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Discussion Starter #1 (Edited)
I have been running a 3-speed overdrive and have found it to be a poor choice. I have the same opinion as others that have tried it. First gear is too high and the spread from 2nd to 3rd is too wide. It is a 46% drop. That requires revving to max RPM in second gear and bogging into third with minimum throttle until there is enough power. Adding the 3000 RPM spring would only be a patch for improper gearing. I have decided to swap to the M5R2. I would like to share what I learn as I go.
 

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Discussion Starter #2
I compiled a lot of AverageF250's info into a document for myself. Here is my compilation of his posts, so others can find the info in one spot:
The M5R2 is Ford’s light-duty, Mazda-built 5-speed. It’s been used since '88 on 1989-present day F-150s, Broncos and T-bird Super Coupes. Ford calls them the M5OD-R1 and M5OD-R2. The designation used most is M5R2 for the F-150 version. The two trannies share a few parts inside and their design is identical. They're close-ratio, reasonably strong, and very available. In fact, I bought one today for $100 and it appears to be rebuilt. It came with a 1356 transfer case. The Mazda units are pretty solid, actually impressive as to what they can handle, if you keep them full or a little over full of Dexron 3. The M5R2 is small, but it has 3 bearings supporting each mainshaft and countershaft. The gear ratios are the best you can get for a diesel, because the gear spread is perfect. The M5R2 holds up fine behind a 105 horse 4BT in a 5000-pound truck. I think if you exceed the 350-lb/ft mark with this tranny under a big truck it won't last long, but otherwise it's a good choice for an economy built DD truck. I've installed 2 4BT's in front of M5R2's without any issue. The M5R2 in my '71 had 390K miles on it and it came from an ‘89 F-150 4x4. I drove the truck to the shop 20 miles with no 3rd or 4th synchros. The pocket bearing and thrust were trashed and it was filled with gear oil. $10 for the two bearings, $20 in synchros and regrinding the mainshaft thrust surface in the lathe. It's good to go for a good while longer. The M5R2 behind my 4BT now has under 10K on it. I just changed the fluid out of curiosity (ATF is cheap) and it looked great. If you like crashing 1st-to-Reverse while offroading, then at least find a '92 or newer one. You will destroy reverse doing that with an early tranny. The early 89-91 trannies have weak reverse and 5th synchros, which wear out early even under easy use, but the later trannies are good. But you'll want to find the ‘88-‘91 M5R2 as it has a mechanical speedo. If you find a '92 and newer M5R2 you can't put a speedo cable in it. But they do have a far better 5th and reverse synchro assembly than the earlier tranny that might be worth swapping in if you have the opportunity. Another place to find an M5R2 is from a T-bird Super Coupe. The supercharged V6 cars run a special M5R2, believe it or not, as an upgrade from the T-5. The T-bird trannies need the truck top plate and shifter to work in a truck though. . The M5R2 is a completely different design from the ZF. You'll never stretch the case of an M5R2. If you ridiculously overload one you'll blow the teeth off the input and cluster. The T-19 is a lot different from the M5R2. The Mazda is a lot longer and uses a slip yoke. The shifter is 3" or so further back and the tranny mount is in a different spot, but the same rubber mount works. The clutch is the same T19/M5R2. The M5R2 is a great tranny. I build several of them weekly and while that doesn't seem to say much for their durability, every single M5R2 I've fixed has failed from horrible shifting practice, low ATF or running the wrong fluid, like gear oil. The M5's biggest weakness is the 3 rubber plugs at the rear of the top plate. They have a very bad leaking habit from 3 rubber plugs. If they get even a pint low, the pocket bearing and thrust die quickly. Replace the 3 rubber plugs with 3 Dorman, 5/8" steel plugs (#555-108). Put metal plugs in, don't shift it like a Honda and change the fluid ever 15K and it'll last a good while. Also, the factory rubber shifter pivot seats are usually toast along with the shifter seal. These are usually sold on e-Bay in a kit for around $30. That seal is spendy, but should be replaced if it's cracked. Check a used one to make sure it was run on ATF. Gear oil is instant death for one of these. There's a magnet in the drain plug. Check it for pieces of bearing cage, under a teaspoon of shavings is fine. Wiggle the input shaft, a little side-to-side is fine. These trannies like about .005" end clearance, but if you can "clunk" the input around it has bearing or other issues. If you're so inclined, pull the top shift cover off and check the synchro clearances. Push the synchros one at a time squarely against their respective hub. Bad Mazda synchros will have less than .030" showing between the synchro teeth and the gear face. Good ones are .040"-.060". You can usually eyeball them.
 

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Discussion Starter #3 (Edited)
The gear spread and the swapability with the 3-spd OD is why I chose the M5R2. I believe I can stay within the strength limits of the trans. This is the gear spread and the overall gearing with two rearend options:
1: 3.90 .........3.54 x 3.90 = 13.81...3.08 x 3.90=12.01
2: 2.25 42%
3: 1.50 33%
4: 1.00 33%
5: 0.80 20%...3.54 x 0.80 = 2.83.....3.08 x 0.80= 2.46
 

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Discussion Starter #5
It's my pleasure. Thank you. I hope that this thread is helpful to others who are thinking of this swap.

