MUA-5 Transmission Swap.

IZU069
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Post by IZU069 »

And that's why the GMH Piazza reverted to a mechanical dizzy...
(LOL. I'm having a dig a their mentality...)

But what a STUPID oversight. I'm sure I am not the only person in Oz that would have NOT allowed that to occur?
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Post by ImpulseRocket89 »

I am trying to draw up a diagram to show how the relay would be wired. Once I get it done I will post it up, and anybody that is better with wiring than myself is more than welcome to correct any mistakes I have made.
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

RIP 1989 Impulse Turbo, aka "Rakete"
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Post by ImpulseRocket89 »

Ok, lets see if my grasp of wiring this relay is on target.

Image

This is with the car in gear, the original NO factory switch, since it is now closed by the difference of the shafts in the quadrant becomes the activation switch for the coil on the relay.

The relay is a 5 pin SPDT relay, and a new 12V ign. switched circuit sends power through the relay to the cruise module. While in gear, the relay is in the closed terminal position, 87a, which keeps the circuit closed and allows the cruise to function.

Once I go into netural, the NO factory switch now closes, activating the coil, and opening the circuit and switching to the 87 terminal and grounds it out., thus telling the cruise to deactivate.

I hope I am on target.

Also, I know that I could have done the wires a little differently as well. I could run a new fused ign. switched circuit to the switch and ran the factory wires through the NC circuit to the cruise module. Either way it would work.

Feel free to throw in any advice, changes, or tell me I did it wrong if you wish. I don't claim to be the best with this electronics stuff...
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

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

I fitted the box, unfortunately the quadrant box hits the tunnel when the gearbox crossmember is about 5mm lower than it should be, so i'm going to have to pull the box back out and hammer the tunnel a bit in that area.

It is also a complete pain in the arse lifting this gearbox onto the jack while under the car! Heaviest gearbox i've ever had to handle.. After that fitting it is pretty straight forward. To tilt the engine back take the end off a pipe clamp and it can be used as a spreader between the swaybar and the sump.
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Post by IZU069 »

ImpulseRocket89 - no connection to 87. (Definitely NOT to GND!!!)
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Post by ImpulseRocket89 »

Bugle wrote:I fitted the box, unfortunately the quadrant box hits the tunnel when the gearbox crossmember is about 5mm lower than it should be, so i'm going to have to pull the box back out and hammer the tunnel a bit in that area.

It is also a complete pain in the arse lifting this gearbox onto the jack while under the car! Heaviest gearbox i've ever had to handle.. After that fitting it is pretty straight forward. To tilt the engine back take the end off a pipe clamp and it can be used as a spreader between the swaybar and the sump.
The fitment doesn't surprise me. I just tried to test fit mine with it in the car and ran into the same problem.

I have been hacking away at my alloy housing to build my own shifter assembly, but I am stuck with getting that linkage arm/ball off the shaft. I could use a little advice in that area...
IZU069 wrote:ImpulseRocket89 - no connection to 87. (Definitely NOT to GND!!!)
Ok, so just leave it open? As I said, I am not the best with electronics, so explanations help lol.
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

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

On your diagram it seem like 87 is to GND/earth (0V).
Hence when the relay closes, you short +12V to GND through 30 - 87.

If you have the "wrong sense" of switch - ie, NO when it should be NC - then a relay (or transistor etc) is used to invert the signal - ie, change NC to NO and vice versa.

NC & NO means Normally Closed and Normally Open, where Normally means the state of the switch (or relay) when "on the shelf" or un-energised etc.

Those gearbox switches exist in BOTH senses - NO & NC.
I have some Isuzu gearboxes (Gemini?) with 2 switches - one is NO and the other is NC. They are physically interchangeable.
Ergo, if you can't fit the correct switch type, you can use a relay to invert the signal.


Note that if a cruise control or reverse light requires grounding when "active" but the switch is grounded when not active or actuated, then the relay's 30 & 87a are connected between ground/earth/chassis and the "target" - ie, reverse lights or cruise control etc.
I mention that in case the cruise control is activated via grounding and NOT by supplying +12V. (I don't recall its switching offhand - I'd have to look it up.)


And when using a relay to "invert" the switch type from NC to NO or NO to NC, only the 87a (normally closed) contact is used.
Hence if power is supplied to the relay coil so that the relay is on (energised), the 30 to 87a contact is open or "not on". If relay is off (de-energised), the 30-87a is closed and hence "on".
Note to that 87a means an SPDT or "changeover" relay, not the more common on-off (SPST) type.

