'96 F150 4X4 straight 6, M50D manual trans. A potential problem has been recurring more and more often. When I shift into 3rd gear, there is literally no resistance at all (all of the other gears just have a slight resistance - normal shifting, IMO) and as it goes into 3rd gear, there is a millisecond of gear grind. It started happening infrequently, and it's getting more and more frequent. Now, it happens about every 5th or 6th time shifting into 3rd. Is this something I need to worry about, or just keep an eye on? Not really looking forward to the prospect of dropping the trans for any repair work in this 5-degree weather.

 

Sounds like the synchro is starting to wear. Nothing horrible, but over time it will continue to get worse.

The resistance in the other gears is the brass synchro grabbing the gear and matching the speed. Thus it has a bit more "feel" to it. The worn ring is not doing its job thus it just falls into gear, but raking some as it goes.

 

OK, thanks Freightrain! I don't have my service manual here at work, but I assume this means the trans will have to come out and be rebuilt, or at least taken apart?

 

Yes, fully stripped to get to it. I purchased a M5OD to put in my '89. I've got it fully apart to replace a shift fork and the reverse synchro(yes, they put one on reverse gear in this box).

Not a real hard box to work on, this is my first. I'm used to Toploaders 4spds.

 

Wondering if you used any of the Ford Rotunda specialty tools for the M5OD?

 

Nope. The only deal I had was the large nut on the output shaft that retained the rear bearing. It has a crimp on it to retain it. I just used a pipe wrench on the output splines and a large wrench on the nut and it came right loose. Upon putting it back together I'll do the same and just align the crimp on the same spot and reapply the dimple with a small chisel. I'm sure they have a custom real deep socket that reaches over the end of the shaft and torques it. I'll just align the spot and that should be good.

Everything else is just snap rings and bolts.


I've been inside a few TKO's and can do a toploader blindfolded. All with common hand tools.

 

Wouldn't hurt to pour a bottle or 2 of Lucas "trans fix" in and see if that helps. I've done it with successful results in the past with transmissions not worth rebuilding. It provides a little tack to help worn synchros grab.

Like freight said though, very easy trans to work on.

 

Well, for you guys who have apparently opened up transmissions before, I believe you when you say it's "easy". But I haven't done that before. I'll take a look in the service manual when I get home and see if I can understand the steps they show in the book. The worst I can do is screw it up, and bring the pieces to someone that knows what they're doing, right? Let me ask you this: Does this sound like something that can wait until may/June and warmer weather? I drive it everyday, FTR.

 

Yup, drive it.

They are like a chinese puzzle. They come apart one way and go together one way. Not for the faint of heart, but not rocket science either. I keep things in order and lined up to help with remembering the sequence. Never used a book or manual.

When I did my first toploader 25 yrs ago, it was a real learning curve. This is my first M5, so I'm learning what it takes.

 

Dump some Lucas in, worth a shot to make it more tolerable til spring.

 

OK, you guys seem knowledgeable on the transmissions so I'll ask here. I have been reading a lot of threads about guys swapping a ZF5 into their rigs. From what I have read, as long as I can find a ZF from a 4X4 (like mine) and it's not from a big block or diesel, it should fit right in. So here are my questions:
1) Why is the ZF5 so desireable?
2) In order to get a direct fit, what year ZF5 do I need to look for (I have a '96 4X4 300 straight 6).
3) The only reason I'm entertaining the idea is because a direct swap of transmissions looks a lot easier than tearing apart the trans and replacing the synchros in my current M50D. Does this sound logical? I don't want to eff up my truck and make the wrong decision!
Thanks for your help!

 

The zf5 is desirable for those who need it's benefits...it's differences are advantageous for those who need something to hold power, use their trucks for 4wheeling (granny gear), tow heavy (granny gear), or combination of the above.

The differences are: it's much more stout, and the first gear is a creeper gear

It might not be a better trans for you, however. It's not optimal for street gearing as there are only 3 acceleration gears (2,3,4) and for the purpose of the discussion, 1st and 5th are not used for acceleration. 1st is too slow (I always start in 2nd) and 5th is for highway cruise.

Any small block zf5 will bolt right up, but you have to consider the source. A junkyard trans is cheap, but it could have the same worn synchro issue that you have now.

Another thing to consider is if the differences of the zf5 are benefits, because the zf5 is not a better trans, it just has differences that are beneficial to those who need them.

 

If all you do is daily drive it then there is no real need to upgrade to a ZF. If you plan on using the truck harder then the present then maybe. Like F2urd said you still don't know what you are getting when buying used. I got my M5 for $75 at swap meet. I'm putting $40 into it to make it right.

 

Ah, I see. The main reason I would do the swap is to avoid having to dive into the innards of my M50D. I see your point - might not be worth it to do the swap if I have the same issue/different trans in a year or so.

Yeah, and it sounds like those benefits aren't what I need driving around the streets of Detroit! Although with all of our potholes, some might consider it heavy-duty 4 wheelin'.......
Bottom line, looks like I'll wait for warm weather, and attempt the synchro installation on the M50D in the spring (along with a clutch kit). Thanks for the sensible post, '89F2urd!

 

What swap meet? In northern Ohio, I hope? I have been looking for swap meets nearby. Toledo is only 45 minutes away. I go the the Jeffs Bronco Graveyard one every year as it's only 20 miles from me.