I need a M50DR1-HD Transmission expert.

[gw33gp]

I have posed before about my problem and thought I had gotten it resolved, but apparently not.

It all stared with having my original transmission looked at because it had nearly 250K miles on it. It was working very well, but did have a very light rattle in 1st gear when cruising slowly with no load. It was determined that it was in very good condition but 5th gear was worn. I told them to replace what was needed and install all new bearings and seals. It worked well (except the slight rattle in 1st as still there) for about a year and then it started popping out of 5th. I took it back to the company that did the work and even though it was slightly beyond warranty, they covered the repair. It was determined 5th gear was worn again and the bottom shifter bushing was totally deteriorated. Apparently, they did not replace the shifter bushings.

The second repair lasted less than a year and started popping out of 5th again. I decided at that point to purchase a remanufactured a remanufactured transmission done by Zumbrota. Once I got it installed I could tell it as working better than my original transmission ever had. They told me to use non-synthetic ATV only or the warranty would be voided, and that is exactly what I used. They wanted my original transmission as a core but decided to pay the core charge and keep it.

I did take the original transmission back to the company to determine why it failed. Again, the 5th gear cluster was worn. This time I asked specifically was was worn and was shown the engagement teeth were worn, not the gears themselves. They told me that they could not get OEM parts for this transmission and they felt the after market gears were just inferior. I suggested I obtain a new 5th gear cluster through my brother's shop at a discount. He always bought from Zumbrota and felt they had the best parts. They agreed and installed them for $300. At least I had a spare transmission now. The M50DR1-HD transmissions are becoming hard to find.

Well, the Zumbrota transmission also started popping out of 5th gear within a year. They took it back under warranty to repair. They did not tell me the cause of failure but I have a good idea of what it was. Fortunately, I had a spare transmission but was getting tired of changing them every year or sooner. I installed the original transmission that was repaired for the 3rd time. I could tell an improvement in the shifting compared to what it was when new. The 1st gear light rattle was gone too. I had high hopes I would not be replacing transmissions again. Once I got the Zumbrota remanufactured transmission back, I put it in storage just in case.

Last week while coming home from a long trip, the third repair of the original transmission started popping out of 5th gear again. This time it lasted more then a year and I thought I had gotten the 5th gear failures resolved. I have not installed the second Zumbrota transmission yet and am considering trying to get a new fifth gear cluster cryo treated to see if that would make it more durable. I have heard good things about improved wear life of gears once cryo treated.

Is there there anything I should be looking for in the transmission that would cause excessive wear on the 5th gear engagement teeth? It seems odd that both transmissions have the same problem. I have looked for external issues that could keep 5th gear from engaging all the way and have found nothing. I was making sure that when I shifted into 5th that it would go all the way in, but I also noticed when I let out on the clutch and put power to the transmission, the shifter would move back a little. I never saw this happen in any of the other gears.

I have a Ford shop manual and am thinking I would like to take on the repair myself this time. I am a very detailed in work that I do and may get everything better spec wise and have better results. I am frustrated with this and want to get it resolved.

 

[2011Supercab]

Have to ask,
Are you one of those people that drive with your hand resting on the shifter while cruising down the road?

 

[rubydist]

Also, have you confirmed that 5th gear engages all the way? It could be that the shifter fork does not move the collar all the way on the engagement teeth.

 

[BlackBII]

Do you have any pics of the "worn" gears?

The 5th - R shift fork has a detent on the shaft that should hold it in place.

16, 17 and 18 here:

 

[BlackBII]

There's also the hub; it has "C" springs in it that can break

 

[lowspeedpursuit]

Not an expert, but I have spent entirely too long staring at the inside of an -R1 tailhousing this summer. I can think of a few different reasons why you might lose the dog-teeth on 5th, even multiple times over in the same trans, but across two entirely different transmissions is pretty wild. Supercab already covered question 1, but I assume you're gonna say no because you talked about seeing the shifter jump on clutch engagement in 5th.

I'm going to tag along with the next few posts and say something is wrong with your 5/R slider or fork. To explain why it's the case in both transmissions, I'm also going to go one step further: when I was rebuilding my trans, I saw Zumbrota (USA) doesn't appear to sell that fork, or even the slider anymore (it's been listed "out of stock" for ages now). So, someone who rebuilds an M5OD at this point exclusively with "top-tier" Zumbrota parts necessarily can't replace those particular parts if they're worn, and maybe just slaps the old ones back in because there's no alternative.

I would call Zumbrota and ask if they actually have some in the back, or if they literally can't produce those parts, what exactly they're putting in their complete remanufactured transmissions. Then I would run the rebuild myself, and make sure I replace literally everything that touches 5th gear in the tailhousing, whatever I have to do to come up with the parts: off-brand, eBay, etc.

