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Discussion Starter #1
I am currently looking at buying a 4BT that has a SAE #3 adapter and flywheel. Does this pattern fit any manual transmission? I have been searching this forum plus done various other internet searches but with no luck. The answer I receive may ultimately determine which transmission I use.

I would prefer to use a Ford/Mazda M5R2 transmission but may need to buy an adapter to fit the Ford transmission. Would the current flywheel fit either the SAE #3 adapter or the Ford adapter.

Thank you in advance for your help.
 

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The block adapter and flywheel are in pairs. You can't mix and match them.

You can run a Spicer trans (search here for that) but that thing and its associated monster flywheel aren't my cup of tea.
 

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the SAE are all med duty trans ( Allison ,Spicer ,rockwell ,fuller )....
Well, maybe for #3. But SAE does not necessarily mean medium duty transmissions. The Warner T19(commonly found in 1/2, 3/4 and 1-ton apps) was mounted in diesel Scouts using SAE #4 parts.

I have an SAE #4 clutch housing that came on an NP4530. So with a simple adapter(see below) I could use this #4 clutch housing to mount a light duty NP trans(like NP435) to an SAE #3 flywheel housing.

This company makes adapters to go from one SAE # to another.
http://www.phxgrp.com/saeadapters.htm
Note part numbers 26-01305 and 26-0035, both of which adapt an SAE #4 clutch housing to SAE #3 flywheel housing(what's on the 4BT you're considering).

The Ford/Mazda trans is not SAE so would not mount up as things are. But because of the Ford based 4BT/T19 equipped stepvans this trans could be used with available parts, IIRC. I'm sure I've read about that trans on this site.

Keep in mind you could definitely sell the SAE parts off that engine(flywheel, flywheel housing, starter).

Ken
 

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I agree about the SAE #3. Mine looked large until I saw the Dodge housing, and found it was almost the same exact size. The flywheels are almost the same as well, with the medium duty flywheel being around 1/2" or so larger. Dodge uses a 12.25" clutch, while my SAE #3 uses a 13" clutch. I drove a 2.5 ton Deuce 500+ miles with a Spicer 3053a, and I have to say that it shifted quite well, better than many older 3/4 and 1-ton 4-speeds. They have synchros and an overdrive, so they are well suited to everyday use. I think they may have gotten a bad rep by people using abused, high-mileage versions taken out of old trucks. I have one set aside for my '96 Ram Cummins, which will be going in after I'm done with the 4bt Durango project.

Jim
 

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I have one set aside for my '96 Ram Cummins, which will be going in after I'm done with the 4bt Durango project.Jim

Jim I am really interested in this, any chance of a write up? Initially on the gearbox/flywheel/clutch and then on the 6bt project aswell when you get round to it.:beer:

Gaza
 

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Discussion Starter #8
Thanks for the info, guys. I appreciate it.

My brother, father, and I will need to decide what we want to do. I did some research on the Spicer box and got a bit spooked at its creeper gear and wider gear ratios since our truck will be a go-getter and commuter which rarely tows, if ever. The gearing issue of the Spicer concerns me since we will be running stock-sized tires and have a 3.73 rear. The gearing of the Ford/Mazda M5R2 transmission had appealed to us. The M5R2 seems ideal for a leisurely Sunday-go-a-meetin' kind of truck.

What would a new SAE adapter, flywheel, and starter be worth, if we sold it?
 

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the SAE are all med duty trans ( Allison ,Spicer ,rockwell ,fuller ).

Scott
On my Caterpillar powered Chevy I have a#3 SAE Adapter, and I used a bellhousing out of a Kenworth. The index hole is the same size as the early GM NV4500. Also the same as the GM NP435 I have. My flywheel is custom though. We simply redrilled the Kenworth bell to match the NV4500. Also drilled patterns for other transmissions that I thought I might try if the NV4500 didn't hold up. It held up, so didn't use the other holes.

Bob B.
 

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I think there is a clark 5 speed that is found pretty cheap out of school busses and such that is sae #3 also... It is a round, "industrial" or "commercial" pattern. We sold a industrial 4BT with a SAE #3 pattern but it had some sort of hydraulic pump flywheel that was not useable with a common clutch. Hope it helps...
 

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Most "medium duty" transmissions have an SAE #2 clutch housing.

If you want the most transmission options the #2 flywheel housing is the one to have.

The pilot diameter (hole in the center of flywheel housing) for an SAE #2 measures 17.625"
Bolt circle diameter measures 18.375"
Nominal outside diameter of clutch housing is 19.25"
Uses twelve 3/8-16 bolts.

An SAE #1 housing has a 20.875" bolt circle and uses 7/16" bolts.

I have an Eaton Fuller Roadranger manual covering most all their transmissions, they only list SAE #1 and #2 housings, no #3.
 
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