93 MX3 GS ATX to MTX questions

stepchyld · Post by **stepchyld** » December 1st, 2005, 9:35 pm

I'm in the middle of a swap, with 93 GS, ATX to MTX. Manual transmission is reportedly from a 93 as well. At this point the tranny is on the engine and under the hood. The only tricky thing has been working around the different starter location, everything else has mounted fine, to this point...

1. The ATX had studs for the fuel filter mount bracket; the MTX does not...I could see eliminating the need of the bracket and the U-shaped "fuel pipe" (which connects to a U-shaped hose in an S-curve...Why?) and hanging the filter with less hose, less restriction. Would this work?
Manuals show the studs, but my MTX doesn't have them. Did some not have it?

2. The CV Joints don't fit. I understood, and at least AutoZone's computer agrees, that only the Driver side axle had to be replaced. But the Passenger side slips in, but has play, so it cannot 'lock' into place. I also stuck in the Driver side, to discover the same situation. So I guess I have to replace both, as the MTX seems to use a thicker diameter axle. I guess this also means the axle is thicker where it slides into the wheel hub assemblies. Do the hubs have to be changed as well?

3. Backup Light Switch. I'm supposing this needs be connected to something... I figure it's in the transmission wiring, which means I'll have to splice it. But, I already removed the ATX's ECU (which my 92 RS parts car doesn't have), and am not willing to guess at this. Will I need to reinstall the ATX ECU, or can the ATX engine ECU take care of it, with the proper wiring?

4. Clutch Switch. Another part to figure out... How could I wire this in? or is it just for the safety of the car being in neutral when started? I habitually push down the clutch when starting the car and wiggle the stifter, so can I just leave this unplugged as there's nothing to plug it into? (this could be rather convenient when working on the car)

If anyone has answers or advice, it'd be greatly appreciated...
Thanks!

hppwdn · Post by **hppwdn** » December 1st, 2005, 9:51 pm

You don't technically need the neutral switch on the clutch pedal. Mine doesn't have it working and I know a few other people that do it like that too. It's like a preference. Now I can start the car with none of the pedals pressed down.

As for the CV joints the parts stores seem to give me a different axle everytime I get one. I must have gone through five axles on mine and they looked different each time.

All the KL engine transmissions have the the speed sensor and the reverse sensor. There should be a plug on the wiring harness that goes to both of those on the tranny. When we recently swapped a probe from ATX to MTX both of them were there. And I have swapped back and forth from MX6 to MX3 transmissions on my MX3 with no difficulties.

Hope that was of a some help to you.

PATDIESEL · Post by **PATDIESEL** » December 2nd, 2005, 1:10 am

You have to trick the neutral switch for the car to start. The neutral switch on your new MTX pedals is located just under the clutch pedal (but don't use it) Since the ATX uses a neutral switch that is connected to the tranny you need to find the plug and loop a wire from one pin to another so that the ECU thinks the car is in Neutral all the time. (this will nto hurt the car or its performance, it just lets you start the car) For a pic of what plug and which pins to jump look at Perry's BP swap page and he has some pics of it, the page can be found at http://www.atlantamx3.com/mocaforum

You do have to have the half-shaft and axles for a MTX MX-3.

As for the fuel filter it will be ok if you just shorten the hoses and let it hang or you can try and mount the "C" cup to the shock tower with some short sheet metal screws and put the filter back in it. (careful to not puncture the shock with the screws)

As for a back-up light switch we haven't figured that out yet. We also don't plan on trying since it is not that important unless you drive at night or it is your dailey driver. You can contact Grants on the forum and he can tell you how to wire the ATX plug into the MTX trans sensor to get back-up lights.

jschrauwen · Post by **jschrauwen** » December 2nd, 2005, 1:13 am

I believe JWMX3 just did such a conversion.

stepchyld · Post by **stepchyld** » December 2nd, 2005, 1:17 am

That's kinda what I was thinking about the switch, so I'll leave it alone.

The ATX I pulled didn't have a backup light switch like the MTX has. So I still get to figure that out. The speed sensor is sitting pretty at the moment, awaiting my response to the lack of mounts for the fuel filter bracket.

I'm gonna harass my 'local' Mazda dealership on the driveshaft specs tomorrow. AutoZone does not seem to have all the facts on Mazdas, as I've seen already with my RS valve cover gasket.

atlantamx3 · Post by **atlantamx3** » December 2nd, 2005, 1:18 am

Here is the Jumper wire to bypass the start switch/ safety switch like Pat mentioned above: (the white plug with the red jumper)

It is located on the drivers side of the car, pretty much right under the air-flow meter.

The car WILL NOT start without that jumped or hardwired.

atlantamx3 · Post by **atlantamx3** » December 2nd, 2005, 1:26 am

You are going to need a carrier bearing (I think thats what its called) for your GS as well, since all Manual GS's had them. The bolt to the block and house the jack-shaft. I dont think that the Auto GS's had a jackshaft.

Good luck finding one if it doesnt have one already!!

