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Need to knurl ID of .996 pin hole in transmission case.....

H

heckinohio

Aluminum
Joined
Aug 25, 2009
Location
Ohio, USA
I have some transmission parts I am try to get estate prepped. I am assembling all the four speeds here into salable lots rather than boxes of nondescript parts. Two down to this point.....however, I find my self in need of a way to knurl the ID of a .996 pin hole that is just barely too big & would more than likely leak oil. Muncie M-21, big pin case.

Any ideas........???

PJH
 
How much is barely? Knurling is not likely to stop oil leak. Knurl and retaining compound and it might work.
 
All muncies will eventually leak oil on the countershaft pin. Knurling won't do it. The fix is to bore the case and install a bronze bushing.

Or get an aftermarket "super case" which have an aluminum soft plug.
 
Is it possible to cut a groove to retain an o-ring on the shaft in the problem area? Be sure to chamfer the hole in the case so the o-ring is not sheared on insertion.
 
Try making a radial knurl made from a ball bearing modified on the OD with a V crest to create a couple of parallel knurls in the bore. the displacements will be at right angle and radial to the flow of oil. Doen't take a lot of tool pressure to slightly enlarge the bore.
 
MSC knurlers.........a bit too pricey.....I can buy 2-3 small pin main trans cases with $300.........problem there is then to get them bored to the correct .994. front & .996 rear dimensions. Barry can do that, just have to work it in between his projects.....winter is best time for that.

The O ring is a good idea, not sure this shaft can be machined & might be complicated by making a suitable champher on the inside of the crowded case interior to keep from shearing the O ring on installation. Now an O ring groove in the aluminum case would be more practical application as the front of the pin has a slight champher.

Locktite.......the method of keeping the 88 loose 1" long bearings inside the very long gear set up is a waxey compound liberally applied. The the shaft is motor oiled so as to slide through this minimum clearance internal packing of bearings.......when the shaft reaches the front (culprit) hole, it is pushing a small ridge of oily wax. Be awfully hard to clean the shaft/case well enuff to insure at least some of the locktite would get 360 on the shaft & around diameter of hole.

Super case.......I am not aware of the existence of these.....good idea if this was a keeper or I intended to use it myself.......the only four speed car we still have is up & running so I cant justify what may be an exorbitant outlay for something to be sold out of my estate.

I have another case for another project........I will have Barry bore it from its existing .750 to the needed .994 & .996 dimensions......then approach the oversize one at a more leisurely pace. Suspect I will try a bushing.....

Many thanks.......

PJH
 
Perhaps you could 'knurl' it with a thread tap? A thread forming tap or a bespoke 1 " tap that you don't mind ruining by grinding chamfers on the front of the thread teeth specifically to prevent them from cutting. I've repaired loose fitting dowel pin holes this way. A standard tap is typically a couple of thousandths over nominal diameter.
 
guest said:
All muncies will eventually leak oil on the countershaft pin. Knurling won't do it. The fix is to bore the case and install a bronze bushing.

Or get an aftermarket "super case" which have an aluminum soft plug.
Click to expand...

Quite so. Still, on occasions when for some reason I did need an "internal knurl" I would make a hardened steel, straight knurl pin of the correct diameter (maybe with a slight taper lead) and press it into the bore and then press out.
 
HuFlungDung said:
Perhaps you could 'knurl' it with a thread tap? A thread forming tap or a bespoke 1 " tap that you don't mind ruining by grinding chamfers on the front of the thread teeth specifically to prevent them from cutting. I've repaired loose fitting dowel pin holes this way. A standard tap is typically a couple of thousandths over nominal diameter.
Click to expand...

I am gonna try and remember this one. Definitely sounds like a good last option quick fix.
 
heckinohio said:
...Super case.......I am not aware of the existence of these.....good idea if this was a keeper or I intended to use it myself.......the only four speed car we still have is up & running so I cant justify what may be an exorbitant outlay for something to be sold out of my estate.

