Hi all, I have a '91 full size Bronco with the manual 5-speed. I just finished replacing the three rubber service plugs on the M5OD tranny last night. They were leaking pretty bad, I also replaced the poly bushings that the stub shaft sits on. All went well except for the small pin that fell out of the top cover. I had in on my work bench and herd it fall out. It's a solid small machined pin about 3/8" long by 1/16" in diameter. Looks important, but I put the cover back on anyway and it shifts like a brand new transmission. Does anyone know where this pin may have came from and is it mission critical? In other words can I get by without it or is this going to leave me stranded some day?

Thanks in advance!

 

See the thoughts at the bottom of the instructions.


Top Cover


Disassembly

1. Position top cover assembly into Top Cover Holding Fixture T88T-7025-C or equivalent.

NOTE:
For reference during assembly, notice that grooves in bushing align with slots in lower shift lever pivot ball. Notice that the notch in the lower shift lever faces toward front of transmission.

2. If necessary, remove dust boot and shift lever from top cover, if not removed during transmission disassembly. Remove three dust cover retaining screws using a T30 Torx® wrench. Remove dust cover.



3. Remove backup lamp switch from top cover. Remove backup lamp switch pin from groove in top cover.


Spring and Detent Ball Assembly



4. Invert top cover assembly on Top Cover Holding Fixture T88T-7025-C or equivalent. Using a 5/32-inch drift punch, remove spring pins retaining shift forks to the shift rail.

NOTE:
Discard original spring pins.



5. Make sure that fifth/reverse shift rail is in fully forward position. Remove spring pin from end of fifth/reverse rail.

6. Remove three rubber plugs sealing shift rod service bores.

CAUTION:
Perform the following shift rail removal procedures with great care. Cover the lock ball bores and friction device and spring seats with a clean cloth held firmly in place during shift rail removal. Failure to firmly cover lock ball bores and friction device can result in component loss when the ball/friction device and spring forcefully leave their installed positions.

WARNING:
WEAR SAFETY GLASSES WHILE PERFORMING SHIFT RAIL REMOVAL PROCEDURE.

7. Remove fifth/reverse shift rail from top cover through service bore. If necessary, insert a 5/16-inch drift punch through spring pin bore and gently rock shift rail from side to side while maintaining rearward pressure.

8. Remove first/second shift rail from top cover through service bore. If necessary, insert a 5/16-inch drift punch through spring pin bore and gently rock shift rail from side to side while maintaining rearward pressure.

9. Remove third/fourth shift rail from top cover through service bore. If necessary, insert a drift punch through spring pin bore and gently rock shift rail from side to side while maintaining rearward pressure.

10. Remove fifth/reverse cam lockout plate retaining bolts using a 10mm socket. Remove fifth/reverse cam lockout plate.




Assembly

NOTE:
During assembly apply Motorcraft MERCON® Multi-Purpose Automatic Transmission Fluid XT-2-QDX or -DDX (E4AZ-19582-B) or equivalent to all rotating or sliding parts.

1. Position top cover into Top Cover Holding Fixture T88T-7025-C or equivalent.

2. Position fifth/reverse cam lockout plate to top cover. Install fifth/reverse cam lockout plate retaining bolts and tighten to 8-10 N-m (6-7 ft-lb).

3. Position third/fourth shift rail into top cover through service bore. If necessary, insert a 5/16-inch drift punch through spring pin bore and gently rock shift rail from side to side while maintaining forward pressure. Position detent ball and spring into top cover spring seats. Compress the detent ball and spring assembly using a suitable tool, and push shift rail into position over detent ball. Engage third/fourth shift fork with shift rail. Position friction device and spring into top cover spring seats. Compress friction device and spring assembly using a suitable tool, and push shift rail into position over friction device. Install spring pins retaining shift rail to top cover. Install spring retaining third/fourth shift fork to shift rail.

4. Position first/second shift rail into top cover through service bore. If necessary, insert a 5/16-inch drift punch through spring pin bore and gently rock shift rail from side to side while maintaining forward pressure. Position detent ball and spring into top cover spring seats. Compress the detent ball and spring assembly using a suitable tool and push shift rail into position over detent ball. Engage first/second shift fork with shift rail. Position friction device and spring into top cover spring seats. Compress friction device and spring assembly using a suitable tool, and push shift rail into position over friction device. Install spring pins retaining shift rail to top cover. Install spring pin retaining first/second shift fork to shift rail.

5. Position fifth/reverse shift rail to top cover through service bore. If necessary, insert a 5/16-inch drift punch through spring pin bore and gently rock from side to side while maintaining forward pressure. Position detent ball and spring into spring seats. Compress the detent ball and spring using a suitable tool, and push shift rail into position over detent ball. Engage fifth/reverse shift fork with shift rail. Install spring pins retaining shift rail to top cover. Install spring pin retaining fifth/reverse shift fork to shift rail.

6. Install rubber plugs into service bores.

7. Install interlock pins into first/second and third/fourth shift rails. Make sure that large and small interlock pins are installed into their original positions.

CAUTION:
Improper installation of interlock pins will prevent activation of neutral switch and/or backup lamp switch.

8. Apply sealant to backup lamp switch and neutral switch threads. Install switches to top cover and tighten to 25-35 N-m (18-26 ft-lb).

9. Position lower shift lever and dust cover assembly to top cover. Install three retaining screws and tighten to 8-11 N-m (6-8 ft-lb).


I would check and see if you have reverse lights. I would guess that it is one of the interlock pins that go into the first/second and third/fourth shift rails in step #7.

 

Pony Racer, That's exactly what it turned out to be. I stoped down at ford and got an exploded view of the M5OD and talked to one of their techs. Took it apart last night and put the interlock pin back in the shift rail. It was quite a job, but works better than ever. Just wish I would have had your directions to follow during the process!!!! Will definately print them off and put them with my shop manual.

Thanks!

 

Sorry to bring back this old thread but my vast search for this part has led me here. Does anyone know where I can buy this 'interlock pin'?

The closest thing I can find is this pin for a jeep trans in the picture below along with a picture of the one I do have. Not even sure if it's the right dimensions but I'm getting desperate. Bought a top for a m5r1 which normally has only one of these pins and of course it was missing.

 

Can you send the part number for the interlock pin you bought and where you got it from

 

Did you ever buy that pin? If so, did it work for you I'm having the same issue thanks