What happens in a transmission rebuild - Part 10

[Mac VP]

LINK TO ORIGINAL POST:
https://www.fordbarn.com/forum/showthread.php?t=278347

Here is where many things are going to happen. The cluster gear and reverse idler gear are already placed in the gearbox, and the main drive gear has been put in the front of the case. The mainshaft has been installed in the overdrive adapter, along with the remaining transmission gears (low/reverse slider gear, second gear, and the synchronizer assembly).

I place the gearbox front face down on my work bench, positioned so that the main drive gear sticks downward through the hole I have in the bench for that purpose. I have just trimmed and placed the rear face gasket to the backside of the gearbox casting. I have also placed the caged roller bearing inside the pocket of the main drive gear, and the high gear synchronizer ring on the tapered cone of the drive gear.

I carefully hold the mainshaft & gear assembly so that the front end hangs down through the back opening of the gearbox, guiding it down slowly so that I can position the front pilot end into the caged roller bearing in the main drive gear. During the final movement downward, I must align the front synchro ring slots with the matching synchro inserts on the front of the main synchro assembly. It helps to slightly rotate the drive gear from below while making the final drop......you can feel the two components line up and drop into place.

Since we had already just positioned the rear gasket with fresh sealer, I want the overdrive adapter (with the gear stack) all the way down against the back side of the gearbox. Sometimes it helps to tap it down with a soft hammer. Make sure that the 4 bolt holes are aligned. Then, install two of the four bolts with washers to tighten the castings against each other. This will remain this way at least overnight. However, we can proceed with more assembly in the meantime.

Once I return to the assembly, the cluster gear and countershaft have to be positioned in place.....remember that the cluster gear has been sitting on the bottom of the case (with bearings, spacer tube, and thrust washers). The cluster gear must be raised up so that the 7111 countershaft can be installed through the gear and case. The first photo of this process shows the misalignment of the cluster gear when looking through the countershaft bore in the back of the case. The second photo shows how the gear, roller bearings, and rear thrust washer have been aligned with a tapered drift. It helps to slightly rotate the mainshaft gears to let the cluster gear ride into mesh with the mainshaft.

The next photo shows the 7111 countershaft inserted into the case (through the OD adapter, the gearbox case, the rear thrust washer, the spacer tube, and the two roller bearings). I mark the end of the 7111 shaft to draw a line showing the direction of the lockpin hole. As the shaft is worked all the way into the gearbox, this will need to be correctly aligned with the lockpin passage in the case. Otherwise, the lockpin can not be inserted all the way through both shafts.

A look at the next picture shows how I get an eyeball on the alignment of the shaft by placing the lockpin temporarily in the passenger side opening for the lockpin. Do not push the countershaft all the way in yet as the front thrust washer must now be wiggled into alignment. By setting the gearbox in its regular horizontal position, you can use a tapered drift punch to align the 7119 front washer, and then work the 7111 shaft through it.

Once the countershaft is started through the front thrust washer and into the front bore of the gearbox, you can stand the transmission back up vertically and finish tapping the 7111 shaft down into place. I use a small flashlight to shine a bright light through the lockpin passage. That way I can see that I have tapped the shaft far enough into place AND that the shaft is still rotated correctly to let the lockpin pass through the countershaft. If it's not aligned, tap the 7111 shaft out and rotate it slightly to get the correct pin hole location.

Lastly, push the 7155 lockpin into the case (passing it through both the 7140 idler shaft and the 7111 countershaft). The small head of the pin should sit flush with the side cover mounting surface. I usually smear some sealer on the pin before I tap it into place.

[Mac VP]

So now we will assemble the various parts of the overdrive section of the transmission. The first piece to go in is the 7662 Balk Ring & Gear. The photos below show this as two parts: the gear and the tension ring. After cleaning these two pieces, you need to check the tension of the ring on the shoulder of the balk gear. Fit the ring into place (undercut side to the gear) and put a couple drops of oil on the shoulder where the ring fits. If you pull one end of the ring away from the other end, the ring should rotate around the gear easily. If you push the one end towards the other ring end, there should be resistance to rotating. This was measured as about 3 lbs of force. You can check this with a fish weight scale. If the tension is too light, it can often be tightened up by slightly compressing the ring by itself and reinstalling. I sometimes bounce a large rubber hammer against one side of the ring while holding it edgewise against a block of wood. If you can't seem to get a proper tension, you may have to replace the gear & ring.

Fit the 7662 balk ring & gear into the recess on the overdrive adapter casting. I use a generous film of transmission assembly grease here. Then install the 7690 pawl in the slot for it. Note the position of the notch on one side of the pawl. You can always make sure you have it set correctly by noting how the slanted end of the pawl always fits into a matching slot in the balk gear. After setting these in place, I rotate the ring on the balk gear into its blocking position. This keeps the pawl pushed out (in the non-overdrive mode) which makes installation of the electric solenoid much easier later on.

[Mac VP]

Next comes the 7665 Plate & Trough, which fits right over the balk gear and the shift pawl. This plate should fit flat in place, and will be secured by a large round retaining ring (7666).

