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AOD died on my 5.0l LX

6K views 36 replies 10 participants last post by  quickford 
#1 ·
Hi, I think my transmission is completely shot. I have no reverse and neutral anymore.

It all started after 1st gear began to slip. I replaced the fluid and it really smelled burned. Because I have no experience with automatic gearboxes what so ever, I search on this forum for a solution. It seemed like Lucas Transmission Fix might help, but that the transmission would be on borrowed time from thereon anyway.
So I went to the store to get a bottle. Unfortunately no one sells it here in Europe. I should have just ordered it online, instead I let myself talk into buying Nulon Transmission Improver. Needless to say it was not a succes. The transmission started to shudder between first and second gear. Not what I wanted but it did something at least. I figured some of the passages or valves were getting unclogged and it just needed some time to do it's job. It only got worse instead, to the point that the TV-cable broke off the lever on the throttle body due to the shudder, with the aforementioned result.

Now I need a new transmission or rebuild this one. Does anyone know what it would cost to rebuild it myself, including upgraded parts and a shift kit?
I can get a second hand one for 400€, but I'm planning on turboing the engine, so it will probably not last long as well.

I'm really tempted to do a 5-speed or 6-speed MT conversion at this point. Unfortunately all the usual gearboxes to do the swap with are very hard to come by here.
I can get a old Getrag 265 for the same price as the AOD, which I know can handle the intended torque. It has a separate bell housing and I believe it even has the same input shaft spline as a mustang T5. The drive shaft will have to be altered anyway, so the output shaft is not that important to me.
All I need then is a clutch pedal, master and slave cilinder, a bell housing and adapter plate, and a clutch kit with flywheel to fit a 5.0l.

I've read that the starter motor from an AT is the same as from a MT, except with a different mounting position because of the smaller flywheel/flexplate. Is that correct? What bell housing would fit if I go with the 157 tooth flywheel and clutch from a foxbody mustang?
 
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#2 ·
A T5 swap uses the same starter as the AOD, so if you use the fox Mustang flywheel, clutch, and bell housing, you can reuse your starter. One issue with that though is you will have to adapt it to a hydraulic clutch, since the Mustang used a cable setup, and there really isn’t room under the dash for the Mustang clutch pedal setup. I don’t know anything about that getrag trans, but one thing to keep in mind is the shifter location. You need it to be around 29-30” from the bell housing to the shifter.
 
#6 ·
I scrounged a free clutch pedal out of the parts bin of a friend of mine. It's from a Mazda MX5 NA.
I just test fitted it and it seems fit quite well. This might be a cheap and easy to find alternative to the SC pedal.
I'm out of town for work this week. I'll try to fit it next weekend and post an update if it works.
 

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#7 · (Edited)
I installed the MX5 (miata) clutch pedal yesterday. I used the existing hole as the lower mounting hole and used the gasket of the master cilinder as template to drill the two other holes.
I was planning on altering the clutch pedal so it would fit next to the brake pedal, but I quit like the position of the clutch pedal. It allows me to rest my foot next to it. Now I'm thinking of altering the brake pedal. Does the pedal assembly have to come out for this or is it possible to disassemble the pedal only?
 

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#8 ·
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#11 · (Edited)
Here's a update on the miata pedal install. For the third mounting point, I cut a triangular piece out of the black liner under the dashboard. Underneath, there was a slot for fitting a threaded clip. After poking out the insulation above, I managed to fit a M8-threaded clip. After reinstalling the clutch pedal it turned out that the mounting point sits exactly above the clutch pedal bracket.
 

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#12 ·
To mount the bracket I used a long bolt, a self locking nut and two washers that were exactly the width of the bracket so the bolt could slide without falling out.
The bracket itself is a bit to long and will hit the wiring loom, so it had to be cut.
 

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#13 ·
Here is how it all fits under the dash. Very snug, almost a factory fit it seems.

In order to mount the master cilinder, I had to use shims because the threaded ends have a collar that extends trough the firewall. This is almost impossible to get right and rattle free, especially because you have very little room to mount the cilinder and keep the shims in place at the same time. Fortunately the forces on the pedal are so that you can get away with rubbers shims. So I cut two piece of rubber hose that fitted snug over the collars and had them stick out 2mm past the ends, so that when you tighten the nuts, the spring pressure of the rubber keeps everything in place.
 

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#14 · (Edited)
I unbolted the brake pedal and bent it on an anvil to where I wanted it. You don't have to disassemble the whole mount for it like the article (Thunderbird to Mustang Pedal Conversion How-To) says btw, just the bolt the pedal pivots on and the clip that secures it to the brake cilinder.
I then cut the original plate off and fabricated a smaller plate that has the same size as the clutch pedal so that the rubber cover fits both pedals.
Retaining the original plate and cutting it down like in the article is only possible with the mustang covers because the rubber covers aren't stiff enough.
I found two Mazda 323 covers with the same size as the miata covers and the same striped pattern as the ford's. Very important for making it look OEM in a police state where almost all modifications to a car are illegal!
I'll post a picture as soon as they arrive.
 

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#17 ·
That's the BOO - Brake On/Off (aka 'Brake Light Switch' to any other vehicle.)

It goes around the pin that connects the brake pedal to the master cylinder.

RwP
 
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#16 ·
Nice work, that's coming right along. About idea how close the shifter will be to the stock hole in the console? I'd think that is your next hardest task in making it appear stock. Good luck on the finish. Looks good!
 
