Joined: Nov 18, 2014 Posts: 128 Location: Connecticut
Posted: Thu Feb 24, 2022 4:04 pm Post subject: Greaseable Throwout bearing
I'm putting my drivetrain back together and considering drilling and tapping two holes in my new throwout bearing for grease fittings. I would put the two fittings 180 degrees apart so that it is still balanced when it's spinning. Has anyone ever considered this or done it themselves? I'm wondering if it would be worth it to make the TOB greaseable or if it's not worth the time. _________________ Jake, Central CT
51 M38 s/n 35627
Joined: Oct 02, 2014 Posts: 1905 Location: South Carolina, Dorchester County
Posted: Thu Feb 24, 2022 5:42 pm Post subject:
Hi Jake,
I know finding quality parts nowadays is a challenge, but I thought they were factory sealed (and lubricated) for a reason.
Do you think there's enough clearance inside the bearing housing to do that?
I'm under the impression (right or wrong) that a quality throw-out bearing ought to last as long as the clutch disk.
When it's time to replace one, it's time to replace the other.
Good luck! _________________ Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51
“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari
Joined: Nov 18, 2014 Posts: 128 Location: Connecticut
Posted: Thu Feb 24, 2022 6:07 pm Post subject:
So I drilled a hole through my old bearing and it looks like there's plenty of thickness to thread the grease fitting into. If I place the hole in the right spot, there should be plenty of clearance inside the bearing for the threads to protude in without catching the carrier for the carrier.
I'm curious to know if anyone else has tried it. I'd love to able to grease it just for the peace of mind. I'm sure sealed bearings will last quite a long time, but maybe 15 minutes of my time to drill and tap two holes can help it last even longer? _________________ Jake, Central CT
51 M38 s/n 35627
Joined: Oct 02, 2014 Posts: 1905 Location: South Carolina, Dorchester County
Posted: Thu Feb 24, 2022 6:24 pm Post subject:
Not me, I never did it. Never even heard of it before, but I'm a rookie. But will follow your effort with interest.
Do you think any metal shavings got inside the drill hole?
It's a $25 part. Even if grease zerks made it last longer, are you saying that when your clutch disk needs to be replaced --- that when you have it apart you wouldn't also put in a new bearing anyway?
Never saw a throwout bearing with grease fittings. There's always a first, and you might have a new patent idea that would make money.
On the other hand, throwout bearings have been around a long time. Maybe all those design engineers over the last 100 years missed the opportunity for product improvement?
It might be better when drilling for the zerk if it's done on the assembly line, to better keep metal shavings from wrecking the idea.
Post a photo or three for us!
Good luck! _________________ Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51
“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari
Joined: Nov 18, 2014 Posts: 128 Location: Connecticut
Posted: Thu Feb 24, 2022 7:15 pm Post subject:
So I Googled it quick just to see if I was crazy even for thinking about it, and it turns out that there are quite a few tractors and Ford diesel trucks that come with greaseable throw out bearings. From what I can see, some tractors have the zerk fitting that goes right through the side of the bearing, and there are quite a few that have the fitting on the TOB sleeve itself, but it's hard to tell if that's just to grease where the sleeve slides on the front output bearing retainer or if grease can work it's way into the bearing as well.
As far as keeping metal chips out of the bearing itself, I've got a few tricks that I've used in the past for similar tasks. This was something I tested when I drilled my old bearing, to make sure that I wouldn't be destroying the new bearing by introducing FOD, and I'm confident that I can keep the chips out while drilling and tapping.
If I ever need to replace the disk again in the future, I would replace the TOB and any other wear components as well again. The TOB sleeve itself gets worn down by the clutch fork, the clutch fork wears down the pivot ball, the retaining spring for the sleeve gets stretched out with time, so there are definitely a lot of components to replace together, otherwise you're just wasting money on new parts that mate with old junk.
My basic idea of greasing the TOB for longevity isn't to try and extend it's life past the life of the other major wear items associated with it, rather to guarantee that it's life will at least match those other key components. I mean the inspection cover is literally right on top of the TOB, if it just takes a quick pump of grease once ever other oil change to guarantee it lives as long as the clutch, then I think it's worth it for that piece of mind alone. I would just absolutely hate to put all the time and effort into everything that I've already replaced up to this point just to get grounded by a noisy TOB after a few trips in the woods. _________________ Jake, Central CT
51 M38 s/n 35627
Joined: Nov 18, 2014 Posts: 128 Location: Connecticut
Posted: Fri Feb 25, 2022 6:44 am Post subject:
I didn't take any pictures of the test hole in the old bearing, but when I'm back in the shop on Monday I'll start documenting!
And thanks for that link, definitely some good reading in there. It's interesting to see how many people come up with ways to grease those sealed bearings! _________________ Jake, Central CT
51 M38 s/n 35627
I found the article interesting because of the much larger percentage of those that agreed making a sealed bearing greaseable was not a good idea. The most important notion was simply that Increasing the longevity of one part of an assembly while not ensuring that the other parts 's longevity can be equally extended is a waste of time and money. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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