MUA-5 Transmission Swap.

IZU069
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Post by IZU069 »

I'll second that beautiful comment. At first I thought get a transparent bell housing so we can see the clutch etc - you know, whenever we are under it - but then I thought protect the whole gearbox with wax or lacquer.
I used to get my boxes like that but soon I learned it was pointless. In fact the best protection was to have it covered in oil - especially against our red dirt which seems to etch into alloys (and probably does; ochre, caustic, etc).


IMO it's a good move to the 4ZE1 reduction starter. The 4ZE1 reduction starter has become the standard starter for all my vehicles noting that they are all left-side mounted starters as on the GW twincams and Belletts/Wasps and early Florians.
[ The RHS mounting 4ZE1 starter does not foul the LHS exhaust manifold nor body as it does on Geminis with GWs that do have the diesel engine cross-member and hence ability to fit standard GW exhaust manifolds or extractors. I'm not sure about the RHS reduction in RHS-starter vehicles like the GZ Geminis etc, but I think they fit ok.) And later reductions (mid 1990s 4ZE1 Rodeos) seem smaller (shorter) so they may have more mounting possibilities than the earlier Jackaroo(Trooper) & Rodeo reduction starters. ]
Be warned, although diesels to the C190 inclusive have LHS reduction starters, some have bigger flanges and hence will not bolt to the "standard" MSA, MSB, MSG, MUA etc starter flanges. And the earlier diesel starters that do fit are much larger.
Take the above with a bit of salt as these findings have been mine from wreckers vehicles which may have seen various inter-model sparts changes.

The big benefit with the reduction starter is its lower current, hence longer battery life.
Mine takes ~140A compared to ~240A for standard starters (original G161-OHV and Gemini GZ types).
Furthermore, the reductions will still crank acceptably down to a 5V battery voltage. [I was going to see how low they'd crank, but unfortunately my engine fired up LOL! That's a G-OHV with RB dizzy (Gemini GZ dizzy with RB Gemini reluctor & IgCoil to suit the G-OHVs & Jap SOHCs).]

And the reductions have good torque. I have often used it to "crank" the vehicle up ramps, over 4WD-track humps,out of bogs, etc.
And my reduction has suffered about 3 months of clutchless in-gear engine starting when needing to stop at intersections, and morning starting in reverse or 1st up my inclined driveway. (I threw in a spare starter last week just in case. But the original is still fine. It was from a wreckers though I might have replaced its brushes which is standard procedure for my acquired alternators and starters.)
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Post by IZU069 »

I thought I'd split clutch stuff etc from the reduction startermotor above....

According to a catalog, the Isuzu D-Max (8DH?; 5/02 to present) clutch slave is a 3/4" bore (as opposed to 4Z 7/8", and hence 36% more throwout).
And from its small accompanying pic it looks to have the same "C" mounting as the 4Zs & MUAs.
The 3/4" D-Max was to be my next option, but the current Piazza etc 5/8" master with Hyundai 13/16" slave (horizontal 2-bolt) works fine. (Rodeo 5-speed box with its st'd LH starter bell behind a G161-OHV and clutch.)

I'd assume Isuzu have stuck with their larger clutch hydraulic fittings and pipes/hoses. AFAIK that's been consistent from their 1960s Wasps through to the 1990s 4Zs (though the earlies used a course thread as they also did with brakes).
That makes it a bit of a pain when wanting to use other marque stuff which usually use the same threads & pipe sizes as their - and our - brakes. (However the 4Z slave banjo suited my Wasp's Hyundai slave so that was no problem with my st'd 4Z master and pipes/hoses albeit pipe shortened and reflared.)

BTW - I don't think I said earlier that while our LHD Florians and Belletts had mechanical clutch linkages, according to my sparts books, the RHD versions were hydraulic. That seems obvious anyhow from the "universal" pedal brackets they all used (with hole and bolts for a master) and the need to get to the gearbox's RHS clutch lever. (They didn't use clutch cables back then.)
Unfortunately I can't remember that detail from my Swedish diesel & G150 Belletts when I was 10 years old, nor from my visit to the Finnish Isuzu club some 30 years later. (Where's those pics? OMG - they are physical; pre-jpeg etc - I'll NEVER find them!)


Bugle - I note a common occurrence and maybe complaint with the 4ZE1 flywheels - they have a tendency to craze the clutch surface. I noted the same with my 4ZE1 Jackaroo.
I'm not sure if that's related to 4WD'ing, or the larger nature of the 2.6L and Rodeos & Jacks etc.
I did note the much heavier nature of the 4ZE1 flywheel and its sunken clutch surface (which no other of mine have, including 4ZD1; my Piazza 4ZC1-t's both being autos).
I wonder if that causes an uneven heat gradient that stresses the surface? Or is it a longer wearing clutch plate and maybe a trend with others too?

It will be interesting to to see how yours behaves.
Maybe you'll lighten the flywheel later...? (The 4ZE1 flywheel being so much heavier, but that's fine as the 4ZE1s were all "commercial" types - utes and 4WDs etc.)


Also interesting with the one-sided buttons...
I may question my Exedy guru about it. I'm thinking of a new Exedy for the Wasp rebuild - the G161's slightly torquier cam grind has meant clutch slip for the past 200,000km (with one intervening clutch & pressure plate change).


It's good also seeing the generally compatible exchange situation and gearstick position, and improvements like better flywheel bolts etc.
Funny though - lower mounting hole from early course to fine and back to course. Maybe the fines stripped to easily? But I'll often pre-helicoil them if it that's a concern.