The final note, and the other thing I learned recently, is to triple-check the various shaft play specs. The reverse split washers and thrust washer specifically are going to affect 5th-gear engagement. Again, it would be really, really weird (and thus unlikely) if two different rebuilders were just ignoring those specs, but it's something to pay close attention to when doing the work yourself.

 

[gw33gp]

Have to ask,
Are you one of those people that drive with your hand resting on the shifter while cruising down the road?

The answer to that is; absolutely not. After It started popping out of 5th, I did try holding it in gear to see if it would help. I quickly realized it did help but was not a good idea to continue because of additional wear on the fork or other components.

After the second failed transmission, I checked to see if anything external was interfering with the shifter causing it to not totally engage into 5th or to ride on it while in 5th.. Found nothing.

 

[gw33gp]

Also, have you confirmed that 5th gear engages all the way? It could be that the shifter fork does not move the collar all the way on the engagement teeth.

I don't know how to confirm that. As I indicated before, I do shift into 5th paying attention that it comes to a stop and feels like it is fully engaged. I also notice the shifter moves back a little after engaging the clutch. When working properly it stays in that position. If I push the shifter forward again without the transmission under load I can feel it is moving forward but will move back to the original position as soon as the transmission is under load again. That made me think is was not fully engaged, but without x-ray vision I can't tell.

 

[gw33gp]

Do you have any pics of the "worn" gears?

The 5th - R shift fork has a detent on the shaft that should hold it in place.

16, 17 and 18 here:

I do not have pictures of the worn gears. I have the original gears that were supposed to be worn. I can look for them and take a picture. It was not popping out of gear with those though. I was questioned by the original builder if it was popping out of gear because of how worn they were.

I see the parts you pointed out. Is there a method of measurement that locates the detent in the shaft to make sure it is in the right location?

 

[gw33gp]

There's also the hub; it has "C" springs in it that can break

Nothing was ever mentioned about broken "C" springs, just worn engagement teeth. I will check that out when I get the transmission out. I don't want to take the transmission out until I decide if I want to have the 5th gear in the second Zumbrota transmission cryo treated.

 

[gw33gp]

Not an expert, but I have spent entirely too long staring at the inside of an -R1 tailhousing this summer. I can think of a few different reasons why you might lose the dog-teeth on 5th, even multiple times over in the same trans, but across two entirely different transmissions is pretty wild. Supercab already covered question 1, but I assume you're gonna say no because you talked about seeing the shifter jump on clutch engagement in 5th.

I'm going to tag along with the next few posts and say something is wrong with your 5/R slider or fork. To explain why it's the case in both transmissions, I'm also going to go one step further: when I was rebuilding my trans, I saw Zumbrota (USA) doesn't appear to sell that fork, or even the slider anymore (it's been listed "out of stock" for ages now). So, someone who rebuilds an M5OD at this point exclusively with "top-tier" Zumbrota parts necessarily can't replace those particular parts if they're worn, and maybe just slaps the old ones back in because there's no alternative.

I would call Zumbrota and ask if they actually have some in the back, or if they literally can't produce those parts, what exactly they're putting in their complete remanufactured transmissions. Then I would run the rebuild myself, and make sure I replace literally everything that touches 5th gear in the tailhousing, whatever I have to do to come up with the parts: off-brand, eBay, etc.

The final note, and the other thing I learned recently, is to triple-check the various shaft play specs. The reverse split washers and thrust washer specifically are going to affect 5th-gear engagement. Again, it would be really, really weird (and thus unlikely) if two different rebuilders were just ignoring those specs, but it's something to pay close attention to when doing the work yourself.

That all sounds like good advice. I am going to take a hard look at the second Zumbrota transmission. It is actually a different transmission than their first one. Somehow they lost the first one when it was shipped back to them. I am going to pull out my Ford shop manual and verify as much as I can while I am trying to decide to pull 5th gear for cryo treatment.

I will be in contact with Zumbrota with many questions.

 

[gw33gp]

One thing that I forgot to mention is, I had to use the extension housing off of my original transmission for the Zumbrota transmission. I have a manual transfer case that requires special bosses on the extension housing to mount the transfer case shifter linkage brackets. So, before I installed the Zumbrota transmission I swapped the extension housing from my original transmission.

I could not see anything that would affect the function of the transmission by swapping the extension housing. As I recall the only part of the internals that contact the extension housing is the rear bearing. However, I don't want to leave any possibility untouched. Is there any way swapping the extension housing could have an affect on 5th gear engagement?