what are the four holes for in the bottom of the TO-30 differential case?

   / what are the four holes for in the bottom of the TO-30 differential case?
  • Thread Starter
#101  
Thanks! I'm glad it's apart and that the casting is intact. Even if I'd had to make the press plate by other means (torch/drill), it definitely would have been worth it. It was also handy for getting out the outer seal and the bearing cup. The 5/8" thick steel seemed adequate. The bearing cup and rollers have corrosion, so I'll be shopping for new ones of those:

left_rear_bearing_corrosion.jpg

Cone is a 3795 and cup is a 3720.
 
   / what are the four holes for in the bottom of the TO-30 differential case? #102  
Yeah, those puppies are shot! How'd you get the race out?
 
   / what are the four holes for in the bottom of the TO-30 differential case?
  • Thread Starter
#103  
The casting has two convenient notches (180 degrees from each other) in the shoulder that the cup of the bearing seats against. Had the casting supported by the press plate on wooden blocks and used a scrap aluminum rod to tap the cup out with alternating hits in each of the notches.

rear_axle_bearing_casting_notches.jpg
 
   / what are the four holes for in the bottom of the TO-30 differential case? #104  
Oh man, that's just too easy!:) But, hey you deserve a break at this point.
Have you given any thought to doing the other side while you have it apart? After all, you did find a damaged bearing, so I'm thinking maybe beside the seal leaking onto your brakes there might have been some water/condensation in the axle housing over the years which caused the failed seal side to destroy the bearing. And for teh same reason, moisture, the 'good' side could be running on a dead bearing. I think it would at least be worthwhile to take it apart to see, and if no damage OK, fix it anyway so both sides are fresh for a long time to come. JMO
 
   / what are the four holes for in the bottom of the TO-30 differential case?
  • Thread Starter
#105  
Good point about the other side. No real good way to inspect the bearing without removing the shrink collar and pressing the shaft out. Guess I could chalk it up to preventative maintenance...

Last night I clean-up machined the major OD and outboard end face of the casting. Today at lunch, I masked the ID, sandblasted, removed masking and washed, and put in the oven to outgas. Here's what it looks like post-outgas:

rear_axle_bearing_retainer_casting_outgassed.jpg

My carb had a similar bronze/gold tinge to it after outgassing.
 
   / what are the four holes for in the bottom of the TO-30 differential case? #106  
Yeah, you've got the method down, might as well do the dark side now - so much easier having invented the wheel to just bang it out. If you don't, and the other side seal goes south you'll have unanticipated down time, have to waste fluids, time, and parts may be less available as time marches on. JMHO
 
   / what are the four holes for in the bottom of the TO-30 differential case?
  • Thread Starter
#107  
I'll need a break from the snow and cold in order to get a chance to go snatch the other wheel off and pull the axle assembly. I'll probably finish getting this one all put back on there before I do that. It may be warm by then...

To make a long story short on my search for a replacement bearing, Sparex lists the cone as a 3780 (in contrast to the 3795 I took off the shaft). A call to Timken regarding 3780 vs 3795 difference said the 3795 has a "special frontface radius" (which translates into layman's terms as "this bearing will be more expensive than the more common 3780"). Their CAD file says the 3780 is about a 1/32" frontface radius and my measurements (of bearing and shaft) say the 3795 is about 3/32". Sent email back to confirm with their engineering (since the CAD file I downloaded for the 3795 has the exact same frontface radius as the 3780).

As to why the Sparex catalog says the 3780 bearing fits the TO-30, I'm guessing Ferguson may have changed the radius on the shaft at some point and earlier models did in fact have a smaller radius where the shaft jumps from 2" (bearing ID) to 2.375" (outer seal ID). Mine's a '54, which was the last year of the TO-30s, so it seems plausible.

Here's what the 3780 / 3720 cross-section looks like (0.140" is the backface radius, 0.0325" is the frontface radius - which is the one that matters in this application):

Timken_3780_3720.png
 
   / what are the four holes for in the bottom of the TO-30 differential case? #108  
Good fun...

When I pulled mine off I found 2 5" chunks of old axle in the housing and lots of loose chips floating around.
 
   / what are the four holes for in the bottom of the TO-30 differential case?
  • Thread Starter
#109  
Ranchero50 said:
Good fun...

When I pulled mine off I found 2 5" chunks of old axle in the housing and lots of loose chips floating around.
Click to expand...

That sounds bad. What caused that?
 
   / what are the four holes for in the bottom of the TO-30 differential case? #110  
Honestly I have no idea. My '55 To35 had a backhoe hanging off it for a long time and pretty much everything was shot when I got it. I had to gut the differential area to replace the pump that blew apart and found the chunkies while cleaning up the mess inside.

The funny thing is that as bad as your bearing looks, it's probably fine to use at the speed and load it'll be run at.
 
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