling the ATCU? There were some quirks with the transmission's electricals. Checking it with ConZult tuner edition
showed random fault codes when the transmission was running OK. Plus a random discrepancy in displayed ATF temps versus actual temps.
Wondering if it was something to do with the ConZult program, I contacted DTA Motorsports where I'd bought the software.
They responded that they had seen a number of old or damaged ATCUs mis-behave in a similar way.

Gratuitous pic of ConZult Tuner Edition's AT test page -



Also had the occasional bit of "weirdness" in the shifts, with no fault codes. "Weirdness" is a vague description I know, but other
auto Zed owners will probably understand it. Not holding lockup consistently was just one of the quirks. Dropping line pressure was another.
New OEM ATCUs are available @ $585.00 USD from CZP in the USA. I'd already bought a used ATCU from Adelaide Z cars, tested and having a
limited warranty for $80.00. It was less quirky than the original one but still not 100% right.

Short version is - no more wierdness or inconsistencies since the ATCU was reco'd. But there was a lot of other stuff
done during the rebuild so I'm not 110% sure how much benefit was had from reco-ing the controller. But for $150.00 why not?

The HOLY GRAIL of auto transmission diagnostics, no more fault codes -

 

Part 11 - Wiring & connectors.

While the transmission is out, it's a good time to check the wiring looms attached to it. Parts of them might be a bit toasted by now -






Make sure the heat sheathing and corrugated tubing are in good condition. If not, now is a good time to replace them. Not wanting to leave
anything to chance, I unwrapped the whole lot and inspected every individual wire for chafing, stiffness, heat damage etc.
All good as it turns out, but the couple of hours spent checking it then re-wrapping the looms will give you much peace of mind.
If you ever find yourself trying to diagnose an AT control / wiring fault, it's not much fun trying to check those looms in situ.

While you're at it, check the ends of the ground cable at the rear, maybe add solder to both connections as well -




I spent many hours trying to find a possible bad ground in the control circuits. Never did get a conclusive answer, but since
it all went back together the problem has disappeared. It might have been that grounding cable...

All ready to go back in -

 

Part 12 - Summary.

First off, a disclaimer ( sort of ) -
One of the problems with replacing or repairing or up-grading a bunch of things all at once is this -

When it all goes back together and all works properly, you can't be 100% sure which parts were causing which problems. I try to be
accurate in documenting faults versus fixes but I'll admit to some vagueness when it comes to the control and line pressure faults I
was having. Was it the ATCU? The solenoids? Bad connectors? Overheating? Something inside the transmission? All of the above? Dunno
------------------------------------

It's not easy to give a summary which will make sense to all readers here. In some cases I'm preaching to the converted. Some others
think autos are a waste of time. Some folk are curious about whether to throw money at their auto or convert to manual. Then we have
track versus street versus drags, stock power level versus big HP engine, daily driver versus weekend weapon, so on and so on.

So the merits of the above set up come down to personal observations of how it worked out for my car and driving habits.
All in all I reckon it's a MASSIVE improvement over the stock setup in terms of performance, reliability, and -
let's be honest here - COOL factor Our Jatcos are pretty good boxes when they work properly.

VERY HAPPY with it so far, in spite of the not-so-good bits.

And there's always a better way to do things so I'll just keep on tweaking it all. Thanks for reading guys

 

Would the stage 2 shift kit alone be worth it? To be honest that's all I could bare to bother with any more.

I replaced my tranny with a brand new patrol box a year ago with a big external cooler then installed a new manual radiator without the old transmission cooler built in.