I've recently had my top cover off to do a rear seal replacement (with freeze plugs), and shifter bushing replacement. While I had the cover off, I noticed that the rear fork is very worn - see pic below...


And here's a shot of the open gearbox, which seems to generally look fine...


Which gears does this fork control?
If it breaks through, I presume I'll lose the ability to select those gears, yes?
What would cause the fork to wear in this matter? As you can see, the one up front looks perfectly fine - no indication of wear at all.

If I wanted to hunt a new fork down at the junkyard, I presume it's just a matter of driving the pin out and then removing the rail once I've pulled the plug. Yes?

I presume the donor could be from a 4.9 or V8 powered truck, correct? What about the M5 from a Ranger? Same part or no? Lastly, what's the approximate date-range of the donors that would be suitable? i.e. What year might this part have changed?

Appreciate any feedback..

 

I dont think you will get anything better from a salvage yard. If you do come across a good one, they arent going to let you take just the shift fork out of a perfectly fine transmission. You will either have to buy the whole trans or order a new shift fork to replace your worn one. From the looks of the shift fork, you might have a problem that will eat another shift fork without finding out why it is heading south in the first place. Good luck.

 

I can tell you the #1 reason for VERY worn shifter forks...


Lazy arsed owners that use them for a arm rest while driving...

SWEET HOLY MOTHER JESUS THAT MAKES ME MAD...

Because of that very thing...My shifter handle is as loose as my ex-wife, even AFTER the upper shifter bushing replacement...


As for the years...1987-1996 M5OD-R2 is what you're looking for...In the parts houses, it's listed as the Koyngo or something or other...

Ford Ranger=M5OD-R1
F-150=M5OD-R2

Similarly different tranny's...

Partsguyed.com has them for, IIRC about $45 a pop...He's in Seattle and is a FTE vendor/supporter..

 

I've had this all back together for a couple weeks now and all has been fine - mind you, I shift even more delicately than ever now, knowing the condition of that rear fork.

Although my plan is to replace the worn fork at some point, it's not at the top of my list right now. My thinking is that a worn fork is really only a shifting problem, and it's not going to effect the strength/reliability of the gear-box as long as it's still getting into gear properly. Is that a reasonable assumption?

Reason I ask is that I'll have to tow a light load soon, but for a couple hundred miles. Again, my thinking is that the only failure concern I have here is with respect to the shifter, and that's something I can have some control over.

 

You should have replaced that fork when you had the top cover off. The fork can fail suddenly while driving and leave you without a couple gears. New forks can be picked up cheaply from Allstate Gear. I've even got a new set waiting to go in my R-2.

M5R2 Ford F150 5 Speed M50D Standard Transmission Parts

 

In an ideal world I would have replaced the fork while I had the cover off, but I really needed to get the truck back on the road, so it had to wait. It's not like it's a big deal to take the cover off, and now I know not to be surprised if I get the gearbox stuck in gear when reassembling.

But back to my question, I'll ask it in a different way now... Does the fork actually hold it in gear or just place it in gear and then go on break until it's called on again?

Just to confirm, the rear fork is the 3-4 one, yes?

 

Here's your picture with what gear the shifter forks control.

 

I had this problem with my truck i replaced the fork. Ring and Pinion, Transmission and Transfer Case Parts - Drivetrain.com caries them, yes drive the pin out and pop off the plug on the end and slide the rod and remove the fork. Being that thin its very unpredictable when it will break. But the fork only comes into play when you shift into that gear and takes out when you change gears. But if it breaks and that metal piece falls in those gears and bearings it could mess them all up and your looking at and overhaul or new trans. and yes your pic is labeled right you need the 1st and 2nd shift fork.

 

Thanks for this - I had them reversed - it's the 1-2 fork that I need.

 

Thanks for all the info. For now, thinking I might go with a 1-3 shift pattern whenever I can.

 

I was able to get a 1-2 fork in perfect condition from the junkyard for $5. Gotta love U-Pull-It junkyard! Installed the "new" one yesterday and all is well, but not without a little drama. Apparently the design of this fork was updated to be more service-able at some point in the early 90's. The early design requires removal of the middle rod (and thus the other fork) while the later design allows for removal of only one rod and fork (the one being replaced). I'll post some pics eventually that show the difference.

Hopefully I won't need to do this job again, but if I do, it will be easier now that I've got the later fork.

 

Finally a moment to post some pics. Here you can see the difference between a worn fork and a like-new one...


And here you can see the engineering change which was made on the later forks ('92+?) which enables you to swap the fork without removing the center rod.

Of course, I had to remove the center rod any way to get the old fork out. I briefly considered fracturing it with a hammer but realized that was probably a bad idea.

And here's the new fork installed ready to go back in. No drama with being stuck in gear this time. The key is to start out in neutral before you begin.

Still not sure WHY this fork was worn as badly as it was. Was it simply a matter of the previous owner using the shift lever as an armrest, or is some other issue at play. The fact that the fork was changed to be more easily replaced does tell me that this is a somewhat common issue.

 

I have a 1996 F150 and I just removed the top cover of my transmission to replace the 1-2 and 3-4 shift forks due to them being worn. The part number on the forks are as follows

1/2 fork - S501 402
3/4 fork - S501 404

Can anyone verify that I actually need the 1995 forks from the part numbers stamped into the part? I believe I have the exact same for that is shown above on the right.

 

I just read some where on here (rather recently) that some shift forks are cast out of aluminum and others out of steel (I think) and one of them just has a tendency to wear quickly, I had to replace my forks a month after i bought the truck so at that time she was at 164-165k miles, both of em went and they as bad if not worse than the one you replaced

 

If you look at the forks in the pic above you'll see that they share the same casting part# even though they are a little different. Either one will work, but given a preference you want the later one with the U-shaped opening rather than the enclosed hole. The U-shaped one makes R&R easier and quicker.