FYI - Some refer to change-over SPDT types as "5-pin", but since there are SPST types with 5 pins (ie - two #87 output pins), I avoid that name.
Also some tend to get all relays as SPDT types and merely leave the 87a unused if a mere on-off SPST is required. Provided cost is the same, it means all their relays are interchangeable - ie, one relay for all SPST & SPDT (on-off or changeover) aplications.
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Post by Bugle »

ImpulseRocket89 wrote: I have been hacking away at my alloy housing to build my own shifter assembly, but I am stuck with getting that linkage arm/ball off the shaft. I could use a little advice in that area...
It has a roll pin inside a roll pin to lock it onto the shaft, you'll need to make a punch for each size, or maybe you can punch both out at once. Take the bolts out each side of the housing and push the pin out through the side of the housing.
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Post by Piazza_man »

I know the MUA boxes we are talking about here is in reference to the 2.6lt 2WD, but does that mean these are the same boxes that bolt up the V6 or the 2.8 (4JB1) turbo diesel variants? My point here is that they look the same externally but will they bolt up the same way, and have the same spline count as the 2.6 (4ZE1) boxes?
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Post by Bugle »

They probably have the same spline but the V6 and diesel each have their own bell housings so they won't bolt to 4Z engines.
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Post by Piazza_man »

Thought so. Thanks bugle.
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Post by ImpulseRocket89 »

The gear box I am using is from a 3.2L Rodeo. I originally purchased it as part of my attempt to squeeze a 6VE1 into the car, and decided after seeing the difference in size vs. the factory transmission that I would like to make it work with a 2.6 build. So yes, they do work.

As Bugle said, the bell patterns are different, so you will have to swap out the front case/bell of the transmission for a 4cyl version to make it work.

One note to touch on, and it is something that I have run into on my case swap is that two of the bolt holes are slightly off in pattern. This doesn't mean the case patterns are different at the center section, but It most likely means that Isuzu drilled each case set as they were put together, much in the same way the cam towers on the 4z heads must stay with the head they came off of.

I can fix mine by simply slotting those two holes a very small amount, but to avoid potential headaches like this it would be easier to simply get an MUA box from another 4cyl application.

Instead of fixing it though, I am actually going to trade it in as core on a nice clean rebuilt unit. I wanted to rebuild mine as it was, but with that and a couple other issues I have run into it would save me time to simply get a nice new shiny box with all the work already done. It might cost me a few hundred more, but saving me time and work = makes up the cost difference. I am using the current one to simply get the rest of the work finished on it.
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

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

Just to clarify (AFAIK) - the two "off" bolt holes will be part of the normal machined production. That is also the case with certain other gearbox (to engine) variants.
Cam towers are matched due to line boring of the cam bearings whether shells or part of the cam caps.

But your info is very useful. Many thanks!

I've been meaning to check the V6 boxes in case there is some advantage (and there probably is - ie, stronger, better, newer).
It sounds like it will be the usual case of the odd bolt alignment, matching the clutch plate & its throwout, and the input & output splines, and of course transmission hump clearance and gearstick position. The rear mount is probably similar and the box is likely to be the same traditional length - though shortening of drive shafts is no big deal, but in my swapping of 5 speeds for shorter 4-speed boxes I have only had to use "other" Isuzu driveshafts - eg, a 5-speed into the Wasp (Bellett ute) required a Florian shaft. And so far I have found all output splines to have versions with the traditional Bellett/Florian/Wasp (Cortina etc etc) 1" universal joint - not that they are ideal for big power, but it's a nice feature until a heftier UJ is devised.

Hmmm - gearboxes are 50% off at my local Pick A Parts today & tomorrow (hence ~$40 for 4 cylinder, but maybe ~$90 for 6 cylinder 5 speeds [though mine would obviously be from a 4-cyl Rodeo LOL]). It's just a pity I don't have the cash... Then again, today is going to be 36°C and tomorrow 41°C.
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Post by ImpulseRocket89 »

internally the V6 and 4cyl boxes are the same. The bearings, gears, and syncros between the same year versions of a 4 and 6cyl rwd MUA will be exactly the same (according to everything I have seen so far at least).

The only differences I found between them was with the front case sections, which on the V6's have horizontal fins on the front case up to the bell housing. If this was done for strength or cooling is beyond me. The other being the slave cylinder and arm locations being on the other side.

This is my MUA box when I first bought it, straight out of a 1997 Rodeo with the 3.2 V6.
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1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

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

I bought my MUA box a few weeks ago with the alloy quadrant shifter, so I'll be following impulserocket's lead with putting the Piazza quadrant on a machined angled surface, and then adding a sports shifter to top it off. I'll be looking at this thread very closely when the time comes. Excellent write-ups by impulserocket, followed by bugle. All of the guess work has been eliminated.
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