I have another case for another project........I will have Barry bore it from its existing .750 to the needed .994 & .996 dimensions......then approach the oversize one at a more leisurely pace. Suspect I will try a bushing.....

PJH
Click to expand...
The Super Cases run about $250 IIRC.

As you mentioned, there is a little taper, which is how the countershaft makes it's seal. The hole just eggs out over time. You can apply some permatex to the end of the shaft between the case and the bellhousing- that will stop off the leak for a while.

Better to sell the trans as a rebuildable complete trans and do nothing- the new owner can decide what to do about the countershaft. It's not something unusual to muncies, and it's better than buggering up the case with knurling, which will just leak worse than it does now.

It's not uncommon to see a muncie case "stretched" around that bore. You take a punch and make a series of deep dimples about 1/8" away, all around the diameter. This tightens up the bore a little bit and (depending on how out of round) seals up the leak- again for a while....
 
A long long time ago, I can still remember how the music used to make me feel.. ( American Pie) At that time Every car leaked something some where. For a Muncie, a 6oz hammer worked the area around the countershaft pin hole to close it up a bit, then clean it, smear #2 permatext in it, then assemble.
 
In a round about way, this problem is of my own doing. There is a small factory about 2 blocks from me, GKN Sintered metals. It used to be Federal-Mogul. During my time as a drag racer, 1959-2011, I had more than a few "jobs" done there, Federal-Mogul....... I would write up a description, meet someone I knew who worked there in the morning, have him take it in & that afternoon, I would retrieve it from him or the plant guard. I did not abuse this very handy arrangement.

When ownership changed, so did the outlook toward "gummint-jobs".....although I knew enough of the old hold overs from FM to manage some........this case was one of those. The retiring machinist who did this one bored both case hoes to the same dimension.........996. even though I had magic markered the needed sizes. He may have set it up to larger size & bored all the way through......

PJH
 
heckinohio said:
MSC knurlers.........a bit too pricey.....I can buy 2-3 small pin main trans cases with $300.........problem there is then to get them bored to the correct .994. front & .996 rear dimensions. Barry can do that, just have to work it in between his projects.....winter is best time for that.

The O ring is a good idea, not sure this shaft can be machined & might be complicated by making a suitable champher on the inside of the crowded case interior to keep from shearing the O ring on installation. Now an O ring groove in the aluminum case would be more practical application as the front of the pin has a slight champher.

Locktite.......the method of keeping the 88 loose 1" long bearings inside the very long gear set up is a waxey compound liberally applied. The the shaft is motor oiled so as to slide through this minimum clearance internal packing of bearings.......when the shaft reaches the front (culprit) hole, it is pushing a small ridge of oily wax. Be awfully hard to clean the shaft/case well enuff to insure at least some of the locktite would get 360 on the shaft & around diameter of hole.

Super case.......I am not aware of the existence of these.....good idea if this was a keeper or I intended to use it myself.......the only four speed car we still have is up & running so I cant justify what may be an exorbitant outlay for something to be sold out of my estate.

I have another case for another project........I will have Barry bore it from its existing .750 to the needed .994 & .996 dimensions......then approach the oversize one at a more leisurely pace. Suspect I will try a bushing.....

Many thanks.......

PJH
Click to expand...

what if ya assembled it dry with a shortened piece of undersized rod installed then pushed it out with the proper shaft. shaft would come through clean as a whistle and ready for loctite

I am imagining this is the countershaft if like the old british ford stuff I have done, where you lower the countershaft in with strings and pray you do not knock a needle loose and have to start over.
 
Not worked on any Ford stuff, but you seem to have a grasp on the situation. Your suggestion would work as far as I can see......... I do have a damaged shaft that can be cut for a dummy. As mentioned, the waxy grease is just for holding needle bearings in place. Does a really good job, totally eliminating the need for a dummy shaft. It is really rather difficult to dislodge the bearings once greasy waxed into place.

PJH
 
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