Bronco Forum - Full Size Ford Bronco Forum banner

1 - 20 of 28 Posts

·
Registered
Joined
·
537 Posts
Discussion Starter #1
Hello, :beer
I am new here, I am literally leaving in a few hours to pick up my very first Bronco. I believe it is either an 87 or an 89. I guess I'll know for sure in a few hours :) I do know it's an EFI 5.8 with an auto. And I despise slushboxes ;)

Let me preface by saying that I've done some searching of threads on the topic.
I've found some great information for the ZF transmission swap.
However I intend to use a M5OD transmission instead.


:whiteflag
I understand many will feel that M5OD will be an inferior choice, and that I should go with the ZF. I will thank thank you now ahead of time for your advice, and will be the first to say "you told me so" after I break the M5OD since the ZF is not the trans I will be using.
:whiteflag


So that being said, does anybody know what I will need to do for an M5OD swap as opposed to the ZF swap. Such as driveshaft length, transfer case mounting, crossmembers, trans mounting, bellhousing, etc. etc. Basically the whole 9 if need be.

I don't suppose I'll be so lucky as the only difference will be the trans I use.

Thanks in advance!
 

·
USAF C-17 Maintenance
'94, '92, '88, and '84 Broncos
Joined
·
6,970 Posts
Well I'll be the first to tell ya that I like your M5OD-R2 choice. So much fun in the '92 with a 302. Handshakers forever!



What tranny does the truck have? Could be a C6 (PRND21) or a E4OD (PRN(D)21 and OD lockout switch).

Adrianspeeder
 

·
Registered
Joined
·
869 Posts
Hey if you do go through with the swap, take step by step picks and a detailed write up, along with cost of everything.
I plan on doing this to mine within the next year or so. After I move off the island.
 

·
Registered
Joined
·
537 Posts
Discussion Starter #6
Why don't we just swap spots?
I don't think I would mind Hawaii much :)

Well I got the Bronco and it turns out she's an 88, well I was close. I'm positive the transmission is a c6, there is no O around the D on the shifter indicator, and no lockout switch to be found. She also only shifts twice from a stop and that's all ya get. The engine runs great, the transmission behaves beautifully (for a slushbox ;) ), however nearly everthing else needs help in a bad way.
It's defanently turning alot of Rs on the highway. I'm just below indicated 3000 at indicated 65. I don't know what the stock tire sizes are, this one has 31's on it though. However I don't think that really changes the indicated mph/rpm relationship untill you change the speedometer calibration... Tangent..

Anyhow, when I do get into it I'll be sure to document the whole thing. I've done work in the past and have been scolded for not documenting the project, so I've learned my lesson there :)
I'll have to get my old dailiy driver back into service before I begin of course, but I should be good to go right about the same time the weather starts to get consistantly nice I think.
 

·
Registered
Joined
·
403 Posts
the M5OD was never offered with a 5.8/351w, so i dont know if you could find a flywheel that would work, i could be wrong tho..
 

·
Registered
Joined
·
403 Posts

·
Registered
Joined
·
65 Posts
I hear ya on the revs thing...aside from the retarded-crazy bronco indicated in my sig thing on the left there, my other Ford experience is a '89 F350 Dually with a 460 motor and C6 trans. Turning 3200 RPM down the highway with that motor isn't fun!

Before the whole cummins nonsense overtook the project Bronco, we had a Mustang 5.0HO motor with the Mazda 5-speed. It was originally an Eddie Bauer edition Bronc, so the 5-speed was a conversion. It got blown up twice, once when plowing snow (which also took out the rear 9") and once when towing my jeep XJ rockcrawler around, but I guess that's asking a bit much from it. If you just plan on driving the truck around and not doing any heavy-duty work with it, that trans should work out fine for you.

As far as I know, the ZF trans has a slightly larger (although still 10-spline) input shaft from the clutch as compared to the Mazda. I don't think the Mazda unit ever came behind the 351 motor, so you may find yourself at a loss as far as a pressure plate/clutch/flywheel combo that'll work for you. If you're up for the challenge, a Jeep Cherokee clutch disc has the right splines and diameter to mate with the Mazda 5-speed, and is only .25" smaller overall diameter (and the same thickness) compared to the ZF disc, so you might be able to make one of those work with a 351 flywheel and pressure plate, with slightly less friction surface though. Your other challenge may be to find a pilot bushing that will mate the 351 and M5OD.

You'll also need a clutch master cylinder from a truck that had the 302 or 300, and preferably an earlier year. Since we put the ZF trans in a Bronco, the clutch line fittings are different, since the ZF has an external slave and the M5OD uses an internal slave with flare fittings outside the bellhousing. We managed to splice together the two lines using compression fittings, but it would probably be easier for you to use the smaller master cylinder.

