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Mk1 Automatic Gearbox Info


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#1 Steve_Wright

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Posted 04 August 2012 - 03:44 PM

Just some info I have found about them, not alot of info about them out there, will continue to add the stuff I have found.
  • There are 2 types, pre 93 and 94 on. 94 on have electric kickdown, pre 93 have an adjustable kickdown switch on the throttle pedal.
  • The box is a Jatco 4N71 http://en.wikipedia....71_transmission the 93 & earlier is a N4A-HL (mazda id) and post 94 is a NC4A-HL
  • 1.6 autos have a 100bhp engine tuned for more torque than the manual (different cams and slightly lower compression), 1.8s have the same engine as the manual.
  • Auto box shiftpoints:
Posted Image

  • Exhaust manifolds on manual and auto engines are the same, it is the front pipe between the manifold & cat which are different.

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cheers

Steve

IMAGE_126-1-1.jpg

'97 Eunos Roadster B2 Limited 1.8 Auto B-2's thread

'96 Eunos Roadster special 1.8 Auto Red-2's build thread
'91 Eunos Roadster 1.8 Auto Red-1's build thread
'93 Eunos Roadster V-spec 1.6 manual, bone stock
How to fit a 1.8 in a 1.6 with standard ecu


#2 Steve_Wright

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Posted 04 August 2012 - 03:56 PM


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cheers

Steve

IMAGE_126-1-1.jpg

'97 Eunos Roadster B2 Limited 1.8 Auto B-2's thread

'96 Eunos Roadster special 1.8 Auto Red-2's build thread
'91 Eunos Roadster 1.8 Auto Red-1's build thread
'93 Eunos Roadster V-spec 1.6 manual, bone stock
How to fit a 1.8 in a 1.6 with standard ecu


#3 Curlie.

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Posted 08 September 2012 - 02:08 PM

I have a 1991 1.6 auto import, you say about the kickdown switch on the throttle pedal? mine is having difficulting kicking down on occasions so if this is adjustable does it need readjusting and could this be the problem?

thanks.
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#4 andyhess

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Posted 23 August 2016 - 06:37 AM

What sort of power can these boxes take? I have an early 1.6 which I'm planing on putting a turbo on in the near future. Will the box be able to take the extra power??
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1.6 auto, me221, tdo4

#5 Ecosse

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Posted 24 August 2016 - 10:12 AM

A guy (RocDoc anyone?) in Scotland, (of USA TrackDog experience) long campaigned a bloody quick supercharged-water injected bla bla 1.6 Auto without issues.

 

I was in it for a few pax laps. It was really brutally quick and 100% reliable Think it popped out 200+bhp.

These boxes saw global service in much heavier production vehicles...not a lot for them to do in a lightweight 5 really.

I've been regularily caning my 1840cc Auto for a decade. It's perfect. Mind you, it gets new ATF & filter every 3 years or so.

 

So did a former Nutz poster call "Gixer" in Greece...but his was a BRG 1840cc supercharged, and modified through losing an arm.

Never heard from Gixer for a long time.

 

Don't worry about a serviced Auto. They are hard as nails.

If for some odd reason it croaks, the likes of AK Automotive will ship one off for little money.


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#6 bettabuilda

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Posted 30 August 2016 - 05:17 PM

Just found this thread and Ecosse is right with the auto box being used in light commercials in Japan and it also found service in Nissan powered London cabs believe it or not! :) they are very robust and the bushes causing sloppy shifter are one of the few (small) issues. There is a "how to change them" on the net somewhere, I think Mazdamenders have it covered IIRC. Whilst I didn't totally fall in love with my mk1 1.6 auto I had (having come out of the supercharged mk1) they are quite nice actually to drive and I learned to hold it in second on B road driving and it was fun :)

Barrie
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MK3 2007 RED & CARBON WRAPPED 1800GT 1st at MX5 OC 2018 Spring rally lightly modified section :) now gone!
MK1 '91 Classic red 1.6 Eunos Meisterr's nothing to report! :) now gone!
MK1 '91 Classic red 1.6 Eunos Meisterr's automatic standard trim :) now gone!
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#7 Steve_Wright

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Posted 10 January 2017 - 10:19 PM

Digging this up again as trying to find the max hp/torque one of these boxes will take. So far the highest hp rating they are fitted to I have sound is a 240hp nissan. It is the later E variant but that only means it is an electric shift not hydraulic, I think wiki is wrong about the L being a light duty and the E being a medium duty box, they are the same and it is the control of the box that is different. Planning on a v6 conversion on mine with 242 bhp & 212 lb·ft of torque, should be easier on the box than a turbo'd 1.8 torque wise so should be okay.

