Transmission Info Needed: 5 speed

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markshipo
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Transmission Info Needed: 5 speed

Post by markshipo » Sun Aug 14, 2016 6:48 am

Hello,
I need technical information on the 1983 to 1989 Impulse 5 speed transmissions. Any help would be appreciated.

Questions:
1. Is this transmission name MSG-5T?
2. Is there any difference between the Turbo and Non-Turbo transmissions (Close Ration vs. Semi Close Ration, or material strength)?
3. Major difference between the MT w/ Turbo, w/o Turbo, w/ Cruise Control, w/o Cruise Control?

thanks,
Mark
markshipo

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Post by IZU069 » Sun Aug 14, 2016 1:06 pm

Hi Mark,

Anyone else with better knowledge should chime in and correct - i'm running on old memory...

1. MSG sounds right, and maybe the 5T. MSGs have the split gearbox with a central vertical sandwich or bearing/gear-retainer plate; their RHS & LHS startermotor bells can be interchanged (noting the ball & needle bearing layshaft variants). Later MUA from 4ZE1 (2.6L) etc types are larger but have the same bell-engine mounting dimensions. Earlier MSA & MSB(?) boxes were single piece on earlier Isuzus and the earliest Geminis.
I'm not sure about the 5T designation. There may be info in places like bellett.net and there are good threads elsewhere - especially involving RodeoBob on ozgemini-com and maybe from September 2005 somewhere here. These usually listed the various ratios.


2. Here in Oz we have the 4ZC1-t Piazza turbo. Its manual is 5 speed (of course!) and it has a steel central carrier plate as opposed to alloy in other Isuzus. Supposedly this is to make it stronger though i am unaware of any quantitative comparisons nor any complaints (of alloys breaking...).
AFAIK ratios are all the same and i haven't seen any difference between turbo & non-turbo ratios (not that we have non-turbos except as privately imported).
Ratios seemed to change more by year and sometimes model.

3. No differences AFAIK other than by year etc. Cruise Control is entirely separate.



FYI - below is some Piazza ratio info i have from various sources plus my favourite Gemini box which had a 0.782 5th as opposed to the more common 0.855, and MUA (aka TFR?), for comparison.

Piazza (4,5; G200Z, G200W) 3.312 2.054 1.400 1.000 0.840 3.550
Piazza (6; 180HP) 3.174 1,963 1.364 1.000 0.775 3.402
Piazza (13; 4ZC1-t) 3.431 1,963 1.364 1.000 0.775 3.402

Gemini (2) 3.467 1.989 1.356 1.000 0.782 3.438
MUA to ‘91 3.767 2.314 1.404 1.000 0.809 3.883
MUA after from ‘92 has a 2.248 2nd

Sources:
(2) = World Cars 1984 & 1985 – Japan Isuzu Gemini 110HP – 1984 LG, LJ, LS, LT & 1985 LJ, LS; Gemini TF Diesel
(4) = World Cars 1984 & 1985 – Japan Isuzu Piazza 120HP – 1984 XJ, XL, Belia & 1985 ditto & XN
(5) = World Cars 1984 & 1985 – Japan Isuzu Piazza 135HP – 1984 & 1985 XG, XE
(6) = World Cars 1985 – Japan Isuzu Piazza 180HP – 1985 XE & XS
(13) = Piazza Workshop Manual (Australia)


PS - i was going to say my preference has been for the 0.782 Gemini boxes behind my non-Piazza Isuzus (Belletts, Florians, Wasp) though my 400Nm G200W apparently twisted an output shaft hence my intention to migrate to the heavier TFR/MUA boxes (400Nm G200Ws are my standard build engine).
IZU069 - ISUZU means a lot to me.

markshipo
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Post by markshipo » Mon Aug 15, 2016 7:20 am

400Nm (~300 ft lbs) = nice! I have heard the MUA is a stronger box. I am looking to build a MSG due to size constraints and that I am not pushing 300 ft lbs.


Below is the information I was able collect from a US website (highlighted or starred match):
Gearbox Type.............................1st........2nd........3rd.......4th....5th........Rev
1981-85 iMark...........................3.77........2.31.......1.40.......1.......0.81......3.87
1983-87 Impulse Non-turbo………3.785……2.165……1.413……1……0.787
*1985-89 Impulse Turbo……………3.431……1.963……1.364……1……0.775
Including 1987 Impulse RS
*1988-89 Impulse Non-turbo………3.431……1.963……1.364……1……0.775

Piazza (4,5; G200Z, G200W) ………3.312 ……2.054…1.400…1……0.840 ……3.550
G200Z SOHC 2.0L engine 90hp
G200W DOHC eight valve engine 135hp
Piazza (6; 180HP) …………………………3.174……1.963…1.364…1……0.775 ……3.402
*Piazza (13; 4ZC1-t) ……………………3.431……1.963…1.364…1……0.775 ……3.402

Do you know anyone who may have cores of the 81-85 iMark or 83-87 Non Turbo Impulse transmissions and 85-89 Turbo (+88-89 Non Turbo)?

How tough is it to find the Piazza 180HP box?

Can you remove and replace all of the gears in a MSG-5T (swap in 1st gear 3.174 for the 3.431)?

I need to find a donor box to take apart to understand how it works.

Thanks for sharing your knowledge and info,

Mark
markshipo

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Post by IZU069 » Mon Aug 15, 2016 10:31 am

Not sure on newer MSG boxes, but i suspect the same as earlier - gears do not interchange.

The 180HP would have used the standard box - ie, i doubt there was any special box for the 180HP.


Have you got a running Piazza whose gear ratios you are not happy with?
IZU069 - ISUZU means a lot to me.

TrooperRs
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Re: Transmission Info Needed: 5 speed

Post by TrooperRs » Sun Dec 17, 2017 12:49 pm

markshipo wrote:Hello,
I need technical information on the 1983 to 1989 Impulse 5 speed transmissions. Any help would be appreciated.

Questions:
1. Is this transmission name MSG-5T?
2. Is there any difference between the Turbo and Non-Turbo transmissions (Close Ration vs. Semi Close Ration, or material strength)?
3. Major difference between the MT w/ Turbo, w/o Turbo, w/ Cruise Control, w/o Cruise Control?

thanks,
Mark
I have a 5 speed for sale from an 89 Turbo Impulse RS with 85K miles on it.

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