Just saw this on the Z-Car-Digest and becuase it's written by Tom Bell I tend to believe it.

 

Date: Sun, 9 Mar 2003 23:23:07 -0600

From: "Bell, Tom G (IT)"

Subject: RE: Tranny slipping

 

>Mark Bethke wrote:

>Hello fellow Zphiles,

>Don't laugh but I have the autotransmission

>

>This is the question: As you who have been following my delemias (dilemmas),

>

>I have noticed the trans slipping a bit in gear . It's not a major slip just

>a bit. What I would like to be advised is about how much time does it take

>these

>trannies to finnaly fail. We drive it about 50 miles per week. Also is

>the Lucas auto tranny treatment worth it, or will it just gum up the works

>....

>

>...{s> .......anyway thanks alot for any comments ...

 

 

Z32weasel (with a happy wife)

- -----------------------------

 

That's one happy wife!

 

Anyway, the 90+ autobox problems are pretty well documented. The design

Nissan had for the Z31 car just wasn't up to the torque of the stock 300 HP

TT motor, so Nissan re-engineered it to develop a bit less HP (280), then

designed the tranny for that power level. Didn't work well and the box was

re-engineered every few months until they 'got it right' in late 1992.

 

Nissan's put out several technical bulletins on how to fix the autobox and

how to minimize the damages. The problem is fluid circulation and materials

degradation due to excessive heat. It's not going to get any better if you

use a 'tranny treatment', because the stuff you put in can't heal the

damage, and it's going to circulate poorly anyway.

 

Here's a plan: Replace the radiator and top off the tranny fluid with the

recommended stuff. Then, find somewhere where they exchange ALL of the

fluid in the tranny and the torque converter, and have them do that with a

flushing agent. After an extensive flush, refill with a high temperature

synthetic fluid. Drive the car for about 500 miles or so, then repeat the

flush and refill.

 

You're planning to replace the tranny with a Level 10 box, so you might

consider installing a tranny fluid cooler and replacing the radiator with

one that's for the manual tranny cars.

 

Hope this helps!

 

Tom Bell

IZCC 2802

 

------------------------------

Flushing it again after 500 miles? you found out how much these autobox places charge for a proper flush through? (under line-pressure).

 

Still, cheaper than a rebuild I suppose!

When I went through this trauma last year I did some basic research into the cause of the gear box meltdown (asides form the rather obvious - I shouldn't have been humiliating that Subaru in the first place!).

 

For anybody interested it was that one of the 2 box cooler circuits in the rad was blocked - net result fine if driven gently / gearbox melted at 145 (I guess that's not gently?). the advice then to change the rad is good advice in my opinion except - its fairly expensive.

 

I went the other way - I fitted an air / oil cooler in place of the rad circuits. I got this device out of the front of a turbo supra. so far so good 10,000 miles of hooning without any problems.

 

NB. anybody got any idea whatsoever why Nissan fitted an oil temp sensor in the box without any kind of warning / derate system attached to it? the only fault I've found to date with Nissan engineering!!

Z Centre have recently started to sell this............good price too.

 

http://www.zcentre.co.uk/performance/perf2/oil_cool.htm

 

Have a look!