 

Never found out what box is fitted to the mk2, all web references have auto listings up to 1997 only.


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cheers

Steve

IMAGE_126-1-1.jpg

'97 Eunos Roadster B2 Limited 1.8 Auto B-2's thread

'96 Eunos Roadster special 1.8 Auto Red-2's build thread
'91 Eunos Roadster 1.8 Auto Red-1's build thread
'93 Eunos Roadster V-spec 1.6 manual, bone stock
How to fit a 1.8 in a 1.6 with standard ecu


#8 Ecosse

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Posted 11 January 2017 - 10:35 AM

Steve,

They also saw sterling service in London black cabs bolted onto the Nissan 6 pot turbo oilers.

These things are no lightweights as you know, and we can imagine the hundreds of thousands of brutal miles they have done/do.

As I said if...it goes pop...they are about £50/100 complete with ECU from just about everywhere. 

You mentioned the 240BHP Nissan, which is likely a lot heavier...kinda sums it up?


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#9 frontslide

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Posted 19 February 2017 - 07:12 PM

Got a problem with my 1.8 auto where it has started hanging on to 2nd for too long and not changing up when going downhill any ideas what this could  be?

Thanks


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#10 Ecosse

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Posted 21 February 2017 - 12:49 PM

It has it's own computer linked to the ECU.

I'd wager the issue is in there...if it's just 2nd gear.

Or, could be a clutch issue. Check the ATF level...that can bugger things up.


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#11 frontslide

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Posted 22 February 2017 - 09:06 AM

It has it's own computer linked to the ECU.

I'd wager the issue is in there...if it's just 2nd gear.

Or, could be a clutch issue. Check the ATF level...that can bugger things up.

 

Would that be this Ecosse? Where is it located?

Thanks Mark

 

BPF4 Automatic Gearbox Control ECU

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#12 Ecosse

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Posted 22 February 2017 - 12:08 PM

No idea. 

They will know.

http://shop.doctormx...1998-8500-p.asp

 

:thumb-up:


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Location:Stirlingshire.
Beware the imbecile you did not bargain for. Perhaps in a Zafira  at Tesco waiting to self combust.

 

 

 


#13 frontslide

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Posted 22 February 2017 - 06:01 PM

No idea. 

They will know.

http://shop.doctormx...1998-8500-p.asp

 

:thumb-up:

 

Thanks. I have found this which is very informative.

http://www.mellens.n...s_diagnosis.pdf


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#14 Steve_Wright

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Posted 22 February 2017 - 08:28 PM

sounds like it could be a sticky solonoid, first off with older boxes, check all electrical connectors then replace the fluid.


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cheers

Steve

IMAGE_126-1-1.jpg

'97 Eunos Roadster B2 Limited 1.8 Auto B-2's thread

'96 Eunos Roadster special 1.8 Auto Red-2's build thread
'91 Eunos Roadster 1.8 Auto Red-1's build thread
'93 Eunos Roadster V-spec 1.6 manual, bone stock
How to fit a 1.8 in a 1.6 with standard ecu


#15 frontslide

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Posted 25 February 2017 - 11:59 AM

Which gearbox will my 95 1.8 have fitted NC4A-EL or NC4A-HL and what is the difference does anyone know?

Thanks Mark

 

Answered my own question :thumb-up:

 

http://www.natpronet...ans/3-4N71B.pdf


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#16 Ecosse

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Posted 26 February 2017 - 02:38 PM

Bloody scary when you see all the bits innit?  :mellow:


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#17 frontslide

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Posted 26 February 2017 - 06:28 PM

Bloody scary when you see all the bits innit?  :mellow:

Very! still got to sort my issue but had oil and gasket done by a reputable gearbox firm he said box is good. 


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#18 Steve_Wright

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Posted 09 May 2017 - 08:55 PM

Just found ratio info:

 

NA: 2.458, 1.458, 1.000, 0.720 reverse 2.182 torque converter stall ratio 1.9

NB: 2.450, 1.450, 1.000, 0.730 reverse 2.222 torque converter stall ratio 2.3


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cheers

Steve

IMAGE_126-1-1.jpg

'97 Eunos Roadster B2 Limited 1.8 Auto B-2's thread

'96 Eunos Roadster special 1.8 Auto Red-2's build thread
'91 Eunos Roadster 1.8 Auto Red-1's build thread
'93 Eunos Roadster V-spec 1.6 manual, bone stock
How to fit a 1.8 in a 1.6 with standard ecu


#19 frontslide

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Posted 08 July 2020 - 06:33 PM

Digging this up again did you ever do the v6 conversion Steve?


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