Take the 7680 Fork & Rail and position it into the overdrive adapter casting. The 49-50 Mercury fork & rail has two shafts that are fitted into openings. Later Ford overdrive transmissions have a single rail/shaft and there is a separate pin located in the adapter casting to provide that "dual" mounting.

The 7670 Sun Gear must be installed along with the fork & rail because the fork blade must engage the fork groove of the sun gear. Lift the fork & rail up slightly to engage the sun gear as it is dropped down onto the transmission mainshaft. The photos show the fork fitted to the fork groove of the sun gear. I also apply the assembly grease to the sun gear. In fact, we use the grease on most every component in the overdrive section, along with a light oil. Not only does it help with assembly, but it provides a brief period of lubrication for the entire overdrive section before the gear oil penetrates everything on initial operations.

[Mac VP]

Our next component is the 7673 Planetary Gear. All of the R10 type overdrives use the 3 pinion planetary gear. This is the most endangered part in the whole overdrive section when the unit runs low on oil, or is operated for years without a change of gear oil. The pinion gears ride on very slender needle bearings, which fail under these conditions. After cleaning this part, be sure to check the fit of the 3 gears in the planetary cage assembly. If you can wiggle them in a cockeyed fashion, the needle bearings are failing and the gear may need to be replaced. Some technicians have found a way to replace the needle bearings but it involved taking the unit apart and restoring these elements. In general, it is usually less expensive to locate another good used planetary gear or try to find an NOS gear.

The planetary gear is aligned with the ten splines on the mainshaft and pushed down toward the sun gear. You will have to slightly rotate the 3 pinions with your fingers to allow the gear teeth to mesh for the last bit of travel.

The 7675 Freewheel Cam Assembly goes on next. It also has ten splines to guide it onto the mainshaft. The open end of the freewheel cam faces up (or toward the rear of the transmission when in its normal setting). Be sure to clean and inspect the freewheel cam before using it. There are 12 steel rollers that will sit in 12 sloped ramps in the inside hub. If you see heavy wear, galling, or pitting on those ramps you may have to reject the cam assembly and replace it with a better part.

The freewheel cam assembly and the planetary gear will be secured to the mainshaft with two U shaped clips (7674 is the large clip and 7676 is the smaller clip). I align the freewheel cam clip groove with the last groove in the mainshaft, and then install the small U clip. Use a rubber or soft hammer to tap the clip into place. Then raise the planetary gear up slightly to align the retaining groove in it with the mating groove in the freewheel cam assembly. Tap that U clip into place and this part is done.

[Mac VP]

The installation of the 12 steel 7679 rollers into the freewheel cam assy is next. We use a thin rubber band around the cam assy to help hold the rollers in place. This rubber band will roll down and off the rollers after the ring gear is installed and will remain inside the transmission. You could also use grease to hold the rollers but I want to be able to test the one-way action of the freewheel cam assy so I use the rubber band.

Having learned the hard way once, I always use a paper shop towel around the top of the gearbox when installing the rollers. If you have butterfingers with one and it drops, there is an even chance that it will fall into one of the openings on the backside of the gearbox. You can go crazy trying to fish it out, so take this step to eliminate any aggravation. That way, if one falls it will bounce off and land in some dark corner of your workbench instead.

The overdrive mainshaft with the ring gear and bearing must be assembled now, in preparation for installing over the freewheel cam and planetary gear. It might be easier to handle the bearing and the speedometer gear installation if you wait to install the ring gear. The pictures below will show the ring gear being affixed first though.

The mainshaft gear is simply set into the end of the 7653 ring gear. The large round 7654 snap ring will fit into an internal groove of this end of the ring gear. Start one end of the snap ring into the groove and compress the snap ring enough to let it pop into the groove the rest of the way.

The rear ball bearing must be placed onto the mainshaft with the snap ring groove toward the front side. Press the bearing into place. Place the small woodruff key into its slot in the shaft and slide the 17285 speedometer drive gear all the way up against the ball bearing. Place a 7160 snap ring into the groove on the shaft to secure the location of these parts.

With the overdrive mainshaft & gear assembly completed, you can now install these onto the transmission output shaft (onto the freewheel cam & rollers and the planetary gear). As you drop the assembly down, use your free hand to manipulate the planetary gears slightly to let them engage the splines inside the 7653 ring gear. Give the mainshaft a clockwise twisting action with the hand holding it.....this will move the freewheel rollers inward slightly to let the ring gear move downward.

[cas3]

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thanks mac!

[rotorwrench]

That unit is a bit different that my early 51 Mercury transmissions that I'm more accustomed to. There must have been at least two variations in the transmissions that still had the half bell and the 1 3/8" 10-spline input. The later 4 bolt pattern 1951 transmissions are different than the earlier ones by a good bit.

Keep up the good work.

[Mac VP]

Additional pictures and details have been added to Part 10.

[Mac VP]

More pics and details added to this part 10 thread. The assembly of the overdrive extension housing will be in Part 11 (coming soon).

[Mac VP]

BTT for the morning guys....