You'll also need the pedal assembly from a truck before '92...when the interior style changed, the assembly mounting did also due to the airbag and more complex steering column. You'll also need to change up the transmission wiring harness a little bit, by shorting the neutral safety switch connection - I'll tell ya, we sat there for a half hour trying to figure out why the damn thing wouldn't even crank after we swapped the 5speed in place of the E4OD, and it was because the neutral safety switch was left open after just unplugging the harness and leaving it there.

I don't recall there being any issues with the crossmember, although I can't remember if we used the same one from the E4OD or used the one from the donor M5OD truck. Either way, I know there's a way to do it that doesn't require any custom fab or cutting/drilling etc.

You'll find your auto one has all the body punchouts necessary for the clutch master, as well as the stick shift boot and a manual-shift transfer case if you don't have that already.

That's all I can think of, good luck with the swap! The truck was definitely much more fun after we got that auto out of there.
 

·
They call me "MR FLAT TIRE"
Joined
·
4,582 Posts
I have a manual trans x member if you need it. cheap. and it is for the M5OD...stamped right on it.
 

·
Registered
Joined
·
537 Posts
Discussion Starter #12
Aslong as that transmission came behind some kind of Windsor I know I can find what I need to make it work.

Vetteboy, thank you for taking the time to write all that out for me. Plenty of good info there, one thing sticks out to me like a sore thumb though. The M5 using an internal slave instead of an external one. I'm not a big fan of that design. I'll have to get it all together and look at what I can do, I've always preferred cable linkages instead of hydrualic anyway. Does anybody know offhand if that slave is a pusher style slave, where it serves as the release bearing aswell. Or is it just working the fork.
 

·
Registered
Joined
·
1,616 Posts
Bellhousings for the M5ODR2 are integral and were 4.9/SBF only (SC3.8 aside) so no worries there, not sure about the ZF. I would grab the transmission crossmember to be safe. When I went from a T18 to my M5 my x-members were different, although I am still unsure if that was due to the transmissions or 2wd/4wd differences. Decide what size clutch you want ahead of time, 10" or 11". Most likely the flywheel you use will be drilled for both sizes. Bolt sizes (pressure plate to flywheel) are different between the two, FYI. While it's out, go ahead and order the updated metal plugs for the top plate if it doesn't have them already.

The M5 isn't all that bad of a transmission...just a little lighter duty than I prefer in a truck. Mine has hauled several bed fulls of scrap metal to the scrap yard, towed an '82 Town Car, been wheeled with and completed moderate yard work with no problems.

Edit, you posted while I was typing: The M5 is full hydro, no fork (other than shift forks of course). Click here: http://www.amsautomotive.com/ , click on Products on the left, then go to the right of the screen and click on Hydraulics, then Slave cylinders. The picture of the Concentric Slave cylinder is almost exactly what the M5 uses/looks like. If you wanted to know.
 

·
Registered
Joined
·
981 Posts
Seijirou-

Let me know when you have taken out that SBF C6. I am looking for one now. I'd love to see your project also.
 

·
Registered
Joined
·
912 Posts
Remember, there was a damn good reason Ford didnt put this tranny behind a 351.

Have fun
 

·
Registered
Joined
·
537 Posts
Discussion Starter #17
VA92, I'll send you a pm when it's ready for a new home. :beer:

Hipropos, interesting products, but well out of my price range. The page did have some great news about adapting Ford 4WD transmissions to transfer cases though :)

Lazarus, wel that answeres that. No cable operated clutch for me. Ohwell, compromise is the name of the game. However now that I know the transmission will bolt up, the clutch/flywheel won't be a big deal, and mating the trans to the xfer case won't be too difficult, I'll just count my blessings and be happy with it. It's turning out to be less challenging than I anticipated.
 

·
Registered
Joined
·
537 Posts
Discussion Starter #18
Franklin, I'll defanently send you some good photos of the shrapnel that was my M5 when it blows up, should I blow it up, so you'll have some good giggle material :)
 

·
Registered
Joined
·
65 Posts
Yeah, no cable clutch with the Mazda unit. A concentric slave/throwout unit is pretty much what you're stuck with.

I've never heard of anyone putting anything besides a Borg-Warner t-case behind that trans, so I think you're stuck with that too. I only say that because we broke one of those as well during a snow plowing incident, and I wasn't impressed. (it takes a decent blowout to impress me).

Like I said though, as long as you're not putting it through anything real stressful like plowing or towing, it should hold up fine even behind the 351. Good luck with the swap.
 

·
Registered
Joined
·
912 Posts
Seijirou said:
Franklin, I'll defanently send you some good photos of the shrapnel that was my M5 when it blows up, should I blow it up, so you'll have some good giggle material :)
I do not want to "giggle" as you say. If you would compare the torque ratings on a 302 vs.351 and the ratings on the M5od to ZF it will be obvious. I wouldn't laugh at the avoidable misfortune of others, just want you to know the facts before you do this.

You do now. Good luck.
 
1 - 20 of 28 Posts
Top