T 84 rebuild question

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ghiltgen
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T 84 rebuild question

Post by ghiltgen » Tue Apr 18, 2017 6:48 am

I'm rebuilding my t84, all the internals were badly rusted. I'm using Robert Notmans book a a guide. He shows pressing or tapping the rear mainshaft bearing on the shaft which suggests the inside race fits tightly on the shaft. My bearing slides on easily by hand and rotates on the race rather than the ball berings. This doesn't seem right. I tried the bearing on the old output shaft and it fits the same. I got the bearing new from Ron and it's a sealed bearing on both side compared to the original which was not. Should the rear bearing fit tight and need to be pressed on? Any one know what the Int diameter spec of the inside race? The new shaft is a NOS from WOF so should be ok.
Thanks for and advice on this.
Greg
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Re: T 84 rebuild question

Post by Joe Gopan » Tue Apr 18, 2017 8:28 am

That bearing is not a press fit, it slides easily. Don't forget to wire the shaft and rear bearing in place until you are ready to install the gear box. :wink:
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Re: T 84 rebuild question

Post by dinof » Tue Apr 18, 2017 11:10 am

Sounds normal. I used a small "C" clamp to hold that bearing on and tight up against the t-case so you can get a good idea when it comes time to measure the slop of the transmission.
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Re: T 84 rebuild question

Post by Ralph » Wed Apr 19, 2017 6:54 am

Greg, the double-sealed bearings are packed with grease as you know.Until it is fitted with the transfer case and its intended load it will turn in a sticky way.I think your're ok with it.
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Re: T 84 rebuild question

Post by dinof » Wed Apr 19, 2017 8:51 am

I don't think double sealed bearings were originally used but everybody seems to want them now. I don't get it. Some say it stops oil transfer from box to box, but in my transmissions & T-cases I've used, the levels are always fine. Just lucky? I think not.
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Re: T 84 rebuild question

Post by ghiltgen » Wed Apr 19, 2017 6:34 pm

Thanks for the input everyone. I got the transmission together but I have issues. There is some play between the input and output shaft. The input shaft is and aftermarket and the output shaft is a NOS from WOF. The roller bearings were new (after market). I might be that the bearing cover that bolts on the front isn't holding the bearing tight against the front of the case.
Also the second and third shift fork doesn't want to move. Not sure if its a problem with how I put the syncro together. Going to try to find someone who has experience go thru it with me.
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Re: T 84 rebuild question

Post by artificer » Thu Apr 20, 2017 3:58 pm

There very few adjustments in this transmission & they are all pretty simple & forget about shift levers until you have these other adjustments completed properly.

1. Adjust the counter gear to transmission case bosses so there is about 0.006" total end float when the correct thrust & spacers are fitted. Then the countershaft shaft needs to be dropped until all the rest of the fitting is done.
2. Adjust [if needed] the input bearing retention.
3. Check 2nd gear float is not too much once the shifter hub & circlip are in place. over 0.002" adjust.
4. Make sure the needle rollers in the input shaft to output shaft are a good tight fit & the last needle roller can only be pushed in like a keystone. This fit should be just like a roller bearing feel & no slack between the shaft & the rollers.
5. The output shaft depth in the transmission is the critical one it positions 2/3 shifting hub 2nd gear & the correct positioning of the baulking rings. It is adjusted using a spacer between the circlip & the bearing so it is inside the transmission.
6. Sometimes it may be necessary the adjust the bearing encapsulated in between the transmission & transfer case.


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Re: T 84 rebuild question

Post by dinof » Thu Apr 20, 2017 4:29 pm

Here are some tidbits I learned as well-

Also if you are installing a new input bearing onto the shaft, make sure you do not press it too far. You only want enough room for the snap ring to fit into the groove that it meant to sit in. You will see what I mean as far as how close the bearing sits inside with the input gear that is right near it.

Make sure you clamp the bearing on the output shaft when checking the baulking rings for proper slop.
This is only to get it close. I suggest you bolt up the T-case and install the gear that goes through the case to get a truer look at slop. Do not leave out the oil slingers. They account for the slop adjustment! And make sure you put them on right. The slinger cannot be installed so it would pinch the roller cage. Don't laugh, it is easy to forget. My rebuild did not need any other shims, so don't worry if you don't use them.