As far as axles-- Mazda is going to rape you if you get them from them. All you need are Manual GS axles (and that jackshaft/carrier bearing!)

Your ATX had a plug for the back-up lights, but its a different shape than the one for the manual and will not fit. The reverse lights are not ont he ECU harnes, but on the "dash" harness which goes into the car thru the drivers side foot well. I do not have mine wired up because mine is not a daily driver and I usually just back into spaces so I dont have to use them trying to pull out.

They can be hardwired- we just have not done that yet.

stepchyld · Post by **stepchyld** » December 2nd, 2005, 2:29 am

For the jumper to work, I guess the ATX ECU will have to be plugged in, or it may not start? I'd assumed it was no longer needed and removed it. I didn't cut any wires, so I'd just have to reinstall it. Damn...

The ATX does have the carrier bearing/jackshaft setup, just like my 94 rs. So the half-shaft for MTX should bolt right up in the same location. I'm just nervous about the hubs, as I'm sure they may be different as well. and there's no way I'll be getting them from Mazda! though since they answer questions for free - you do get a reach-around...

Thanks!!

now what about that fuel filter? how is it mounted on your MTX GS? I don't see anything wrong with streamlining the fuel flow and can't think of any pros or cons...

JWMX3 · Post by **JWMX3** » December 2nd, 2005, 2:48 am

why in hell do you guys jump the starter interlock, it just as easy to wire up properly as it is to jump it, just run 2 wires from the pins you jumped thru the firewall to the connector on the clutch pedal, if you dont have the connector, go cut one off at the junkyard... done

as for axles, you can use the pass side axle from your automatic, just need the proper intermediate and drivers side

the back up lights are also simple, 2 wires for reverse come out of the tranny, and the connector that had the back up lights for atx, i believe i cut the connector and just found the 2 wires that were reverse lights for atx and solder them to the 2 wires coming from tranny, Its been a while since i did this, i can look up in my papers to find out exactly which wires, but the wiring is really simple

oh and use your atx ecu, no need to change it, george chicken, who has done 12 tranny conversions and 100 engine swaps, actually says his 5spd cars run better with the atx ecu (makes no sense but theres no point in changing it)

stepchyld · Post by **stepchyld** » December 2nd, 2005, 11:14 am

Thanks for the pictures atlanta!

JWMX3, from what you said, the hubs don't need to be swapped? I've ordered the Driver side CV, but haven't picked it up yet. I just got up, so I haven't called Mazda yet about it. But if the hubs can remain, I'd be a happy man. Just get the fun of disassembling the passenger side CV to swap the intermediate shaft.

For the starter interlock, whether I run wires to the switch on the clutch pedal or make a jumper (as I usually do all my work alone, it would be handy to not have to get all the way in the car to turn it over), I still have to reinstall the ATX ECU??
I figured the box under the stereo, just behind the ashtray, was the ECU for the ATX. I had to remove it anyway to deal with the shift cable and the interlock cable for the ignition switch. I assume now it must be put back in. Is this correct?

I had to also remove the engine ECU, but I understood it would be fine for the MTX conversion. But they weren't ok the other way around, ie. that one for MTX wouldn't work on ATX.

Thanks alot for the help!!! I'm so ready to have this car on the road

JWMX3 · Post by **JWMX3** » December 2nd, 2005, 11:50 am

You dont need new hubs.

the way I wired it, i left the atxcu and there were 3 or 4 ATX specific wires going to the main ecu, i disconnected them all (dont know if i had to because i didnt try it without) but my car is wired as good as a factory 5spd so if you copied me it wouldnt be a bad idea

since you already removed the atxcu , just put the main ecu back in and after you wire it try it and see what happens, make sure everything works..... i'll get back to you with exactly what wires you can disconnect on the ecu if you want to do that (again you could try it without disconnecting thm)

it wont make any difference if you use your atx or mtx main ecu, they are probably the same anyways, its the wiring harness that is different, the atx cars have those extra wires going to them, so which ever ecu you use, the wires are still there-

JWMX3 · Post by **JWMX3** » December 2nd, 2005, 1:06 pm

check your PM stepchyld

stepchyld · Post by **stepchyld** » December 4th, 2005, 4:25 am

ahhh, yes... Talked to Mazda, and they confirmed the hubs are fine and the jackshaft, or intermediate shaft has to change as well at the Driver side. Nice. and they want around 180 for the intermediate. ya gotta be kiddin me!! needless to say, I will not buy it from them!

The fuel filter is hanging by a zip-tie, I don't know about mounting it to a shock tower. Too far to bother with it, and my battery still needs a home! The MTX has more room in that area than the ATX.

The wiring is gonna be fun, and thanks much for the help there! I'll get to dive into that at the end of the week.

Thanks a lot!!

stepchyld · Post by **stepchyld** » April 25th, 2006, 12:46 pm

Just had to post this: It works!!!!
Thanks to everyone who posted to help me out and to those who sold me the remaining parts I needed.
Lovin' the GS finally!