#19 · (Edited)
I was thinking of using a BMW gearbox. The GS6-53DZ seems indestructible and the 123D version even has the starter motor in the right position. But the 157 tooth flywheel is too big. I've heard rumors that a 77 Mustang 5.0 has a smaller flywheel. 148 I believe. But I couldn't find one and didn't want to bother with re-balancing.
If anyone knows of a smaller flywheel (<300mm) that fits the 5.0L H.O, let me know, I'm still interested. Even the 520D gearboxes are strong and only cost 75€.
Instead I bought a Getrag 265 from an Opel Senator/Monza 3.0. They have a separate bell housing and a remote mount shifter, so the position shouldn't be a problem. They aren't cheap anymore however. I payed 500€ for one that needed new bearings. A good one cost 1500€ nowadays. I remember when they only cost 150€. They are strong however. Jaguar used them with their V12's and BMW re-used them in the E30 M3, even though it's successor was already available. I believe the Jaguar and BMW ones even have the same input spline as the foxbody 5.0. The Opel ones have the GM spline.

I will make a new build threat about it, if and when everything fits.
 
#18 ·
Yeah, I found it, thanks. Was the only place it could fit.
However, I have another problem. I don't know where the interval governor was mounted.
I've should have taken way more pictures before disassembly. My memory isn't what it used to be. :(
 

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#20 ·
I did a quick measurement. With adapter plate it's about 4" shorter than the AOD and the shifter needs to move 4" further back as well.
This is easily done by making a new bracket and extending the shift rod. I will probably need a two piece driveshaft too.
I never seen one as long as the original one. I wonder how close it is to it's critical speed.
 

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#21 · (Edited)
Here's an update on the Getrag 265 swap.

I test fitted the gearbox onto the bellhousing. The lower bolt holes are fine, but the top ones are not ideal. They are too close to the original ones of the bellhousing. So I decided to go with an adapter plate, thinking that I could always alter the clutch plate afterwards if it didn't fit the input shaft properly.
I took a 15mm thick aluminum plate drilled a bolt hole, scribed the outline, the other bolt holes and the center circle. Cut it with a jigsaw by clamping it between two rubber blocks, drilled the other bolt holes for the bellhousing and a center hole that fits around the input shaft of gearbox.
 

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#22 ·
Here you can see how close top top bolt holes are to each other. I had to countersink both and turn the bolts off(?) down(?) (how do you say that in proper English?) on a lathe. One of the gearbox bolts was close to the edge too. I hindsight, I could have extended the plate there a bit, but I think it fine. Then I cut out a rough shape the size of the gearbox end plate, so that the adapter plate fits over it and bolted everything together for a test fit.
 

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#23 · (Edited)
I ordered a 10.5" stage 5 pressure plate for a mustang and a 10.4" sprung clutch plate with the GM type spline to fit the input shaft (for a jeep cherokee I believe) from ClutchXperts.
I also had to weld a piece of pipe over the clutch release bearing guide tube to enlarge it a bit. A piece of pipe from an old vacuum cleaner seemed to do the job perfectly :grin2:.
 

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#24 ·
It turned out that the clutch plate didn't engage with the input shaft fully. Not even with the center section of the clutch plate reversed.
The pilot bearing didn't engage fully with the input shaft either, but that was something that could easily be fixed by putting shims behind the pilot bearing.
After some measurements, I decided the best course of action was to see if I could drop the adapter plate.
Even without the adapter plate the clutch plate wouldn't engage fully so I reversed the center section anyways.
I drilled out the rivets, took out the center section and put it back in backwards, tapped holes in the standoffs and screwed everything back together with allen bolts.
 

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#25 · (Edited)
I punched the center holes using the adapter plate as jig. Some are close to an edge, but doable if I clamp the bellhousing to the drill press.
The one in the right top corner sat right in between the original bolt hole and the the hole for the clutch fork pivot point.
In Ukraine they would say: Not great, but not terrible either :wink2:.
 

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#26 · (Edited)
For the bottom holes I can use large washers. For the top ones I wil have to devise something.
I had to cut a large hole for the gearbox end plate too, so that the gearbox would sit flush with the bellhousing.
 

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#27 · (Edited)
I used the adapter plate again as jig for this. It turned out that the center hole in the bellhousing is the exact same size as the top section of the end plate. I only had to trim a tiny piece off. For the bottom section, I cut a hole with a hole saw and trimmed the corners a bit.
 

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#28 · (Edited)
This is what the end result looks like. For mounting the two top bolts, I cut the clutch fork pivot mounting stud flush with the original bolt hole and made two pieces out of angle iron where the top bolts fit into. It's not pretty, but it's functional.
From the outside it looks way more OEM now than with the adapter plate. The guys at the vehicle inspection will be pleased!
 

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#29 ·
I test fitted it all again and now both the clutch plate and pilot bearing engage fully with the input shaft. Even the clutch fork bearing sleeve sit right where it needs to be. The original automatic gearbox mount almost fits perfect too, almost like everything was made for each other. I only had to drill two holes in it and make the slotted hole of the center support a bit longer.
The only thing I have to do now is find a drive shaft, make a new bracket for the gear shifter to bring it back a bit and find either a pull type slave cilinder or make a bracket for a push type one. Anyone any idea how far the throw needs to be?
 

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