Here are some websites with more info on the M5R2:

Different Tranny Part Numbers and Applications
www.icgb.ca/_downloads/Trans_Rebuild Catalog_2005.xls

T-Bird M5R2 Rebuild and Different Gear Ratio
www.mn12performance.com/mn12how-to/m5r2_rebuild/m5r2-rebuild-howto.html

Schematic Breakdown
http://www.midwesttrans.com/diagrams_40-41.htm

Information and Picture
http://www.motivegear.com/tech_info/tranny_guide/tranny_guide.html

Ford Transmission Gear Ratios
http://www.hardcore50.com/technical_articles/GearRatios.htm


It appears that the T-Bird trans with an F150 shifter might be a stronger choice (maybe a larger input gear?) and have a 25% overdrive instead of 20%.
 

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Discussion Starter #6
The 1985 clutch assembly part numbers that I currently have do not match the clutch assembly part numbers that belong on the 1990 5-speed. The internal slave cylinder and throwout bearing are obvious, but I don't know why the clutch disc and pressure plate need to be different yet. I hope to find a source for the 5/8" plugs and shifter seal this week...and maybe work on the swap this coming weekend. We'll see how life goes!
 

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You can use any clutch that will bolt up. The 5/8" plugs are dorman # 108-555 you can buy them from rockauto. The shifter seal is a tranny shop or dealer part. They should run you about $12 a pop, get the little plastic seats too, they're usually cracked.

I've done a few T-bird M5R2's and, though I haven't tried, I don't think you can switch gearsets and cases. The T-bird tranny uses different center and rear mainshaft bearings. I don't recall exactly why, but it seamed there was a pretty obvious reason why you couldn't bolt the truck shifter to the bird case. Thinking it was something with the 5th/reverse shift pivot, the bird tranny doesn't have it or any provision for it. The bird trannies main advantage was they had a shorter shift throw which necessitated lined synchros. You can't get these synchros anymore. I rebuild them using the truck synchros, but you can't slam the gears quite the same anymore.

The truck M5R2 has a thicker mainshaft too.
 

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Discussion Starter #8
Thank you for the info. I'll try to get the stuff tomorrow. I'm glad to hear that I can keep the clutch. It only has about 5 miles on it! Bummer about the T-Bird trans/gearing not working, but it's good that I wasn't going down that road before you corrected me.
 

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Discussion Starter #9 (Edited)

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Discussion Starter #11
I had seen their name before, but I didn't realize they were an online service. I got the plugs today from our company's hardware supplier. The parts from the Ford dealer had to be ordered and should be here in a day or two.
 

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What bell housing do the M5R2s bolt up to? Are they a direct fit from a NP or a SM that came in the bread vans? Also will a gear driven transfer case bolt up (NP205)?
 

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They are the Ford windsor/six bellhousing pattern. They bolt directly to the 4BT with the very common Ford bellhousing used in breadvans.

The Ford NP205 bolts directly to the 4x4 M5R2.
 

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ok so NP205 will work thanks do you know if a Dana 20 will bolt in as well since I already have one that would be easiest. I have a complete early bronco chassis and drive train that I'm trying to figure out what to do with. I really like the B3.3 as my next project will be about mpg. I already have a 2001.5 2500 CTD for my pulling hauling needs. I'm thinking about an early (28-34) ford 3or5 window coupe body on the bronco chassis.
 

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Discussion Starter #15 (Edited)
I got the parts I ordered from the Ford dealer today. The prices were much higher than I saw on other websites! Fortunately, I get 20% off of List Price!

Old Number..........New Number......Ford Name...List Price

E8TZ-7277-A.......6L5Z-7277-A........Boot........$38.65

E8TZ-7Z120-A.....1L2Z-7Z120-AA.....Washer.....$7.15

E8TZ-7E018-A.....E8TZ-7E018-A.......Shim........$1.40

F5TZ-7228-A.......1L2Z-7228-AA.......Spring......$8.55
 

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mr52

Can you really get these trannis for that cheap? I have a friend that has a 89 f150 with a bad tranni. (the previous owner put gear oil in it!) Around here All the yards want 700 or higher. Any chance you could buy a couple and ship them? Thanks in advance for any suggestions.
 

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Discussion Starter #18
I got mine off craigslist for $200 and had a long drive to pick it up. Pick-Your-Part sells their manual transmissions for $90 and you get to pull it. I didn't want to wait until they got one in.
 

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Discussion Starter #19 (Edited)
The rubber plugs in the shifter tower were loose (from shrinkage), but they had not started leaking yet. I replaced them with 5/8-inch steel cupped plugs using a 9mm deep socket. They drove in very easy. The shift tower was worse than I expected. The shifter seal was dry-rotted and the shifter socket bushings were completely gone. The shift tower only had a lower spring washer (not shown on the diagram from another website), a damaged upper shim, and an upper spring washer.
 

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Discussion Starter #20
After removing the shifter handle, I punched the alignment pins out of the way. For reinstallation, I didn’t follow the diagram. Here is how I did it:

1. Lower spring washer
2. Shim
3. Bushing
4. Alignment pins
5. Shifter handle
6. Bushing
7. Shim
8. Upper spring washer
9. Shifter seal

The shifter had a little spring-loaded, up-and-down movement. I don’t know the official spec is, but that is what seems correct. The last picture is of the bad parts.
 

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