Advice I often give - when getting a gearbox, ensure to also take its gearshift & stick, clutch throwout lever and bearing block.
I found so many variations in throwout-block inner diameters & lengths; pivot bolt lengths and threads; and gearstick & quadrant box depths and gate widths. Granted, that's mainly with older stuff, but it took years before the inconsistencies became apparent to me.
And though the throwout/clutch levers seem fairly consistent, eventually that pushrod hole wears through... (as mine did last year).

It looks like that MUA lever is shorter than earlier types ie, it protrudes less from the bell. That would explain the differences in hydraulic ratios - the earlier boxes requiring a smaller slave cylinder (relative to the master). But that's another of my TBD stiff - I have both types out back. (For now I'm on a clutch and gearbox strike having spent so much effort substituting my Wasp OEM hydraulics.)

Of course we know to do all this stuff OUT of the vehicle - fit boxes and align the slave cylinder with correct pushrod length to a properly angled throwout lever etc (preferably with the correct throwout distance, and slack clearance); remove bell material etc (generally just a bit if fitting to earlier gearboxes).
My Wasp's torsion bar made the above a PITA in situ in the vehicle, otherwise IMO it would not have been too bad. But externally assembled is far easier!
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Post by Bugle »

Have never painted a gearbox before but thought I might as well to try and stop it corroding after cleaning all the old oily dirt off it, hopefully it doesn't leak oil all over it now.

Yeah even if running a 4ZC1 flywheel the 4ZE1 starter looks like a good replacement. Should also be easier to maneuver in/out of the engine bay with everything else installed being more compact that the original.

I forgot to weigh the flywheels but it didn't feel like the 4ZE1 flywheel was heavier. They are almost the same in design apart from the pressure plate mounts being further out and not protruding out as far as the 4ZC1 ones (4mm vs 20mm).

I had ordered a heavy duty full face both sides clutch but they didn't have any so gave me this one which is supposed to be one better. They reckon for 4WDing it's better at cooling when you slip it heaps? So less chance of it crazing?

I'm actually using the MSG throwout fork, it's the same as the MUA fork except that MUA one has an extra bit sticking out the end with a hole in it which I assume is for a return spring, but it looked like it had never had anything hooked up to it because the paint was still all intact. The MSG one was less worn out where it contacts the throwout bearing so I used that. Would just stick out less due to the bigger bellhousing.
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Post by IZU069 »

Ah good, same fork length. (And hence allowance for a bigger and deeper clutch. Bells tended to "expand" as models progressed. That's a trap when fitting old bells - especially for us twincammers.)
I expected the same fork length, but seeing as the Wasp had a higher master/slave ratio for a longer throwout... However the OEM Wasp pressure plate is the the older coil-spring type (not diaphragm spring) - along with its OEM generator and Bendix-spring starter, AND cast-iron gearbox with syncho-less 4.499 1st gear; needless to say none of which saw the road after I got her - except the gearbox which was lucky seeing as we took the coastal 4WD road (track?) from Cape Tribulation to Cooktown for her running-in present.


All my old boxes also have the return spring hole on the fork. (When using Gemini etc boxes with GW bells, I relocate the mushroom pivots and fit the hydraulic & mechanical-linkage type shift forks.)
In fact I just fitted a return spring (a rather heavy Wasp brake-shoe spring) since the Hyundai slave has an internal spring (unlike the OEM Wasp slave) and I wanted to ensure the thrust bearing disengaged.
(I also fitted a 4mm spacer to the pushrod for less slack, and rotated the hose banjo 90° to face upwards to remove the hose tension, hence my deepening of the slave's U-shaped banjo retainer was in vain. I muse how the further one gets into some mods, the less work is found to be required... LOL, or shit!)


But well done or your fitment Bugle. And thanks heaps for your info and pics, and answering the myriad of questions. {Ah yes, OzGem may still have some great members!}
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Post by Bugle »

No worries, happy to help if it saves someone from having to remove/install their gearbox multiple times!

A cast iron gearbox sounds like fun to remove/install, weigh even more than a MUA?

I just remembered that i'd wrapped up my 4ZC1 flywheel in the packaging the 4ZE1 flywheel came in and the post office label was still on it, they weighed it as 8.21kg (was sent only wrapped in a plastic garbage bag), I weighed the 4ZC1 flywheel and got 8.18kg. So they're pretty much the same weight. 4ZE1 pressure plate probably weighs slightly more.
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Post by ImpulseRocket89 »

Bugle wrote: I just remembered that i'd wrapped up my 4ZC1 flywheel in the packaging the 4ZE1 flywheel came in and the post office label was still on it, they weighed it as 8.21kg (was sent only wrapped in a plastic garbage bag), I weighed the 4ZC1 flywheel and got 8.18kg. So they're pretty much the same weight. 4ZE1 pressure plate probably weighs slightly more.
I mentioned the similar weighs earlier in this thread. They are, near as makes no difference, the same weight. The 2.6 flywheels will have a slightly higher moment of inertia vs the 2.0 units (There is slightly more mass further out from the center), but otherwise they weigh exactly the same.


BTW, I am glad you mentioned that the clutch fork and other parts can be used in this application. That saves me quite a bit of time having to search out and then drop another trans on a rodeo/pickup just for that assembly.
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

RIP 1989 Impulse Turbo, aka "Rakete"
IZU069
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Post by IZU069 »

D'oh! I thought the 4ZE1 flywheel was much heftier. Must be my old age, or was it a hot day?

And yeah, that iron box was bluddy heavy. I've been meaning to weight it to compare.
I've been assuming that my Wasp's 1340kg or 1360kg rated carrying capacity (tare 1040kg; gross 2400kg) is now over 1400kg after ditching the cast iron gearbox and engine head (plus its lighter alternator and starter motor).
But it is about time I did some weighing.
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