Here is a video that might help you. I used John Bartons tutorial as the assembly path.

https://www.youtube.com/watch?v=Wd-b4oFCAfA
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Re: T 84 rebuild question

Post by ghiltgen » Thu Apr 20, 2017 7:43 pm

I think there is s problem with the input bearing even though it is new. First IV all, when I put it on the input shaft it covered the the snap ring groove a bit such that I had to make the snap ring thinner to get it in place. Also the bearing retainer isn't holding it in tightly it's as if need a shim on the out side of the input shaft bearing to get the retainer to hold in in place better. For example when the retainers in place I can move the input shaft side to side and if I hold it with a clamp these almost no movement.
I just ordered a different bearing from a different vendor and got a digital caliper to take better measurements. The inside of the tranny was really bad so I had to order everything new or NOS. I understand now that I have to have the in put side secure before I can determine how much to shim the output shaft bearing if at all.
Diagram helped too thanks.

Greg
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Re: T 84 rebuild question

Post by ghiltgen » Thu Apr 20, 2017 8:18 pm

That video helps a lot! I was trying to look at John Barton's tutorial but the pictures never come up. I got sent to a different web site site for pictures depository but enemies though I registered to get access the pictures are viewable!?
Thanks again everyone!
Greg
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Re: T 84 rebuild question

Post by artificer » Thu Apr 20, 2017 8:24 pm

Pictures are on http://www.Jeepdraw.com
Luc's video was a good simple presentation of what needs to be done. Not really rocket science....
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Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.

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Re: T 84 rebuild question

Post by dinof » Fri Apr 21, 2017 7:12 am

When you drove the input bearing onto the shaft, it probably needed to go down just a little bit more. But like I said before, not too much to where the input gear is scraping the bearing. You mentioned the input shaft having too much play even when the bearing retainer is on. Some is normal. If you remove your bearing retainer, see what is making the input shaft wobble. Is it from the bearing balls, or is the whole bearing loose in the case? The bearing should fit tight as much as needing a little tapping with a rubber mallet or plastic type.

Can you tell me how much did you grind down the snap ring to fit it? .010? .020? .030? or? This does make a difference to answer this question.

As you have it now, the input shaft is a tad FOWARD. But may not be a problem.
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Re: T 84 rebuild question

Post by ghiltgen » Tue Apr 25, 2017 4:29 am

Here is a picture showing how the bearing covers the snap ring groove. It is on as far as it can go. There is play in both the inner and outer race of the bearing (again it is new). The bearing goes into the case without much tapping but feels snug. I cant tell if the bearing cover is holding it tight but I may try a schim to see it it helps. Do you know what the diameter of the bearing opening on the case should be? I'm going to disassemble and measure every thing, especially the bearing height and diameter. I have a new bearing from a different vendor coming to compare to as well.
imput shaft reduced.jpg
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Re: T 84 rebuild question

Post by dinof » Tue Apr 25, 2017 6:15 am

The front case bearing opening should be about 2.8347 with a tolerance of .0003-.002. The bearing on my NOS case that I rebuilt was a French WOF. The bearing had to be lightly tapped in with a plastic mallet. To remove the bearing it took removing the snap ring first and them using a slotted screwdriver into the snap ring slot and jarring the screwdriver up against the case a few times to get it out. Your case sounds a little looser at this point but after you tighten down the carrier to the case, it will not take up all the wobble you feel when you wiggle the input shaft. Their will be a little wiggle. I was told that excessive amounts of wiggle or wobble can cause jumping out of second gear. Maybe so, but making sure your second gear & bushing is in spec is more important to keeping second gear from jumping. When second gear is on the mainshaft, you should only be able to get a tiny bit of slop. Very tiny. It can't be snug tight, it must have just a little slop. I believe that video you watched addresses that point. Get this right or just tolerate jumping out of second when you take the foot off the gas. I hate that so I took the time to get that correct!

Now about that snap ring & input shaft situation. Like I said before, the bearing has to be pressed down so it almost touches the gear. I would say about .010 and I've had it even closer like .005 in my last transmission. Are you that close? By the picture you posted, the ring looks so close to the gap of the ring groove. Removing a little bit off the snap ring, or even another snap ring might be thinner as I've bought several from good suppliers that are different in thickness.

Hope this helps -ask away if you need and other advice.

Dino
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Re: T 84 rebuild question

Post by ghiltgen » Wed Apr 26, 2017 8:35 pm

I took measurements after the new input shaft bearing arrived. Both bearings from the different vendors were identical. The input shafts had differences in the length of the shaft which the bearing rides on (See picts). The new after market shaft has a shorter segment which explains why the retaining ring wouldn't go on. Its doubtful in my mind that this would affect how the tranny functions as long as I use a thinner snap ring. The opening in the case for the input shaft bearing was within spec based on what you posted. Have you ever herad of, or have you ever shimmed the bearing cover to hold the bearing in tighter?


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