2.9 with an M5OD-R1 HD

[ecgreen]

Greetings. The M50D R1 HD is a nice upgrade. You didn’t mention what transmission you currently have but I see your profile list an 89 BII 2.9 manual. So do you still have the original FM146? There will be a few things to consider.

Yes the 146 and she is tired. Any advice is appreciated...

 

[fastpakr]

You should be able to use any 4wd version of the M5OD-R1 from a 2.9 or 4.0.

 

[ecgreen]

It's worth mentioning that the HD version isn't really an upgrade from the regular R1. It's just different. Either the regular R1 or the R1-HD would be equal improvements in reliability from the FM146 stock unit.

True, but since the HD were later, I am finding a lot of lower mileage units available.

 

[fastpakr]

Understood. That's not a bad plan. To the best of my knowledge there's nothing specific to an 'HD' swap that's relevant to you as long as there are no switch/sensor concerns.

 

[ecgreen]

Agreed. Upgrading from the FM 146 to either R1s is not simply a bolt on upgrade. Flywheels, clutch, slaves, masters, starters, index ring, and cabling all need addressed before trying to assemble components that are not compatible

I can do all that. I thought you could use the 2.9 flywheel, starter and the like though. I will upgrade eventually, and maybe now, but I am just wondering.

 

[ecgreen]

The 2.9 uses a 8 7/8 inch clutch. The m50 uses a 10 inch clutch. You will need the flywheel for a 4.0 and the engine plate also. Grab the positive battery cable if available. There are 2 wires on the 4.0 starter. There is an automatic and a manual starter also. I used a 1990 Ranger Master and slave cylinder for 4.0 when I did the switch. I found a 1993 Explorer complete so I had everything for the changeover.

This is from the Tech archive, and seems to suggest that I would not need to replace the flywheel. I probably will, just like to understand everything before I start a project:

"
Replacing a Manual Transmission with a different Manual Transmission:

All 2.8, 2.9, 4.0 V-6’s and transmissions are the same. keep flywheel, bellhousing, pilot bearing, throughout bearing, clutch release mechanism(s), flexplate, torque converter with the transmission.

The only modification that will need to be done is to the floor plate. You can either cut it to fit the new shifter or you can remove the front seats and pull the carpet back to get to the (4) 8mm bolts that hold it on and swap in the one from your donor. All that may be left is to trim the carpet. If you take your time, the piece that you trim out can be used to replaced the gap it will leave behind the shifter."

 

[fastpakr]

I believe that's meant to be interpreted as keeping all of those items together with their appropriate transmission. I.e. if you're putting in an R1, use the R1's flywheel/throwout/clutch release, etc.

 

[tw205]

@ecgreen
Thing are coming in fast here so I’m gonna just let fly Here we go.
The article states keeping all components with the transmission. Meaning clutch flywheel ect ect ect.
However, I believe the HD is from a sohc engine which means the flywheel would be an 8 bolt not a six like the 2.9 or 4.0 OHV. So if you are scavenging the HD from a another rig the flywheel won’t fit your 2.9 and you would need to purchase it elsewhere.

 

[2 bronco 11s]

I got lucky and had a complete Explorer which was basically an easy swap. I would install the factory 4.0 rear seal also. It comes with a steal sleeve or wear ring . It does require a special tool to install however. Been awhile , but I believe 2 bolts in the M series were longer. No problem getting them. Be nice if you could find one still in the vehicle!

 

[ecgreen]

OK guys, let me process all this and re-read my stuff and I'll post back.

Thanks a million times over

 

[Uncle Gump]

I sure didn't see a Bronco II in my future when I sold my 94 Ranger... Good running 4.0L with M5OD. Just didn't have room to keep it.

 

[tw205]

OK guys, let me process all this and re-read my stuff and I'll post back.

Thanks a million times over

Good call. Regroup and re assess.
My upgrade was simpler as I used a complete 94 explorer to swap as I see others here did as well.

 

[tw205]

I believe that's meant to be interpreted as keeping all of those items together with their appropriate transmission. I.e. if you're putting in an R1, use the R1's flywheel/throwout/clutch release, etc.

interpretation is correct leading to the issue that an HD is a sohc transmission with an 8 bolt flywheel. 2.9 and 4.0 OHV have a 6 bolt flywheel. Without looking I would say the article in question was written before the sohc engine and HD trans were introduced. Perhaps an update to the tech article would help.

 

[tw205]

@ecgreen
Not to overwhelm you but consider the lack of bosses to mount the shift linkage for a manual transfer case on the HD. If you have an automatic transfer case you’re good.

 

[ecgreen]

@ecgreen
Not to overwhelm you but consider the lack of bosses to mount the shift linkage for a manual transfer case on the HD. If you have an automatic transfer case you’re good.

Being overwhelmed is why I do this stuff! The feeling of being overwhelmed is the first stage in epic achievement!

I read about the lack of bosses as well. Even so, my T-case is electronic and it works well.